![Most Head-Slaps Are Proiluced by Males Although Females Account for a Srrali Percerltage of A]L Disptays Seen](http://data.docslib.org/img/523e089759f43dfc3b87a22cb585a9f4-1.webp)
Most head-slaps are proiluced by males although females account for a srralI percerltage of a]l disptays seen. The displays performed by females tend to be much less intense than those of na1es. Often a female performs only a jaw,clap with no accompanying body posturing, tail swlsh or vocafization.
Alligators select specific areas from which to iaw claD. Tlrrs site selection often occurs as mLrcl as fifteen ;inutes_before the display is actualfy perforned. Dispfay sites are usuafly very near the shore or other physi-cal objects (such as energent togs in the water), often in secluded portions of the 1ake, and are often under overhanging vegetation.
A head-s1ap alisplay apparently causes other animals to bead-slap. Often a display is followed by t,ro or three other head_stap displays within the next fifteen to twenty mlnutes and then no displays ale heard fo! thirty to forty-five minutes. The fleqEncy of heaal slaps varies throughout the day. Head-slaps are frequent (ca- 4.5/hr) in early morning, less frequent during the morning basking perlod, nost intense during the afternoon hours (6/hr) and then drop off through the evening basking perioals anat alusk-
I have only bri.efly described the most conspicuous acts in the repertoire of alligator social behavior. Alligator social communication is fa! more complex than can be indicated in this paper. Subtle cues, sucb as shifts ln movenent patterns in relation to other alfigators, or sfight changes in body posture, have not been discussed- The intricate processes of social communrcation of the afligator are stifl poorly kno\{n and require furtber study.
Literature Citeal
Garrick, L.D., and l-ang, J.W. 1977. Sociat signafs anat behavior of adult alligators and crocodiles. Am. zoo1. tjt 225-239 -
Garrick, 1--D., tang, J.W., anat Herzoq, H.A-, Jr. 1978. Social signals of aduft American alligators. Bu]1- Am- Mus. Nat. Hist. 160{3): 153-192.
Herzog, fl.A., Jr- !974- The vocal communication system anal related behaviors of the American altigator (At I i qai or rLississippiensis) and other crocodilians. MS thesis, Univ. Tennessee. Knoxville, 83 pp.
Kellogg, R- 1929. The habits and econonic importance of alligarors- Tech. Bul1. U.S.D.A., Ns 147-
McIlbenny, E.A. 1935- The Alligator,s !ife History. Chrislopher Publ. House, Boston, 117 pp.
Reese, A.M. 1907. The breeding habits of the Florida alligator. Smithsonlan Misc. Col1. ouart. Issue 3: 381_387.
Reese, A.M. 1915. The Alligator anal its Al]ies. putnamrs, New York, 358pp -
271 STATUS, CONSERVATIONAND UTII,IZATION OF THE NILE CROCODILE IN ZIMBABWE
D. K. BIAKE Natal Parks Board Pieternaritzburg, South Africa
E!3!!q CURRENT: There is only one species of crocodile in zir.babwe - That is the Nile crocodile {crocodvlus niloticus laurenti). While the fortunes of the Nile crocodile population in ZiFibabxre have fluctuated over the last century they can currently be classified in terns of the luCN definitions as being "out of alanger". This is a result of sound crocodile conservation anal utilization policies implemented over the Iast twenty years by the Department of National Parls and wildlife Management.
HISToRICAI: Prior to the advent of the European into the country, crocoaliles were seldom killed because they haal no comnercial or food value to Lhe local people. The early European hunters with their more sophisticated weapons shot the odd crocodile more to placate the local chiefs than for the trophy- with the opening up of more remote areas and a growing human population. the conflict between crocodiles and hunans increased. This resulted in a reduction of crocodile populations except in the more remote areas of the country mainly limited to stretches of t}re majo! rivers, which 1ay outsiale suitable agricultural areas- The construction of farge alams even within these areas has alloweal reestabfishnent of odd populations-
Today crocoaliles are distributed throughout the country, but nainl-y below 1.500 metres in altitude. They have established themselves in most alams contructed below this altitude and even in some above thatr the Ngesi anal Sebakwe being classic exanples in which marginat populations exist- Being miglatorY animafs, during the rainy season they quickfy re-settle the upper stretches of the rivers and move down-stream once the rains abate.
PoPULATION: The uide Clistribution of crocodiles through the country make an accurate estimate of the population i.Iilpractible. the major populations occur along the zancezi river and Lake Kariba as well as in the Sabi,/Dundi river systems of the south- east Lowveld.
Irl a subnission to IUCN in 1982 the population of crocodiles in zinbabwe was estimated as being in the region of 40/50.OOO crocodiles, Of these 34.000 were estinrated to occur in the zanbezi systems. This was based on aerial surveys and niqht counts conducted alonq the shoreline of l,ake Kariba, Taylor q! g! (1982). Counts during 1983 over longer strelches of Lhe shorefine indicateal lower alensities than previousfy obtained.
212 For the lake itself the poputation has been estimated at ?,6 crocodiles per kilometel of shore-fine resulting in a reviseal figure of 13.000 crocodiles. Counts along the Zimbezi river between the Rukometjie and Chewore rivers have qiven estimates of between 20-40 crocoaliles per kitometer of river. Taking the lower figure of 20 crocodiles per kilometer and the tengti of the river from Karlba dam to Kanyeftba as 195 km.. this ;ive an estimateal population of 3.900 crocodiles- Usinq the fioire of 7.6 crocodiles per kilonetre for the river upsiream fr;m Kariba gives a population of 1.200. This gives a population for the Zanibezi river (includinq Kariba) of minimum of 18.OOO crocodiles. The rest of the country can be divialed into the rivers north of the watershed and those south of the watersheat.
In the northern watershed there are 10 main rivers flowinq lnEo the Zambezi system. These each have a rinimunr of 2OOk.ilo;erers of suitable habitat. Taklng a nominal population of 2 crocodiles per kilometer, we have 10 x 200 x 2 = 4.000 crocoaliles -
In the lowveld there are 7 main rivers. ilorkina on the same formula lre arrive at 2.800 crocodiles
Thus we have population minimum of 25.000 for the countrv. This flgure is probably much higher as no allovance has been made for population in many alams such as Kyle, McIlwaine, Dan"/enda1e, Ngezi. etc. The known population population for Ngezi dam alone is some 70 crocodi les -
]t can safely be assumed therefore that the revised clocoalife population for Zihbablre is in the region of 35.000 crocodifes.
Crocodile popUlations in Zirnbablre have shown an upward trend since the early 1960's, especrally in those areas in which the crocodile is protected. Recent intensive surveys on Lake Karrtra have shown a marked increase over the last four years. The same situation exists in the lower Zambezi and is supported by counts made in 1971 and L9al/A2 (unpublished Departamental recoias) - observations by Departamentat staff have indicated increased populations in the upper zambezi as weft as the Sambi,/Lundi river system of the south eastern lowve1d.
Conservation
Unti] 196l crocoaliles coulal be hunted \.rithout licence and there was no restriction on skin sales. The world demand ilr the l95O,s for crocodife skin led to even the more remote poputation of crocodiles being decimated.
The Wlldlife Conservation Act (1961) classified the crocodj-le as a game animal with the result that it coufd only be hunted under licence.
273 Skins coulal no longer be sold unless they weie taken unaler a cr:oppiprg pernit. Probably as a result of-these measures anil aided by the renoteness and inaccessibifriy of sore stretches of the major rivers the Nile crocodile was not exterminated.
In the mid-1960's the Department of wlldlife conservation aflowed the utilization of the growing crocoallle populations alol]g the Zambezi River including Lake Kafiba.
In 1975 the promulgation of the Parks and wild Life Act (19?5) passed responsibility for aI1 animals to the fand holder. In order to safeguard the crocoalile populations along the zamlcezi river systen, afl crocoaliles afong the river (including Lake Kariba) were by Government Notice 969 of 1975, placed under the protection of the Director of National Parks and Wild Life Management for five years. This notice was replaceal by Statutory fnstrurnent ?19 in 1980 thus affording protection for a further five years. At a meeting in June 1984 between the Departnent of I,Iational Palks and wild Life Management and the Crocodife Talmers Association of zimbabwe it was agreed that crocodiles throughout zimbabwe should be placed untler the protection of the Director of Nationaf Parks anal Wild Life Management. sihce the inception of crocodile Farming the Department has formulateil a strong policy on the Conservation anal lvlanagement of crocodiles in zitnlcabwe since 1982- utili zation
Utilization can be divialed into three main categories:
SPORTHUNTING: under sport hunting a total of 12 crocoalifes per annum are allocated to five safari operators along tbe shores of Lake Kariba. These crocodiles are only taken by bgB fide Safari Hunters and the quota is not always taken up.
A quota for local hunters of 3 crocodiles per annutn on a section of the Zaribezi River below Kariba was allosred up to 1983- This nas stopped in 1984 as it was apparent that the crocodiles were not being hunted as trophies but rnerely as "Par't of the Bag". on private land a nuniber of Safari Operators allott the hunting of crocodifes - whife exact numbers are not known, a total of five trophies were exporteal in 1983. The proposal to place all clocodiles 1n the country unaler the protection of the Director woulal mean that these crocodi.les would have to be hunted unaler perm].E. cRocoDILE FARMING/RANCHING: crocodile ranch i ng ( rearing) stations nere originally started in zinibabwe in 1967 (Bfake. 1982). Ranching was seen as a means of utilising a growing crocodile population on Lake Kariba as wefl as a desire to provide a sufficient source of legal biq quality skins so as to inhibit poaching. This r,ras fulfifled and, in addition, the emerging vafue of the industry catalysecl funds for research and the monitoring or wifd stocts
2r4 which resulted in a widening pubfic appreciation and toferance of the species. Authorities to ranch wele only issued once the foflolring criteria had been mer:
a) The Departnent was reasonabty satisfied thet wild stocks could support the annuat harvest of eggs anal younc,-
b) It was satisfieal with the bona fides of the applicant including his capital resources and ability t; nalntain the venture until a financiaf return could be expecteal after an anticipated three to five years; anal
c) The operators undertook to proviale the Departnent with grown crocoaliles arnounting to lOX of tbe number of eggs or young originally coflected.
By 1971 three of five stations started vere stilt in operation. and making satisfactory progress and it was decialeal to hold the industry at this level until these stations coulal alemostraEe their economic viability as well as tbe Department being reassured that the wild populations could sustain the necessar:y egg harvest- At the outset there was llttle knowlettge of the generaf biology of crocoaliles or even on ho}l they should be raised in captivity. It soon became apparent that catching young crocodiles was uneconomic anal biologically wasteful, anal that rearlng stations would bave to depenal on collection of eggs, preferabfy those with well developed embryos as they tra;;f best. In 197? it was decided to al1ow aatditional stations to open up anal there are today 6 stations operating in the countly.
NAUg POSTTION ESTAB!ISHED 1. (ariba Crocodile (ariba, I,ake Kariba 1965 Farm (Pvt - ) Ltd. 2. Binga Crocodile Ranch Binga. Lake Kariba 1967 3, Spencer's Creek Victorla Fa]ls 1971 Crocodile Ranch Upper Zambezi (Pvt.) Ltd. 4. Sengwa Mouth Sengwa Mouth 197'7 Crocodi.le Ranch ],ake Kariba 5. Rokari crocodife Ume estrary 1981 Ranch Lake Kariba 6- l,ion and Cheetah Harare District 1983 Park
Egg quotas to the stations have been allocated to the stations on the following points: 1) The nunber of eggs believed to be available in the areas ln which eggs are aflowed to be collectecl.
2) The capability of the station to house aod rear the batchlings.
The allocation of eggs to the stations for the 1984,/1985 season is 14.000 eggs, of which 11.000 wj.lf be collecteal along the shores of Lake Kariba.
This quota is based on known nesting sites and the estimates of eggs available are as follows:
1) Estimated Population of Lake Kariba 13-000 II) Estimated Proportion of Mature Adults (252) 3.250 III) Estimated Nuhber of Mature Pemales {50u) 7.625 IV) Estinated Number of Nests (75%) 1-214 v) Nurnber of Nests likely to hatch (60%) 853 vr) Number of eqqs available 853 x 40 per clutch 34.120
During collection 102 of the eggs founal in nests are rejecteal as non-viable and therefore the allocation of 11.000 is in fact a 90% figure. The eggs which will be disturbed by coflection f.i1l be therefore 12-222 or 305 nests. which is approximately 36x of the nests available.
FARMING: Tn order to increase the viability of the crocodile industry all stations have been encouraged to start farming
Problem crocodiles captureal by the Department have been sold at nominal rates to the stations over the yeals. In 1983 authority was granted to Sengwa Mouth to carry out their own capture operations on a section of the Lake where there was a conflict between fisherman and crocodiles. Over a period of 8 nonths only 14 crocodifes were caught. In March and May,/June 1983 a metbod of i'mass capture" was tried out by the Department. fn these two operations a total of 15 and 14 crocoaliles were captured. Of these, twelve breeding females were letaineal. Tt eras agreed at the 1984 Crocodile Meeting, that nass capture would be carrled out as a combined operation between the Department and the various stations in order to buifal up their breecling stock. These crocodiles wilf only be captured in those areas where there is conflict vrith human activities.
216 STOCKS HELD BY STATIONS AS AT I'UNE 1984
REARING BREEDING STATTON HATCHLING Stock Stock Male-Female Binga 2.230 3.243 542 Kariba 2 -200 4. 650 22 23 Lioh and Cheetah 295 Rokari 1.650 2 - 29',7 38 Sengua !,louth t.9'79 3.843 s 16 vlctoria Falls 3. rt2 2.214 11 74
16-241 52 186
PROJEC'TED SKIN PRODUCTION F'ROM 1984/85 SEASON
5 Stations at 2.500 12- 500 1 Station at 1. 500 1.500
14.000 962 Hatch = 13- 440
II. Eggs from larms
Ringa 1.680 Kariba 920 Lion and cheetah 920 Rokari 320 Sengua 640 Victoria I'a]1s 2. 960 1.440 85% Hatch 6 -324
79.764
?Oz to slaughter stage = 13.835 skins in 1986/87
CONCLUSlON
The combined policy of Conservation and utilization aalopted by the Department of Nationaf Parks and wildlife Management in the early 1960's has paid off.
2r7 Starting off lrith a crocodile population that had been severely depleteal by skin hunters, the crocodile population has recovereal to a polnt where they are in some areas quite common. More inportantly a value has been placed on them which is accepted by the public.
For the future, danger Lies in loss of value due to a moving away fron crocodile rearing to farndng which wilI fessen the dependence o!| the \"riId population. It is extremely unlikely however that such a swing would be one hundred per cent. Another ilanger lies in the "commercial value't of the wild populatlons. zin rablte as an "Emerging State". is Ehort of foreion currecy and tle suggestion has already been made to Ministers to crop the crocodile populati.on.
Fortunatley to date the Departnent has been consulted and such proposals rejected.
Provided tle Departnent keeps and implements its crocoallle Policy and has the zinbabwe Farms Crocodile Association as an "Advisory Body" the future of the Crocodile in Zinibablre is assured.
Tayfor R., Blake D.K. and Loverridge,il. P. 1982. Populatlon Nunibers of Crocodiles (c- nitoticus) on Lake Kariba anal Factors Influencing Them-
DepartneDt of National Parks and wildlife Management - Nationat Parks Policy - Conservation and Management of crocodiles in zinbabwe.
Bfake, D.K. 1982. crocoaile Ranching in zinibabwe. The zinbabre Science News, Vo. 16 Nr 9.
2ra PRELTMTNARYEXAMINATION OF CROCODITE POPULATTONTRENDS IN PAPUA NEW GINEA FROM 1981-1984
Martin Hollands
Crocodile Management Project Dept. of Prlnary Inalusbry PO Box 2141 Boroko NCD Papua New Guinea
SUI,IMARY
A prefiminary analysis is presented on 3 years data on trenils in the PNG populations of Crqcldylgs oorosus and e.novaeouineae Aerial nest surveys were conducted at 23 sites along a 200 km. sectlon of the Sepik river and associated nesting habitat. Surveys wele conducted in March and October each year,to incorporate the peak of each species, nesting.
Indices are calculated to show changes nithin different habitats for each species, and these are combined. with appiopriate weighting, to give a nestlng index for each species. There has been an increase of 38X in the inalex for C. qqyeesgle€. q. porosus remained unchangeal from 1982 to 1983, but increaseal in 1984 to 232 above the 1982 level-
It is suggested that temporary nesting habitat alestruction prior to the 1983 survey resulted in a reduced proportion of females breeallng; anal that both species are likely to be i.ncreasing at a steaaly rate. Possible reasons for the increase are consialereal, as are renaining probfems.
An analysis of crocoalile trade statistics. together with very Iimited survey data from othe! areas? is used to argue that ttle situation in the Sepik, which produces about 381 of the countries skin crop, is unlikely to be in major conflict with the national situatlon. It i.s conclualed that the management programme is not only providing a good economic return to the country, but is alfowinq an expansion of the crocodile popuLation-
219 Introduction
Since the nid 1960's Papua New Ginea's populations of Crocodylus porosus and e. novaeguineae have been actively managecl to iJrFro\e the biologlcal efficiency of harvestiDq. The government was keen to ha.It a sevele alecline in numbers, and steer the harvest towarals the long term goal of "maxinun sustainable yield cloppirg". Tle rationale behind the p.oelrarnme, based on a gradual shift from wild killing to the ranching of wild caught hatchlinqs, has already been extensivefy described (Bolton and Laufa 1982.Beh1er 1976, Do&:nes 19?8, New York Acatlemy of Science 1983).
An i.ntegral part of such a prograrune has cfearly to be a research and monitoring component. to assess the effects of harvesting on the wild population, anal to give tle understanding neealed to make correct management decisions. Regrettably this aspect of the PNG progranune was underenrphasi sed in tl|e earfy stages, onfy being implemented in 1980. As the project ecoloAiists have always made cleaa, the initial research will be geareal to monitoring population trenCls, not tryinq to quantify the resource (Graharne 1980, 1981, Hollanals 1982(a)J. however this 1s sufficient for management needs at present, and is a more realistic option with limiteal resources. Three years surveys, as have so far been conducteal, are not sufficient to safely rdentify popuLation trends -fet alone understand them- anal pose as many questions as they answer.
In Papua New cuinea a fa.ge nunrber of people are heavily alepertbrt on crocodiles as the only. anal onfy foreseeable source of income. h view of this, and the fact that crocodiles have never been "on verqe of extlnction' there, it has been the governmentrs pollcy that the restructuring of the industry has to occur lrithout closing it down until afl the answers are available. It has therefore been necessary to aalopt a hiqhly ffexibfe attituate, and to continually review management options in the fight of the best information currently availab]e. For this reason a prefiminary analysis of the monitoring data has been conalucted, and wlf.l be presented here, despite, lrbatever qualms the author might. have about discussing 'trends' at this stage.
The pledominance of heavily vegetated swamps as the primary habitat occupied by crocodifes in most of the country has fed to the utilizatlon of aerial surveys of nest nunbers as the principaL fielal monitoring technique (crahame 1981 lb), Hollands 1982. cox 1984). This has proved hiqhly suitable for such areas as the Sepik flood plain (Fiq. 1), which proaluces approximately one thirtl of the crop of both species, nest survey results fron this area constitute the main data for this analysis. Trade statistics analysis is also an essential part of the programme, wlth both the crop size, and more particularly its structure, providi.ng valuable information on the wild popufation. In some parts of the country, particularly the more aliscreet rivers in the west south, niqht counts are also xun- However, as these bave been conducted over a shorter period than the nest counts. they can tell us little at present about changes in nunJcers.
224 Methods
Although there is a large amount of excellent crocodile nesting habitat within the study area, it is in many relatively small sttes, separated by unsuitable habitat (Figs.1 and 2). When one takes into account the further requirement of good visj.bifrty from the alr, the potential survey areas become even more fragmented. It was thelefore decideal that untit information was avai]able on percentage visibillty of nests in different habitats, and accurate mapping of the area with regards to habitat had been conalucted, it would be considerabfy more cosE effective to preselect survey sites and routes, anal survey these eactr season as an index of nesting, instead of trying to quantify nest nrmbers. Sites were selected to incfude atl major nesting habitats appropriate to aerial surveying, areas with differente harvesting regimes, and areas with different nest densities. As more information becomes available new sites wiff be incorporated. anal probabfy son€ dropped, to give the optimaf ba.lance between variables.
The nest. counts are made by one experieoced observer in a Hi]ler 12E helicopter, which afso carlies a pifot. and a navigator/reco rder. survey routes ale predrawn on serial photographs (scale approximatefy 1:50,000), which allorrs accurate navigatio[ and plot]:ing, despite extremefy complicated swamp formatiors. A 100 netre wide banal is searched from .r height of 150 feet above ground levef. at a ground speed of 25 knots. Due to the frequent directionat changes causeat wh€n foflowing a lake fringe, or an overgrown barat (small rlve!) and a fack of equipment for accurately correcting alr,/ground speeds, the ground speed the qround speed is somer^,hatvariable.
A1f nest sightings are inspected from a height of 25-50 ft. depending on vegetation, for an assessment of age of the nest, activity status, vegetation, lFor details of the team's classlfication and visual assessrflent of nest age and activity status see Cox \1944 /. Surveys are onty conducted during good light conditions, without rain or hiqh i.rinds. More than 50% of nests seen from the air are visited for fult data coLlectio!, either durlng the survey or by surface transpott
The timing of the surveys has been set to give the hiqhest possibfe count of actlve nests. The freshwatei crocoatile (q. novaeouineae) surveys are carried out from the end of October lnto early November, and are irinlealiately after the laying period, but before many nests have hatcheal. As sites are clearly visibfe for sometine after hatchinq, anal specles determinatlon is possib-le from shefls alone (Cox 1984), it is safer to be late rather than early in the surveys. Although the saltwater crocodile (q. porosus) nests virtually all year round ln the Sepik, there is a significant peak in ,tanuary,/ February (Cox 1984) and the surveys are set for just aftei tnis tlme- There is as I'et insufficient information to predict the effects of rainfalt Fatters, or water tevef.
22r on the precj.se timing of nestingr it may well prove necessary to use these to set the optima.l survey dates for each season, rather than using the sane date6 each year.
Results
Tab.Ies 1-4 show the numbers of crocodile nests of each species that have been seen on the six aerial surveys conaiucted between Oct. 1981 and March 1984. Results are presented both for survey sites {Tables 1 & 3) and within different habitas (Tables 2 & 4).
There has been a highly significant increase in the nunber of frcshwater c.ocodile nests seen durinq this period (p < O.05, Wilcoxan matched pair sign rank test). There has also been ah increase in the number of saltwater nests over this period.
As there is insufficient information available on the trrr The inabiLity to equate the numbers seen in alifferente habitats tith the number present, and the absence of accurate habitat Inaps of the area/ also cause problems in ho\,r to cornbine the resufts within habitats to give an overafl index. We need to combine the individual habitat nestinq inalices with a r€iqhtjnq proportional to the importance of that habitat in nesting to the crocodiles in the areat i.e. proportiona.I to the totaf percentage of nests whi.ch occur within that habitat. unforbmately we do not know this. The habitat distribution of nests seen during aeriaL surveys is 1ike1y to be un representative ; habitats have not been surveyeal proportionaffy to their overall dlstribution. and visi.bilitl' from the air differs considerably between habitats. A better approximation to the true distribution of nests can probably be maale from the habitats distribution in the (farger) sampfe visiteal by project staff after their discovery by local hunters. During the course of other activities most habi.tats are crossed frequently by vilfage trteople. who always have an eye open for crocodile nests. Although thele are undoubteally nunerous biases in their discovely of nests It is likely to give us the best approximate to the true distribution that is avail-abfe to us The habitat distribution of hrmter reported crocodile nests in the Sepik {Cox 1984) is as fo-Ilows:- Clocodvlus novaeourneae nSve:CUIjl:aj 1 Lake fringe The floating vegetatlon 1.9X fringing open boali.e s of water 2 Scroff swales & levies serial patte!:n of high 572. and"he low bands formed by river benal erosion,/deposition 3 Channels & barats Either the bank of small 74% channels or on floatinq rnats whlch have grovn over them 4 overgrown oxbow6 oxnow lakes across which a 70% vegetative mat has developed Cfocodvlus porosus 1 Lake fringes 3lz 2 Scroll s\"ra.les and fevies 332 3 overgrovn oxbows and channels 36% These percentages have been used as the welghting when combininq the indivldual habitat lndices, to give an index for each specles wirj.oh is likefy to ref-lect changes in the total breeding popiaticn of the middfe sepik. crocodile Nestino hdex 1981 r9a2 1983 1984 c. tTqyecgul4gee 100 131 138 q. p9r99!g - 1.00 101 L23 It snould be noted that the habitat in which nest numbers of, both species have fared -least we11, the floating mat fringes of -Lakes. is considerably over-represented in the surveys. This is due to its ease of location, known distribution and location, anal good aeriat visibi.lity, alf co.nbi.nlnq to it bei.ng extensivefy colrered ln lnital surveys- Nolr that rre have a better knowledge of the distribution of nestlng habitat in the area, new survey sites wllt be incorporated to rectify the imbafance. Irntil such time the raw survey data alone gives a slightl.y less optirFistic 223 Discussion on nestinq trenals in the Sepik In this paper it is only intended to consialer the results of the surveys in terns of popufation trends aDd their relevance to management decisions. Obviously the results are of wider uterest, but other aspects are coverecl j.n a fuller description of the nesting ecol.ogy of crocodiles in pNG (Cox 1984). Unless these data are purely arl artifact of the surveying rnethod, such as a result of improved nest spotting abiflties, there has been a significant increase j.n the breeding poput atidl of freshwater crocodiles i.n the Sepik. This increase appears to be of at least simi-lar magnitude to that seen in nest numbers of Louisiana alfigators fron 19?0-19?9 (Joanen and McNease 1980), a population geherally considereal to have a low Level of exploitation. The situation with regards to saltwater crocodiles is not so clear, wijJh a significant drop in the nunber seen in 1983, thouqh not in the more appropriate index, foLLowed by a farge rise in 1984. However, anafysis of interhabj.tat differences. and due considera tion of other factor€, gives us a reasonable understanding of what happeneal in 1983. Prior to the 1983 saltwater nesting season the Sepik area had oeen exceptj.ona-Ily dry, which had two slgnificant effects on crocodifes. The lncreased accessibilit.y to hunters combined with the concentration of crocodiles into lakes and sna11 barats made hunting much easier. As skin prices had been extremefy low for some time this alid not result in an increased comrercial harvest., however, in many areas it encouraged hunters to kifl Large crocodiles for their neat. The more accessible habitat,and fess timid behaviour of the salties made them moie vulnerable than freshies. In a few areas the effects on the saftwater crocodiles were devastating, for instance Lake Kwasenam (map.ref. 21), dropped from 15 saftwater nests in 1982 to only 2 in 1983 and 1984. Under the laws of PNG j-t is only the corurtercial kl11ing of breeding stock that is prohibited. The second effect of the dry was far more apparent to those on the survey. but nore of a short term problem for the crocodiles. It is norlnaL practice throuqhout PNG for hunters to burn off vegetation almost as soon as rt is dry enough. This is used directfy in hunting sorne game/ such as wallabies, and also facilitates movement for other hunting. ?he da,rage to crocodife nest.ing habitat is usually refativefy minor, as key habitats are normally too wet, however in extremefy dry years the effect can be substantial. Vast areas of prime nestlnq habitat were brunt off in fate 1982 and earfy 1983, anal the regrowtb of vegetation was not far enough advanced to support the floating nests noffla-lly useal by crocodiles in this area, and there was lnsufficient naterial present for nest construction. It seems that the salt\.rater crocodiles responded in two ways !o the loss of nest sites, some apparentfy did not breed at all (or may have bred considerably later in the year, but we have 224 had no indicatlon of thls). and sone moyed to less disturbeat, remoter, areas away from the open water. This movefilent is j-ndlcated by the fact that the changes that. rere observeal in nest numbers betireen 1982 and 1983 were not uniform across habitats- fn the most accessible habitat, the floating rqats fringing open water, there was a drop of 50%, the nwnLrers in overgrown oxbows and channeLs remained constant, and there was actually a rise in the number of nests in the remote scro1l swales. By the following season the floating mats haal recoyered and there ras a move back to the lake frinqes, with scloll nests dropping in number desptte the large-overatl increase in nesti.ng, indicating such areas are only sub-opt.imal reselve nesting sites. When the appropriate habitat weighting is given to the sa_lt ater crocodile results they indicate there was a 23% rise in nest numbe.s between 1982 and 1984, showinq that the d.op that occurred in some habitats during 1983 was nainly attributable to the temporary foss of nesting habitat, not to tl]e killing of breeding stock. It is therefore considered reasonable to assune tnat. both species are increasing in number, and probably for the same reasons. There are a number of factors that could be contributino to The main legislative protection given to cxocodiles in pNc rs a ban on tne trade of skins above 20,, befltwidth, a measure lntended to at.Ieast protect the breeding stock from cornnercial, if not t.aditional exp.loitatj.on. itowever political pressure caused the lepeal of this law in the Sepik, soon after its uLroduccion in 1975. tt soon becane afparent from skrn exports that where the faw was in effect there was a recovery 1n nunoers, 1n comparison to a continued decline of the industry in the Sepik, resufting in its reintroduction there. Although this faw does not give fulf protection it has probably been a trtajor factor in aflowing the breedinq poputatlon to increase. Thrs analysis has concentrated on data from the Sepik, as tnls r.s Lhe area ln vhrch tne monrtoring team has condu;ted most work. One consequence of this has been a greater awareness of conservation and management issues in the area. particufarfy p.essure to stop setling hooks at nests. In many vlllages there argunents have been well received, and hooking breeding females has either stopped or been nuch reduced; sone locat councifs have even passeal faws protecting nests. Any redsction in the deliberate removaf of nesting females must be beneficiat. One of the principal concepts of the progralfine is that by sh-iftiDg cropping from larger animals to the more readily replaced hatch l ings/yearl ings , for farm rearing, the vafue of the industry can be raised. Furthermore, it was predicteal that as crocodiles are harder to catcli afrve, there would also 225 be a realuction in the total lrumber harvestedl ( K!.apena/Bolton , 1940, Bolton,/Laufa, 1982). It now appears that this is being achieveal, and over the last 5 years PNG has been increasing skin production, despite a alrop in the number removed from the wild (Hollands,/coudie , 1984). As the crop also includes nore young stock the biological impact on the popufation will have dropped even moFe. The Sepik is one of the main supply areas for stock for the farms, supplylng approximately 63x of both species, and the shift in harvestj.Dg is more advanced there than in most areas. In a number of vi.llages hunters now concentrate on live coflection not skins. It has been extremely encouraging to Dote that rn areas such as Kamlemu (Fig. 2, map. ref. 12),lrhere hunting is heavy, but is now primarily directed at live cDl.lecticn, there has been such a large increase in nest numbers- Such a situation obviously bodes 1,€1I for the future of crocodile malagemeDt i.n Papua Ner Guinea. A.Ithough there appears to be an upwards trend in nesting numbers, the results do show that there are stil1 problems to be tad Tn most lolrland areas of PNG crocodile nests have long been explorted as a food source. A saltwater crocoalile nest can yleld up to 8 kg- of eggs, and the nest site offers an easy opportulity for kifling a large crocodife for meat. In t.he seplk as many as 35x of saltwater nests. and 25u of freshwater nests may be raided for eggs. and up to 15% may ha\,'e baited shark nooks or nets set for the females. One probfem encountered is that the 20" maximum size limit does not fulfy cover oreeallng stock, particularly the freshwater crocodile whlch starts Dreeding in the wiLd as small as 15" (Hollands 1982) .so a nesting fema.le might yield a saleable skin. However as a nrajor reason for setting a hook is to obtain neat, lt seems rmlikely that an indirect method oftackling the probl.em, such as reduclng the nraxinrum size, would be effective. The Crocodile Advisory Board has therefore recommended that a law should be introduced banning the setting of hoohs or nets within a prescribed distance of a crocodile nest. It is likely to be a much longer ta,sk to stop tlF present egg harvest, though 226 frequent aliscussions on this point are held in vilLages, with increaseal protein becoming available from other sources, and increased ecloaomic vafue of the hatchlings, there should be a gradual reiluction in the rate of nest harves ting. The go\ElrtrlEnt is afso considering a trial egg harvest progrannre for farm rearing, in areas where high proportions would be rerroved for food any\,ray. The National Situation An indirect indication of the statrs of the wifd population on a national levef can be taken from trade statisticsr it was in fact these that initialfy drew attention to probfems of over- expfoitation in the 1960,s. It has lonq been known that water level"s throughout the year have a s t:ong influence on the number of crocodiles harvested anal we now know there is a markeal correla tion (r = 0.55) between the price of skins and the nuniber exported. Due to these factors and the gradual shift towards ranching, the annual harvest totals (fig, 3) are of little use in assessing t.rends in the wifai population. However. the size structure of the harvest. can give a useful indication. For reasons of simple economlcs, hunters prefer to kifl large crocoaliles for therr skins. Durinq the 1950,s, when the population was over-exploited, the average size of crocoalile that the hunter managed to catch sfol,rly dropped. By 1965 the average size skin exported fron PNG was only 7 inches- Due to the changes brought about by the introaluction of live purchase schemes, the introduction of maximum and minimum tradable skin sizes, and farm production of skins, a dlrect comparlson of the current average export size (12,29 inches for I'W and 10.8 inches for SW) are onfy of comrnercial and economic interest. However, if only wi.ld skins between 9-20 inches are considered, to remove t.he effects of farm skins, it can be seen (fig. 4) that there has a steady lncrease in the size of skins available to hrnters -which supports the j.dea of an expanding wifd population. Due to their preference for open water, less t.imid behaviour and greater skln value, the saltwater crocodlle is in a more vulnerabfe position for over-expfo i tation . Concern was therefore feLt as to whether the previous decl.ine in saLtwater crocoaliles would contlnue, until they were no longer available rn economic nrmbers $rhen hunters' attenti-on lrould then turn to the freshwater crocodi.le -by no means alr unusual scenario in the history of crocodile exploitation. Figure 5 sho s that the previous aleclilre in the proportion of saltwater crocodiles in the country's harvest has now been hafted, anal they constitute a stable 201. This gives suppolt to the argument (above) that, despite a baal nesting year in the sepik in 1983, the saftwater crocoalile population increase is of a similar olaler of magnituale to that of the freshwater crocodile. A nj.ght spottinq survey progratnne has now been incorporateal into the rnonitoring prograrune for rivers in western, Gulf anal Central Provlnces, however these have not been conducted over a I'ong 221 enough perj.oal to be of any assistence yet ip identifying trends. OnIy one river has had directly conparable counts mqde oyer a sufficient period; this is a 120 kn stretch of the Bensbaeh rj.ver in the extreme southwest of the country. Counts here show that there has been a substantiaf inclease in ttre non- hatchling popu.Iation si.nce 19?9. Many of the rivers in the de-lta system of culf Province which are now covered ln ttre surveys were frenquently icountedi for interest whi_lst being traversed on patrol. Those same officers say that the numbers they now see on systematj,c surveys have increased dranatically -particularly in the numbers of hatchlingF. Aerial surveys of nests have also been made for four years tn Waigani swamp, a 2 km. -long lake near the PNG capitaf, whose ffoating frlnge supports both saltwater and freshuater crocrodile nests. Annual nest counts on this frinoe have been: 1980 - 4, 1981 - 5, 7942 - A, 1983 - 11 This is a surprisingty nealthy popda tion in vig.l of ttle farle nulber of people who regulary fish and hunt the swamp- The timidity of thls popu.Lation j.s Seen by the fact tbat althouqh on the serial counts both nests and adults are seen. t$o hatchlings and one 3-4 ft. crocodife are the best our team has ever xecorded there in a night. It soould also be noteal that there has been an lncrease in tire numbei of problem crocodiles reported to the authorities. Although ttle monitorinq progranune is sti11 at an early stage, the inalication to date is that boti-r species of crocoalile in Papua New cuinea are increasing in number, and the current managenent progranme should therefore be continued as it gives considerable benefit to the country, particularly to remote groups with no other source of income, and the cropping appears to be within the sustainab.Le llnits of the wifd Dopufation. Acknowledonents This report wouLd not have been possibfe witbout the continued hard &ork of our field team in the Sepik, particufarly Jack Cox, Benny cowep, Tom titzgerald, Kayama sinba and Thomas wiIlie- Also special thanks go to the pilots of the suruner lnstitute of Lingulstics who have put up with a lot over the last three years. Jack Cox anal Dr. Mike Nunn kindly reviewed an early alraft, anal Sue Hollards and Veronlca Rau helped in its preparation. The author woufd also like to thank Papua New Guinea's Departament of Primary Industry for its supportof the crocodife nonitoring 224 References Behler, J.Ir. 1976. The Crocodile Tnatustry irl papua Nelr curhea. A. report to the uhited Natj.ons. Wildlife in papua Ne_ cuirrea, 77/25, wildtife Division, p.O. Wards Strip. waigani, P. t{.c. Bolton, M., Laufa, M. 1982. The Crocoalile project in papua Nelr Guinea. Biol. Co\s. 22, 169_179- Cox, J. 1984. Nesting Ecology of crocodiles in papua New curnea. FAO/UIIDP PNG/14/O29 tr'ie1d Docur.ent N! 5- Downes, M. 1978. An explanation of the National po]icy for the Crocodile Prograrnme. Wrldlife Division publicat-ion 79,/10 P.O. Wards Strip. Waigani, papua Nelr G\rinea. Grahame, A. 1980. Monitoring Workptan- FAO,/UNDP pNc/74/029. Assistance to the Crocodife Skin Industry. Grahame, A. 1981. Monitoring Final Report. ].\O/uNDp pNc/.|4/ 029. Assistance to the Crocodile Skin Indus try. Hoflands, i,'1. 1982 (a). The status of Crocodite populat.ions in Papua New Guinea. proceealings of the 6th uorking meetinq of the IUCN Crocodile Specialist Group, Hetd at St. Lucia, South Africa, Septenbre 1982. liolfands. M. 1982(b). protecting tl]e breeding Crocoaliles in the !ri]d. Crocodile Management Bulletin Nc I pp. 11-15. Dept. of Pr-imary lndustry, p.O. Box 2141 Boroko NCD, papua New Guinea - Hol1ands, M., cbudie, c, 1984. I4anagement of the Crocodite Industry in papua New cuinea, proceedj.ngs of the ?th. working meeting of the IUCN Crocoatife Speciafist croup. caracas/ Venezuela, october 1984. Joanen, T., McNease, L. 1980. Managenent of the Alliqator as a renewable resource in Loutsiana. proceedrnqs oi the 5th working meeting of the IUCN crocodile Specrilist croup. University of I'torida, USA, August 1980. Kwapena, N., Bolton. M. 1980. The Nationa_t Crocodile projecc 1n Papud Neyvcuined- a suftnary oI po]icy and progress. Proceedings of the sth working meeting of the IUCN Crocodile Specialist croup, University of Florlda. USA, August l9go. New York Academy of Science- 1983. Crocodiles as a Resource for the Tropics. Report of the Ad Hoc Commitee of the National Research Council in tbe series ,'Managing TropicaL Anj.ma1 Resources , - Webb, c. 1977. ?he Naturaf History of Crocodyfus porosus. pp. 240-310- Fromo ,,A stuaty of Crocoalvfus porosus 1n iilorthern Australia. Shakespeare Meatl press, Sydney 1977. 229 Table 1 I,OW-WATER AERIAI SURVEYS OI q..ryEqgINgAE NESTS IN THE SXPIK MAP. I.OCATlON REF, 1981 1942 1983 COMMENTS 28 0 3 Korasameli o. g. bar Olal Hauguaba barratt Kapalmerj- 27 0 1 )n salvinia rsland ;IaIEDdai Oxbow scroll 0 0 Suapneri I -t I 24 1 I 3 Not hunted for 3 yrs -alue to WalrnauIaqoon salvinia ,7 Yafiibi Yauwe 23 0 2 Extensively burnt 1983 Lapangal scro1l 22 3 2 Extensive caboe trails Lake Kwasenam 1 5 6 Heala hunting + llooks Bllhba lagoon 20 3 3 I MoaIhunting + Hools T9 5 5 10 Nyari Not hunted, Kanai Nyari, ren ai laeoons Heaw huntinq & Hooks Kwanalimbe laggon 18 7 5 1 lvlod huntirg.Little r€sl e)(pfoitati cn wagu^{asui fringes L7 2 2 3 YoaI-Huntings. Good sli ' PoP- Afso has safties Khapar og barat 0 0 I llot lunted. Paiyagat head oxbou 2 3 t flunted + Hooks Pwiftaki1lapa t4 20 20 No hunting Yessan scroll 13 5* 5 l0 Heavy hunting Kamiemu main scroll 12 l0 I4 22 Moal Hunt. No eggs tal Ramiemu (S) Baratt 11 3 5 10 Females - Hooked 80,/81 Kamiemu (W) scroll 10 4 4 No Hooks (N) swasup 9 7 9 I No Hooks. Eggs eaten Kwaisi- 8 6 6 Females left, Eggs taken '7 Biaga scroll 3 4 Kubkain og oxbow 6 3 2 5 geavy Rubkain open oxbow scr 5 0 0 3 hunt. Females left llouna levels 4 11 9 Highwater hunting Kubkain lagoons 3 1 4 Heavily hunLed. Take eggs Kelpi swamps 2 3 3 2 Heavt'hunting Browaml mountain lakes 1 4 2 0 with following 1€ar's survey' 234 * Denotes imPerfect route compatabil-ity sg )6 ,9 .a 9- *9 l/t cl o0 dtd HS I !l c; H5 pn U 7 o '115l zn .i 91r Fsn xllql tg sE El o qrg6: Ul zqr zl ;5 ..: 3r1 Hl oH Al g9r q ,s p :fl 9B o 91| 83 9 4s, 2s F o,E I 2 F !6; d F] I a E cI g, F fi9 4 Ed ft a 23r C. PCROSI]S ARIAL NESTIT{G SURWEY RFSULTS HIGHWATER (MARCH) NEST COI,NTS ON IDENTICAL ROUTES lhp. 1982 1981 1984 COMMENTS 27 2 2 i?"ilY.3H5|l"g".uli'ldi' Kwandinlce t8 2 3 3 Deep fringe- Little burning NyaIr,/Kanai 0 0 3 ranai, slallow, no hooks wagu lagoons 1',7 10 10 14 No hooks. l4odexate Burning Kamiemu 4 6 6 Paiyangat 0 2 2 Hooks + nests useai in past Kubkain og.oxbow 6 0 0 2 No hooks - eggs taken '7 (ubkain oxbor scroll 5 5 8 No hooks - eggs taken Swagup 9 6 I 3 Eggs harvested 4 I 0 Total 45 30 43 24 Salvinia cover stoDDeal 5 5 Huntinq. Eoss sti11_ ta](en ,f,apandai 26 3 1 Heavily burnt Korasmeri 2a 0 4 S.D-A. area,hooks set for skin 38 53 Blackwater 6 Mindimbit 30 3 LOW-WATER (OCTOBER/NOVEMBER) NEST COUNTS Map. Ref- 1981 198 COMMENTS Khapar barratt Nestin Wisui laggon 232 AE I ,o vis ; F z v; g8' HE "i :c E er G6 o q0 F 9 tr9 a9 ?! E EP, rR E !?tr€d L! q4 !?l o t6 bl r.lHl !r d6 >l q E& E3 8l gv 5 .a g> ? tq t4c 9t Eg, qr 6, .E ge, 6:l ti iq E fiE !0 OF 2,3 3A 9,^g 9i9 a 9X3 sq" T E 233 HI N c,l o lo Bl ..1 dr 2l tB lEr F.o1o2 Al .d f -t ii at| ..r 4l Ht t xt o I'l | ! ol 0,) r4l or Jl ri al at o ll o) t! e E Ell z 2 r\\ft., 0 {) V 6A :._1A Z*\.n.'.,.,\ 6 a.\ zj =* =- Ie. 9t 6'E . iiti; i 6 Yr^l6r']'\-' Figure 3 TOfIAL CROP OF FRESEWATER (*---*) A}rn SALTI{A?ER (O-.--O} CROCODII,ES TAKEN II{ PAPUA NBIf GUIIIEA DURING 1976 . 83. 5 ?n 9q 6) aFt a. 5 ||.) lz 0 6 -t o d,l zl o"" -'--o--- o---"-4---'-- --r---___o /o 78 ot 236 Figure 4 AVERAGE SIZE ( IBCEES BELLY I{ID:TH ) FOR TIIJ) SKIBS BB1i{EEN 9 _ 20 II{CHES DI'RING | 975 - | 983 TRESEWATER (O----O) SALII{ATER (ts---{} 11 13 z 12 ll I l0 FI O qt a F h E 9 A a ditr Ug HC 3li 4A UIJVfiJTCS SSVTNIJUTIiI 234 CROCODYLUSPOROSUS - A TEN YEAR OVERVIEW: THE PoPULATION MODEL ]\ND IMPORTANCE OF IDRY WET' SEASON AND STATUS, MANAGEMENTAND REMVERY H. Messel. G.C,Vor1lcek, W.J. Green and T.C- Onley ^t Fn!'ir^hhah+:t Dhv (Note: This paper is to from part of monograph 18 To be published during 1984) 239 CONTENTS 1- ABSTRACT 2. INTRODUCTTONAND THE POPIiIATTON MODEL 3. LIVERPOOI..TOMKINSONRI!'ERS SYSTEM, JUIY 1-5 ANd OCTOBER13-18 198 3 SURVEYS 3.1 July 1983 surveY 3.2 october 1983 survey 3,3 An eiqht Year overview 4. BLYTH-CADELI RTWRS SYSTEM, JUI,Y 15- 18 and ocToBER 25-29 1983 StryEYS 4.1 General 4.2 JulY 1983 survew 4.3 Cctober 1983 survey 4.4 A ten Year overview 5. THE TIDA], WATERWAYSOE ROLLING AND JUNCTION BAYS, JUNE 18-21 and ocToBER 1-4, 1983 SURVEYS 6. ALT'RNATIVE HABITAT 6.1 Anamayirra and Beach cree](s, June 27-2a a^d october 10_11 198 3 surveys 6.2 Toms creek. July 1 and october 13, 1983 surveys 6.3 crab creek, June 25 and october 20, 1983, surveys 6.4 Cadell Big and Cade1l Garalens Billabongs, June_July and October 1983 surveYs 6-5 Extreme upstream section of Blyth River km.49-8-59 and bilfabong km.6o.6-54.6, Julv 11-12 anal october 23-24'1943 surveys 6.6 Upstream liverpoof River, kn 60-66-4, June 29 and october 8, 1983 surveys 6.7 General 7. NGANDADAUDACREEK, JUNE 26 anil OCTOBER12. 1983 SURVEYS 8. GLYDE RIVER ' ARAFUM SWA.IVIP 8.1 July 7-8. 1983 survey 8.2 october 6-8, 1983 survey 9. DISCUSSIoN 9.1 'DrY wet' seasons 9.2 An ;verview for the rnonitored waterways in lhe Maningrida area 9.3 Recovery of the g. oorosus population 9.4 Management of the g. Dorosus population 10. ACKNOWIEDGEMENTS 11. REFERENCES 12. TABLE5 13. FIGURES 244 Message to the Ree.der" Betore reading this paper please tuin to T€.bles ! to ? and in e€.ch case spend severat ninute; carefuuv looking d@n Lhe nunbers in eacl cot!.T. -hen r.an on 1. ABSTRACA ?his paper provides the overall results for I0 years of spotlight surveys carried out in the tidaf waterways in the Maningrida area of northern Arnhem tand. In previous publications we have developed a model of the dynamics of g-.ru populations on the tialal waterways of northern Australia, based on-the resuLts of repeateat censuses. fn this paper, by utilizing the results of additional surveys carried out in our n;nitoring area in June-July anal October 1983, further confirmation anat refinement of the basic features of the moatel is obtained and more ls adated to our already detailed unalerstanding of population clanges in the monitoring area. This paper focuses particular attention on a question raised in 'dry our previous paper: what rote do wet' seasons ptay in deterndniq observed influxes of (3-6,) and especratly t:rqe c. nbrosus onto the main sections of the tidal watenrays anat wlere ao tne-inliats come from? The wet season of 1982-83 was a ,dry' one, as was that of 1991_82, and this has enabfed a detailed analysis, baseat on our node1, of the population dynamics aluring such perioals. we found it essential to carry out surveys, in both June*July and Octsd3er, of two additionaf systems ]ast surveyed in 1979. NganaladauclaCreek anal the clyde River- Extensive aerial surveys of the large Arafura Swamp, draininq the clyale, were also carried out. With thes; adatitional surveys r we believe we have essentially unravelled tle importance 'dry of lret' seasons in the dynamics of c. porosus populations in our monitoring area. There is very consialerable interaction between our monitoring area and ttte Arafura Swamp, some 150 km away by water. Animals forced out due to the drying back of the swanp habitat bave moved into our monitoring area and a proportion have remained, giving rise to an lncrease in the number of targe animafs in the systems. Some of these animals may well have been originally recruited in our monltoring area. We afso review the results of some ten years'work on tbe 330 km of tialal waterways in the monitoring area. The results and anatysis of this work clearly indicate that further work in this area would yietal litt1e new knowledge in the short-term and we wil] now shift our attention to another section of northern Australia, to check whether our model is applicable there and if it is not,then to develop it further. Different estimates are given for the very high ]osses (but it is at least ?0%) that we have found as C. porosus orows to sexual naturiLy, and these rnost-Lyac.ount ror rr-lssentiarlt unch€nqed number of (3-6,) animals and for the onfy smal1 increise in lirge animals that we have founal over ten years. ft is afmost as if there were a set number of territories or slots in a river systen, and tbe crocodiles themselves are primarily responsible for the very high losses that occur in the process of trying to secure these slots or to increase them in nunber. After reviewing prospect for recovery and management of Australia's q.pglS€lla population, we feel we can realisticafly and unfortunately conclude only this about the salt{rater crocodile's fUture: fT HAS NONE 241 2. INTRODUCTION AND IHE POPULATION MODEL It is twelve years since the University of Sy&rey crocoalile Research croup commenced its study of Crocodvfus porosus in northern Australia. The results of this lengthy and extensive study have appeared tn numerous publications covering the physiology, nesting, growth,nsrenent, mortality aDd population structure and status of q. porosus over much of the northern australian coastline. Our baslc work on the status and population dyDamics of q. pg!.gslL€ in tidal lratervrays up to and incfuding 1979 has been presented in a series of 1? monographs and 2 reports by Messel and bis co-workers (Messel et aI. 19?9-1982). fntensive population surveys and studies were continued durinq 1980, 1981, 1982 and 1983 on some 330 ]cm of ticlal waterways (I'igs. 1 to 3) centred on our northern Arnhem l,and headquarters at Maningrida on the Liverpoof-Tonikinson Rlvers System( llonograph 7, also see pages 14, 15 and 440-446 Monograph 1 where tbe results of the 1980 and 1981 surveys appear as adalenda) - The results of the 1979-1982 surveys were anall'sd and aliscusseal in a paper entitleal "The continuing and mysterious Clisappearance of a major fraction of sub-adult q. ps!958 fron tidal watervrays in nortbeFn Australia" presenteil to the 5th Working Meeting of the IuCN/SSC Crocodile specialist Group at St. Lucia, South Africa. Septemlcre 2a-3O, f9e2. Tle results of our october 1982 surveys appear as an Appendix to the above paper. For brevity, we shall refer to the 'st. paper and appendix as the Lucia 1082' Paper. The moalel which i{e have bui}t up (see especially chapter 5, Monograph 1 anal Monographs 5,'1 , 9, 1o, 11, 16 and 17) and have been refining as more tlata is obtained, enables us to account :in a consistent fashion for the vast store of field observations and results lte have accumulated for some 1OO tidal waterways in northern Australia- It also enables us to prealict successfully, results to be expected on future surveys -as we did in July 1982 when we made prealictions about the decrease in the number of small and/or laige g. porosus which woulal be sighted in october 1982. on the 330 km of tidal wa+-errrays monitored in the Maningrida area. The model runs as foflows: The tidaf waterways of northern Australia habe been classified according to their salinity signatures into TYPE 1, TYPE 2 and TYPE 3 systems as alelineated in Chapter 3, Iig- 3.4.11A of Monograph 1 (pages 100 and 101). TYPE 1 systems are tbe main breeding ones anal non-TYPE 1 sYstems are usually poor or non-breeding systems. It is the TYPE l systems and the freshwater billabonqs and semipermanent and permanent freshwater swamps assoclated with them lthlch account for the malor recruitment of g. pglgEllgt the ot'her systems contribute to a Iesser degree anal they rnust depend largely upon TYPE 1 systems and their associateal freshwater completes for the provison of their crocodiles. Iron-TYPE 1 sYstems also sometimes have freshwater complexes associated with them but tlese are normally quite ninor. In Tabte 9.2.1 (page 419) of Monoqraph 1, our result show that in TYPE t systefirs some 2'l% of the crocodifes sighted are hatchlings {of whic} sone 50% are normally lost between June of one year anal June of the next, page 394 Monograph 1) , whereas in TYPE 2-3 systems this figure falls to 14% and ln TYPE 3 systems down to 42, showing a much alecreaseal hatchling recruitment in non- TYPE 1 systems. In TYPE 3 systems the percentage of 242 crocodlles in the hatchlinq, (2-3') and (3-4') size cfasses combineil is solne l1z whereas trl TyPE 1 systens it is at least 52%- On the other hand the percentage of crocodiles in the (4-5') size classes is some 39X in TYPE 1 systems and 732 on TYPE 3 systems. Some 792 of the Don- hatchling crocodiles are sighted on TYPE 1 waterways and 21% on non- TYPE 1 waterways (page 419 Monograph 1) - The relatlvefy few large, alrd more frequebt smalf freshwater billabonqs anal semipermanent and permanent freshwater swamps associated with tidal waterways are kDown to contain g. porosus but have not been inventorieal systematically, except in a few cases. The accurate extent of their non-hatchling .q..p.glgqfq popllations in unknown. BaEed upon the fact that the number of large freshwater swamp areas, with substantial ater (normafly bordering old river channels), in northern Australia is very Iimited -perhaps 400 km2 naximum- anal upon limited observations, we estimateal that in 1979 the non-hatchling [email protected] poprlaticn vEs less than 20x of ttre non-hatchlirg trrpulaticn sighted in tidal systsns (paqe 433 Monogrpah 1, note error cn paAe 433 when tlE statsrert "less than 202 of the pogrlaticn siglted in TYPE 1 tidal river systems" is made, and aqain in the Table below itt the words '?YPE 1' should have been onitted- T}e figure of 836 is based on 20% of the nunber of non-hatchling sigbted in tidaf systens) - We now believe that that the 20% figure was an overestimate for 19?9 -an rmusuaL year associated with one of t,}]e 'driest wetr seasons on record. It appears that the popufating of non-TyPE 1 systems (hypersaline or partially hypersaline coastal and non-coastal waterways) results mostly form the exclusion of a farge fraction of the sub-adult crocodiles fron TYPE 1 systems and any freshwater compfexes associated with them. Adult crocodiles appear qenerally to tolerate hatchling, (2-3') and sometimes even (3-4') sized crocodiles in their vicinty {but not always -they sometimes eat them, page 43 Monograph 14- or kill them, page 334 Monograph 1), but not larger crocoaliles. Thus once a crocodile reaches the {3 4') and (4-5') size classes, it is likely to be challenged increasingly not only. by crocodifes near or in its own size class (pages 454-458 Monograph 1) but by crocodiles in the large size classes and to be excluded fron the area it was able to occupy wben it was smaller. A very alynanic situation prevails with both adults and sub-adults beinq forced to move between various components of a system and between qfstens. crocoalile interactioris or agressivelress beti.reen crocodiles in alI si?e classes increases around october -during the breedlng season (page 445 Monograp} l and St. Lucia 1982) and exclusions, if any, normally occur around this period. A substantial fraction { 80%) of the sub-aalults, mostll in the {3-6') size classes but also incluiling inunature larger crocodiles, are eventually excluded from the river proper or are predateal upon by larqer crocodiles, of those crocodiles that have been exclucled, some may take refuge in freshwater swamp areas and billabonqs associateal with t}le hraterway fron which they were excluded or in the waterways ' non- TYPE 1 creeks if it has any. others may travel along the coast until by chance they final a non-TYPE 1 or another TYPE 1 waterway, however in this latter case they nay again be excluded fron itr others may go out to sea and possibly perish (perhaps because of lack of food, as they are largely shallow water on edge feeders. or tley may be taken by sharks). Those finding non TYPE 1 systems, or associated fresh,rater complexes, frequent these areas. r^rhich act as rearing stockyards, for varying periods, until they reach sexual rnaturity, at which time t})ey endeavour to return to a 243 TYPE I breeding system. Both sub-adults and Just mature adults miqht attempt to returh and be forced out of the system many times befor; finally being successful in establishing a territory in a TypE 1 system or in its associ-ated freshwater complex. Clocoaliles may bave a homing instinct (this important point requires further study) and even though a fraction of crocodiles may finally return to and remain in a TypE i systen or in its associated fresh,eater complex, the overall sub-aalult nr]fibers missing -presumed dead- remain high and appear to be at least 60-702. Since a farge fraction of the crocodiles sighted !n non-TypE I systems rnust be alerived from TYPE 1 systens anat their associateal fresh\,rater compfexes, they are predominantty sub-adults or lust nature adults (page 431 Monograph 1) . Nornally, the fresh^€ter compfexes (swamps and/or bilfabongs) associated witb tidal systems, are found at the terninal sectjons of small antl large creeks running into the main waterway, or at the terminal sections of the mainstream(s). Though tbis alternative habitat is usually very fihited in extent, sporadic (ar]d sometimes yearly) nesting does take place on it. ftere are, hor^rever, severaf fair11/ extensive freshwater compfexes associated with TYPE 1 trdal systems ;nd tlese are important as they may act both as rearing stockyards anat as breeding systems,just as the TYPE 1 waterway does itself. Examples of these are the clyata River with the Arafura Swamp (Monograph 9), the Alligator Region Rivers with their wetlands (Monographs 4 and L4), and the DaIy, Finni ss , Reynolais anal Moyle Rivers with their wetlands (Monograph 2). Not onfy can the loss factor, whicb appears to occur during the exclusion stage, be expected to be lorr/er for movements into and out of swamp areas associated with a TYPE 1 waterway, tban for movement into and out of coastal non-TYPE 1 systems, but the loss of nests due to ftooating can also be expected to be less- We have observeal nests made on floating qrass cane mats in t})e Daly Aboriginal Reserve area. Thus recovery of the q._.Doroslls population on TYPE 1 tidal water.ways, wlth substantial associateal freshwater complexes, can be expected to be faster than on other systems (page 445 Monograph 1, paqe 98 Monograph 14) - Though we are confialent about the correctness of the basic structure of the above model. tlis is not to inply that amendments will not be necessary in the future as more data become avaitable. Every good model should be capable of refinement anal improvenent, based upon turtsI.€r systematic and accurate observations - Tbe folfowing aalditional important results, some of srhich lave been only partly incorporated iDto the model itself, are understanalable on the basis of it (pages L4, 15, 440,446 and chapters 6 and 9 Monograph 1, sr. Lucia 1982) : 1. Because of the 80% exctusion and at least 60-?0% Iosses of sub- aalult crocodiles as they proceed toward sexuaf maturity, tlere has been no slgnificant sustaineal increase in the non-hatchling g. porosus population on the tidal watenrays of our monitored area in northern Austrafia sidce the commencement of our systematic surveys, a period of 244 2. Assuming the results from our monitored area appfy etsehrhere, any significant sustained increase in the non-hatchling g. porosus lopulaticns on the tidal waterways of northern Australia must be measured in decaales. 3. Though there has been no sustaihed significant ihcrease in the number of non-hatchling crocodiles sighted on the tidal warerwal/s srnce our surveys started in 1974, the size structure of the anima.Is ;iqhted appears to be changing sIowly. Notwithstanding substantial fluctuations, the ratios of smalf (2-6') to large ( )6'), and (3_6') to farge animafs is alecreasing on the Blyth-cadell, may be decreasing on the Liverpool- Tomkinson and is alecreasing overall on the tidat waterways of the Maningrida monitoring area- Thus there is some inalication of the colunencement of a slow recovery phase, However even thls could be open to alispute. 4. Though there are wide fluctuations, especially after ,atry wet' seasons when the animals are concentrated into the tidal waterways _ it appears that as the number of large crocodiles 1n a tldal watlnray, increases, there is d tendency for the number of sub_adutts (3-6')size in the classes to decrease or increase marginalty onlt. Thus tlle total (3-6,) number of and large aninals siq'ht;d app3ars qenerally to be holding steady or increasing slowly only. it i" uj,o""t .J ir tl.r" set a number of territories or stots in a river system,and the crocodiles".o themselves ar€ prrmarily responsibte for the very heavy losses of 7OZ rn t4e process of tryrng to secure these stcrs or to increase them jn nurirer. 5- When a steady state is reacled in a 'recovered' population, the ratio of (3-6') to large aninats migbt be considerably 1ess than one. 6. If one considers a qroup of 100 of the sub-adult crocodiles in a TYPE 1 tidal system,one can expect some 80 to be exctudeal from it, at least 60-?0 to end up nrissing -presumed dead, less than 15_20 to successfully establish territories on the system without having to lea!€ it and the remainder might eventualty also return and establish a territory when beconing sexuatty mature. The very nature of ttlis matter is such as to preclude precise figures and they must be lookeal upon as broad estimates onfy, however study of Tabtes 4, 5, 6 and 7 now indicates that the missing-presumed dead figure is ]ikety to be in excess of ?0, 7- Wlen there is an exclusion of sub adult animals, mostly (3-6') in size but also including larger imnature animals, t'his takes place mainfy in the breedjng season, normally commencinq around September_ October and apparently fasting throughout the wet season. Any influx of animals, in the {3-6,) and/or targe size classes, appears to occur in the early dry season and to be completed in the Eune-early September period, but may in some years be earfier- ,dry 8- After a single wet' season there is a substantial inftux of Iarge and sometimes (3-6,) animals, forced out of freslr^rater comDlexes. into the tidal waterways and these are siqhted during June_July;urveys. Surveys made in October-November of the same year, usually ieveal a substantial decrease in tbe number of (3_6,) and/or Iarge aninals sighed, however the number of large animals sometines remains hiqher anat hence a number of the new large aninals alo not return, to from whence they came. These animafs appear successful in establishing a territory on the waterway, and it coulal be the waterway from which they had oriqinally been exclualed. The 'tlry wet' variation in the nuftber of animals siqhteil appears to be €uperimposeal upon the variations normally founal during surveys folloving usual wet season -which generally result in extensin€ flooding on the upstream sections of th: tidal waterways. Hatchfinq recruitment on the tidal waterways is generally greatly enhanced dfrirq 'alry wet' seasons but appears to be greatly realuced in major swamp habitat. The reverse appears to be true iluring normal or heavl. wet seasons. Observation 8 indicates the impurtant role which 'dry wet' seasons pfay in the alynamics of g. p9!.9€!.9 populations and this is the main subject of t}le present paper, which also reports tbe results of our June-July arld October 1983 surveys anal gives an overview of the surveys carried out over the past ten years in our monitoring area. It is fortunate that we continueal to monitor the tidal watentays after 1970. If our survey prograrune had been Cliscontinued at the end of 1979, it would have been natural to interpret the significant increase, between the 19?5 surveys and the 1979 resurveys, in tbe non-hatchling q. pggElfE population sighted on a number of major tidal waterways. as indicating the conmencement of a sustained recovery in the population (chapters 6 and 9 Monograpb 1, t}len also see pages 440-446). ahe results of the october 1980 resurvey of some 330 km of tidal systens in our Maningiiala monitoring area, and of the resurveys made in June-July and octobbr - Noveniber in each succeeding year inalicates tbat such an interpretation would have been premature. one is viewing an €xceedingly complex antl dynamic situation in relation to g. p.S!.gsgg populations, which apparently atoes not lend itsetf to facile interpretations anal Not only were we fortunate in continuing our survey prograrnme after 19?9, but we were afso fucky in that the 'driest wet' on record. that of 191A-1979, was followed by two usual wet seasons, those of 19?9-1980 'alry and 1980-1981. These in turn were folfowed by two consecutive wets', 'dry those of 1981-1982 and 1982-1983. Though the latter wetsi were not as dry as that of I9'7A-I9'79, we again observed in 1982 a repetition of the events given in (8) above, in relation to the influx and deparature of (3-6') anal,/or targe crocoaliles. Two major questions quickfy cone to minalr where did the influx in 1979 anal again in 1982 of (3-6') and large crocodiles come fron and where did they go to wlen they left? litrat happened to these temporarily missinq (3-6') and large aninals? By the end of the 1980 surveys / it was atready becoming evident tbat in oraler to eliminate sone of the many possible answers, we would have to survey all possible g. porosus habitat to which we could gain access in our nonitoring area. was a alaunting task and a helicopter would be required to ferry survey"his boat and staff to nany of the areas. PraqnEtic cost considerations, as well as the logistics anal tifi\e anal effort involved -especial-ly after already having spent some 10 years working on g. porosus on the tialaf waterways of one of the ]trtorld's most remote ateas -rnabE us wonaler whether further understanding of the dynamics of g. porosus populations really warranted the money and enormous effort reSuired. Each of the two annual resurveys made of the watenays in our no;itoring area r€quires over 1.OOO km of survey boat travel at night anal 20 hours of helicopter flyinq time. The 'dry wet' of 1981-1982 246 settleal the issue, again bringing about an ihflux of (3_6,) and talge anihafs into the tidal watersrays of our monitoribg area- The decision to continue for two further years was probably coirect, for we believe we have essentially unravetled another import;nt component of the dynamics of C, porosus populations. The success of our nroalel ln being able to account in a consistent faslion for the data resulting from the repeated niglt surveys of the tidal waterways and their associated fresln"/ater complexes in the Maninqrida area on the northern Arnhen Land coast, anal to successfully predict results of surveys, indicates that it would now be mole revarding scientificafly to shift our centre of stuaties. It is unlikely_that-a further 4 years, study on the waterarays in tlE tadingrida area- would aald much to the picture gained over the pa;t 10 years. Forthermore, the senior author (HM) retires from the University of Syatney in 4 years' time anil it is most impoltant that before that happens we determine r"rhether one is justified in extrapolatinq the concluitons. gained from the study of q- porosus on some 460 km of waterways in the Maningrida area {Tables l and 8, I.igs. 1to 5) , to tidal systems elsewhere on the coast of northern Australia. We believe that on" aar, do so, but this point must be tested and it will take tbe 4 vears to do so. The University of Sydney Crocodile Research Facility at Maningriala was closeal in Novenber 1983, after functionihg in this ;emote anal costly area for some 11 years. Tron 1984 onwards our studi_es will on the water$/ays of the southwestern culf of Carpentaria (Monographs 12 and 13) using our excellent researcb facility at urapunga on the noper River (page 440 Monograph 1). we may also resurvey i numuer of othar important tidal systems which we have not resurveyed since 19?9. 3. _LIVERPOoI-ToMKINSoNRMRS SYSTEM, JuLy 1-6 and ocToBER 13-18,1983 The 1983 surveys of the Liverpool-Tomkinson System (Fiqs. l and 2) were particufarly important because this was the first occasion, since our research prograrnme commenced 12 years ago, that there have been two 'dry consecutive wet, seasons, those of 1981-1982 and 1982_1983. These coincided with the now famous El Niffo weather pattern which drasticatty changed weather conditions in many areas of the wortd. The results of the surveys are shown in Tables 1, 2, 3, 5,'7 arld a. J. .r JU-LV -t9dJ SUTVeV We sighted a total of 54 large aninals duxing our July 1983 survey {the same nuriber as in July and october 1981), compared to 69 on the octder 1982 one- On the Liverpoof mainstream we sighted 7 large animats tess, on the sidecreeks 71ess, and 1less on the Tonikinson River (Table S). This decrease was not unexpected- In the Appendix to the St. Lucia 1982 paper, we pointed out that the number of tarqe animals siohteat on the System, during Lhe october tc82 survey, had n6t yet aecreaiea and that this was largefy due to the latge animals entering the sidecre*s of the Liverpool-Tofiikinson Systenr, probably on their way out. ADarentty, as predicted, the exclusion from the System evantually dial occur. lfhere dial the excluded animals go? 247 No overall increase in the number of large animals frequenting the tidal rtraterways of Rollinq anal Junction Bays (Fig. 1) was siqhted during the June 1983 survey -in fact 3 less were seen (Tables 6 and 7). E) Tab]es 1, 2, 3 and 5 show the number of small animals sighted during the July 1983 survey- At first sight, the jurnp from 171 snatl animals (2-6r) siqhted during the october 1982 survey to 257 on lhe JuIy 1983 one,Iooks spectacular. However, nattets are not as good as they seeli- of the increase of 86 small animals, Table l shows that some (83-16)= 6? are in the (2-3') size class. In June 1982, 193 hatchlings were sighted and frorn Table 8.4.1, lronograph 1, one could expect some 452 or 87 of these to be in the (2-3') size class in Julv 1983 (note that the Blyth- 'drY cadell survivorship figure was also obtained for a wet'. that of 1g'78-Lg'79J. This was approxlmately so with 83 being sighted. Ho^€ler from our previous results one can expect a large fracion of the increase to disappear once the animals enter the (3_4') size ctasses. be noted that for reasons unknown to us, but perhaps related It is to 'alry to fosses being greater during usual wet seasons than aluring wet' ones, the 289 hatchlings of July 1979 gave rise to onlv 51 sightings in the (2-3') size class in october 1980. unfortunately, we are unable to say how many {2-3') animals there were in June-July of that year as no surveys were made during that period. Fhoush we include the l2-3') size class in the smafl animals in order to alecrease errors in size estimation, the more meaningful size classes to consider are those in the (3-6') range. This is so because it appears that it is crocoaliles in these size classes which are nost susceptible to exclusion and loss from the tidal wateiways; interactions between crocodiles generalfy increase with size. Note hor"rever thai caution in requireal wh;n intertreting alata for an individual size class or small group of size classes because of inevitabfe errorin size class deterfi[nation' 6n;une surveys one can sometimes classify animals just in the (3-4') size class ai (z-:') animals thus yielding too large a nunrber of (2-3') animals and too few(3-4') ones (page 335 but also pages 80 and 389 Monograph 1). Examination of Tab]e 5 shows that for the liverpool-Tomkinson system, t}1e number of (3-6') animals sighted during the July 1983 survey nas 1?4, compared to 178 in June 1982 and 155 in october 1982- The number: of (l-6') crocodiles srqhLed on thc July lo8j survey Lhus appears to have returned almost to the June 1982 survey fjgure. The number of 244 (3-6') anlmals sighteal on the Liverpool mainstream, km 3_60, was 59 in ,lune 1982, 78 in October 1982 anil 67 in.tuly 1983, on the sidecreeks the number were 34, 28 and 35r and on the Tomkinson River, km 17_73.?, the numbers were 85, 48 and 71 respectivley- Our field data enables us to analyse every section of the river system surveyed/ even down to fractions of a km and we are able to follow changes on various sections of the \rate!.way. For instance, one coulal easily see fron the October 1982 survey results that the iDcrease. since the June 1982 survey, of the 19 (3-G,) crocodiles siqhteat on the Liverpool mainstream sections (mainly in the vicinity of t;e mouth of tbe Tomkinson River, see Appendix, St. Lucia 1992), probably mostty came fron the mouth sections of the Tomkinson River and fronr m.rrqar,]*olo Creek, where decreaseal nunbers were siqhted (Fiq. 2). Likewise; essentiafly the same phenomenon appears to have occuffed in reverse when one coJnpares the october 1982 data with that of the Julv 1983 survey. one point which stanals out strongly from our data (Table 5) is that the- Toftkinson River, the present main breeding area of the Liverpool_ Todkinson Rivers System, is where many of the maior ctanqes in the population of hatchfings, (2-1,) and (3-6,) crocodites oicur. The nr)mber of large animals sigl]ted on the Tonkinson has remained fairly constant since 1976. first hovering around the 20 figure and then around 24 since 19?9 with fluctuations up and alown on these. Changes in the nurber of large animals sighted occur also on the Liverpool mainstream and its sidecreeks and there is tittle doubt that s;me large aninals are excluded from the System and later re_enter rt. Since hatchling recruitment on the Liverpool is very tow, the fact that one sights over 60 (3-6,) animals on it each year shows that these must come larqely from the Tonikinson. Some of the snatl,and especially animals in the (3-6,) size classes, may also teave the Liverpoot, TofiJ Fatchling lecruitment on the Liverpool-Tomkinson over the ,dry wet, of 1978-19?9 appears to have been excellent, with 24, 5 and 260 batchfings being sighted on the Liverpool nainstrean, sidecreeks and Tonkinson River, respectively, on the Juty 1979 survey. Following the ,dry wet' of 1981-1982 there was again a major input of halchling with 1?8 being sighted on the Todkinson during the June 1982 survey (Table 5). Then came the second consecutive ,dry wet,, that of 1982-1983, anal one would again bave expected heaq' hatchling recruitment. However this was not to be. Why this was so, we do not know. Only 91 batchtings were 249 sighteil on the Tonkinson, but hatchling recruitnrent was up slightly on th; Liverpool mainstrean where we sighted 27 on the JuIy 1993 surveY- Could be that some of the females alo not nest each year, or coulal it be that some nest more than ooce in a wet season? coulal it be that food supply ls the proximal factor involved? Perhaps the second consecutive 'aiv wet' resulteil in a substantial decrease of available footl and hence sone of the females ditl not nest since their conalition factor might 'dry be low at the onset of the seconcl wet' season? This lpull already 'dry not necessarify be so at the beginninq of a first wet'- We now return to a furthe! perplexing matter which we discusseal at some length in the St. Lucia 1982 paper. This is the matter of nestihg on tbe Liverpool nainstream and the Tor&inson River. Fron our capture progranme of 19'73, L9'74 and 1975 lre know definitely that tlere were at fe"lt gZ, 34 and 60 hatchlings on the l,iverpool mainstream alurlng those respective years (Tables'1.2 to 1.4, page 59 Monograph 7) anal that on the Tonkinson River there were respectively 55, 53 and 10 hatchlings. In 1972 one of the authors (HM) sighted over 100 hatchlings on the Liverpool malnstrearn and 44 (2-3') aninals were caught on it in 1973- After one of the largest floods ever recorded, over the 1975-1976 wet season? very few hatchling were sighted -onty 19 on the overall Liverpool-T;mkinson system, during the July 1976 survey-lTable 5) ' Tbere;fter 1ow lratchting recruitment persisted until 1979 hen 260 hatchlings antl 24 large animals were sighteal on the Tordkinson during the July survey. on the Liverpool mainstream only 24 hatchling were seeni however 29 large animals were sighted. Thereafter, latcblinq recruitment remaineal 1ow on both the Liverpool anal Tomkinson, until the 'alty wet' of 1981-1982 tthen, during the June 1982 survey, 7 hatchlings onty and 30 large crocoaliles were sighted on the Lj-verpool mainstrean and_178 hatchlinqs and 2? large animafs on the Tordkinson. Essentially' we haCI a repeat of the above along the same lines, over the second consecutive 'dry wet' of 1982-1983. The Liverpool mainstream has some excellent nesting habitat { Monograph ?)rthisha6itat was utilizeal during the early 1970s anal batchling recruitrnent on it was equal to or greater than on the Tomkinson. The ii"erpoor mainstream attd the tomki.tton appear to contain roughly equal numbeis of large animals. whY is the major habchling recruithent now taking place o., ttt" ro*kit.ott ralher tban on the Liverpool mainstream? Why did_it change? Again, has food supply sonething-to do with this maiteri could the food supply on the Liverpool have decrease'I, and increaseal on the Tomkinson? If so, why haven't the breeding animals moveal froh the Liverpool mainstream to the Tomkinson? we simply 'Io not have the answers to lhese questions and obviously consi'Ierable further research into breeding anal nesting is inaliceted. The purely descriptive fielal natutalist studt stage of breeding anal nesting is over' Now the hard questions should be researcbed. 3.2 October 1983 survev Table 5 sunmarizes the results obtaineat forn the october 1983 survey f"t the Liverpool-Tomkinson systen and the first seven entries of".ii". Table I show the ielevant data fo; surveys of various associated alternative habitats. 250 On tbe Liverpool River nainstream anal its sidecreeks, the nunber of animals sighted on the October survey was down on the nun Jer sighted durring the June 1983 oner 7 hatchlinqs. 13 (3-6') and 3 larqe aninats were nissing, 10 of the missing 13 (3-6') animals were from the sidecreeks - As in June, again the most important changes occurreal on the Tornkinson River. The nufirber of hatchlihgs sighted dropped form 91 to 40. a fall of 572. This is to be compared with fatts of 452 and 24%, over the same time periods, for the 1979 and 1982 survey series respectively. However, it should be noted that during 1982 there lrere a nunber of late nests on the Tonikinson River which hatcheil after the June survey (Appendix, St. Lucia 1982) . Tbougb the number of hatchlings sighted fell steepty, it is interestirq to note that the nuniber of (2-3') aninals siq}|ted durino the October survey was only one less ol1 the Liverpool mainstream, oie more on rts sialecreeks anal 6 less on the Tomkinson River, than on the June survey. The matter of high hatchling and very low (2-3,) losses is consialered again in our discussion of the Blyth-Cadett results where the same +l'i h^ ha^nana^ The number of (3-6') g. porosus spotted was 18 less than on the ,fune survey and in aaldition 10 (3-6,) crocoililes were missinq on the extreme upstlean km 73.7-81.3 section of the river (Tabte 8). ihe nulnber of Iarge animals sighteal decreased also, from 24 to 1'7. This is the largest variation between two consecutive surveys, in the nunaer of large animals sigirted on t})e Tomkinson River, since 1978- on the overall Li ve rpool-Tomk ins on System there '77 was a decrease from 121 to 63 hatchlinqs, from 83 to (2-3'), L'74 to I42 (3-6'), and 54 to 45 large animals- In aaldition. on the atternative habitat (Tabfe 8) tbere was a decrease from 45 to 19 small animats; all of the 25 misslng anill\als were in the (a-6') size class- Thus (32 + 26) = 58 (3-6,) and 9 large animafs are to be accoirnted for between the June and October 1983 surveys. undoubtedly some of the 58 (3-6,) aninals joined the ranks of the missing -presumeal dead and host of the renainder probably took refuge- as appeared to be the case on previous occasions- in the inaccessible sections of the Tor,kinson River (upstream of km 18.3) and in the numerous unsurveyable tiny creeks. Of t]1e missing 9 large crocodiles, 7 were missing from the Tonkinson and the decrease was spreail fairfy uniformly over it. A number of tbese ? missing animals are 1ike1y to be upstream of km 81.3- 1\{o adalitional farge animals were sigbted on Tom's and Maragulidban (km 3?.8-42.5) creeks and 3 adalttionat ones on the extreme upstream Liverpool River section, km 60.0-66.4 (Tabte 8). Thus, there is no problem in accountlng for the 9 large animals missingt they appear to be still in the System but excluded to the alternative habitat. This matter also highlights the importance of compartng lesults for equivalent survey seasons, that is, breealing anal non-breeding versus non-breedlng periods whenever possible- For exampfe, october -November surveys should. if possible, be compared with other October-Novenber surveys and not June-July ones. It is interesting that the influx of both (3-6,) and large animals into the Liverpool-Tomkinson System fotlowing the ,dry wet, of 1981-1982 was almost totally dissipated by the time of the October 1983 survey 254 when the nurdber of (3-6') animals sighteal was only 9 rnore than in octder 1981 and the number of large anirnals was in fact 9 less- So far, the outcome of tbe 1981-1982 and 1982-1983 'alry wets' contrast with that of the 1978-2979 'dry wet', when the number of large animals sighted on the System estabfished itself at a level of around 54 farge animals rather tban 40 $ihich appeareal to be the level before 1979 (Table 5). 3. 3 Arci&-fc3r--9vqrv-L!e]{ rn figure 6 lre have plott.ed, using Tables 3 and 5, the nunber of (3-6'), Iarge and their sum (3-6') plus farge, or ( )3') animals siqhted on the 13 surveys of the Liverpool-Tomkinson Rivers System over the past 8 years- As is evident frorn our population dYnarnics moalel and as mentioned previously, the more important size classes are the (3-6'), lalge and ( >3'). A plot of sma11 and non-hatchling crocoaliles can be alistorteat because of temporary variations arising from the input of (2-3') animals after a heaEr hatchling recruitnent year as after the 'dry wets' of 1978-19'79, 1981-1942 and 1982-1983- This variation appears to soon disappear once the animals reach the >(3-a') size classes. I'iqure 6 demostrates vividly the process of dynamic change which \,re have come to associate with g- pglgEgg populations. any influx of large and/or (3-6') animals usualfy occurs in the May-earIy September period anal any exclusion of such animals occurs largely iluring the breedinq season arounal october- It is in this fatter perioal that many large and (3-6') animafs appear to join the ranks of the missing -presirmed alead. Aggressiveness between animals of all size classes, whether mating or otherwise, appears to reacb a peak during the breealing season. What can one say about the trend in tle number of (3-6') animals sighted on the Liverpool-Tomkinson Rivers system aluring tbe surveys of the past I years? one does not require any esoteric trend analysis to be c€rried out to see that there has been but little overall clange. we started itb sone 130 (3-6') aninafs in July 1976 and endeal up with 174 in Julv, and 142 in october, 1983 r.tith substantial variations in between. There were 140 (3-6') animars sighted durinq the october 19?? survey. The three substantial increases, one in May 1977 and the two in;Iune 1982 analfuly 1983. following tl]e 'dry wets' of 1981-1982 and 1982-1983 when the animals lrere concentrated onto the tidal waterways, haal disappearetl by october 1983. we are unable to say whether the 'dry wet' instiqateal increases consist purely of aninals originafly recruiteal on the Li\rerpool- Tomkinson System or whether animals reciuited originally in such places as the Arafura Swamp are included. we believe the former to ]argely be I'ollowing the 'dry wet' of 1978-19?9 t}e number of large animals sighteal increased spectacularly, from the 40 siqhted on tbe JuIy 19?6 and september 1978 surveys to 74 on the Jufy 19?9 one. However by the October survey of that year the nur'Jrer had dropped to 58 and t]]en r€fiained closely the same for the 1980 anal 1981 surveys, the october 1981 survey revealed 54 large aninals. Following the 'dry wetr of 1981-1982 there was an influx of tarqe animals again but not quite to the same deqree as in 19?9t the June 1982 survey revealed 67 larqe animals and the Octcber one, 69. unsurprisingly anal as aliscussed previously, tbere was a alecrease from 54, insteaal of an increase in the number of large animals sighteal on the Liverpool-Tomkinson System on the July 1983 survey. This 252 was followed by a futther atecrese of 9 farge aniroals; 45 were on the October 1983 survey. Comparing equivalent survey seasons, JuIy 1976 with ,f,uly 19e3 yields an incjease of 44 {3-5') and 14 large animals anit compa;ing October 1977 with october 1983 surveys yielas an increase of i (3-6,) animals jarge on.ry, ano lo ones- OBVIOUSLYTHE EXCLUSTONSAND,/OR I,OSSES OI, ANTI4ALS IN ALL SIZE CIASSES HAI'E TO DATE NEARLY EOUAILED THE INPUT. It should be stressed that the faxge size classes are includeil; that they also suffer substantial excfusion and/or losses for we knolr fxom our recapture work that sone (3-6') anilnals do enter the large size class and yet the overall number of large animals sighted lncreases marginally on1y. However the eviatence does indicate that some t4 to 20 additionaf large animals are in the process of successfufly establishing a territory in the Liverpool_Tonikinson System. we have calculated rough est:imates for the exclusion and losses of previously (for animals instance Chapter 6 Monograph-l,i;e 1, St. Lucia 1982). These estimates can now be recalculated for the rpool_Tomkins on Systen usinq data from surveys nacle over tlte past I y;ars. One can obtarn ah esLirate for the maxjmun averaoe percentaqe of hatchlinqs which survive to tbe (2-3,) stage by tat A broad estimate for the minimum percentage of (3_6,) crocoalifes which are excluded and,/or lost from the Systen ;ay be obtained by notrnq {Table 5) that 130 (3-6') and 40 larqe animats r,rere siqhtea durin; the Jufy 1976 survey and that the octobe; 1983 ..\r"il"d a5 ]arie crocodifes only. Each of the (3-6') animals"o.\r.y of i976 wourd, if th;y survived, be in the large size class by 1983 and hence t}le mlnlmum percentage whlch have been excluded and/or lost (minimum because we have assumed that al1 the increase originated from the t30) by October 1983 is (130-5)/130 or 96%. rt is mora usefuf however to made in equivalebt periods - The ?able below gives the"".i"i","r""y. minirnum exclusion and/or loss percentage for varlous rmpoftant cases- Ilowever one views the matter, tle excfusions and,/or losses are very ,dr:y higb. If one assumes that the wet, ot :.gal_lge2 and concentrateal back into the Li verpool-Tomki nson, practicatly alI of the surviving farge aninafs orig:nal1y recruited there -and none origi.nating from elsetitEre_ then 69 to ?92 becomes the estinate for the missing _pr6sumed dead 3_6,) anirnals. l.4inifin-Inu of (3-6') SuFey Us€d Large ( >6,) ardir€fs excluded ard/or lost Jufy 1916 130 AA 6cber 1983 45 (130-5)/130 or 961 Jufy 19'76 130 40 July 1983 54 (130-14),/130 o!: 89x July 1976 130 40 (130-21')/73o $ 19* itrDe 1942 67 Octcber 197? 140 25 Octaber 1977 45 (140-20),/140 o!: 86x octcber 1977 140 25 (140-44) oct 4.1 ceneral s)Etern (Figs' 1 and The eiqht-eent}l ard nireteentlt general suneys of tlle 811'th-Cade11 been carrie'l *J" in Julv anal october 198i' rhese survevs have ,t-r;; calibration a span ot iO year. anal are in ad'Iition to the 204 (Monograph 1) ' J".""v"_"rri.i"irt "".t we rnaae ll two 10 km sections of the waterlray well acquainted with ii i"'no exaggeration to state that we are rather qulte different from iii"-..."i" iid excellent tialal waterwav hich.is were fortunate to iire- r,ive ip"of-r"*rins on system to the west of it' we of q' p94)e!C ft".r"-U"."' -;" to concentiate our study, of the dynamics "Uf. tnese two different major tidal 'raterwavs ' Eowever'the iii"r"iiil"", has the stualy in human tertns, in such a remote area-of Australia cost of rt is ;;; ;;y;;; i^"qi"i!r;" -aside rrom the srisrv rinancial aspect' unlikely to be repeated. more our July 1983 survey of the BlYth-cadell-followins systen l'as in.some regards 'drv wets'' irp"iiiit-ir''i",.,.,.r.i- tt was on two consecutive ln tnrs paper and ;ur October 1982 survey had indicated iliscussed elsewhere the z8 larse animals had'been excluded from the svsten between ;;;i:;; in tlre surveys of last 'rl"a-year' would we find an increase i"i" aninals returned? ""a-o"a"l"tof large animals signtJii tot" of the exchd-ed nunber from?.Jf thev hadn't i'l-ii.r1"i ri"'a returned, Jtrere lad thev returned were they' if-stiIl alive? returned, then whaL happeneo i" lf'"Int 'i1tt" sighte't be up or 'lovtn what about the (3-6') woul'l the number ""r-.a"ii., and how voulal they be distributeCl throughout the System? Anat how woulal the number sighted retate to the tvo co;secutive 'i", ..r"_, with the nunber of (3-6,) and -large. anim-als sishred i. ah; surveyed in June-July 1983? what about natchlinq reciuilment-;aiy ";;;r;L;.y= survivorship ano on the Blyth-cade]I after t*o .on".6ol i,,. wets,, it be woura up, down or remain essentially steady? our .ru]y suiirey woura proviile answers and,/or leads to most of thlse questioi_rs. 4.2 Tab]es 1,2,3,4,7 and 8 on the matter of the 28 missing large aninals from the Blyth-Cadetl october in 1982r nore that th€re haal b;en an influx of 28 1iige animars between the october 1901 and tbe June 1992 survey ititl"-Zf. Is is norir apparent that tbe influx lras triggered by the inlervening ,alry wet, r981-1982, of when falting water revels in iwamps, U"ii,-i.rd. anal smaft, simpfy forceal t}e crocoalites back ihto the tidat waterwiis _perhaps back to the same tidal waterway rrom which they were recruited. lne sane events had transpired in 1c79 after the ";i;;;;ii;,diy wett of 19?8_19?9, &itnessrne- ,itry I: y::: :l:: a repray of the te?o evenrs afrer the wet. aL lr6r-ry6z. .the results of the many surveys carried out, especially those of 1979 and 1982, feft no doubt that Ui,ir, iirl"-""a-r3_6,) anntBts were- entering and leaving the Blyth_Cadetl System via the mouth of n.tyth the Rrver. We nc,.wbelieve that the influx of 35 (3_5,) anal 32 large animals--anal- - especiall]/ those animats in size classes not especialfy !tS_g,1, the 7' anirnats, Table 1_siqhted in,rune lgid ana tne influx_of 28 large and 36 (3-6,) aninals _especiaffy trrose aninals in size classes >(4-5,) -siqhted on the Blyrh-c;dert dirrin! ihe June 1982 survey were mostly crocoililes forceal out of the Arafura Swamb fF.ids- i and 4) some130 km by sea and river to the easr, r^,t,i.r,r,ia-ir5.i .Eii"" as a rearing stockyard for them, and that tbese animafs ,""y-;;;.--__"" originally been excluded from the Blyth-cadelt system -n trud b""., recruited. By t}Ie October 1982 survey, 28 large animals were"hi"t nlssang from the system, practically att of theh from ihe downstream sections ano tney must have Lravelled eastward for we did not sioht an increased number of large crocodiles in the waterways surveyed to the west of the Blyth-cade11 or in the alternative habitaL survey3d (Table 8). T}ese animals we]]e probably on their way back to the Arafura Swamp anal otner minor freshwater complexes via the Milingimbi complex of tidal ,dry waterways. However, a second wet, inter;ened anat it is likely that the crocodiles remaineal in rhe Milinginbi Complex and clyde River waiting for - the usual wet season to raise th; water ]lvels in the arafura Swanrp and.other small swamps, If this is so, there woutil be nothinq to trig;er an influx in 1983 of sub-adults, both small anat large, into the Blyth:- CadeIl System from the hypersaline Milingimbi ComptJxi ,ary wets, coulat be expected to have liLtte direct effecL upon animats frequenting the hypersaline tidal i./aterways. on thrs basis, one would ;oi -"*-, -" *^ f .ind a major increase in ihe n\rnber of (3_6,) and rarse i",,""i. tgit"a on the Blyth-cadelt sysrem during the July 1983 sur""!. or., the otl;r hand, if the crocodiles did return to the Arafu;a Sean.p ovei the ,alry wet, of 1982-1983,--then one migbt expect an influx of th; animals again exctuded trom it. However, the results of our June_July 1983 surveys of the Llverpool-Tomkinson (Tab1e 2) and of tbe water;ays of Junciion and RoIling Bays (Table 5) showed no major inftux of cxocoalifes into these 255 svstems.Furthermorethelargeanimalssightedon'thel,iverpoolllBirrstrean appeare'l' ;,;';;;.r;;i; it" mouth; durins the october 1e82 survev' their wav out of ;;;";;;-;; it'"i. ".iidi"ttil,ttion near tie mouth, to be on JuIy 1983 survey' ifr":;"i.r""v. This was confirmeal by the resufts of our ,ri-r." . a"".i."" of 15 large animals was foun'l the tiverpool-Tohkinson of large svstem- Hence if thete {tas substantial increase in the number on the Blvth-caalell on the Julv 1983 survev then the most !i,i*"i" .lshi"a 15 farse anirErs iiil'ii".""iJ-;r tr,ese woulal have to be from those the Liverpool-ronkinson"''i.ar. svstem' rhese animals would ;;;l;a.a-i;"* to the Arafura ;;;;ii; .r'.o."'t.t the Blvth River mouth on their wav back hence might attempt to enter it' As can be seen from the !r.*" .i'ta additional ill'i'it""i""ilii" a'liti"-.pp!i." to have been the case for 11 were sighte-dl one could tbus expect that the octobre 1983 i".a"-."f*"1. it is :;;#";;ia-;;.ir i'i"t most of this increase had 'Iisappeared as ."V-"r it,".. aatalirional animals would be attowed to remain ,iiiX3 ti:'in"t- been in irr" ilrytrr-caa;I1 system, especially if they had originally recruited on the Liverpool-Tonikinson ' the 'alriest ltet' on record of 1g7A-\9'19' we fully expecte'l to Foltowing in 1979' Hcf,Je\€r' ii"a-i".i""."a hatchling recruitment on the Blvth-cadell to fi;d that the nurnber of hatchlings sighte'I on the *"-".r.-""ipil..d j.ttt. (86 Blvth' 37 on ii.i.i'a"iiii-irr. rgls^=u.\/ev was onlv 123 an the compareo co 1/r (13? on the Blyth, 36 on the cadell) siqhted the Caatef,lj, wet season iiiii"q-ih"'i"". i9:s .,-tt.'"v (rabre 4), which followed a normal it" substantial flooding of che upstream nestin-g sections of the *iift Tomkinson River wateretay. T})is was in contrast Lo vhat happened on the 'sl the JuIv 1979 survev' ii.ui. where 260 hatchling were sighted during c" par"a to only 1? sighted on the September 1978 one' of Thus already in 19?9 it was evialent that even thouqh heavl' floo'linq alnrost invariably letl to the catastrophic. loss of riverside not ;;;4""."ti"q'-h.b'ft.t i.i; down alurins the Janua;v-March period'non floodins did inalicate ih"t ilt....".c tratclfing recruitment would follow ""..".i.itv rt . rt wis obvious that floodins or non-froodins of i;;;;-ii-il";;;;p.r, in hatchlinq ,,!"i. onlv-one of a number of important factors involved """ Thismatterhasbeenbroughtmoresharplyintofocusby.theresultsofour surveys. Tn the section on the Liverpool-Tomkinson svstem' i"""-j"ly 1983 the the surprising result of sightlng only 91 batchlings on ".__af"."i= t-he ;uri 1983 i= compared to.i78 hatchlings durins ;;di;;;; durins wet rgszo',J {t"lr" s) ana possiure",tt""v reasons for thls result ' A;-;;;; 'dry one or . ^rhe, seasoh of I982-Ic83 had been a weL' as had been the only minor flooding on the upstrearn nesting sectlons iit"." had been the ""a .v al\rring both of the wei season' study of Table 4 for Ji-ti,"-,rit"t on the Blvth iiyiii:c.a"il iv"t". .!t.' .atleis even nore comprex' piir". a recoral I46 hatchlings"pp""' were sighte'I- and yet on t}le ."itt=tt.l* drop on caalell River onfy 9 were seen. what htppened? why the sudden mainstream? we are tir"-c.a"if ii.r.t-.t a the sudden increase on the Blyth these questions satisfactorilv at present but believe "i!ui"-t"-"".*"; food an'l the condition factors of the animafs ii-t"i irr. level of avail;ble in the l"'i"""i""a in a"t".*i"i"q whether. thev nest earlv or late il;-.;;; during it' ;;i ;;;;"t and whether thev nest once or twice or even at all 256 As shown iD Table 2, tt|e nunber of small crocoaiiles sighteal, increaseal from 197 in Noveniber 7992 to 2Sa il] July 1983- Howev;; t;rs significant at the 9sz lever, consisted of 55 (2_3') ."a.riy-i-ii_i;i animals. one notes in Tabfe l that the 111 hatchlinq" ;toht.a in N-ovenber 1982 appear to have yielded 9g (2_3,) animais by Juty 1983. On tbe basis of hatchling survivorship studies maale on the ;lyth_cadelf syst-en (Tab]e 8-4.1 Monograph 1) o;e would r,ave 70x of Ene natchlrngs to have survived and hence to have""pec!ea;bout only siq}lted some ?8 rather than 98 (2-3') animals- On the basis of our mlaeiione miqht expect to soon find a substantlal atecrease ih the number of small animals sighteal. However in view of the record hatchting recruitment on the BlyLh m-ainsLreamdu-cinq 1983, fottowing high hat;hfinq lecrurtment rn lebz, the number of smal] and (3-6,) aninals coulal be remporarily exaggerated. even further by the resu.Itant (2_3') aninafs - ltowever. the important size classes to watch are t}le targe and (3_6,) ones. A study of tlre distributionaf pattern of the (3_6,) animals on the Blyth_ (Table Cadell System 4) is of interest anat again hiqhliqhts further the Clynamics of the situation. Though the numbei of (3:6,) animats sighted on the June and November 19e2 and Juty 1983 surveys remaineal esseniiutty constant, 153, 154 and 160 respectively, their di;tribution on the ,ate;dt, varied greatly from survey to survey. This is further atelineated in the Table be1ow, where we }ave also included the atlstribution of large arfr6ls. The km 0-20 section is calleal the moutb section of the Blyth and cqrtains all of the major sidecreeks. The cadetl River Joins the;tyrh at km 19.I. On -June and irufy surveys one normally sights a tigher density of (3_6,) and farge aninals on the mouth section oi rhe Blyih River th;n on octdber or Novenber surveys when the animats have been either forced out of the waterway or further upstream. On the km 20-49.9 section, we founal during the-Ju1y 1983 survey some 23 (3-5')- animals missing since the Noverdber 1982 survey. Howevef, on surveying the mouth secti;n of the Blyth River 14 additional (3-6') animals were sighted and on the cadell River t4 additional ones. This matter simply highliqhts again the alanger of drawing conclusions about g. porosus poputaiions ior a whole waEerway rrom resu.rts galned on only a part of it. (3-6') Size Classes Larqe ( >6,) Blyth River .ttnre 82 \ov 82 July P3 oct e3 ftrlle 8 Nov 8: July A: oct 83 hl 0-20 52 36 41 29 12 24 14 kn 20 49.8 51 34 43 12 13 11 9 Sialecreeks 13 9 10 r0 6 3 2 2 Cadeu RilEr 66 5',7 20 11 10 Totals 163 154 160 151 67 39 50 35 251 4.3 october 1983 survev This survey provitleal aalditional evialence for very consialerable movement of animals between the various components of the river system. Examinaton of the Table above shows that on the Cadell River, the October sulvey revealetl 9 (3-5') animals fess than on the July 1983 one. From Table 4 one can show that 16 (2-3') animals were ndssing also. On the Blyth km 20-49.8 section precisley 16 (2-3') and 9 (3-5') additionaf animals were srqhted. The above Table highlights again the realistribution and,/or excrusi;n of animals in the (3-6') and large size classes which takes between the June-Jufy and october-Nove ber surveys. It also shows that the influx and exclusion of animals occurs largely via the noutb section of i:he Blvth River. However, as discusseal ln the section on Alternative Habitat, a smalf numbet of (3-6') and lalge anlnals appear to be forcetl to take haven in alternative habitat during the breealing season' For instance, an adalitional 3 large anil 2 (3-6') animafs vere sighted on the extaeme upstrean section of the alyth River during the O,ctober survey and p!oba61y includes the missing 2 large animals from the tm 20_49'8 section- fie same phenonenon was noteal in the october 1982 surveys ' Tables 1, 2, 3, 4,'7 and I contain the results of our final survey of the Blyth-cade11 Rivers system. The results contained no surprises in refati;n to the (3-6') and large size classes and followed the apparent pattern for October-November surveYs. The consistency of this pattern in 1982 and 1983 is indeed striking. overall tlere was a 'lecrease of 9 (3-6') i:-e,l ."a 15 lalge animals since the July 1983 survey. The 9 crocoaliles and 10 large animals were nissing from the mouth section of the Blyth River. Recall that 12 additional large animafs had been sighted on the mouth section of the Bfyth during the JuIy 1983 survey' Fuithermore, it had been postulateal tbat this increase may have lnclude'l some of the 15 large animals whicb had been excluded fronr tbe Liverpool- Tomkinson Systen -that these animals were probably on their way back to successful in estabfisbing a territory the Arafura Swanp, not having been '\'/as for themsetves o-n ttti. occasiott. we predicted that if this so, then it was highly likely that the aninals would also be excluded from the Blyth Riv;r by October. our survey results support this contention and th; missing 9 (3-6') and 10 large animals are either missing -presumed aleaal or on their way back to th; Arafura swamp via the Milingimbi compfex' Our october 1983 surveys, however, dial not reveal any aalditional large animafs in crab, Anamayirra ol Beach creeks (in fact there was a 'lecrease) to the west of the Blyth River nouth (Fig. 3 and Tabte 8) and no atlalitional (3-6') or large animals, since the June surveY, in Nqandadarxla creek anal the Glyaie Rlver to the east of the Blyth River (Fig' 4 and Tabte 1). In the aliscussion of the Liverpool-Tomkinson results we referred to the heavv hatchlinq losses (121 to 63) anal very 1ow (2-3') surDrisinqlv DreciselY i".'."r t8i io ?7), letween iheJLrly and ocrober 1981 survey5. of tfre sanre thlng occurreal on the Blyth-Cadell Systen' -The nuniber ;.a"hii;s siq;tea decreased from i57 to 73 (a falf of 54% compared to of the fall of 1Oz to. tg?g given on page 391 Monograph 1) ahd the number for errors 1--:;j an;*af. decreased irom 98 to 95 onlY- Even allowing in size class estimation, these are startifing results' wbY were there .ip".iirly healY hatchling losses during the June-octuber 1983 period 'dry followino the second consecutive wet'? why were there excee'lingly 258 Iow losses (2-3') of animafs occurring at the same time? Are they scrlelsr related? ,Why were there very low hatahling fosses bet$/een November 1982 and July 1983? fie are unable to answer th;se questions. 4.4 A teh year overiew y: g]pttgd, usins rLabtes3 an.t 4, the numberof (3_6,), rnelr:l^lls:-.] (J-b rarse sun l ptus rarge, or ( )3') animats sighted on the 19 gene;a1 surveys of the Bfyth-Cade1f Rivers System over th; past 10 years. plot The reveals in a dramatic fashjon the picture of a!.namic ctrange to whicb we have referreal to so often, especlally wl]en discu;sing the (l_6,) and large aninals. Especiatty note ltre drairatic arop tel\,reSn rhe Septernber and_Octobef lo77 survsys. One has the picture oi a coupfe of hundred (r-o i anrmars which are tre.ing added to year after year from the of hat_cbtings t:c:y:tmelt several years earlier and yet the nlmber of srgf)ted remalEing constant or decreasing. The number of (r-o , anrmals srghtect on the tidal waterway during the surveys of a given year is at a maximum during the May _;arly S6ptember peiiod, ttre non-breeding season when aggessiveness between ;nim;ls of a1I size cfasses rs ar a mtnrmum, anct is usually at a minimum during the breedinq season arouhd the October period, \,/hen aggressiveness bet;een tlle anima-Ls is at a rnaximum. The constant battle which goes o:1 for the establishment of a territory leads to the exclusion, influx anat heav], losses of the (3_6,) animafs. But natters do not rest here for one sees essentially the same thing_happening with t})e farge abimats, many of which are stitf not sexually mature. However, as seen in Fiq. 1, sone of these animats are successful in establishing a territory and hotding it, for the nuniber of -Laroe animafs sighted is increasing, the major Jump cominq after the ,dry wet' of 1978-1979 when sohe 32 large animals were iorced out of the dryinq freshwater complexes and into the aidat waterway. these inrmars then bad 1lttle c}loice but to fiqht for territory- appaiently sone succeeateit- Alf or Enas appears to be superimposed upon a base, made up of sone 15 to 20x of.the 1>3') an-inals sighted !.'hich ;ppear to be succelsfu] in establishing a territory in the wateruay without being exclualeat in the first instahce: Ior example, we have just recaptured (on the Liverpool_Tomkinson) 2 large animals whiclr were captured and markeat as hatchtin;sin 19?3 and 1975 and one of these animals was recaptured at Ure originai capture site anal the ottler only 1.8 km away from its original captu;e stte- T'"/o,other animals captured originally in 19?4 were recaught in 1980 and 1981 only O-8 km and 1,5 km respectivety from their original capture site. Of course we cannot say where these aninals had been in the tntervenino years- It appears that on the Blyth-Caale1l, there has been a atecrease; between 1975 and 1983, in the number of (3-5') animats which could hotd a territory on the System (we do not use the 19?4 figures except in spe_cial cases because the figures of that year incluAe both caitures and sighting of animals missed). whereas in November 1975 the figure was 1g3 (3-6') animals, in october 1983 it was down to 151. This is opposlte to what appears to be happebing witb the 1ar9e aninals. In November 19?5 the number of large animals sighted was 14, in October 1983 it was 35 or an_increase of 21 ober the 9 years, or if one compares the September 1976 anal July 1983 numbers, the increase is 24. it aDDears as if there were a set number of territories or slots in the rive;-system anal the increasing of this number results in the 1oss of a very iriqh fraction of Lhe animals trying to secure these territories. 259 In the Section on the l,i verpool-Tomkins on ? r{e calculated the maximum average percentage of hatchlings whicb survive to the (2-3') stage and found the figure to be 3?2. Doing the same fo$ the Blyth-cade1l, for the years between 19?4 and 1983, yields a figure of 709/960 o''74%' Why is there a alifference by factor of 2? could it be related to the faat that the nunlber of large animals in the 1-iverpool-Tomkinson was generatly grater than in the Blyth-Cadefl over the peri-od? But then itry ao tire-"u.ler of (3-6') animals sighted in the B]yth-cadell appear to have gone down beti^'een 1975 and 1983 and yet the Liverpool-Tonrkinson they app6ar to be about steady? Again e are unable to answer these difficult 'why' questions and leave to future generatlons' As for the Liverpool-Tonikinson we can give a Table showing various broa'l estimates for the minimum exclusion and,/or loss percentages for the {3-6') animals. MininriTr ? of (3-6') Suwel' (3-6',) Larqe () 6') anima-Is excluded anal,/or lost 183 14 (183-21),/183or 892 Nc /€fiber 1975 octcber 1983 35 septdber 1976 171 26 ll'77 4I\ /I1'7 oE 17% Juhe 7982 6"1 'le% Jrme 19'7-l 196 l1e6-A2)/196 or J\me 1982 6'l Nolenber 1975 183 l!83-251 /783 or 86% Novenber l9A2 39 octcber !9'7'7 158 22 (15a-1, /$A or 92% Octcber 1983 35 I'rom the above Table one sees tbat for the Blyth-Cadell the minimun lost pelcentage is very high also, generally in excess excfusion anal/or 'dry of 8O%. Again, if one assumes tbat the wet' of 1981-1s8? had concentrat;d back into the Blyth- cade11, nearly al] of the surviving tirge aninals originally recruited there -and none originating fron -presune'l els6where- then ?t to ?92 reconres the estimate for the nissing dead (3-6') animals. 5. OCTOBER1-4, 1983 SURVEYS The sunmary results from the reduced lrune and october 1983 survey data for tidal waterways of Rolling and Junction BaYs (Iig. 1) are shown in updated Tables 1 aod 6. 260 The fact that the 1982-1983 nesiisiblerloodins trorrou,iX!'oi'iill Xi=.i3'iir.-_i8il -.1p."..IyY::; perhaps reflected Illl, r= in increased hatchling ,..."it.""i, o., Nungbutqarri creek where 34 hatchlinq rtr'6." .;qht;d a,lri"n? trr. .rorr. surveyr the maximun number siqhted o; previoui ,".";t;-;" t0. These hatchtins were concentrared mostty betiveen km s ;;;-i;,-i.,"t"ii creches ;" oo.rr""" were sishted anal it is liiely tr1"t fr,.." -;;i;-;;"h;;;;i;;;"i .^",,r*^^ from onty one or t!r'o relatively succlssful "." were sighted on the October survey. """4;- Hatchlinq recruitment on the coomadeer River in June was 24, nuch same tbe as that found on June-Juty surveys after previous ;d.y I,.".. 1979 (29H), (1BH) - 1982 and ocu;reat on- the same'secii"n" tfl. watervay."..=or,", survey,.33 harchlinss were sishteal i"ei;u;;ns"e that may9l--.1:__9.:g?.. have rhere been an additional input from one o; more late nests. Four hatchling were sighted in TypE 3 Majarie Creek in June, where sporadic hesting is believed to occur (page 6t Monograph 5). No hat_chting were sig}lteal on the october N;' ;;;;fir i"g, ro"." sighted on T!'PE 3 Wuruooi i creek on either";.;.y. ihe t,rn. oi o"ioo.I. Thus overatl, 62 hatchlih;s lrere sighted o" tr," a-..i..ij;s of Junction".r..r.y". and RoIIing Bays during orlr.r,rr.,e survey and 48 on the October one. are to be compared with the previous maxinurn number of ry ndEcnalng srqhred durino the July 1979 survey foflowing t}e ,dry wet, of 19'7A-19'79- The (3-6,)-animals 57 sighted on the overatl systems both during June tte and october 1983 survevs are to be compar-d with the 51 durins ane sigbted the June and october 1992 and s6 and'60 ;. a;" j;;" and ocrober 1981. surveys, respectively. Ttus there has been filife-o.,eratr cf,ange in the number of (3-6,) animats sighted durinq the i".i i'",]r\,.y", o. may be seen in Table 6 there has been only tiitte cf,anqe since the August lo75 survey when 46 (t-6,) animats were.r€hf;J:- rhe row rtqure Iq76 rs probably ?:_:3.Ig: accounre.t for by the r]ist"ii" i-rooas of the wet season when the sea penetrated severaf kitometres inlanat. Many of the smaller animats l^'ould have been swept .".y dispersed the_time- at The number of (3'6,) animals sighteat au.i"i ""aigiz increaseal !o 19 a-nd on the July 19?9 survey 56 were;isbted. ri.r",. doubt now little that this.relativety hish number i" r"i-iy ti," ,e.i."t wet' on (19'78-I9'79) ""i"""i"a record when animats in associated freitrr+ater compfexes were forced, by falling water levets, to re_enrer tr]" pointed iia.t systems. As out in the DlscussloN, we now befieve that some of the increase may have been derived from the Arafura Swamp (howevei a substantiaf number could also have been forced out of s;amps ,1e.i ir,.-coornaae". River) and that a few of these animats nnay t-""i, ret"i"ea to there by the June 1e81 survey- stu.ly of rable 1 shows that nearry ar1 rne:ll"-:I_:l: anlmats of concerned were in size classes )(4_5,) and t})at as woulat be expecteil from our model not many animals in the (3_4,) .ir. "r."" "".. The situation in retation to the large animals is somewhat different. There was a major influx of larqe animals after the recorat ,alry wets, 1978-1979 of and the most tikely sources are the minor swamps of the Goonadeer and the Arafura Swamp. As expecteal, the numbei of targe aninEls sighted droppeal between the July l9?9 ana .r"rr" fSef s;rveys, from 33 to 22 in June 1981 and then to 12 only on the october 1981 ,qg"r" we believe tlat some of t}ese animils may have returned to"i,r""V. the Arafura Swamp and the large fraction to the other. associated freshwater comptexes from which they came. 267 'alry Fofloirinq the wetr of 1981-1982, there was alr influx of large arlii6ls iii" tfr.-tra.f wai"tway. of Rolling and Junction Bays againt the nrhber ttt.r.."lng from 12 to 29 betveen the October 1981 and June 1982 i"i""y"."fqht"a rft. nun;er sighted theD ilropped marginafly to- 24,for the o.i"l!. fgeZ survey anal to 21 for the June 1983 one- The october 1983 25'1arge animalst the 5 additional large animals could i""f"i."".""y-.""."f.a tft. missing 5 iarge animals from Anamayirra, crab and Beach Thus ct""ir tr.uf" 8) oi anirnals from the Loverpool-Ton*inson system' it-;;;.;;; irrat'rew if anv of the 1? additional large animals sishte'I ;; t;; J;"" 1982 survey h:d returned bv october 1983 to the area from tft.y came. This is in keeping with the fact that the wet season 'drv have "fti.trli-idei-i6s: was again a wel' ind hence the aninals would not been able to retur; to the area from which they were force'I to leave oriqinafly because of fafling water levels' the our results show that there can be considerable adjustment between a wate.ways, ln the number of aninals sighted on them' Note the the ;";;;;;" iiom e targe animals sighted on Nungbulgarri creek 'luring o;tober 1982 survey to onlY 2 large aninals sighted dur-ing the June 1983 survey and th; increase from l2 non-hatchlinqs sighted in Malarie creek in october 1982 to 20 sighted aluring the June survey' over The survey resuft for the 4 waterways of Junction and Rol-Iing Bays il. p..t-6 years {rabte 6) appear to le in keeping with th"se for the (T€ble ."t3t""ys of our laaningridad monitoring area 7) ' that is "".._.ii;a;;;y, or malginallv increaiing, number of (3-6') animafs accompanied u.," .r, .ito"..^t iicrease in the nu;ber of large aninals si-ghte'l' comparing (see section on iira l"sit'"t 1975 survey re6ufts with those of June 1983 the the Li;erDool-To-ift. kinson as to why not october 1983), one fjnds that in i""t".=.- i n'rtler (3-6') animals v/as 11 onlv and the increase " "f however that on i..q" i"i."tt was 9 -a relatively targe increase- -note onIY 12 large aninals vere sighted as in 1975' lhe-octoter 1981 survev (3-6') it"t-ir'" igzs .,r.,,"y maaein Auqust). rhe ratio of. to rarse j"i..i"-"pi".." to ie "i.aecreasing but there are. substantial fluctiations ' l".""se of the relatively small numbers involved and the iiilusion"""i.""t.'a^ of Majarie and wurugoij creeks, both rYPE 3 systems' 6. ALTERNATI!'E I1ABITAT surveYs to these two A helicopteiwasuseal for ferrying the survey boat an'I staff (Fiq.-2). when Beacb (r!2'2' km) uas ;";;;;ii;-;;i"i -creek on aluring 1982,"i..t. 6-crocoailes, 3 (3-6') and 3 large were sishte'I (Table The tbe"iri""i.a Julv survev ancl r t5-o / animals on the october one 8) ' (3-6') large ir.""" i,f-i"".'z?,-lrt"= 1983 revealed ? crocodiles, 6 and one irt" sighted on the 'tune 1983 survev was back to however that ii.""i'tit."ri.ii, same nurl]3er"uml"r sightea on tlre Julv 1983 one' Note indicatlns iitJ-.ir.--.ti".t"re of the animafs sighted r^ras different' may have left the creek and others had entered it' tii"t . animals (albeit' "" for'consialerabfe movement of animals the r"iir'"i' from ""iii."".i"""i;;a are slnall) into and out of the waten'av was sained i"iultt" back to the october 10. 1983 survey when the number sighted had dropped sighte'l on the z i:-o') anim.ts. almost the same again as the nuniber is also October 1982 survey. That the animals are moving in and out first 800 inalicateil by the f;ct that nearly all sightings are in the metres. 262 syrlrey lhe of AnamayiEa Creek ((V.3 km) on J-une 28, 1983 resuLteat in the siqhtlnq of 16 crocodlles -exactly the sanre if,.t was during previous sighteat the two surveys of 1942 -quite "u.l"i...r"ir."ii" coincidence- aniriars was e (j-6,) ana" i i"iq. i, Jury, Tl".:+,_"_:.:"::!::rJ-o ano 9f !h: 11 / ) Iarge in October 1982, and 10 (3_5') and 6 iarge tn June 1983. our survey of october 11, tses revealea a'"i"""itiJ" only, 5 (3_6,) and large ahimals. Thus 13 animafs are missing frorn the_two creeks, 9 (3_6,) and 4 large, since our \lune survey. What happeneal to them? 6.2 Toms Creek, Julv 1 and October 13. 19g3 survevs We made our first systematic survey of Tons Creek lqig- 2), a hypersal.ide coastal waterway with a surveyable length of 8.9 km, in igZe ana tf,en annually thereafter untif le79 (st. ru;ia 19821. oi lii.-ii\r. previous surveys, no survey revealed more than 2 non_hatchtings, until in JuIy ;ur resurvey 1983 when 6 anima-Ls, 5 (3_6.) and one taroe 6n" *"r..r-"*-^ -.iZ_:.f, (rable 8)- on rhe october to83 survey 4 crocoa-ti,-ji (4-5,) (6-7,) and 2 animats- Thus To;s creer is ".i. "iqr,i.E,frequenteat a smalf by nuniber of itinerant animals, moving in ana""ii""itv- oui Ji'tne liverpool_ Tomkinson System. 6.3 crab creek, June 25 anal october 20, 1983 surveys This 3 km hypersarine coastal creek (Fig. 3) was surveyed in->7,) Noveniber r9B1 and asain ln october 1982- Two rarqe ciocodites sisb!9d. ieo tei, r^,"." gn the firsr survey anal one crocoaltte (Eota,l; aurins trre second ?:: _(T:b19 9l: rl. survey of June 1e83 asain revJareit'z Jlocooires @w /o , o-t t ano on rhe October one we sighteal 2 animals (5_6,, EO)6,). Thus as.far as q. porosus are concerneal, Crab Creek appears-.nir"f. it provides unimportant; a temporary haven for several (3_6,) i"a-iirq. o"fy. Whetherthese are animals which were j excluded from the Blith or the L verpoo.I systems we are unabte Lo say, however tr," iaiili"ts-tfl"-more 1ikely. 6.4 A helicopter is used ro dain access to the 4 km long Cadell Big ferrying Biltabong, survey boat ahd sraff. The biltabohg triq. ii-!r"= rir.t systemaLically surveyed on Juty 9, 1982 when i g- ioro",js u,ere srghted, 3 Eo.-one (3-4) )7' and a animat (Table 8). o" ti,i-i"iE::o,-;;d-;"e 1983 survey only 3 crocodites were sishre.t, one so >6;; ad_dt (e_10;):. rhe october 9, ""; lqg.l survet revealeat 3 animats and (Eo >6,) . "qji",'.--ii_?,f,(7-8) survey of Cadell cardens Billabong on tbe night of July 10, 1983 yiefded 3 crocodiles. as it did on the Oct;ber rSaZ srirvey. W.'.iqht"a Z and one( XO ta-S,t >6') aninafs. On the survey of October 22, ---1683 rre sighted 3 animals asain, a (4-s,),a {s-6,) ."a tro t;;t---' " It is evident that the caatell billabong nornally only contain smatl rnliL,ers of (3-5-') and rarge animals excruded fiom the cia"ii-ni".i. These numbers with the observarion thar the or-L.taoongsl::,i:,\::p+"s avaitable rooa in these is quite limited- Sporadic nesting a"., p"."i,-r". ",rppry number of hatchlinqs in t9?3 a were caughi in cadell c.ia""r-aiitJ""g Ey aboriginals. 263 6.5 Extreme upstream section of Blvth- RivCf Ln 49iq-and blllabono ffi?612J4.5 ,'ulv 11-12 and october 23-24, 1983 survevs (Fig' The extreme-"iqht upstrean secltons of the Rlytb River 3) v'ere resuntel'ed tfr" Juty 11 and 12. The results of the surveys are shown in""- Table d- "'llot. "f how t}e number of (3-6') and large aninals sighted during the ilZ) in o"toU". 1982 had rncreased fror. the number sighted j""" present 1983 r]i."i""" rsez survev (4) and how again on the JuIv !ri".v-ifr. numler of (3-e') and large crocodiles sighte'l droppe'I from nere ii-i"'r- wrr"...s aluring the october 1982 survey 3 large crocodiles present survey right"a i" the billabon; between km 60'6-64'6, during the none were sighted- predicted As pointeal out in the st. Lucia 1982 paper 6ucb variation.is ;;;--;;;"i ind provides turther suppoit for our contention that sub- il -especiatly the .t" beinq ;tcluded by the larger animals during the ;;;Jid"i"it= rf the animals are not excluded completelv from jnto less ;;a;;.i, """.o,'lthen as in the present lnstance thev are forced watelway' aesiralie habitat such as the extreme upstream section of the season ii". x* Ss to krn 59 the river is very rocky' wit}) the breeding of the over, the animals appear to again return to the main sections the fr..irl"q system. rir-rttrer supfort for this view vas provided bv (3-6') larqe results of the october 1983 survey w:ren the number of and no =iqht"a had increased bv 2 and 3 respectivelv' -Aqair ""i."i.ciofoaife."were sighted on the bl11abonq between km 60'5-64'6' 6-6 Liverpool The sandy and snag-ridalen terminaf section, km 60-66'4' of the prewious xin.i *"i"=t..u., which was not normally surveyed during on three occasions durins 1e82 and 198:r and the ;;;;;y;;-;; survevea (3-6') -i"iq" for- these surveys are shown in Table I' A small number of results to i"i*.fs frequent this section of the mainstrean ard it is for both ;;-";ae6""a that the numl-er of tarse aninals siqhted was larser of the October surveys than for the JuIy one' 6.7 General gaining the some 75% of our survey effort during 1982 and 1983 was spent we believed it I"?".t".ir"" .n""" i" iable 8, for tiose vears- However gain entry to' important to survey every bit of babitat r"e coul'I was tF' €rious i,"ut., vehicles and a hel.icopter, r' order to eliminate i#liriiiiil=';;"Ii"._ io .l'"'" t"e rarqe nurber of apparFntrv.rissinqcroccdires habitat does ;;;;;-;- ei *"v l" seen in rEbre 8, the alrarnative and small anirEts ' iio.'ia"-."." inpircanr rcarinq stockvards for both laroF ro hundreds i;;-;;; ;;;.;';i animals invorved i; snall conpared the 28.larqe anlnals *i=ri.q. rtt" october 1983 survev vielded 24.13-6'-) -and the Julv 1e83 ;;;;;;a to 48 (3-6') and 25 larqe-anrnrals siqhted durins (3-6') larse ;;"-:-;";";""."-"iqltt"a to rable ?, sho;s that of all the and 5% of tbe (3-6') .ri^"i" during the october 1983 survey' some habitat' ."a ZSz Iarge inimals Itere sighte'l in the alternative "f-tn" 7. hypersaline creek (Figs' 1 and.4) was first surveved on This important or ;;i"il:;- e;' ls r-5'ana aqain on June i4, 1e?e when the universitv ;;;;;;;" research v".=ei used to qain entrance to the Milingimbi "a. 264 Complex of (Monograph tidal waterways 9). For togistic reasons. we were. unable t-o resurvey Ngandadauda Creek until ju.,. of-rye t wntcn lame a heltcopper was useai to ferry our survey boat anal"t crew to this TYPE 3 coastaf creek which has a navigavle i.ngit ot ZO.S t., and a sidecreek at km 9.? with a navigable ];nqrh of iome 3 km. It was most important that we resurveyeal the creek this vear both in June and ,ary October- Foltowing two co;secutive weis',.our moaef woulal suggest that the creek shoutal be actinq u. .'f,i.,.r, to.. substantial number of both (3_6,) and large ;nimals excluded from the Blyth River and excfuded o! forced o.,i rro. 1},. iiva. ai""._ Arafura Swamp- Thus, it coutd be acting as a laven toi- some or trre 28 larqe aninals which had lefr the Blith aivei lv tfr. [irn" or o,_,. Novenber 1982 su!:vey (Table 2) _ probaily on thei; l..x to tfr. Arafura Swamp from which they had been e;ctuded or ""ytoicea out previous ,ilry aluring the wet, of 19e1_1982. gornever anothei ;ai" *.t, lntervened and the animals t^rould essentj-ally be ,caught;-in the Milingirbi complex and the clyde River untii ttre wet"season of 1983_ 1984. It is fikely that some of the animals on tfreir rviv back to the Arafura Swamp had been recruited on the B1yth_cadeft syitem original1y. The survey on the night of June 26, 1q8) futfilled our expectatrons, 30.crocodiles \,/ere sighteal. 20 (3-6,) and 10 1ar9e s".""., note from Table 1 that of the 30 aninals sighted 13""i^ii'". were Eo, suggesting tlrat these animals were exceedingly wary and hence that a fi:cLlgn of theF. probably :lsl had enuerea iti creet< onry recentty. rnese resutEs are to be compared wtth Lhose of Septiembei 1975 when r naLchlrngs, 2l2-3t),9 (3.6,) and 5 large animals were sighLedl and with those of the June 1979 survey, foitowtnq the record-,ary wet, of (3,6,) -19'78-19'79, when 10 and 11 f;rge anlmal; were observeo ltabfes 9.22 and.9.23 Monograph 9 and present Tabte 1) . Ngandadauda Creek was resurveyed for the second time durinq 1983 on the night of October 12. On this occasion 21 crocodites we.p The results of the two latest surveys support further our conrentaon that Ngandadauda Creek, which is a TypE : waterway, is farqely frequented by animats coming from other waterr\rays; such as_tha Blyth_ Cade11 System and the clyde River-Arafura Swamp; !rh.ich act both as breeding and rearing systems. The creek acts ai a temporary haven and/or rearing stockyard for sub-adults exctuded or f;rceC out from other systems, like those above, untit the animats are abfe (pages 39, 40, L22 - 124 and 125 Monograph 9). We record here tr.ro important observations made during our last survey. The_measured satinity sone 4 hours after tow water oi trq;n;adauda creek at,km,20-9,the terminaf-survey point,was g3ol00. Tlis ii to le compared wrth lhe measurement made at hiqh tide on Creek C of the adetalde River in September 1979 (paqes 375_37?Monoqrapti t) of 85olOO. Furthelmore a (4-5') c. porosus was srghred at km 2O.i on ns."a.iJ"d.' ;"eek where the 265 satinity was 78ol00. We have never before sighte'I a crocodile measureil (7-8') i;-;;a;;" as hypirsaline as this. The previous record was for a anlna1 siqhted_Ln creek c of the Adelaide River; the measure'I high tide 610100 anal the extrapolated lolr tiale value was 75'5ol00 ""fl.itv;as(same referencie as above). rn the early monographs (Monographs 3, 5, 6 and ?-) of the serie of 17' we stateal r6peatedly that our results inalicated that g' oorosus appears to toterate ityp"r""iine conditions poorly an't that crocodiles tende'l to ieave highty i-ripersaline waterways. we were perple>(ed-by this matter for a numbei of years. Holrever by 19?9 nurnerous additional observations toferate very showeal that 9. porosus in all size classes are able to frfon salinitfes, but probably for sbort perioals of time only that the that ii,i" p.ii"a may be siie dependent (paqe 380 Monograph.l) -' .since gfands in both g' Doroius' date iaplin'iofrnsto"f ani c.igg discovereal fingual salt .na g. th;; providing a m.ihoa of getting ri'l oJ excess salt' rn aaaillEi-ie havl a nuch clearer unalerstanating of the 'Iynamics of a. ;;;;;"" populations""w and of the itinerabt crocodiles. mostfv sub-adults ' ;".rt"titto ih; hvpersaline TYPE 3 waterways - Exclusion of some 802 of ii!-."t-",iuft croiodiles fron TYPE 1 tidal waterway an'l their associated freshwatet comPlexes appears to be the dominant factor involved in the DoDulalinq of iYPE 3 watenuays- Ttinerant animafs are more 1ikely to i.e_excluaed fron TYPE I and,/or TYPE 3 waterways during the Septerber- Noveniber perioal, the breeding season, when crocodile interactions bet$een alf size -1asse. .ppear to reach a maximum (page 457 Monograph 1) ' This ii." itipp"". to be-ihe period {hen salinities increase rapidlv in the byper.aiine TYPE 3 waterways. A {4_5') crocodile staying in water of g!'o/OO sau"ity must be paying some metabolic penalty; a penalty he is forced to pay to stay in the creek- 8. GLYDE RIVER-ARAI'URA SWAMP The results from the survey of Ngandadauda creek on the night of June 26 dictated that we resurvey the GIyaIe River anal afso make an aerial it"ii""pt.r survey of the Arafura swanp (Figs. 1, 4 and 5)' It appeare'I cruciai that we do =o and resurvey in october, if we were-to obtain a of what was haPpening to the (3-6') and large *oie co.prert""sive_on Picture 'dry animals the northern Arnben Lanal coast, folfowing tNo lret' seasons- This meant re-arranging our 1983 survey schedufe and c\'ru)licating i"rtfr"t tft" areaaly complicatea l;qistics of our survey prograt ne' The Glvale River and the Arafura Swanp are some 150 km, by very rough busb i;;;k, ;";a of Manlnsri.la. Ftvi;s in survev qear bv helicoPter would simply be prohibitiv;ly expet't.i.'" and vehicutar access had to be made' 8.1 Julv ?-8, 1983 survev Following the 'alriest wet' on record of I9'7a-19'79, when many croco'liles had been forceal out of tbe Arafura Swamp, we sighted during the July t9l9 survey of the Glyde River 36 {3-6') and 19 large animals compared i" ir-il-iil and 11 llrge durins the septernber 19?5 survev' Followins t;e two 'dry wets' of 1t81-19s2 and 1982-1983, again we expecte'l to i nurnber of (3-6') and large croco'Ii1es in the Glyde niier."ighi especially""bit."lial on both the mouth anal extreme upstream sections' And so it turneal out. 266 As nay be alealuced from Tabfe 1, 73 (3-6'),of irhich at least 35 were in the (3-4') size class, and 31 large animals were sighteal. I.urthemore there were 19 arimals sighted on the kn O_5 mouth seation alld the majority of these were 1arge, 15 of the animals were sighteal between km j-ndicating 0- and 2, strobgly that they were either ente;inq or feavihg the river (in fact t}le October survey indicates tley vere entering th5 system). ?hree palrs of these large crocodiles were sighted inte;actinq, that is. one was in the water directly facing one up on tbe bank- On the terminal km 40-45.9 section of the river, 3 hatclrlings, one (2-3,), 11 -most {3-6') of which were in tbe (3-4,) size ctass- anal 5 farqe animals were sighted. However on our helicopter aerial survey of the ;ame secticrl of the.river, during the day of JuIy 2, we sighted 7 large (sonre very larqe,) 13r, which one rarely ever sees at night because of their walaness. probably qoing back to the alays of shooting) crocoaliles on the last 2 km of the surveyable section of the ri-ver, th;t is from kn 43.9 to 45-9. It is highly probable that most of these animals hail been forceal out of the Arafura Swamp, because of the low water 'dry levels following on t\ro consecutive wets,. During the JuIy 1979 survey of the clyde;e also observed a hiqh density of crocodites on the mouth and upstrean terminal sections (Fig. 9.59 Monograph 9), however the overatf nu;ber of animals concerned was less than tbat sighted aluring the present survey- The fact tbat the number of targe animals siqhted aluring the July 19g3 survey of the cfyde River was considerably higher than ihe nunber siqbt€d 1n Jufy 1979 ( 31 versus 19) is not surprising. The JuIy 1979 survey- followed on indnediately after tlre record ,drt wet, of 1i?8_1979 and the crocodiles which had been forced out of the Arafura Swamp were spreaal throughout_ the tidal waterways from Arnhem Bay in the eait to ttre 26'7 Two interesting points arlse from a study of the size structure of the animals sighteal. The Glyale River bas qood breeding habitat (so does the Arafura swamp wheD the water levels are up) and yet after a rdry wet' seasoh, when there could be little or no loss of nests dlue to ffoodlng, only 5 hatchlings were sigbted aluring the survey. Surefy there must have been more? coulal they }ave been cannibafized by t}|e increased number of large crocodiles? And wlere did the 35 (3-4') animals, shown in Table 1, come from? Dld they arise from normal recruitment on the Glyale? Tf they did, then there must bave been an excellent nesting year over the wet sea€on of 1980-1981, which we know had heavy flooding. Hence it is likely that host of these {3-4') crocodiles come flom elsewhere -perhaps from the Arafura Swanp anal/or the Blyth- cadelt system? The Arafura Swanp nrust be the more likely source for a majority of these {3-4') animals. we wish to emphasise again what we have been saying about the increase in the number of crocodiles sighteal on the Glyale River, during the July 1983 survey. The increase has not arisen front a major population rin(rease slnce 19?5, but again, as in 1979, prealominantly consists of aninals which wele alreatly present in the freshlrater aCI which, because of the 'dry wet', were concentrated into the tidal waterways - We report here an observation maale on July on the Glyde River at kn 35.9. A (8-9') dead crocodile was sighteal midstrean floating with belfy up and the front half of the body missing. suddenly the corpse appeared to di\re at which tine we sighteal another (9-10') crocodile pulling on it, ag)arently in an endeavour to tear a piece off. considering tbe concentration of large crocodiles on the Glyde, at this time, it is likely that crocoilile lras kifleal by another ohe and that we were witnessing another case of cannibalism. we carried out a daytime aerial helicipter survey of the Arafura swamp (Fig- 5) on JuIy 2, 1983- water levels in the swamp were low anal with the exception of areas near old river courses, much of the swanp area at present coulil not proviale babitat suifable for crocodiles. Practically all of tbe old river courses were conpletely covered by a hea!'y of water byacinths. However, a number of deep billabongs along the olal river courses still had areas of open water. These areas coulal be expected to bold concentrations of g. !9p€.gg which haal not been forced out of the sl/amp and into the Glyde River. we sighted a dead (9-10') crocodife with a rear foot nrissing floating on its back in an old Goyaler River bed anal one (8-9') animal in a large aleep waterhole, also part of an old river bed- Surprisingly, only one probable old nest was siqhted. It appears that Iittle nesting took place aluring the 'alry wet' anal one may ask why. Bird life was very scarce and consisted mainty of magpie geese- 8.2 october 6-8. 1983 survev The resurvey of the Glyde River on the night of october 6 revealed 91 g- pg-fg-qq,s(Table 1). 3 (2-3'), 58 {3-6') and l0 large animars. The 5 hatchfinq siqhted on the iluly survey were missing as were 6 {2-3'). 13 (3-4') and 4 (4-5') anirnals- The nunber of large aninals sighteal xemaineal essentiafly constant, 31 having been slghted in July. The ratio of (3_6) 268 to large animals alecreased fron 2.4 in July to 1-9 for the October sur\,sl'. These nurnbers are consistent lrith the predictions whicb could be made on the basis of the population alynamic model o\rtllend in the INTRODUCTfON. It is to be noteal that, as predicted previosusly? there was no influx, since the ,tufy 1983 survey, of animals returning from the Milingimbi Complex to the Arafura Swamp. The alistribution along the river of the 91 atrimals sighted differed consialerably fron the ,tuly survey when 11 large animals were sighted on the kn 0-5 Rlor.th section of tlF ri\,ier. Cb tlle pr€sent su:veL cnly 6 large anjrnal-s rdele siEhted cn this section, ho,rever tlE nlllber of larqe aninlals cn the q)stream sections above lft 35 lncreased frqn 7 in July to 13 on ttle Octd)er suney. Ttlis furttpr sr{)lorts our viev,r that scne of the animals which had been cn the kn 0-5 section ln July werE ncving bad( to the s\dan[). By Octcber thel' were waiting on t*)eq)st.ream secCic'ns to re--enter the Ardfura Swafip aluring the fortnccnlng r,,et seascn. It seems reasonable that the animals which had been forced to leave the Alafura Swamp first were tbose which haal been exclualeal originally from systems such as the Blyth-Cadefl. One could expect animals hatched and reareal in the Arafura $tanp to be the ones concentrated into the few rernaining larqe billabonqs there. The exclualed animafs could be expected to try to establish territories in the system from whitch they had been excludeal originatfy, however in trying to do so, some unaloubtedly Join the ranks of the missinq -presumed aleaal. Others could still be on their way back, but the matter is very complex to unravel indeed. Some 5 hours of helicopter ffying time lrere used on October 5 and 7 for carrying out an intensive aerial survey of the Arafura Swamp. The swanp water level had dropped further since the July survey and there !/as a mere trickle of freshwater out of the swanp into the clyaie River- Downstream of the Gtyde River Crossinq at km 45.9, the river was alnost totally drained of water for servaf km at low tide. only a few inches of water were seen to trickle between the high exposed mud banks. Wtpreas the sallnitsy rn Juty hias 24o/o0 at km 0 and 1ol00 at kn 20, during the October survey it was neasured to be 34ol00 at km 0 and 20ol00 at km 20- Tn fact Lh- salr nity at kF I0 was str.tJ 5ol00. As during the July aerial survey/no definite old nest were siqhted, indicatinq that very litt-1e nesting occurred in the swamp during the 'dry wets' of 1981-1982-1983. Ofd nests would have been easily spotted had there been any. The failure to nest during the 'dry wet' is przzling. As \dili be seen shortly, there were some 32 large animals concentrated lnto the large billabong at OlaI Arafura and it is surrounded by some excellent nesting habiLat. latly !,/as there essentially no nesting? Twelve large crocodiles irere sighted from the helicopter during the day-time survey (including one very ]arge animal, 14', in old Arafura Billabong) , 10 in the open water biflabongs and 2 trapped in olal river courses, heavily matted wiLh waLer hyacinths. The large anal strategically situatetl billabonq at Old Arafura (Fig. 5) was surveyed on the night of October 7. This blflabono, which has a length of some 4.5 km, had some 2 km of open waterr tha remainder was matteal very heavily with water hyacinths- Even the open area of the biflabong was fringed by a heavy matting of hyacinths. This bilfabonq 269 ioins the Goyder and GIYde Rivers and could be expected to contain anlmals ;oncentrated into lt fronn elsewhere in the Arafura swanp and which ha'I not left via the Glyde River. Animals enterinq or leaving the s amp woulal Dormally have to pass through it. Thus we expectetl to sight a high concentration_ of anirnals. we rcere not disappointe'I, sighting 70 aninals' the highest concentration sighted by us during our 12,Years of research (2-3'), (3-6') on trt"'wat".*"ys of northeri Austrilia. we sighted 22 16 and 32 ()6') animals -a spectacular sight. No hatchfings were sighte'l' all the animals were in or near the edge of the lrater byacinthst some of tt,. 1..g" animals scrambleal frantically through the matting into the open water'when the survey boat approached the edge of the mattinq' i-"i"..iti"qrv, all except 4 ot :-h;22 {2-3') aninals were concentrated in the norih;rn balf of the biflabonq anal this portion of the billabong contaihed only a few larger animals. we sighted 4 pairs of large anilrEls in the southe;n half of ihe billabong, all of which were within a radius of 5 metres. at least 3 other pairs were sighted- These might have Ueen .ating pairs. only one crocodile was sighte'l out in tbe matting exienal"q 6ver tfre remalnaer of the biflabong at the southern and northern oi. spotlight woulil have pickeal up any eye shine to a 'Iistance ""ar.of some 300 metres. (HM) Billabong was first surveyed by one of the autbors in olal Arafura g' iiiy'1glz, at which aine the davtime survey revealed one very large por6sus )14' and another animal (10-11'). The nightime boat spotlight EiiiSy.6veal"a 4 animals. tle )14' aninal sishted during the dav' 2 oitre.'f".q. and one (5-6')- water hyacinths covered much of the billabd\q' However ind especially at the northern and southert ends, in 1972 also' th" *"i. ttot as tbick then as at present an'l theY floated freely over the ""."-surface of it, pushed by the wind- our recor'ls show that Droqress could-""il".ral be made throuqh the matting using a 12' fibreglass dinghy Tfris would not be possible in october 1983' !ia'.*"i r motor- 'dry It sho\rld be noted that the wet season of 19'7L-1'972 nas not a wet' have antl so there ltould not have been the concentrating process that we aliscussed. How many non-hatchlinq g. porosus dial the Arafura Swanp stjll contain i" o.t"i,". 1983? we pEirt"pJqi"" an informed estimate based upon """ lft" iesult. of our spotliqht survey of the strategicafly situated rnajor into cuFideraticn uiifif."s in the swa-mp- tie old Arafura Billabong' Takj-ng lfre temaitti.tg few open water bilfabongs an'l their situation' the almost and ;;a"i-;;;t ;";". tbe old river beds with a mattins of hvacinths the low waaer level "'rof the swamp. the number probably fafls somewhere arounat 200 with 400 being a verY generous upper llmai' just The afmost total absence of old nests makes one wonder how lTruch the breealing aloes take place in the Arafura Swanp and what fraction of that anlnrals are sub-adult itinerant from elsewhere' There is little 'loubt (2-3') ;;;-;.ai;s .loes take place as evidenced bv the 22 animals g' .i"i,t.a in ihe old Arafura Billabong- Apparently the adult Dorosus i*".p mainlv du;ing normat or heavv r'ret seasons and only"i'ii.-ar"r"fi rarely during 'alry"..t wet' ones. 214 9. DISCUSSrON 9.1 'Drv wet, seasons When Monographs 9 to 11 were written in 19?9. we had not yet completect res\rrveying the tidal waterways of the No!thern Territory coast west of Maningriala and were not aware that the substantiaf inlrease in tne number of. non--hatch inq g. Fofosus sighteal during the 1979 surveys, as c-omparealto the nunber sighted on the 19?5 ones, was in fact a general pbenomenoh on the tidal waterways of the Northern Territory coast and appeareal to be connected with a special event _the ,alriest wet, on record. Furthermore, when the 1979 surveys were completeal, we interpreted ttre satisticalty significant (at tle SSx'levei) i.r"r.""" in number of non-hatchling g. ,the g2I9€!C sighted, as indicating a slow but important recovery on certain major sections of the northern AustraliaD coast.. Wheo one analyses the sub_stantial amount of adaiticnal survey date we have gatlered in the interveninq 4 years, it appears that interpretation may have been overly optimistii ar ihat ti;e (Tbbtes l to /) and that tbe additional animats sighled were already present in 1978 and per:haps earlier, but were scattered throughout various associated freshwater complexes. A1l that the ,driesi wet, aliil was to concentrate these animafs onto the tidal waterways. As soon as another usuaf wet came / many of the aninals apparently ieturned from they came. In "Aaldendum August. 1981', pages 440,445 of Monograph 1, we discussed in some detail the influx of large C- porosus into the tidal walerways an 1979, which in some cases was accompani- by an increase (B1yth_c;de1l) and,in,some cases by a decrease (East and Soutb Affigator) in the nunber of {3-6') animals sighted. Comparison of data obtai;ed on surveys aturing- 1978- and.eSain durinq 1979, for a number of rnajor tiatal systems (_ea"f"iae, Bfyth-Cadetl, Llverpool-Tomki nson , East Atliqator, South AIligator. West Alligator, Wildman) established tbat the maj;r inftux of animals took pface between tl]e 19?8 and 1979 surveys. Iurthernore, consialeration of !It" 9?!9 foflowinq the completion of the t9B1 surveys. inalicateat that the 1979 influx may have been due to the ,driestwea, on recorat and that the number of (3-6') crocodifes sighted on subsequent surveys baal returneil to almost pre 1979 levels, whereas the number of ]arge animals sighted r:enained at a higher tevet than previousty, Update T;b1e 6.2-tt, page 14 Monograph 1. This ?abfe (present rable 2l , wlrich was further updatad after our June and October 1982 surveys (Appenalix, St.Lucia 19Br), also provided some evidence that the ratio of sri;l1, and (3_6,), to larqe aninals i.ras decreasing on tbe Bfyth_Cadet] and Liverpool_fomkinson Rivers Systems, though there were substantial fluctiations ln the ratio. There was evidence that an increase in the nuniber of large g. !9I9E!q sig}ted on a tidal waterway (often accompanied by an increise in-G_6,) animals was .usually followed by an eventual decrease in the number of small and,/or (3-6') animals counted. Furtbermore our data inaticateal that the exclusion of sub-adu]ts, voth in tbe (3-6,) and large size classes coincides with the breeding season wbich cotnmences iround the Septierber- October perioal. A11 of these observations and conclusions were an keeping with our model and night wetl be incorporate into it- Itowever, there l/ere a number of troublesome points whicb remaineal to be resolveat. qq qrlgt" {ro[n Lhe St. Iucia 1982 paper: ,we suqsesLad that the common racEor, whrch may fave been connett_ed wiLh thiS-qeneral influx of animals, was-the exceedingly dry wet season of I9'7'-Ig.tg and the severe alrought conditions which prevailed until the wet season of 19?9_1980. Such 21I conalitions might be expected to force any itinerant animals in swanp areas and semipernanent waterhofes back into the tidal waterwaYs. However we pointed out that there are a number of worrisome points about this, firstly there are very few swamp areas in the vlcinity of the Blyth-cadel1 System (certainly not enough to hold the nunber of arlimals invofveal) and secondfy if the sub-adufts were returning from non-TYPE 1 tialal waterways elsewhere (for instance the Milingimbi Complex, see Monograph 9) then whY would a very ilry wet season anal severe drought conaitions trigger the return of sub-adults to TYPE I systems? In addition there were indications of an increase, rather than a Cecrease, in the number of non-hatchlibgs sighteal in TyPE 3 systems in August 1979 (see tbe results for Majarie and Wurugoij Creeks. Table 1). Flnally, how does one account for the alecrease in the number of large crocodiles (from 74 to 58) spotted on the Liverpool-Tonrkinson system during the october 19?9 survey (Table 2) t where iLid they disappear to? The missing crocoaliles coufil not have returned to tbe fresbwater swamps and/or billabongs from whlch it was postulated they haal come, for these 'i{ere even alrier in october than in June anal JuIy. One is thus tempted to dismiss the 'drying up sriamp anal billabong' explanation for 1979. However, the ]9al-1992 wet season along the northern Arnhem T,antl coastline was again a dry one and again there has been an influx of large animals into the Goomaaleer (from 3 to 14), Blyth-cade1l (from 39 to 6?) and Liverpool-Torikinson (from 54 to 67) Syltems (see the resutts for tbe June 1982 surveys in Tabfes 1 and 2). The increase in the number of large aninals sighted on the Liverpool- 'lomkihson System was accompanied by a major increase of smal1 (fron 165 to 20?, significant at the 952 level) and (3-6') (from 133 to 1?8) animals. whereas on the Blyth-caale1l it was accompanieal by an increase of {3-6') animals (from 12? to 163) only. The nunber of sma1l anitnals remaineal co$stant - In June 1979 the increase in the number of large animals sigbted (fron 23 to 55) on the Btyth-cadeIl system was acconpanied by a significant increase at the 952 level (fron 221 to 2A7) in the number of snall, and an increase (from 161 to 196) in the number of {3-6') animals sighted- However, on tbe Liverpool-Tonkinson System this was not so -both t}le number of small and (3-5') animals rernained essentially constant. Thus we ask what role, if any, do the dry wet seasons plaY in determining the influx of small and especialfy large e- pglggE onto the nain section of the tidal waterwaYs? It is to be noteal form Tabte 2 that on the second survey of the Liverpool- Tomkinson System in 19?9. namely the october survey t}le number of large animafs spottetl had decreased (from 74 to 58), but still was at a consideraBly higher level than for the sePtenber 1978 survey when only 4C targe animals ware spotted. The nunber of srnall animals sighted haal also tlecieased, but not si_gnificantly -from 152 to 136. For the Blyth-cadeIl systern there was a similar occurrence, however the next survey, after ti-re .lune 19?9 one, could not be made untif October 1980; the drop in the number of small animals was from 2a1 to 249' just missing being significant at the q5t level' . The resutts of the 1980 survevs (Tables 1 to 7) indicated tbat the number of animals on the tialal waterways in the Maningrida lnonitoring area rernained fairly static except for the further exclusion, between tbe .tufy anal octob;r 1981 surveys, of 40 animals in the (3-6') size classes 'alrv form the Blyth-cadelf System (Table 2)- Then came the wet' of 1981- 272 1982 and aSain the influx, referred to above of (3-5') anat farge animals into the Liverpool Tomkinson and Blyth-Cadetf Rivers Systems. The distribution of the animals sighted left littte doubt thar for the Blyth_ Cadell Slstem, the animals were entering and feaving the system largeiy throungh the mouth of the Blyth River. you could sie the animals on the mouth sections of the waterway in both June 1979 anat June 1982. In ,iAs our St. Lucia 1982 paper we wrote: is eviatent form our discussron, consideration of the survey results for the Blyth_Cadel1 System can be ihdicative onfy as to where the fluctuating nuniber of small and large crocodiles disappear to and retum form. Most of these farqe- c- Dorosus are in the (6-8,) size class anal thus are sexuafly immatu." or-i uii- sexually mature animals for it js known that females ale often ;exually mature when reach the (5-7,) size class (page 339 Monograph l, also personal cornmunication fron Dr- cordon criqg). Tlle evide;ce suggests strongly that most of these large crocodiles and a substantial fraction of the excluded small crocodiles teave and re-enter the Blyth_CadeIl System through the moutl of the Btyth River- Those that leave, qo out to sea and are probabfy lost or they travet along the coastfine uitit they reach anotler tidat waterway to which t}ley gain entrance. To the east of the Blyth River mouth. the closest tidaf walerways are those discussed in Monograph 9. Nganaladauala, Bennett, Darbitta, Djigaqifa and Djabura Creeks, all TypE 3 or 2-3 waterways, and whlch provicte excellent rearing stockyards for sub-aduft and Jus mature q. porosus referred to in our nodel. Ho.wever to reach the first of tlese r"rater ays. Ngandadauala Creek, necessitates a sea journey of some 36 km and ttle rounding of Cape Stewaxt. This creek is afso Joined to Creek B on the Blyth River by an open paperbark swamp anal crocodiles coutd move from one to the other during the heiqht of the wet season (page 39 Monograph 9) - There is a very small but distinct channel joininq the two creeks- When fast surveyeal in June 19?9, 39 large and 44 (3-5,) animals were sighted in the creeks above and since they are all TypE 3 or 2_3 waterways ? nearly al] the animals sighted must have been derived from efser^there. The Blyth-Cadell System is probably one of the sources for On pages 39, 40, 106, L24 ana I25 of Monoqraph 9 ue atso discussed the probable source (s) of the major portion of those crocodiles frequentino Nganaladauda Creek and the remainder of the Milingimbi Compfex, wliich 'lyPE consists of 2, TYPE 3 waterways. Excluding tie small number of animals which are alerived fron within the complex itself and frorn scattered semlpermanent freshwater bittabongs and smatl swarnps brodering it, the two najor and nearest sources are the Blyth-Caatel1 River Systen and the Glyde River System which drains the Arafura Swamp. Our 1979 sulvey resu.Its sLrongly suqgested tt-al the clyde Rlver wis acting as a channel for q. porosus entering and ]eavinq the Arafura Swanrp. On page 106 of Monograpl 9 we stated: "Examination of Tables 9.43 and 9-44 indicates that at least one half of the crocodiles in size classes )( 5-5') haw h:ve bcen deriveal from crocodites movins into the river'i"r".i'""i ;;; ;i;;";;;". since the nearest TYPE I river systems are the Bfyth River in Boucaut Bay to the west and the Kalarwoi River in Buckingham Bay to the east (Fig. 9.1) ,it is hiqhly unlikefy that crocodlles from those rivers woulal enter the TYPE 1 C1lde River. In fact as !.re shall see in the Discussion of the 273 overall Castfereagh Bay arrd Hutchinson Strait results, it is highly likely that some of the crocodiles in tbe >(4-5') size classes spotteal in th; other river and creek systems in the Bay and strait were deriveal fronr and through the Glyde River. This reasoning feads one to conclude that substantial numbers of crocodiles in size classes >(4_5') are moving out of the Arafura Swamp into (and some out of) t!,e Glyde River' Fulth6rnore a fraction of the crocodiles in these size classes recruited from withj"n the river itself are probably also excludeal from the rlver proper. Thls would be in ful] accord with the picture we have leviropea of the dynamics of the populations of c. Dorosus (Monographs That substantial nr.mber of q. pglgElfg in size classes between (4-6') are probably feaving the river. and some ln larger size classes entering it' is supported by our sighting of 12 animals in these size classes u.t".!i i. o a;d 1.2 (iiq. t-59). we have surveyed most navigable ti'lal rivers anal creeks in the Northern Territory and this first occasion on which we have sighteal such a concentration of q. pglg€.gq at a river mouth. It is to be noteal that the alensity of non-hatchlings sighted during the fglS .rr..r"y was 0.61,/km, r,rhereas ilurrng the 1979 survey it was 1'39lkm' The increaae in the number of non-hatchling crocoaliles is hiqhly significant (Table 9.45). Not only is the Glyde River with its excellent ne;ting habitat helping to repopulate itself but the Arafura swamp is helpin6 as wel1. rhe woolen River, Hutchinson strait and the Milinginbi crelt iompfex are undoubtedty recipients of some of these croco'Iiles ' rf," arafui" Svarnp is probablt functioninq both as rearing stockyar'l and as a breealing system". Anal on page 124 of Monograph 9, where we aliscussed the increased nuhber of non-haichlinq crocodiles siqhted during the 1979 surveys of the (s) Milingimbi complex, and again aliscussed possible source of these we wrote: "es aiscussea previousfy, the increase observed o"".o.oiif"", in" clva. River can be accounted f6r by reciuitment on the river anil by crocodiles entering the fast flowing upstream sections of the river iiom tle arafura Swami, vhere certain parts may act as rearing stocl Reference to rig. 9.1 indicates that the Blyth-cadell Rlvels system foim r,/hich some 80x crocodilies sighted in tbe (2-5,) sise clas;es aluring the 1974 survey were missing by 1979 {Monograph 1), and the Arnbem Bay Rivers (Monograph tl) fron !{hich sor,e gg% were rnisslng, are the fikely candialates from which at teast a portion of these crocodiles came',. Further analysis of our extensive survey data obtained since l9?9. and especially that of the June and October surveys of 1982 and 1983,which included the survey arlal resur!-ey of alf rnalor and minor alternative habitat (St. Lucia 1982 and Tabfe 8) we could galn entrance !o, suggests strongly that a substantial fraction of the INCREASEDNIIMBER of crocodiles sighted. not only on the Milinqimbi Conplex in 1979 and on Ngandadauda Creek and the clyde River in 1983, but afso on the Blyth--Cadel1 anal Liverpool-Tomkinson Rivers during the 1979, IgA2 resurveys, were animals RETURNING from the Arafura Swamp. D A further important result comes fron our resurvey of Nganalaatauda Creek in June 1983- This TYPE 3 creek '.ras first surveyed in SeDtember 1975 uhph q l?-A'l -*-v- --,.nals were sighted in it; on the resurvey of June 1979, 10 (3-6') and 11 large animals were sighted, indi cating an influx of( !-6') and probably sone different large aniriats into tbis TYPE 3 waterway -most likely of aninals moving between the Blyth River and Arafura Swamp. on the October 1983 surv€y 14 (4-6') and 7 large animals were sighted, inalicating a foss of 9 animals. As aliscussed in the Section on Ngandadauda Creek, it is reasonable to assume that on tlis occasion many of these shoutat be classified as missing- presurned dead. 215 The situation in relation to the l,iverpool-Tomkinson System appear6 to be somenhat alifferent from that of the Blyth-cadell system. There is cobsialerabfe alternative habitat available for sub-adults exclualeal from the Liverpool and Tomkinson Rivers proper (St.l,ucia 1982) - r'or instabcie, Morngarri-, llunqaralobolo, GudJerma and Tons Creeks, which are part of the Liverpool-Tonl It is not possible to do so as easily for the substantial variations in the numler of large animals sighted during the 19'19' 1982 and 1983 surveys (Table 2). e study of the distribution anal variation in the number of large animals sighted on each individual survey sectlon,for all surveys, auggests (but certainly does not prove) that perbaps one half of tie inciease of 34 farge animals siqhted in June 19?9 mav be altributed to animals returning from the extreme lerminal sections of the Tomkinson River and the unsurveyable terminal swamp an'l billabong ."ctions ot Maragulialban creek and perhaps of the ot}er snall creeks as $efl. Elowever. ttte di.t.ilution of the remainder of the animals on the down-stream sections of the Liverpool River and ttle doltnstream creeks suggests that the remainder of the increase may have been deriwed from outside tle Liverpool-Tomkinson systen- This is especially so for the apparent increise of 13 large animals sighted during the June fsSz ;";!yt an increase of 11 larga animals was sighted on the mouth section of the Liverpool River. Rolling and Junction BaY waterways r^rere not responsible for the increase sighteal in June 1979 and 1982' for there weie increases ln the number of large animals sighted on tho." as vrelf (Tabfes 6 and ?). similar remarks apply to the alecreases."o.,r"y. Furthermore the same applles to the Blyth-CadelI System and hence one is folceal to assume that some of the animals returned - from or to a substantial rearing stockyard and breedinq sYstem the Arafura swanp. The perplexibg question of what bappend to the apparent 16 missing tarqe ciocoaiies fron the Liverpool-Tonkinson system-in october 1979 muii le con.iaereal again. If these animals were exclu'led by the time of the octoberlg?9 survey, they certainly coufd not have returned to 216 -jncfuding swamp habitat the Arafura_ for sucb habitat was even nore dried up in October than in June. ?hus we are forced to surmlse that large crocodifes excluded from theLiverpoot, Tomkinson System probably entered the Milingimbi Conplex of tidal waterways and reiurned to the Arafura Swamp when the wet season of 19f9_1980 arrived. The sane probably occurred witb the 23 large animals exclualed from the Btyth_ Cadell System by the tine of the October 1980 survey. rf ," to O" stressed 'I tbat we have no direct proof of this _we cinnot survey sucb arge complexes conLi nuousty. We thus now believe that our original contention (Monograph 9) lras correct- The only reasonable explanation we are abte €o qive, which is in accord with the observations made during the 1979, 'dry i982 and 1983 surveys following wet, seasons. is itrat the Arafura Sr"ranpis acting both as a breeding system (aluring normaf wet season periodsi and as a rearing stockyaral of varying extent. for sub_aalult crocodiles from Arnhem Bay in the east to the King River in the west (Fiq. 1). The B]yth-Cadell Sysren is a very impo;tant component 'dry of this: During a severe wet, season as in 19?8_1979, the water levels in smalf and large swamps fa11 drastically and crocodiles inhabitinq Lhese have no choice but to teave. They can only return to the tlcla1 waterways. both TYPE 1 anat non -TypE 1, and tlis tbey do_ as tbey atid in 1979 and 1982. Mahy aninals frequentinq the atte;native freshwater babitat must have come from TypE 1 tldal b;eeding -pr;babsysteris and hence. as the swamps dry, some of the sub_adult anl mals ly return to the tidal system from whence they orlginally th" oihers apparently have to frequent non-.IypE 1 tidal sysiems -;ven"amel though temporarily_ until they can go back to the swatnp rearing stockyara or a TypE 1 system- Sone of t]]e returning large animals appear successful in establisbing_a terrlrory for themselves (and piitraps a fei{ of the r r-o , anrmats alsoj: the others appear to be excluded yet again -and especially the (3-6,) and sub-adult large aninats_ on the conunencement of the irreeding season. When tlle next ,dry wet, ariives lrr tnere nas been the usual \^ret season (s) in between so that the animals could have returned to the swanps (s)) large anal sometimes (3-6') animals again are excluded rrom Lhe swamps ;nd the deqree of the. process must depend upon lust how ,atry, the lret season is _upon much the swanp water tevels fatt. The \,rh;Ie process is superimposed upon the normal exclusion anal re_entry of animals lrhich taies ptace in usuaf years and whicb accounts for most of the sub-adutlc An interesting possibility which follows from t}le above picture or noalel rs that c. porosus may bF abte to 'sense, how drasiic -r.,jr-.iiJlav+r^a ^raF in freshwater revets b;, for rhe influx of sul-"a"rts occurred before the June"'irr surveys -perhaps before the Nater leve1, which forces the animal to 1eave, is reached- 2.-1 a matter rrthich lsq6mss somewhat clearer on the above picture is why the influx of large animals i.s sometirnes accornpanied by an Influx of (3-6') animals and sometimes not (see Table A.1 on page 422, Monograph 1 anil Table 2). Though there probably is an interplay of a complex set of factors, it is reasonable to assume that large animafs require higher water levels than smalf animals and hence in some years anal from 6ome swamps onfy the large alrimals are forceal to leave. rn adalition, tbe number of large an'l,/or adult animals in the tidal waterway may also be a factor involvecl (st.l,ucia 1982) -anal perhaps tending to prevent the (3-6') aninafs from remaining in the \'{aterway over the dry season (see Table 2, July 1979 survey of the Li verpool -Toniki nson system) . 9.2 An overview for the monitored waterwavs in tLe Manindrialaarea fn fig. 8 rire have pfotteal using Table ?, the nrlnber of (3-5'),large anal their sum, (3-6') plus large, or (>3') aninals sighted on surveys ove! the past I years of the l-i verpool-Tornkins on, Blyth- Cadel1 ancl the 4 \taterways of Rolling and ;Iunction Bay6. The waterways of Rolfing anal ,f,unction Bays could not be sulveyecl every time the Blyth-cadelf anal Liverpoll-Tomkinson uere, thus resulting in a nuniber of inconplete totafs. These cases are referreal to in the caption of Table 7 and certain corrections are suggested- Unsurprisingly the graph shown in Fig. 8, largely mirrors those shown in Figs- 6 anal 7 for the Liverpoot-Tonikinson and Blyth-cadell respectively. we refer the reader to the Overview sections for each of those systems, for essentially the same broad general remarks can be made here as were nade there. The number of large crocoaliles sighteal on the overall Systems alurlng the surveys of 1976 was 83 and th; number of {3-6') aninals was 340. The number of both (3-6') and large crocoililes sighted then essentiafly held steady or even declined slightly until June-iluly 1979 when there was a dramatic Jurlp foUor"ing the 'ttriest wet' on recoral of 197A-!9'79. By the time of the June-July 1981 surveys the number of (3-6') animals siqhted was back to afnost the sarne figure as in 1916 1347 versus 340) whereas the nrmber of large crocodiles rernained at a higher level, 113 versus 83.obviously a number of the returning large animals were being successful in establiEhing a territory for themselves, probably in the very water$aYs from which they had been excluded, but many of their less successfful rj.vals were Joinlng the ranks of the missing -presumed deaal in the process. two 'alry wets' of 1981-1982 and 1982-1983. Then came the '12 Again there was an inffux, this time of 13-6') and 58 large ai:inalst 3t2 (3-6') anal 163 large animals (amaziDgly the number for 1979 bad been 162) were sighted- Again substantial fraction of the increase. especially for large animals could only bave been derived fron aninB]s excludett from the Arafura swamp. By the tilne of the June-July 1983 surveys the nuniber of farge aninals sighted had dropped to 125 whereas the nuriber of (3-5') aninals remained almost constant (392 versus 391). Then came the expected alrop in numbers for the October 1983 survey when 350 (3-6') and 106 large aninals llere spotted- obviousfy only a relatively snall number of additional (3_6') animals rnay have been successful in establishing a territory for themselves aluring the 8 year perioil; it is as if there were a fairly alefinite nuniber of slots or territories on the water'ways for the (3-6') animals 2?B and the number anat size of those slots can vary dependling upon a complex set of factors of which food suppty is one-. Of ioo."" (3-6') tt" anihals utitizing these in 1983 wlrl not the sa;e animats wich filled those slots in 1976. superimposeal upon this is the increasingly aggressive behaviour of the ;ntmals as th; october_ period November approaches anal the more aggresive-durtng behaviour of the large animals tor,rards the (3-6,) onel the Ureeafng for_the targe :l: !1:t"r" animats is atong the same fines. ccnparing the surveys of July-September 1976 with those of June_,tufy 1983 indicates that an aaldltional (125-e3) = 42 larSe animals i.rad or were well on the way to establishing a territory foi themselves. Study of Tables 4, 5 and 6 reveals that, as expeateal, those teiritories were in the-TYPE I wateruays. On the other hanat,since only 106 large animals were sighted during the October 1993 survey, at is apparent L}|at a number of farge animals which hetd a terlitory in the July 1983 period could not do so once the breeiling season cofiunenced. Again one must realize that one is viewtnl a highly alynamic situationt a large animaf may be successful ii totaing_a teffitory foi only a limited period, Even the larqest animals mav eventually be deposed by younger and hore aggressiie ones. This continual battle for the eventual riqht to breed is documented for many species. The losses involved during tbis process in the case of g. porosus are startingfy hig}. What deterrnines the carrying capacity of tidal waterway in relation t9 9. opfpg-gE-? This is a compfex matter. obviousty the avail.biltty of food, nestlng habitat basking habitat anal many lther factors are involved. The resutts presented in Tables 1 Lo 8 and the above discussion of them make one woDder whether the tidal nraterwavs which we have been monitorinq in the Maningraala area have a];eady almost reached tbeir maxim\rn carrying capactty under present alay conditions. Or is it that the dynamics of th; populalion in such that a major sustaibed increase in the number oi l:_e,1 and large crocodiles, and the change in population structure from a alominance in the number of (3-6,) to a major dominance in tl]e nurnber of tarde animals (ratio of 13-6')/L < The above views imply that we do not believe that the tidar waErrays ln the Maningrida area have reached their maximum carrying capacity and furthernore tbat lre befieve that poputation numtceri oi 40 to 200 years ago were far greater than they are today. .vre 'no Of course are ln a wj,n' situation in trying to prove this for no systematic sur\ sjr work, that we have heard about, was ever carrieal out or recorded for C. porosus in northern Australia. However the reports of early explorers such as Phitlip parker Ring, Lort slokes, caalelt (see Monograpbs 4, 12 and 17) and many others, of perhaps less repute, 279 leave Do tloubt hatever in our mj.nds that g. plfgEgg numbers were gt""t.t in the past than thev are at present' No-reliable "i"iiystatiitics are available, but it is evident that tens of thousantls of animats were taken for thej'r skins aluring the 1950's and 195o's anal tlrere was a smal1 but viable industry during this perio'l,based on crocodiles. That could not be true today. we must also give strong crealence to reports to us by individuals such as-Hugh and ioU"ii. if".."t managar of our Maningrida Research Facilitv pilot of the universiy's research airplane) wtro was- a pilot 'luring itr" ls:g-tgEs wal and flew numerous patrols along the northern Arnhem Lanal coastline. He and his co-pilot saw hundreds of large them ciocoaifes fying on the beaches along the coastline and-used for machine gun target practice. This was recorded in letters to his no$' wife; Maidie. iodaY vou can flY for davs and see no gn a coastal leactr- the fact that mostly large crocodifes weie"i"""aif" .iqht€;a is easily unders tanalab 1e . on the basis of our mo'Iel' (3-6') one can-welf imagine ihat as the ratio of latge to animals increases along ;ith a major increase in the nrmber of large lead to animafs, tne iicreasing c;mpetition for gooal habitat would tbe exclusion of big numlcers of Iarge aninafs. Life would also be very tough and relaiively short -even more so than to'Iay- for nost of the ( 3-6 ' ) animals - we As we dial for the Liverpool-Tomkinson and BlYth-Cade1f Systems' calculated for tle over;1I wateflrays monitored in the Maningrida area, the naximum average percentage over the past 8 years' of hatchling which survive to the (2-3') staqe and find it to be eiA/$g4,'o. 529^. rhe broad estimates for the minimum exclusion and u.,a,Zor fo"" percentages for the (3-6') animafs are shown below we have ai"' lng flb]e 7. Thus for the overall waterways "lt.i""a^ "" the minimunr excfusion an'I'/or loss percentage is a tr-en monltorlng 'drY very hiqh 88%. Again if lre assume that the wet' of 1981_1982 tbe haal con;entrated back into our nonitoreal waterways nearly all of -and surviving large anirnals originally recruited tlere none the originating fiom elsewhere -tehn ?6% becomes the estimate for misainq- presumed dead (3-6') animals- r1in.z of (3-6 ' ) animals excluded ( 3-6 ,) Larse ( >6') July,/sept 1976 340 83 l34A-42) /34o ar aAl Jufy 1983 125 July,/sept 1976 340 83 ( 340-80),/340 or ?61 Jwe/J]uIy 1982 163 2AO Recoverv of the c- porosus population On the basls of the results above, it is small wonder that the popufation of g. porosus appears to be recovering at a very slow rate and that it may take many decaales to recover _if ever. In fact, one may ask legitimately whethei the population is alreaaly below a critical level, fron which it cannot recover. We do not believe this is so, but it is one possibitity sr€gested by the results. One thinq that continualfy impresses us is the snallness of the numbers we are atealing with- The variations we are talking about are measureal in tens, not bundreds or thousands, The results of the ten years of systematic anal carefullr/ recorded surveys speak for themselves. It is no exaqgeratlon to state that no one is more surprised by then than lre are but we have finafly reconcilied ourselves to them. In 1972 wben the ban on the export of crocodile skins and products was imposed by the Arstralian Government at the request of one of us (HM) and cotrunercial hunting grounai to a halt -more because of the paucity of crocodiles than because of the ban -we felt very confldent that given a decade or so of protection, Austrafia could again Iook forward to a subtantia-l crocodile skin industry- We were further encouraged aluring tbe19?0,s by the apparent very rapld recovery in alligator populations in tbe southern States of USA. Duiing that period it was cfaimed by the refevant wildlife authority that the atligatoi number haat increased from some 450,000 to ?50,000. An alligator skin industry started up agaln in the USA. We, along r,rith many other individuals, hoped and in fact believed, that the same would bappen with g. ootosus. But alligators are not saltwater crocoaliles; they may appear to be superficiafly the same but in fact they are very different. C. porosus appears to be its own worst enemy. Perhaps a further reason for tbe apparent differinq recovery rates of alligators and saltwater crocodiles relates to the nature and amount of the habitat available to be utilized. In the souttrern States of the USA there are evidently sti11 substantial areas of slramp habitat available for afliqators and the alfigators appear to be thrlving in it. We have stressed the importance ofswanp; habitat for g- porosus in the present paper and elsewhere (Monograps 1,2,4 9 and 14) and pointed out the very high loss factors for (3-6,) and large crocodiles on the tidal waterurays coutd be exDecteal co oe considerably fower for aninals inhabiarng swamps (s;e especiatll Monograph 14). The fact remains however, that eveo though in recent history there was littIe swamp habitat available in northern Austra-lia, much of what there was has been destroyed by feral water buffatoes- Examples of serious alestruction may be seen in areas around the Adelaiale, Mary, and Alligator Rivers Region, areas which contaln some of the best and most lmportant TYPE 1 river systems in norttrern Austrafia- The remaining areas in the Dafy, Iinniss, Reynolds and Moyle Rivers region (Monograph 3) and the Arafura Swanp ihus take on 281 The taudable steps being taken by the Australian Govelnment to include most of the waterways in the Alligator Rivers Region in a large nationaf park (Kakadu) is leadinq to closer management of the feral water buffalo population there and hopefulfy may lead to the eventual recovery of the swarnp habitat- This matter nay be of major importance for the recovery of the g. lglggUg population in the park and surroundinq areas. In Table A.1 page 442 of Monograph 1we sholt the number of (3-5') and large aninla.ls sighted during surveys made of the Aalelaide River and rivers of the All1gator Region aluring 19?8 and 19?9 and one notes that tlle ratio of (3-6') to large animals was already less than one on Murgenelfa creek and on tbe South Afligator and wildman Rivers. Of course it must be recalled that the 1979 survey was carried out after tlte record 'alry wet' season of 1978-1979 and hence nEr!' of the animals had been forced out of the swamps and into the tidal waterways. However, this evidence alonq with that presented in this paper indicates tbat as the g. porosus population recover6 and increases, there wil] be many more farge than (3-6') animals. How many non-hatchling -but more inportantly {3-5') and larqe- saltwater crocodiles are there remaining in Australia? our estijlBte for 1979 was a maximum of 15,000, but as discussed elsewhere in this estimate was based on numbers obtained in a year when most of the crocodiles were concentrated into the tidal waterways and coulal well be too hiqh- Our present results indicate that there j-s no reason to j-ncrease this estinate for 1983, although we nust check to see whether the results qained for tbe ltaterways nEnitored in the Maningrida area are generafly appficable to waterways in northern Austrafia. It shoulat be apparent that the present wild q. porosus population coulal not support a commercial skin industrv based on indiscrrminate shooting. 1f every saltwater crocodlle in northern Australia was s)rot today, anal the sklns brought an averaqe of 9100 per skin, the total value would only be around $1.5 million- This is considerably less than themoney spent over the past 12 years to gain the scientific information presented in our 17 Monoqraphs and numerous papers. 9.4 lvanaqenent of the c - --po-tqs!E ,Pqpu-l-e!!s! Wbat are the management implications of our resufts? We are not management authorities, but are aware that a multitude of factors -sorne of then politicaf- must be taken iDto consideration. For example, for reason based on pubfic safety, Australian society could alecide that aff waterwavs utllized for business and,/or pleasure or which haal settlements near them. shoulal be cleared of q. porosus and that g. porosus should be alloweal to exist _and Fe.Aaps r"""v"., only in a numbe! of designated parks and,/or reserves useal for scientific and/or reserves used for scientific and,/or tourism purposes. such a decision would result in the removaf of c- p.qr-gEllg from many of tbe waterwavs in northern Australia and could have fal reacbing ecological consequences /manv 282 of whicb probably coulal not be foreseen beforehand. Based on exampfes froh efsewhere in the world. the removal of a prealator from the top of a complex food chain cannot occur w_ithoit some major consequences. The Australian peopte would lave to aleciale whether the unhinalereal enjoyment of the waterways of northerD Australia is worth the risk of possibjy disastrous consequences to the whole ecofogy of the waterways. The fishing indus-try rs one grouF that readify springs to mind as a possible sufferer. Or it might be decided to encourage the establishment of a cqnrErcial porgsus g. skin intlustry based upon the wilal population. SiDce at Ieast 701 of the (3-5,) aninals are lost -and these are the mosr valuable ones commerciaLfy- one is tenpted to believe that their removal beforehand would yield a valuable resource without harming lt. But one nust proceed with extreme cautioh before embarkrng upon s.uch an eDter.prise. Undoubtedly tbe exclusion and/or loss of some 80? of the (3-6')animals ls an integral part of the vital proces. of sorting out the successful fron the less successful, of serting out the stronger and more dominant component of tbe icDulaticn. Removing a qiven fraction of the population ,night very well renove the stronger component anat thua over tbe long term sel the popuLation on a tlecfining course. We simply do not know. On paqe 15 of Monograph 1, we proposed in 1981 a critical experimlni to tesc effect of removing a given fraction of the (3_5') c. porosus potrx.rlaticn antl proposed that some 25 to Aox of the (3-6') animatl-Efremoved annually for a period of 4 to 5 years from the downstream secrtons of the Adelaide River to see what effect if any this had upon the population in that river. For the experinent to be meaningfuf, one had to monitor the population changes on another set of control tidal waterways in which the C. porosus_ population remained. ?he Unrversity of Sydney financed the costly monitoring of a controf group of waterways for 4 years and this uork has now been completed successfully. Though the proposed experiment had very impoftant ramifications for the management and ranching of the e. oorosus resource/ no financial support had been forthcominq. from relevant autborities, for the other balf of jt. The opport;nity has nolr been Iost, thus ensuring that decisions made in relation to randhing will perforce be made on a much weaker scientific base, we have already discussed in Monograph 1 (pages 43? and 445 to 446) various otber management implications arising from our results. These relate to control of feral water buffaloes, Drohibition of net fishing in rivers, estabtishment of marine o, othe. parks and tbe release of hatchlings. We do not repe€t these here ;u, perhaps it is worthwhile to emphaslze one apparent ihportant issue asain, an issue which is of great and fundamental inportance. This relates to allowing net fishibg upstream of anal near the moutls of rivers. Our results show that over 80% of the (3-6') animals are exluded from TypE I waterways and that this excfusion also invotves large animals, that tlere is great and continuing movement of these animafs into and out of the river systems. Aflo;ance of net fishing in or at the mouths of rivers, speciatfy the TypE I lraterways rs certarn to remove an lnportant component of the large aninals and could well ensure that the poputation in those waterways never recovers or even decfines further- Undoubtedly econonic and pofitical 283 considerations are involved in arriving at a reasonable compromise ilr relatioD to this very important matter. We have no desire whatever to become involved in arqumentation about it. However rire would suggest that at the very minimum, a1I net fishing be definitely phased out ovei a period of 2 years in rivers inclualed Most people are not aware that net fishing is stl]l being lEnr.itted in the East Afligator River up to coopers Creek and that refati\refy large nrlnbers of large crocoal:iles are stilf beiEq drowned in that river annually. This river froms the backbone of Kakadu National Park, one of Australia's rnost important nationaf parks. More importantly, staqe Two of Kakadu National Park has just been announced by the Australian Government and most of the lmportant tialal waterways in the Alligator Rivers Region will now be lncludeal in the park. These waterxrays constitute the largest anal probably the most impoltant group of TYPE 1 breeding systems in Australia antl they are associated with large fresbwater swamps which, as discussed elsewhere ln this paper, are of great import.ance- Tbese tidal watenrays must all now be monitored annually. systematically, carefully and completely as we dial in 197"1,797A and 1979 - and net fishing in them totallY prohibited. We now enal this paper with our own view on the long term future of g. oorosus outside of national parks in Australia: consialering tbe present greedy nature of society, IT' HASN'T ANY..- - -. -. - i And even in the rivers of the national parks/ unless net fishinq is prohibited in them, the future for g. polosus is grim. 10. ACKNOWLEDGEMENTS The authors thank tbe university of sydneY and its science Fordaticn for Physics for their great financial support over so many years. Kayama Sinba from the Papua New Guinea Crocodile Project spent one nonth par.ticipating in our final progranme of surveys from Maningrida in order to learn our techniques. It was a pleasure to have him with us- our thanks also go to Doung Martyn anal Cofin wiles. the pilots of the helicoptels used for the July anal october 1983 surveys respectively/ of alternative habitat. Our thanks also to Kim Mawhinnew, llM's secretary, for typing (and retypinqi) the manuscript and Tables- 284 Surveysof TidalRiver Systems in theNorthern Terrirory or Australiaand their Crocodile populations A seres or monographe coverng lhe na! po'rions DJbls-eo aabre or rhe rdar .vefs a.d qeeks or rne Nori.€rn Ter'rorv o/ Pprg1.o. o.--\ s;ney a.,crrd,r.o.9 rq1! MONOGRAPH r The Byth.Cade nvc,s Sysrcd Srudya.d the Stalls oi Cro.odylospo,osrs n t,datwate.vray,cr No|hern r rop.r'o or ,oro-- ,r/,c ,a ^c, 1rrG,^e1w 2 The V'clonaand Frtzmaurce F,ver Sysloms Messe H GansC.wers AG Gr€€nwJ vo,,cckGCa.dB,cnnan r(c 3 Th. Aderadeoar! a^.1Movre R!.,: rJess.1.ts Gansc wc!s ncrnccr..i wJ i thc Atrearo,Feaon F verSvsr.r,1 iri::::l"fff,llj"fT,:.:zL;::l]INlJ.joUi|bd!r'*l^,:l.tolr]vi.sandvr'Emaia!e ' *'ane wlrleor arrrrrani ;:'".:iilt:i:"1"J!,Y"iff i,lT'*" a'd creeks C Sodn na.o ti.i. Dog r--4 ]n, r,o. a,,C ..o. L",o '.- r o, C ,ai rr4sscr ft. W!^ts./\ c nnd G/c.r n v 7 Tne L vcrp.ot.Tomk,r5onRvcrs S,,srcr aia Nungburlah Cr.ek MesseH Wcrs AGa..lcreen WJ I Somc!vc6 andcr.c[s.. ]. [3srco.slo{ ^,nidr Land . r,0 Fosc c!1r or_ c;(..nrara- _ _ nNe,. Muntar cr.ek |.,1 Rrye, w.I(r, nve, and xo"rajo,," n;",' "'' [tesse!.H. Eron.M wcts ^G G,ccnw.runoa,""."n ii' e . :/1t.i:,^a/ or .,.,.i. o. ai. Dr',i.,]J Orrhrr Nln.dadaliJicre.ks andrne 6 ydeanc wooc. arc,: Mcssd H. Vo,jc.k G C w.!s G a.d 6Jecn w J 0 raJ lr' - j I I dat V/alerw.y5 oj ^rir,.n !a! u3w6i!.0;r l|rbq.o. t]ararnf.lr Gobrrpr coroiruL c.1o. frfrra ..frL iia 8!,ufql)I.(/Lc fiv.ri. 12 r dar warcru€ys o. :he solrr lv.-srcrn Coasl or jne Cur or Ca,penr,r! iiil;:,i,:ll;""1)*ii1fil Nava-pwune!"6nsa Pa-''.o' GO w.rs Ac cir.or wJandJohns.n A i3 ida Syn{:ms.f rfc So!|r.,n Co.sLorljc cuf .r or Carrenra.a . r)d o :-;.,. ac,... ' u.r w 'ao':o''n'on n r4 Tr.ra \rralcrwavs01 v.n o,./nen cu I narnnry,,rw!! Sa(wdo an.r Mnm,n arecrs a.d CoastatArns or CobourApc.isu. Hcsu'veysor rhc^r AarorRcAon Rv.rs MessetH Vo.'cck c C. wors A G andcree. w J 15 Work Maosol T dar Wnjcrways . Norlher. Alsrarra N{essetH. Grecnw.t wers A G andvorrcek. G c i6 york Slrveysot Tda Wnrcrwayson Cipe pcnrnsutaOuccnsr..d. AlsratLd a.d ther Crocodiepopva[on5 6 c w.rs ^ G Greenw J, aul|rs.H s.'ro C R R weaveri v."",o,.,so. r i " f.i'w. aid 8vno. |arbours an.l rh.r Tloarrlarerwnys G C. Ero f.l wers A G a.d Grcen W J '13 Flplranon ovnamcs or C,ocody/uspolosrs and Srarls Mafaoeme.t and Becove.y UDdaler979j9rJ3 c C. Gr.en W J andOncy rC Aor.a,jra n trrcsnm. eer6 anapL;brsfcrl by IndWe5Lern Ausr3ra. Governmc.r 1 :l:.'':,f ?tl: o , , r!,. v aL'odl bu'od9. a A ano Me.,d P 245 TABLE 1 l{umberof c, poloeirssighted l\lithin each size class on tidal water ays of the 330 kmof control systemsin the l4aningridaarea of northern ArnhemLand (see pages14, 15,440-446 l4onograph1) and on NgandadaudaCreek and the GlydeRjver draining the Arafura Svramp,during night-time spotlight surveys. The nidstream distance surveyedand density of non-hatchlingcrocodiles sighted on eachwater- lvayis shown,as are the 95z confidenceljfiits for the estinate of the actual nunberof non-hatchlingspresent. The TYPEclassjfication of eachwateruay is given also. Note that we corrected the 1976results for the Liverpool-Tonkjnson, given on pages14 and 416 of l'lonographl and in the Tables of the St. Lucja, 1982 paper, by subtracting 20 animalsseen between the nonnal terminal point at km73.7 and km80,1 on the TomkinsonRiver. This makesthe survey results morecoflparable. The 20 anifiralsare noli shownin Table 8. Size Class Numbers 95? Systens H 2-3 4-5 5-6 '7 EO Levels TYPE MONOCRAPH1 ELYTH.CADELL oct 74 387 89 ':l 58 6 2 4 e1.eI 454-524 1 Nov 75 353 50 .:ll 72 23 2 g4_9I 3.2 462-532 Sept 76 348 82 63 104 7 6 ornl--"1 2-9 403-469 | Nov 76 307 61 6r 103 47 10 2 l9 92.0| 2.7 I Apr 77 327 72 70 r08 48 10 2 4 nr-oI 2.8 386-450 | llay 77 333 88 60 I 94 55 13 4 I 1B ornl--'-l 2.7 370-432 --t.^^ June 77 365 108 69 IO 3 24 90.5| 2.8 389-453 I Sept 77 386 105 41 l7 4 90.5| 3.1 42J-495 "t'"' I oct 77 360 1L2 68I83 47 TB I 3 2l 90.5| 2.7 375-439 -.t-. on"l June 78 432 173 67 15 6 21 "''-l 2.9 393-457 Sept 78 399 155 60l7e 18 8 6 t7 -"-1 2.7 369-431 June 79 123 '- '" 59 31 26 26 3.6 524-598 | oct 80 400 I19 89 171 4B 22 9 4 3B 92.9 3.0 421-495 81 366 86 24 i1 9 33 90.1 3.2 442-510 July 184 oct 81 3I5 72 77 | 60 32 20 16 7 89.9 2,7 Jun B2 408 I36 421ss 49 22 20 49 91.9 3.0 413-479 Nov 82 347 11t o,l* 46 2B 10 2B 92.5 2.6 356-41B July 83 465 157 selor 48 30 19 9 43 91.8 3.4 470-540 Oct 83 354 73 95t69 45 24 1I 10 27 92.4 3.0 427-495 2e6 TABLE l Size Class Numbers I4ONOGMPH5 GOOMOEER Aug 75 46 27 7 5 4 3 I.0 61- 89 Sept 76 18 5 8 5 I 3 9 45.3 0.8 44- 68 June 77 50 2 9 13 10 6 2 7 45.3 1.1 65- 83 July 79 90 29 7 14 10 6 9 45.3 ,lune 81r 43 6 5(3) llB) B(1) 4 3 45.0 0.8 49- 73 oct 81 17 3 13 6 I 5 45.0 0.6 June 82 18 5 12 5 2 4 1l 45.3 0.9 5B- 84 oct Az 9 J 9 I1 5 4 6 1.0 6t- 87 June 83 63 24 5 6 B 3 3 l0 45.3 0.9 oct 83 73 B 5 I 5 7 45.3 0.9 I4AJARTE Aug 75 12 1 I 2 2 I 1 2 20.1 0.5 Aug 76 7 3 4 20.t 0.4 7 July 79 1B 7 c I 2 24.1 0.7 2t- 39 June 81 t9 2 4 2 6 21.2 0.9 22- 40 Oct 81 t7 4 2 I I 22.0 0.8 20- 36 June 82 17 2 2 1 5 23.8 0.6 17- 33 oct 82 I2 4 5 I I 23.3 0.5 June 83 4 5 2 5 24.1 0.8 24- 42 oct 83 I9 I 6 3 3 24.1 0.8 22- 40 I,IURUGOI J Aug 75 4 3 I 0.2 4 Aug 76 I 0.1 I July 79 9 L6.4 9 ,lune 81 6 I i6.4 0.5 6 oct Bl B I 0.5 I June 82 7 16.2 0.4 7 oct 82 B 2 r6.4 0.4 7 June 83 I 0.4 6 Oct 83 3 0.7 * Numbersin brackets9i ve numbersof crocodiI es removed before by Biology researchers 287 TABLE 1 Resultsfor Tom'sCreek included in these surveys; Ju'ly 1976survey, 1 (4-5'); Mav1977 survey, I (3-4') andI (6-7'); Septenber1978 survey' no crocodiles siqhted; July 1979survey, one hatchling and 2 (>7') sighted'- Nofurther suiveys of Tom'sCreek were made until october 1982; results tor lnls and sirbseqLrentsurveys are sho{n under alternative habitat' in Table B and nre not included in the totals below. Previouslyclassified as TYPE2. Size Class Numbers 95% Systems H 2-3 3-4 4-5 5-6 6-7 >7 EO Levels TYPE I4ONOGRAPH7 I LIVERPOOL-TOMKINSON July 76r 228 I9 3e 56 27 13 3 3 68| 152.51.41314-372 I | | 1 | I | 245 40 6151 30 13 5 4r r45.11.4 307-365 l4ay 77 | | l5s I I | 3eI 62 24 e I 30 1.4 2s6-308 oct 77 224 7l 1 1123.4 | 233 31 18l37 '-t' 8 35 141.4r.4 293-34e Sept 78' l6s | | July 79' 515 289 11 34129 20 501150.0 r.s 341-40I l3el43 --t,"., | 79 355 161 16 36 37 zsln 23 '"t'"" r.+ zso-:+o oct | I | B0 295 7T 51 --t'-zol t> 4e 140.6 1.6 oct 137132 | 1337-3e7 256 26 52 4Bl2e 23 l5 48 140.61.6 347-407 July 81 | I15 I I 254 34 33 2ilt4 14 s2 141.r 1.6 13r- 39I oct 81 ls0 134 | I 31123 l7 54 t141.1 1_9t416-482 June Bz 467 193 2e164150 ._t---"^- 384 144 16 --t--^ l7 --t--- t oct 82 I48l51 "rl "rlror 83 432 121 83 32 44 I 141.1 2.2 July 164156 ]|11 1475-545 oct 83 321 63 77 147 139 34t I 14 ouI ror.,1.9 | 400-466 NUNGBULGARRI I 10 15.0 37- 59 Aug 75 29 1 *l': 3 l lt.e 3 13.611.0 14- 28 July 76 15 | 2 5 1 I 1 2 13.6 June 77 *1, 6 I I | |0.e 79 35 4 6 5 4 14.811.7 31- 51 Juiy I10 I 1 6 14.811.7 June Bl ' 4 1 \',"| s 14.811.7 oct 81 ,al 2 1 4 14.811.6 28- 48 June 82 23I 4 3 I 31 14.4 37- 59 oct 82 z :l; 12.0 June 83 :11". 5 5 31 14.411.5 oct 83 38 IT5 1li4 6 s l 14.4| 1.6 2a- 48 2Aa TABLE Size ClassNumbers I,IONOGRAPH9 NGANDADAUDA Sept 75 0.7 lB- 34 ?3.9 0.9 25- 43 ,June 83 23.6 38- 60 oct 83 0.9 6LYOE sept 75 28 45.9 0.6 35-57 July 79 100 45.9 1.4 89-121 July 83 118 45.9 2.5 164-206 oct 83 91 45.9 2.0 130-r68 289 TABLE BLYTH-CADELLRIVERS SYSTEM uDdateTable for the Blyth-cadellRivers svstem (Monograph t) shovtins-the(2-3')' ii:;;i a;; iq-s') sizeilasses grouped together (2-5') andthe size classesabove ihose'inanother grouP (i5'). Hehave also grouped the crocodilessighted into iiiiii t2-o'1, (s-6') ind-tarse(16'). Alsoshown are the ratiossnall/large and ii-o;tlta"ci. ThisTable waa ob-tained by usingthe datagiven in Tablel. see iioii,iir io'iaute 3 for division of the Eocroc6diles among the varioussi2e classes inl'tfre Sectionon the July 1983survey of the Liverpool-Tonkinson System for the ilison wesometirnes use the smaltrather than the important(3-6') size class' Hatch- Small Large Small 3-6', iurvey Totals I i ngs 2-6' >6' Ilrge Lafge ?.60ctober 74 387 B9 286 t2 292 211 48.7 1 November 353 50 40 289 t4 183 20.6 13.1 Ha or Flooding 3 Septefiber 348 82 221 | 45| 240 ?6 t77 9.2 6.8 10.6 4 November 307 217 | 29| 230 169 14.4 t1 ApriI 77 327 12 230 242 172 18.6 t3.2 3 l4ay 77 88 215 30 231 l4 171 12.2 B June 77 108 215 42 232 25 196 9.3 7.8 16 September77 386 105 234 47 257 24 2t2 10.7 8.8 23 october 77 360 t12 204 44 226 22 158 10.3 7.2 l0 June 7a 432 173 219 40 238 2l 173 11.3 8.2 t2 September78 399 155 200 44 221 161 9.6 7.0 No Floodi ng - .Driest {et on Record l0 June 465 723 | ?sr I e\ | 287 55 1196 4 october 80 400 119 220 249 160 7.8 5.0 HeavyFl odin9 9 July 8t 223 67 | 253 167 6.8 4.5 | 3.3 I9 0ctober 81 315 72 I l7e 64 | 204 39 127 ory l{et - lilino r Flooding only ?sJune 82 408 136 166 106 205 | 67 163 2.4 | I 3.9 6 November82 347 111 | 164 | 72 re7 I 3e Dry |lJet- Min r Flooding onl y July B3 465 157 | 221 | 87 l25B 150 160 3.2 0ctober 83 354 73 | 217 | 64 1246 135 151 290 TABLE 2 (cqrr'o) LIVERPOOL-TOMKINSON RIVERSSYSTEM SurnnaryTable-for the overall Liverpool-TomklnsonRivers (l4onograph seecaption jn System 7). of TableI for changesmade retation to ir,i,-s idiO irruei res,,rts. Note.also that.the 1976survey ahor/s.68-(Eo) i iL weretaken to be targe. ign^i"i iil'!i ot u,"." Thisis orobably.too";d""ahtgh a flgur; for ihe iargeanjmats. ll,]lf":iy: recaptureprograftne was carried out-in l97i ,rs-ruiinq iuny ,0"" antmatsmore t{ary than norfial . Most,ofthe aninratsinvotvea-in-ite"recaptr"e tt tnu'likelvthat the true ratios flff:iTn"1"ff":3"11,;nnlt ror ieioare somewhat Hatch- SmalI Survey Large Small Totals l ings >5' 2-6' targe Large l4ajor Floodjng 1BJuly 22A re 1144165 l16e 40 130 4.2 25 May 77 40 r29 76 39 160 27 october 4.1 7l 228 56 118 54 147 25 140 5.9 5.6 27 September78 233 37 l3l 156 40 138 3.9 No Flooding - rriest illet on Re(ord 16July 79 289 | 10e lI7 t52 174 | 141 l9 0ctober 355 r6t l10l 93 136 t58 | 120 2.3 2.r 15 0ctober BO 295 7l 136 88 1i3 122 3.4 2.4 ti"l{uotr"ool!n 2 July 81 ,u 176 54 124 5 0ctober 2.3 81 254 34 ll34 l 86 54 133 2.5 ory fiet - l,4inorFloodi t2 I0nly June 82 467 r93 l16r I lt3 | 207 67 l78 2.7 l6 0ctober 82 384 144 I lr3sl105 ll71 69 I rs5 2.2 Dryl.let - l4inorFloodinq Only ' l July 83 432 t21 | 2r7 | 94 | 2s7 t-s4 I t74 4.8 3.2 13 october 83 327 63 r77 87 j45 rtltll l lzle | t42 4.9 3.2 291 TABLE sumnaryTable showinqfor each survey of the overall Blyth-Cadell Rivers S the numbeiofcrocodiles in the size classesindicated. TheE0 classeshave' .lded toqetherin eachsurvey and 5Ol of thesehave been djstributed equally anong lne aa:4;).(4-5') and(5-ii') size classes;the renaining50* have been distributed io th; {;6') size classeswith I/3 beingallocated to the (6-7') size clrss and i7g to iize .tasses(:i'). Thlsweighta the distributionheavlly in favourof larger crocodiles,rhich are-knownto nonnallybe the-nost-wary. henthe.E0 ls an odd number,the bias is alsogiven to the largersize classes. For1974' all E0 crocodileswere put in the (:7') sjze class' kn tolats >2' >3', >5' >6' Surveyed Density 26 october 74 387 89 294 217 70 12 4 91.9 3.24 I November75 353 50 303 197 114 40 14 7 94.9 3.19 Major Flo dln 23 Septernber76 348 B? 203 i95 45 26 15 92.0 2.89 4 November76 307 246 185l7e 29 6 92.0 2.67 ll April 77 327 72 255 185 75 9 92.0 2.77 3 May 77 333 88 245 l85 88 30 14 7 92.0 2.66 8 June 77 108 257 221 115 42 25 11 90.5 2.84 16 Septenber77 386 105 281 236 99 47 24 90.5 3.10 23 october 71 360 rt2 248 180 94 44 22 10 90.5 ?.74 10 June 78 432 173 259 194 110 40 21 l1 90.5 2.86 12 September78 399 244 184 103 44 23 12 90.5 2.70 No Flooding - Driest lilet on Recoro l0 June 79 46s t23 342l25l 1154ls1 155135 I e4.5 3.62 4 october BO 400 119 281 t92 115 17 92.9 3.02 Heavy Floodin 9 Ju1y BI 290 2041115 | 67 37 20 90.I 3.22 2.70 190ctober 81 31s 72 243 1661101 | 64 39 1B 89.2 ory }let - Minor Floodi Ionl 25 June 82 408 136 272-t230 llfi t106t 67 37 9',1.9 6 November82 347 111 ---l'--t'--t-t'-ree I ror 1121| irl 1a 19 92.s 2.55 Dry |/iet - Min rF oodingonly July B3 465 157 3o8l 2lo l142 87 s0 124 | 91.8 3.36 0ctober B3 354 73 2311186 l1l3 64 3511e I sz.a 3.03 292 TABLE 3 (cor,n'o) Llverpool-Tonkinsonsystern. Also 5o:;:"l"lj"till.rj;f seecapt.ions to rables1, km Totals H >2', >3' >4' >5' >6' Surveyed oensi ty Major Flooding lS,luly 228 19 209 ll70ll03l 65 40 r.37 25 l4ay 77 40 205 199 142 39 19 145.1 1.41 27 october 77 228 172 12t 54 1l 123.4 27 September 78 233 178 40 20 141.4 110 'iest t\o Floodin -Dr l,let n Record 16 July 79 289 226| 215| 168 117 74 37 1s0.0 19 0ctober 79 | | l6l 194| 178I 136 58 l3s 141.1 1.38 15 october 80 ?95 7l 224 173 t28 88 140.6 1.59 Heavy Floodn9 2 ,luly B1 26 230| 178| t22| 851s4 140.6 1.64 5 0ctober B1 34 220| 187| t29 | 86t54 32 141.I Dry Het - t'li1or Floodn9 only t2 June a2 467 193 274t245tt72 113I 67 35 r l4t.l 1.94 0ctober 82 384 t44 z4ol?z4l t66 105| 69 38 | 141.t 1.70 Dry l.let - Minor Floodl g only I July 83 432 t21 3ll 1228| 157I 94| 54 I 30 141.1 2.20 0ctober 83 327 63 2641r87 | I r33| 8714s I 29 | 141.1 1.87 293 P- | - .9N I ::-.J 'l- t-a - E-- .E J F .E : EE E NE 294 4>=s r ooE .E!ecod {2 6Edo E llos :'+ 9xo =-- f,N ::- = 295 E.3 dE E:.3 F' g.e ! ; f< n; os o c) ''"i € - d ' €-' e= ! NN P;g$bH g +o oo -o 3 o= o "=-P e t9 s.. 9* *9 C :g* -P .- : -t c ed > - E@ =:_ .i- .F9 P.3 - ;.:' ': ia a ;Eg 5- ;, E €- ) =! LO E'! L F t.: - ;-g 9; : b- t- t. €,* 9i EE .. +!o 9: c€ o u) q 5.?5 E' 9- E 3lL !o oo : =---.ts.E.a35i BE Ei s ' ".: .9- ie .3 Rp; )t €3 H 3-: 9E rE ; LE3 E" E* . ;.9^ e; 5i f "t; .5 9C 3 389 E,: ;E : 3Ee 296 Eo .; Ea! o ,-o! 9c *,4 Eooo Tr p- o! E .o 0i- c I Eo E c^ ^ ! E 6!o 9E e- ?es 9 I '- '- E- E9 {? 3- 'o o d o:c ' o= E9? k-!E! Foox t@! q d o >r != J tN o crp r o o | 6-P!ole> =bg l- :-E'get3..E o.e < >4 : c 6- 3 c^d=-o ! e o!Eo 5 0-> a.o@>luo4 9o zi s 6 c .EE dE!?gP9 LIJ I ) F 9^ !-6-!i> =----di8 c pafs^rns uDl e J.? 294 GUIF OF CARPEI{J!AIA \ \r^ { 3 2 B E 1\ o PER.aoor'lEr \ )- r lrl,,a.ftir BAY vD^ s srrred,r-caEr kts;;;\'".""'* g 5 ! = i H J t ) I = \ (l =l ; - = fl lff- ? il: Ba= :; .,e ! .E:3d- n tglrcAcrA crEE,(J FrG|n cRF€r( t; | _il' I : - Tcaxlisot RIIER z s ? ^.r- | E '!, I 9 lt' i _._t J 6 { ) a!1 TOM'S SKIRMISHPOINT 12.5 'iror.*o"o O MANINGRIDA CREEK BATISLAND MORNGARRIE 20 CREEK 'o') ,oVro \!d,*-ror,rxrlsonnrveR 25.2 40 50 ilffilotoiiV SRul[ilARDoBoLo" CREEK 60 50 LIVERPOOLRIVER 61.2 ATLASVUO sbF ttirSl.l CREEK 0510 15 6 rss+ ( KILoMETRES pteunr2 THELIVERPCOL - Td.IKINSO.I RIVERS 300 ARAFURA SEA CREEKA ----'-6n;;;a-*'- .'I6NJDADAUD Cftgk BLYTH RIVER 20 CADEL(GAR'6I5 qN ______- _ _ _ -Blu-rBoNgq( Tanrti d " cADELL oLnsiirrot RrvER 816 tsII,LABCNC ARNHEM LAND qO BOTGARDI ABORIGINAL ffi$'"''l? SLYlll P. \ 0510 8lr.l-ABoNC -E=::::- KILq€TRES FIGUREJ THEBLYJH . CADELLRIVERS 301 5f z, q= *il :=,, ==4 -lt a9 ZOtt =z =lu 3 z o ll9 z llt 17 = 'l :i 5 9< I -A tJ -6 -l ; o \r g = oH v3!43 vonvovoNvSN 302 S- l\ r+IlE stm LAI{DING'tO ,------t' a+< ,ooL€rl LYDE RIVER .:-i:=-:- =-:1-= = -=----=: AF'&ET TA\D 'XORICIM! RESER\T 6OYDTNRIVER nreune5 IHE GLYD€-ARAFI,RAAI.ID GOYD€R AREAS 303 a a I 4 t&:B s6 I I I ::E tll 304 R .E ff P? I tr R I g ',€ ttl R 305 I a F EP >.9 0 F9 -.r:9 S - € -5 306 STATUS OF CROCODYLUS POROSUS, JULY 1984, IN THE TIDA], WATERWAYSOT THE AI-LIGATOR REGION AND TN THE ADELATDE RTVER SYSTEM OF NORTHERNAUSTRALIA RECOVERYT'NDER WAY tl. MESSEL, c.C. VORLICEK, A.G. WELLS, w-,J. GREEENand r.C-oNELy Department of Environmental physics, School of physics University of Si-dney Austratia 2206 SUMMARY This paper presents the results of resurveys in JuIy, 1984 of the tidal wate$ays of the A1ligator Region, of ?ypi 3 Salrwater Creek and the Cobourg Complex of TypE 3 waterways, which lle Just to the north of the Alligator Region, anal of the Adefaiile Raver- Most of these waterways were surveyed three times previously, in 19'7'7, l97a anal 1979- The-mode1 of q. porosus pq)ufation dynamics devetoped il1 previous publications prealicts that the recovery of the ;opulation should be faster in TypE 1 waterways with extensive as;o;iated fleshr€ter compfexes? such as in the Alligator Region, than in those lrlthout such habitat, because tbe losses of crocoaliles shoufal be 1ower. The recovery should thus be faster in the Alligator Region than found over the last 10 years in the monitored irea cenired on Maninglida, which has fittle such associatect habitat. The results of the resurveys were in fulf confornity witb the modet: alesprEe continued heavll losses due to drowning in fishermen,s nets, j-n nost of the tialal waterways of the Alliqator Region tbere has been a major increase in the number of iarge 06') crocoaifes between 19?8 and 1984. A substantial fraction of this increase appears to be deriveCl from the freshwater cotnplexes - The Adelaide River was also expected to have a higber recovery rate than that of the nonitored area, for two reaions: there are some remainlng freshwater complexes not yet destroyed by feral buffalo and there is an extenslve systen of mostly TypE 3 creeks on the ilownstream sections lrhich could act as hav;ns during the breeding season, thus decreasing the numbers ]eaving the river through the mouth. Again there was a nost significait tncrease. between 1977 and 1984, in the nwiber of targe animafs sighted. There was no significant increase in the number of crocoalifes sighted in the TYPE 3 waterways of the Cobourg Complex or in TYPE 3 Saltwater Creek between the 19?9 survey anal the 1984 The results of the surveys also confilm the existence of a bottleneck in the (3-6,) size class. As in the result for the monitored area there is an amazing constancy in the nurrber of anlmals in tbis size c1ass, especially if only the {4-6,) animals are considered. The increase in the nuriber of laroe animals has shown however that a significant recovery is undei way in the 307 j.n Alligato! Region anal in the Aalelaiale River- The recovery the Alligator Region would be even nore narked if commercial net fishing were to be stopped. Introaluction The Adelaiale. East Alligator, South Alligator, west Alligator anal Witdman River Systems anal Murgenella Creek -a11 TYPE I systems - (Fiq. 1) $'ere first systematicall'y surveyed in 19?? (the wildrnan in 1978) and then resurveyecl in 19?8 and again in 1979. Just to the north of the Alligator Region, the largest of TYPE 3 waterways in northern Australia the Cobourg Complex consisting of the lfamaryi anal Minimini Conplexes anal Saltwatei creek -were surveyeCl for the first time in 1979 {Figs. 1 and 4). our results for, anal discussions of, the surveys were presented iD Monographs 1. 3 and 18 for the Adelaiale River System and Monograph6 1, 4 anal 14 for the Alliqator Region River systems anal the Cobourg complex. Detailed alescriptions of the waterways were given ln those Monographs also anal full work maps ln Monograph 15. Our systematic surveys of some 1OO tidal watefltays in northern Australia between 1974 and 1083, reporteal in detail in a series of 18 Monographs and 2 western Australlan Reports, revealed that the tidal wat-r,tays in the Alligator Region, along with their associateal freshltater complexes, constitutetl the largest concentration of TYPE 1 9. P.gfgggg breealing systems in northern Australia and coufal plaY a very important role in any potentiaf recovery of the population. Tmportantly, the East Alligator Rlver w;s incfuded in stage 1 of Australia's Kal 308 on the surveys prior to 1980, we continued and::lt:yilS resurvey to monitor the tidal water-s-ih the Manihgrid; .i.. .ia'tf," results of these survevs ehabled uf to refihe .nl9"::Iig:. turtfrer our picture ?5, 9f 9. ?ofo'.r" popurations (see Monosraphs I andt rd/, r'ne population modef rlow runs as follorrs: 1. The tidat waterways of Dorthern Austratia according have been classifled to tleir salinity sjlgnarures rnto TypE 1. TYPE 3 systems TypE 2 anal as delineat;d .in chapter :, ris.-:..i.'iii .r I (pases1oo and 101). rvi,e r systeis ii.'ti!'*.i,, DreedrngI:l:gi:!h ones and non_TypE I systems.are irsually poor or- non_Oreeai-ng is rhe rypE 1 systems and the and:I:t:i:j semipermanent Jr treshirai.i-ui it.oo.,g" and Dermanentfreshwater .""o.iitea *itr, other-them which account for the n "ur.^p" sysrens"",t.ir"."'-i""'l i:":::';':;:::t.;j f;.ffifftsi.ili"- Iarsely uponrypE I systemsand their .3"..i iii"ilJli". the pro;ision or their .,"."ari".."i"a ;;;:;;;; a_rso:gpr:f:-f"l sometimes have i "y.te* freshwater complexes ass"ciatea ,riiit-them but these are normally quite minor. (pase 4t9) of Monographt. that--2:_, 1n]l::!1"-t.2.1 our resufts show TypE 1 systems some 27s of cfre-crocoaires-s;;;;;;-i;;; -;"i"!"i=J""" hatchtinss (of which some sor are ii; "." one year and .rune of "";." ., the next, paqe 394 l.li""siiph-ij ,-;h!reas in rYPE2-3.systems this fisure rairs .rol'n. to rax rii,i l"Ir".u*" to 4x, showinsa *".1 a.",..""a-l.i"r,iiiq-;.!.ii;.;i""E-ii ," :3EJ_:I:::i:. rn rypE 3_sysremsthe percentale """_i" i'i-=jiii!111"9: r-r-r'l and (J-4') size classes conrined"i-.i"""dir". is some f;;d'ii=;=p'"-':"'J'".'"":L'"'""ff'.lt-"i"t",";-#l';:r ts at 'teast 521' on the other 3ot.i ^ rvee-i t t:, Lne:lT. non-herc]ltins :"' H"r, i :;:.:;:: :li:.;;r crocodites on rvi,r rjx on non_TypE I waterwEys lf. r.,iti."Jy" u,,a fpaoe"jgligd 419 tlonograph 1i. relatively J:_- Ih. few large. anat rnore flequent smalt freshwater billabongs and sehipermaneni and permanent ;;;;;";i;;-;;p= associated with tidat r,{aterways a}e known t" .o"i.i"-gl";r""",-i-illl but have not been inventorred systemaeicarly'svsi..-ii--riJ except i:in i-a few cases. The accurate .*a"na-i"".; ol popularions i.,r."".". Iiii ill" ;llt.lili".f; ffff:*",o, _larse{:eswahrer swamp areas, ="t,ti"ti"i ji'i"i"" (normally borderinq "tir, i".",ii,r old river channefs), i" a"s't"ratia very limited -perhaps is 400 km2 maximum_ "".tfr.i"i.it"i'*errratiors, we estirnated that "p""-f in 1979 rhe- non-_harcling""a S] ;"i";"=-p"p"I"tt"" vas less than 20i ot the non_batchting population-siohie-d tidal sysr.ems. rn we now befieve tt"t if,6 :O;-;;;;;; ;;:";;- overestimate for 1979 _an 'driest unusual year ot tn" wet' seasqns on recorat. """";i;t;; "iii,-|r,. 4. Tt appears tbat the DoDulating_of non_TypE I systems (hlTercattue or partially hypersatine coistal and mostty non_coastal waterways ) .resufts from the exclusion of a tarse f.;"ai;;-;; fi;-;;;l;a"rt-;;.;i;*;; :I::99i1": from rypE 1 sysrems and-any freshwaa;. associated with them. Adutt crocodife; "pp..i s.""i.iiy-ti' torerate 309 in batchlings,(2-3') analsometimes even (3-4') size't crocoililes itr"i. (but not always -they sometinres eat,them'.page "lJi"itv or kiII them, page 334 Monograph l) ' but not i'j-lr"""gi"plt i4- (3-4') iarqer 6rocoalres. Thus once a irocodile reaches the !ra"ia-Sij size classes, it is likelv to be challenge'l i"".j"=i"bfy not only by crocoaliles in the larger size cfasses wheD it ."a-i" f"-.j."f"aea tiom ttre area it was able to occupy ;;; ;.ii.;. A very ilvnamic situation prevails with both adults *a beii-rq iorced to move between various components ;f a""u-ia"rt. svstems anal between systems. Croco'lile interactlons or between crocoalifes in all size classes lncreases ior"r"iu."."" (pase ;;;;;-il;;. -durins tt'e breedine season 44s Monosraph uonosrlph 18) and eiclusions' if anv' nornarlY i-;;-p;;;-ioa ( li5""a -.""ilythis p;ri;d. A substantial fraction 80*) of-the """"i in the (3-6') size.classes but-al-so incruding iii:.a"ii., ttie ;;ua;r; rarger ciocoililes, are eventually exclucted from .1""i-pi"p"t'"t are prealated upon by larger crocodiles' crocoaliles that have been exclude'l' some nay take 5. of those wittl refuoe in freshrrrater swampareas an'l billabongs associated iit. i.t.i*"v; iiom *rticrt ih"v ,ut" excluded or in the waterwavs' 1 ;reeks if lt has anv. otbers mav travet afong-tle """-tipr -rr"ir"".tuy ctrance thev find a non-TYPE 1or another TYPE 1 ii""i-""tir e> 310 lraterway does itself. Examples of these are the clyde River wlth cne Aratura swahp (Monograph 9). Lhe AIIigator Reqioh Rivers with rherr_r{etrands (Monographs 4 and 14), and Lhe Dafy, Fihniss, Reynolds anal Moyle Rivers with their wetlands (Mo;oqraph 2). Not only can the foss factor, which appears to occur du;in; the exclusion stage, be expected to be lolrer for rnovements'inlo anc out of swarnp areas associated with a TypE 1 waterway, than j.nto for movement anal out of coastal non_TypE 1 systems, but the loss of nests due to flooding can also be expecteal to be less. We have oDserved nests made on floaring grass cane mats in the Daly River Aboriginal Reserve area. Thus recovery of the g- oorosus Srgrlaticn on TYPE 1 ticlal raterways, wlrh subsrintiat assoclatEFErlsrrwater conplexes, can be expected to be faster than on other systems (page 445 Monograph l, page 98 Monograph 14). 7. Because of the 8OZ exclusion and at least 60_70 losses of sub-adult crocodiles as they proceed toward sexual maturitv.therc - has been no sigr.lificant susiained increase intfre non_tratcfri ino-_ porosus C. population on the tidal waterways of our monitoreal area in northern Australia since the corunencement of our systematic surveys, a period of ten years (Monograph l8). 8. Assuming the results from our monitored area apply elss{tIere, any significant sustained increase in the non_hatchiin; q."".""r- popufatj-ons on the tidaf \,raterways of northern Australia must be nreasured in decaales. However, as discussed in (6) above, on tialat systelns with associated freshwater complexes, the recovery coulal be expected to be more rapial. 9. Though tbere has been no sustained significant increase tD the nr]Inbe! of non-hatchling crocoailles sighted on the monitoreal control tidaf water^rays since our surveys started in 1974, the size structure of the animals sighted appears to be changing slowly. Notwithstanding substantial fluctuations, the ratioa oi srnall {2-6.') to farge ( 6,), and (3_6,} to large animafs is decreasing on the Blyth-Cadefl, may be decreasing o; the liverpool_Tomkinson an is decreasing overall on the tidat waterways of the Manibgrida monitoring area. Thus t}ere is some ibdication of the comnencement of a slow recovery phase. However even this could be open to atispute. 10. Tbouqh there are wiale fluctuations, specially after ,dry wet, seasons when the animals are concentrateal into the tidaf watenravs, it appears that as the nunber of large crocoatiles in a tidal wateffay increases, there is a tendency for the number of sub_adults in the (3-6,) size ctasses to decrease or increase marginally only. ?hus the total number of (3-6,) and larqe animats sighfed apl)edrs generally to be hofding steaaty or increasing slowty ;n1y. It is alnost as if there were a set number of territoriei or .lots in a river system, and the crocodiles themsetves al.e primarily r€_spcnsibte for the very heavt losses of ?02 that occur in the orocesi of trying to secure Lhese slots o.r to increase them in;uncer 11- When a steady state is reached in a ,recovered, DoDulaEaon, the ratio of (3-6,) to large animals night be consiaeiaity Iess 311 12. If one conslalers a group of 100 of the sub-aalult crocodiles in a TYPE 1 tidal system without a substantial freshwater complex associated with it, one can expect some 80 to be exclualed from it. at least 60-?0 to enal up missing -presumetl dead. less than 15-20 to successfutly establish territorles on the system without having to leave it and the remainale! might eventually also return anal establish a territory, especially after becoming sexually mature. The very nature of this matter is such as to precfude precise figures and they must be lookeCl upon as broad estimates only, however detailed study of our results {Monograph 18) now indicates that the missing -presumed dead figure is likely to be in excess of 70. 13. l.Ihen there is an exclusion of sub-adult animals, mostll 13-6') in size but also inclucling imrnature larger animals, this place mainly in the breeding season, normatly commencing arounal September-October anal apparently lasting throughout the season. Ant influx of animafs. in the (3-6') anal/or large size classes, appears to occur mainly in the early dry season and to be completed in the June-early September Period, but may ln some years be earlier. 14. After a single 'alry wet' season there is a substantial influx of farge anal sometimes (3-6') aninals, forcecl out of freshwater cornpleies, into the tidal waterways anal these are sighted aluring June-July surveys. surveys nade in october-Nove ber of the same (3-5') _and/oryear, us;ally reveal a substantial alecrease in the number of large- animals sighted, however the number of large animals sometimes ;emains hiqher than previously and hence a number of the new large animala do not return from whence they came. These animals app;ar successfuf in establishing a territory on the watenray, :nal it coulat be the wateruay from wbich they bad origjlE1ly been exaluded. The 'dry wet' variation in the nunibet of animals 6ighted appears to be auperimposeal upon the variations nornally foind auring surveys following usual wet seasons -which generally resuft in eitensive flooaling on the upstream sections of the ti'Ial waterways. Hatchling recruitment on the tidal Naterways in generalfy greatly enhanced aluring 'alry wetr season but appears to Ue q.e"t1y realuceal in major swamp habitat. The reverse appears to be true during normal or hea\,'l' ret seasons. Thus on the basis of this model one woulal predict that the recovery. between 19?9-1984, of g. pglgE]lg populations }n t}le tidal watetwal's of the alligator Region should be greater than that found on the tialal waterlrays in the Maningrida area, where the inme'Iiate freshwater complexes associateal with the tidal systens are quite minor in comparlson to those associated with the tidal systems in the Altigator Region. However (see Monograph 18) we have stressetl th; inportant role ptayed by the Arafura Siranp for many oi the animals in the Maninq;idl area' rurthermore, even thoush the alestruction (by feral water buffalo) of the freshwater complexes associateil with the Adelaiale River sYstems has been .".r-.t", t".on.ty on this waterway durinq the intervening-5 to 7 year perioa, mi;ht be substantial since thele are over 100 km of 312 saltwater creeks on the alownstream sections of the watervdy,rnany of vrhich coutal act as rearing srockyards r". tr," i:_dii-..ra sexually imnature..large animals. This courd t" io the exclusion and,/or loss factor substantiatly "*p""i"6as'we i"""a "ut the Kalarwoi on River irl Bruckingham Bay (page i6 r.t"""q."in-'iof . The-transfer of the University of Syalney,s g. porosus fiefd headquarters, in November 19aJ. from Maningriala oh the Lrverpool_ Todkj.nson Rivers systen to orapunga on the gaint e"p"i ii"", system -in- the southwestern corner of the Guif (Monograph of Caipentarra 18), provided an opportunity for touitfr-i.ra-tir1ar resurvey of the tidal " watenrays in the A1]igator neqto"-ana of the Adetaide River systems and atso r". i5"ri".v-ii-lr,!' " s urvey boars and sear had to-t.-*"""a rv ::::":g-:"T!l:"j- tnesesystems.^o_u-r_ i:":,]r::-l::. rhe opporrunity to check the drdrse rn Ene sratus ot C.porosus in these waterways during years the last 5 and to tesr our model further in a aiifereni i."., to amend ."a it if necessary, was too gooal to be missed: T;""'r""." decided to charter a ve;se] -The siiralee s tme iairv ils.ei, the Universityrs research vessel. was afreaai-on .i,..i"f i" tn. Australian Instirute of Marine .ro*i."if _scienc.", i", iG,"i"nal and to resurvey the waterways during June_Ju1y 1984. presented The resuLts in this paper are a consequence of this decision- Results Standard survey methods as taid down in aletail irl Chapter 2 of Monograph l were used for each of the spotliqht .".""i" tir. same two spotters (WJG and AGw) were used foi the t97i, ""oI91A, 1979 and 1984 surveys. Sumnary resufts for each of the tidal r,ratererays resurveyed are sbown in Tables 1 and 2. The d;a;ifd results, incfuding the distxibutional aliagrams, foi .""f,-Jr tn. latest resurveys will appear. in due courJe. in Ltonog;aph 19. In Table 1we have updated the relevant portions of Table 9.2-l I by incrudins :l-T:':s.::!h'|aD-Le the resulrs i,r r"iy iil;;*""y=. z_was prepared by usinq the date qiven"", in Tabfe groups l and the size classes in such a way as to focus attelrtion on important aspects of-the dynamics of the g- por".ui p"p"i"ii"" rn t'he area concerned. we found thrs method oE- vtEii_nq_ the Aata very helpful when considering the atata for surveys .ii"i.a in the Maningrjda area. """ We draw attention to two inportaht points when consialerinq and comparing the results shown ih Tabr;s I and 2. Tle firsi ierares to the matter of errors in size class estimation. We ai.cussea tiris matter in some detarl on pages 80, 335 and 389 ot Monooraoh I ano page orj rt/ of r,tonograpb 18, and refer the reader [o tf,".". Ine rnarter concerns t})e rnporLance of comparing results for equrvarenr survey season, that is, breeding versus breeding and non-breeding versus non-breedinq perioals p".riUi.= (pages 124. 125 Monoqraph 18). Foi example,"rierrever o"t"U.i-lr"".ii., surveys shoufd, if possibte, be compared witb other October_ Novenber surveys and not \Tune_July ;nes. IN fns cesr Oi iiE PRESENT JI'NE-JUIY SURVEYS Of T'I]E TIDAL WATERWAYSIN THE AI,LICATOR REGTON, RESULTS CAN BE MOST MEANTNGFULLYCOMPARED WrrA tiOSU rON 313 TBE .]UNE-JUI,Y 19?8 AND AUGUST 1979 SURVEYS RATHER THAN THE OCToBER19?? ONE. Holtever even in the case of the 1979 results, consialerable caution lnust be used. for the 19?8-1979 wet season was the alriest on recoral and many of the aninals that woufal have nornalfy been in the associated freshwater complexes at the time of the survey rere forced back into the ti_dal *it".*"y" (see Monographi 1, 4, 14 and especial-ly Monogrpah 18 r.rhere ti.lis matter ia discusseil in detail). In the case of Murgenelta Creek, the concentration appears to have taken.. plaie in 19?8 (page 18 Monograph 4 and page 75 Monograph l{' ' MURGENEILA CREEK This creek systen (Figs. 1, 2 anal 4 ) is an important one as at i.-i".i"a"a in t'lurgen6lta witdlife sanctuary an'I has substantial freshwater swamps upstream which constitute both important lieeainq and reiring habltat. The creek is closed to comnercial fi"iinq. Howeve; aturing our 19?? and 1978 surveys, 13 po"ctrer"'".i iets were found ind confiscateal by a wildlife Ranger ;orkinq with us. No nets wele sighted during tlte 1979 survey oi ttt.-.rr.tr.y on the night of July ?, 1984. one coufd- thus ft"". if,"t th! number of g. Dorosus sighte'l on Murgenella creek l"ii"q tlt" 1984 survey w6u1d reflect ahd und_isturbed' natural size ;;;;;;ty over at teasi the -aninalspast six vears' rhe nunber and .ii.. ai.itil"tions of the sighted are sho!'/n ln Tables 99x i-i"a z ."a reveal a rnajor and statistrcally siqnificant-( the i..'"i) itr...."u from 125 in June 1978 to 229 iA July 1984 in non-hatchling sighteal. The density of non-hatchlings rr""""rU"l it..u...a "f from 2-87kn to 5'o,zknr' Attention is drawn to a nuiber of other important points in relation to Lhe lesu_Lts: least 1. Note that of the increase of 104 non-hatchlings ' at ;i the (3-4') size class and on the basis of our model reach i""-.."-."p".t".;-t" farge fraction of tbese animals not to iii. " cfasi and hence for the nunber of animals ia-s't'"ir. to i.*.i"i"g in the (3-6') size classes to fall back close orevious-feve]s. Tbe alensitv figure of 5'O is thus :orogwl:t 2' i;;i;;;a;y the fisure of 1l? (l-6') animals shown in rable latter rrtl.ft ai least et are in the (3-4') size class' Ttrese "ianimats woufa have arisen from the excellent hatchling 'drY recruitment aluring the wet' of 1981_1982' ber of a 2. Special attent-ion should be focussed on the nu (5-6') -46 in !nir.i-t in the (4-5') plus size cfasses constancv of tgli,-it "iqltt.aii 9la, ae in 19?9 a;d 49 in 1984' The and iiri" t"i"i is trufy an important and remarkable resuft observing i"ii""t. precisefv the same phenomena we have been svstems fo! l"-lft" li'".tp""f-iomkinson and Blvth-cadell Ravers now the Dast 10 vears (rlonograpbs I and 18) ' Reqard-Less ot sighted in i"ioE-lit"-t.it"itment m;y Le, the nur'ber of animals pr". ls-s'l size ctasses seems to remain closelv ii.'ta--s;l were a ;;;"i;"! o.'i.,.t.."u stowlY onIY' rt is as if there gaven rtver alefinite nuniber of slots for these animals on a increase s1owlv onlv' ;;;;;-;"e lr'"t tr'. number of these 314 ?. ..fhe most inportant aspect of the nurnber count is the increase in the. nunlcer of farge anihats sighteal. incfeasing from i9 rn fgZS !o y5 rn teu4 or an ihcrease of some 61E (Table plovidesstrong 2) . This result support for the contention that one is witnessrng a sustailreal and important recovery of the g. oorosus polulation in l4utgenella creek and its associateal fre;hwal;-r comil;xes. 4. One may obtaln an estimate for the mihinum percentaqe (3-6') -iirg"""-u..of, crocodiles which were exc.Iuateatana,zor rosi ii". creek by noting (Tab1e 2) tbat 50 (3_6,) and sg farqe were sighteal duriilg the June 1979 survey anal that tfie Jufy";imars t9a4 survey reveafed 95 large aDimats. Each ot tfr" (:_e,) animlfs of lt chey :::: y"yr9, survived, be in the tarse size ctasses by .rv64 and hence the minimum perceDtag€ wbich have been excludeal aDo/or fost (minimum because we have assumed that alI the increase originated from the 50 (3-6') aninals of 1978) is (50_j6)/50 or 28U- using tbe figures for the 19?9 artd 1984 ,"ru.v" vi"ia_ .., exclusion and/or loss factor of 32/66 or 4gt. Thes; fiqures are to be compared with those found for tiaaf systems ,u"h ;;-i;;." ," Arnhem Bay (88x, Monograph tl), the Btytil_cadelt nivers iystem paSe 134 Monograph l8), Liverpoot_Tomkinson Rivers System (I ::x, aox, page 127 Monpqraph l8). Each of these tatter waterways are excellent TYPE 1 breeding systems but the freshwater cqlple) 5- Hatchling recruitnent on the Creek appears to continue ro be minimal in relation to tte number of larql_ anrmals siqhted ana hence one is led to believe that a large fraction of;he (3-6,) and farge animals sighted on the Creek must come trom ltre associated freshwater complexes associated with the terninal sections of it. This is further borne out by a study of the distributiona] pattern of the animats (see lfonoqrapi 4 and 14 for previous surveys; Monograph 19 wilI contain-th; alistributional dragran for the 1984 survey) which shows that the numlcer of animals sighteal generally increases as one proceeds upstream, rather than decreasing once the freshwater aections a_re -as reacheil occurs on tidal systems with Jninimal sr,{anp habitat at or bordering their upstream sections {Monographs 1, 12 and 18). Tbe freshwater complexes associateat with th; ulstream secti.o;s of creek Y::9:n.11. are acring both as breedj.ng systems anal reanng srocKyards, wrth substantial interchange with the nrainstream arld its subcreeks. In fact the retatively higt loss factor of 4a1 given in (4) for the t9'79-19a4 period is-indoubteafy pailiatfy due to a fraction of the ahimat; returning to tire ri.eifrwale. complexes after having been concentrated back into the tidal system by the drying back of swamps. The fresh\"/ater comptexeE appear to be as,or even more, important than t]1e tidal itself, as far as recruitment is concerneal. "riter,oay EAST AI,LIGATOR RIVER SYSTEM (FigS. 1 ANd 2) 'Itris tidal waterway, which formeal the backbone of Australia's xiiadu tlational laik stage 1, nas resurveyed for the forttlttime alurinq the period July 4-6, 1984, baving been surveyecl three times previ;usly, in lg11 , 19?8 and 1979- The 19?9 survey was nade a?ter the idriest wetr on recoral, that of 19?8-1979, and Itt. r"".tt,t"y" of that year inalicated that many large animals ;;; G;" foiced out of tbe freshwater complexes associatea. (pages *'itfr tf," system, and concentrated back into it 440-445 to l.lonoqraph i, t'lo.tographs 14 and 18). Did these anlmals manage ;;lJii;; ierritoiiei for tbenselves and to remain on the tidal -vet hov ;;;a;; ;; were they perhaps forced out of it asain? Artd *l"v of tit" targe inimals-were dr'owned in barramundi fishermen's neti set betwee; the nouth of the East Alfigator and coopers creek at km 13- for tbe Austrafian National Parks and wifdlife Service have contj-nueal to allow conLtercial net fishing in tle East. eiligator River from km O to 13 and in coopers creek ltself' rfto,.t6fr ale unable to give exact figures for the number of ^ii.ifs ". arownea, we do k;ow for certarn that the figure is and hence nust be reflected in the exclusion an'l/or i;;;""1=ii"tiir iig"t" to. be derived fater ancl must arso impact heavily uoon tir6 rate of recovery of q. pS!-qEllC on the Fast Alligator East n]ver System. The results given in Tables l and 2 for the Alligator reveaf: 1. That the alensity of non_hatchling g' Dorosug has increased in ii"* z.a7t* in June i978 and 2.9,/km in August 19?9 to 3'3'lkm JuIy 1984. ( level) 2. That there has been a statistically significant 991 the nurber i;.t";;;; from 290 in June 1978 to 389 in 'lu1v 1984' -j'n of non-hatchling q. porosus siqhted {Table 1) ' Even the inclease i.". ieo non-rtaictrtiill tistiqlttea in August 19?9 is stati-sticall'v at the 95t coniidence revel' However note the to-the ;;i;;;;;it"i"tiii""tt hiqh number of (2-3') animars sivins rise tnese increase between 19?8 and 1984 and tbe fact that many ot were unlikely to ever enter the (4-5') size class' increased 3. The number of EYes OnIy (Eo) crocodiles sighted 100 in 1984' ir". iii-i" or rir: a$d 1978, and 58 in 19?9' to s1""" tfr" Eo"""r' crocodiles reflect wariness, the results of oul animals oa."ant-""t.tr.v, ta.uttay indicate rncreasing disturbance of the high Fo l"-tfr. especially upstrean' The relatively di f f i cult ;;;i-*;i;;- ;;' ;namiisuous- dilcussion of the results were ina probablv accouncs for the fact that only 59 crocodiles (5-6') size-classes' rl"iii".iv identified in the (4-5') plus t:ne rsl't,1e78 and 1's7e' s8, e3 and 86' respectivelv' ;;;;;;"-;i'i"s Eo's as ;;;;-Jqha;; in these size classes. rf one distributes the !o Table 2 and then distributes equallv .""""r13a in the caption (also,see ;#;"d; -l1."Js'.pill's--a:i, ii-s;t and (5-6') size class rable i. ilio ti, tte respective numbersfor the 19?7' r9?8' 111, 106, 107 and 93 lespectivelv' igig,."a 1954iurvevs become (4-5') iq"ii-l"ai.iii"q th; relative constancv of the numicerof sightea' As in tbe case of l4urqerplla 'ci".xoius {5-6') siz;d cfass animals 2) this again appears to indicate a fairly constant tp"i"t ' sfots fot biese animals on a given tidal water$ray "uro.t^of 316 4. As for Iqurgenella orle nay obtain an estlmate for the qaclusictl aDal/or loss factol for aninals ih the (3-6') size classes. Usilrg the 1978-1984 and 1979-1984 resufts given in Table 2,one obtains the factors 11911?5 and 153/159 or 68% and 961 respective ly. This suggests that a substaotial portion of the influx of some 50 large animals into the System following the ,alriest wet, on recoral of 1914-1919 haCI been lost (certainly some through drowning in connerciaf fisherrnen's nets, but the exact nuntrer is unknown) or that sone of these animals had returneal to the freshuatet compfexes assoclated with the waterway, or that the exclusion and/or loss factor for animals in the (3-6') size cfasses was high. A cc.rbinatic.r of alL three posslbilities is probably close to the actual situatiqr. 5. The number of (3-6,) aninafs sighted on the waterway duling the surveys of 19'77, 191A, 1979 and 1984 has remained relatively constant, varying between 154 and 181, whereas the nuniber of large animals slghted has increased frorn 101 in 1978 to 151 for 1979 and then only by 6 more in the intervening 5 year period, between 19'79-1984 - This again makes one suspect that sone of the heav)' fosses in the (3-6') size classes anal also beavy losses of large crocodiles are probably due in considerable measure to drowning in fishermen's nets. Compare the respective results for tllrgene]la Creek and the East Alligator River system for the (3-6,) and large size classes (Table 2). Tn spite of the above. the East Alligator River appears to be on the road to recovery and if oDe did not have results for 19?9 and just compared the results of the 1978 survey with those for 1984, one would feel pfeased. 6. The relatively 1ow hatchling rectuitment on the East Alligator tldaf watenray {for instance compare with the Liverpool-TomkiDson and Blyth-Cadel] Rivers Systens, pages 114 anal 115 Monograph 18) sugqests substantial additional recruitment of anlnals from the important feshwater complexes associated with it- SoUTH ALI,IGAToR RIVER SYSTEM (Figs. 1 and 3) This tialal waterway must rank as one of the most important crocdile- itise anCl most ugly scenic-wise in the Alligator Region- Tts inclusion into Kakaalu Natlonal Park, Stage 2, makes lt even nore important. Much of the riverine and swamp habitat associated with its downstream sections has been destroyeal by feral water buffales, but its inclusion into Kakadu National Park could ensure that buffalo nuribers are closely controllea and hopefully the habitat will be restoreal. The upstreanr sections of the waterr,{ay are still associateal with sorne excelfent freshwater habitat and lr[Drtantly Nourlangie Creek alrains much of this and acts as a funnef for 9. oorosus between this freshwater complex and the tidal system. Unfortunatell conunerciaf net fishing for barramundi is sti1l permited from km 0 to km 2{.5 on the South Afligator and again there are heavy losses -mostly of large crocotliles- through dlolvniDg in barlamuntli nets. 377 One is able to view the greate6t concentration of farge crocodiLes on a tidaf system in Australia in Nourlangie Creek antl on the upstream km 90-95 section of the mainstream. During the 1984 survey 28 large animals (some very large, 14ft or more) rdere sightecl on the kn 90-95 section of the waterway anal 31 on Nourlangie creek (kn 84-90) - With the inclusion of the South Alligator River System into Kakadu Park. this g. pqlgglg resource coufd easily become a tourist attraction of considerable national and internaticnal Our previous surveys of the South Alligator Systen highlighted a nuniber of perplexing probl-erns (page 91 Monogiaph 14) in relatlon hatcbling recruitment and the relativefy high propoition of (3-6') and large anj-rnals sighted on the waterway. It is now clear that hatchling recruitment on the tidal system will remain mininal until the riverine habltat is restored and that in the meantime tbe system wilf continue to depend mostly upon the influx of animals from the freshwater complexes associated with it or from other systens in the Afligator River Region. One neeal only examine, for the South Alligator, the size class colulrms of Tables 1 and 2 to see that there is no way that the spectacular increase in the nunber of ]arge animals sj.ghtetl, from 75 in 1978 l:o L4'7 during the 1984 survey coulal be derlved from within the tidal sections of the waterway itself. These animals have come fron elsewhere and are using the watenray prealotninantly as a rearing stockyaral rather than as a breeding systen. Though the south Alligator is a very typical TYPE 1 system salinj-ty-wise, because of the catastrophic destruction of nuch of its riverine habitat, nesting on it is nininal. In consequence, the normal exclusion and/or loss calculations carrled out for the other TYPE 1 systems in the Region are of fimiteal value. for even though there are losses alue to interactions antl certainly hea!ry and continued losses due to corunercial net fishing, these losses are forbmately being offset by an influx of aninals from elsewhere- carrying out our normal loss cafculation for the (3-6') size classes, for the years 1978-1984 and 1979-1984, yields rnininum exclusion andlor loss factors of 1/73 anA 12158 or some 1% and 2lti respectively. I{owever, as pointed out previously/ most of the (3-6') animals themselves come from elsewhere and not from within tbe tidal sections of the waterway itself. other points which are evialent from Tables 1 and 2 are: 1. The number of (3-6')animafs sighted on the watemay has retnained relatively constant, varying between 73 on botl the 1977 and 1978 surveys alofin to 58 in 1979 and back to ?8 on the 1984 survey, Probably the increasing nuriber of large g. porosus on the waterway is keeping the nuniber of (3*6') animals down- Note the alecreasing ratio of {3-6') to large aninals shown in Table 2t do{n fronr 1.06 ln 1977 to 0.53 in 1984. 2. The density of non-hatchling q. porosus sightea aluring the surveys increased form 1.2/kn in 1977 to 2.1,/km in 1984, with the major increase taking place between the surveys of 1979 and 1984 and in the large size ctasses. The density was still onty 1.4,/kn durinq the 1979 survey. 318 3- The increase fron 151 non-hatchling sighteal in .Tuly 1978 to 240 sighted during the July 1984 survey is statisticafly significant at 99X levef. However one does not need statisticaf arguments to see that there has been a spectacular increase anal that most of it occuffed in the impoi:tant large size classes. WES" ALI-IGATORRIYER SYSTEM (Pigs. 1 and 3) This excellent littfe TYPE I waterway has also been included into Australia's National Kakadu Park -Stage 2, but is being slowfy throttfed crocodile-wise by the commercial barramundi fishermen who are able to net legally from km 0 to 17.2 on the 42.2 km of the surveyable length of the waterway. In the proaess, they Clrown large nuribers of large g. porosus and only catch a few barramundi. In addition, feral water buffaloes have destroyedl nuch of the former excellent riverine habitat and a substantial fraction of the freshwater complex habitat associated with the tiilal water$ray. The feral water buffalo problern is likely to be sofved relatively quickly be Kakadg Park Authorities but not so for the comnercial barramundi fishingi there are some hard major decisions to be maale here if the valuable g. p9lgElq lesource is to be alloweal to recover in the National Park. The resufts shown in Tables 1 anal 2 for the west Alligator System show that: 1. The density of hon-hatchling g. porosus siqhted, has jncreased from 1.5/kn in 1978 to 2.4/kn in 1984. Furthermore, this increase was due almost solefy to the increase from 37 to ?? in the number of animals sighted in the (3-6') size classes anal at least 21 of tbe increase were in the (3-4') size class. As Table 2 shows, there was an increase of 4 large animafs on1y, from 20 Eo 24, between the 1978 and 1984 surveys - 2. The nuniber of non-hatchlings sighted increased from 62 in 1978 to 103 in 1984 and this increase is statistically significant at the 99* confidence 1evel. 3. It is probably of limited value to conjectule about tbe dynanics of the population w}]en one knows that so many aninals are lost throuth drowning in nets- During each of our four surveys, in 19'77, 197A, 1979 and 1994, we found the West A.lligator system a maze of barramundi nets (page 55 Monograph 4, pages 91- 92 Monograph 14) and it appears a ndracle that any g. pglgElq at all remain on the k]n 0-17.5 section of the waterway. Carrying out our normal exclusion anal/or loss calculation for the (3-6') size cfasses for the surveys of 1978-1984 sholrs that tbe minimurn loss factor was 33/37 ot 89% anal for the 1979-1984 surveYs the loss was 1OO%. Not only did the 41 (3-6') animals sighted during the 1979 survey, NoT give rise to any additional large aoimals, but 10 of the 34 large anirnals sighted in 1979 were missing aLso. we have no doubt whatever, that one of the reasons for these heavy losses is the drowning, in fishermen's nets, of a substantial fraction of tbe animals on the tidal watenray. of course some of the animals may have returned to the freshwater complexes associated with the System. 319 4. Examlnatiod of tbe nuniber of (4-5,) plus (5-6,) aninals sighteal durj"ng each of the four surveys ls of limiteal value. because of the totally artificial situation created on the waterway througb exceedingly heaw net fishing. The figures for 1977, 1974, 1979 and 1984'vrete 29, 22.21, and 39 respectively anal tbe increase in the nunber for 1984 might be relateal to the relatively large alecrease, from 34 to 24, in the nuniber of large animafs sighteal, hor,rever it is difficult to be firn on this point. 5. The very snall hatchling recruitment rate on the tidal waterway suggests that a large portion of the (3-5') and large animals sighted were derived from elsewhere -from otber tidal systems in the Region and/or fron the important freshwater complexes associated ri'ith the West AIligator SIstem. IIILDMANRI R (Figs. 1and 3) This tidal waterway is very much like the West Alligator System except that unlike the West Alligator it has no surveyable creeks orl its downstleam sections aDd has a surveyable length of 33-5 km on1y. It too, bas fortunately been included in the Kakadu National Park -Stage 2, but again conmercial net fishinq is sti11 permitted from km 0 to 22- Rather than repeating here the introaluctory remarks we gave for the West Alligator System, one sbould reread those and substitute the word "Wildman" for the West Alligator. Thouqh superficially the two water{ays appear much tbe same anal both have freshwater complexes associated with them, our survey results show that crocodile-wise, the Wildman is a far better system, From Tab1es I and 2 one sees that: 1. There has been a spectacular increase, from 1.9/km in 1978 to 6.O/km in 1984, in the alensity of non-hatchfing g. porosus sighted on the waterway- density was 4.0/km in 1979 when rnanjr 9. !.9:SqjfC r^rere concentrated"he back into the tidaf waterway from the drying out freshwater complexes associated with it. The non- hatchling numbers sighted increased from 65 in 1978 to 200 in 1984. This is the kind of increase we had been waiting for,even though at least 106 of the 200 non-hatchlings sighted were in the (2-3') and (3-4') slze classes and most of these were unlikefy to ever reach the (4-5') size class- 2. Tbe exclusion anal,/or loss calculation for the (3-6') size ctasses shows for 19?8-1984 a loss factor of 5/2A or 18* on1y. but usinq the 1979-1984 data shows that not only did the 44 (3-6') sized animals sighted in 1979 disappear, but in addition 12 of the 56 large animals sighteal had alisappeared by the time of the 1984 survey. Net fishing for barramundi must be responsible for the foss of a high fraction of these aninals. 320 3. The number of large animals sighted increased from 21 tn 19'78 to 44 io 1984. however, it nust be noteat that the nunl))er sighted in 1979 was 56 aI)d were it not for the crocodiles drowned in nets it is Iike1y that the figures of 56 woulat have been surpassed in 1984. Note that this w;s the case for Murgenella Cleek where corimercial net fishing for barramundi is prohibited. Note too from ?abte l, that tie missibg large animafs were all i.n the ()7,) size ctassesi decreasin6 trom at Ieast 31 in 1979 to 13 in 1984. However sone of these ani-mals may have returned to the freshwater complexes frotn which they 4. The sane retnarks nray be made here for the Wilalrnan as they lrere for tbe West Alllgator in refation to the relative clcnstanclt until 1984 of t}.le number of animals sighted in the (4_s ') plus (5-6 ' ) size classes. 5. If comnercial net fishing is probibited on the Witalman, the ?ables indicate that a relatively rapid and substantial increase in farge animals could occur since there appears to be significant recruitment of hatchlings on the upstreiir sections of the waterway in addition to the animals bei;g contributed by the freshwater complexes associated lritb it. OVERALL TIDAL WATERWAYSoI' THE ALLIGAToR REGIoN (Fig. 1) Tn I'ables 1 and 2 we show resufts sununed for the 354.5 km of TYPE I water'!,rays surveyed in the Atlrgator iegion -that is for all the TYPE 1 tidal waterways in tbe Region inclualing l\brgerEfla creek and the wildnan River- They show without doubt; that a recovery of g.porosus in the Afligator Region is underway in conformity with the predictions of our moalel, discussed in the introduction. We can also state that, were it not for the drowning of large nufiibers of farge crocoaliles (probably ocnsiderably more than 1O0 annually in the Region) in collunercial fishermen.s nets, the recovery would be spectacutar- The foltowing points are shown by the Tables for the Altigator Region with the Wilalnan: 1. That the number of non-hatchlinq g- porosus sighted increaseat from 693 on the 1978 survey to 869 on the 1979 one and ro 1161 on the Jufy 1984 survey. This 682 increase hiqhly signiflcant statistically ( 992 confidence level), ho.wever a nutnber of qualifying points shoulal be borne in minal. Note that the increase of (1161-693) = 468 animals inctudes the farge increases in the nunber of (2-3,) and (3-4,) anlmafs sighted -increases of 91 aDal 14O respectively- (especially note that these large increases reflect high recruitment during the two ,dry wets' of l9A1_19A2 and 1982-1983, see Monograph 18) and that a very high fraction of these are unlikely to enter the (3-5') size class. Tbe nunber. 549, of animals sighted in the (3-6,) size ctasses is thus a very temporary fluctuation. This can also readily be appreciated by noting the relative constantcy of the ntrriber of (4-5') plus {5-6') animals sightedr 231, 210 and 233 were positively identified during the l9'7A, 19'79 and 1984 surveys respectively 32\ alal if one cortects for the Eo classes then nunibers become 261, 258 and 291 respectively. As pointeal out in the model, it is as if theie were only a certain number of slots on the tidal waterways for the animals in these size classes anal the nuniber of these slots remains relatively con6tant or increases slowly only. Thus the big bottfeneck seems to occur mostly in the (4-5') and (5-6') size classes- 2. The tlensity of non-hatchling 9. Dorosus increased from 2.0/km on the 19?8 survey to 3.3,/kn on the 1984 one. 3. Though the nunicer of animafs positively identified in-the (5-?') si;e class increased from 9? on the 19?8 surveY to 145 on the 1979 one -after the 'alriest wet' on recoral, when most of these animats had been concentrated back into the tidal waterway from the swatnps- only 146 (6-'7') animafs were positively identifieal aurinq the 1984 survey. However, the nunber of ( 7') animals, which were positively identified. increased from 132 to 186 to 233 on the 19'1a, 1979, and 1984 surveys respectively' The increase of only 48. in the nunber of posj.tivefY ialentifie'I Iarge aninals after an interval of 5 years, does not look at alf impiessive, however one must bear in mind that 1979 was a very un_usuat year and many of the large animals which had been forcetl out of ttle swanps woufd have returned to them during the normal wet season of 1t79-1980. Thereafter some could be expected to endeavour to gain territory on the tidal systems over a perio'I of a number oi y.at.. aurthermore, as we pointed out previouslY, fo! the inalivialual waterways, there is irrefutable evialence that exceedingly hea\,1' Iosses were suffereal by animals ln the large size classas ( 6'), through drowning in conmercial fishermen's nets, and hence the increase in the nuhber of large animafs sj.ghteal woufd have been nuch greater, but for these- hea!ry fosses' rf one corrects for tbe Eo crocotliles, then the nuniber of large crocoaliles sighteal increaseal spectacularly from 2?4 in 1978 to 4O1rln 19'79 (because of the drying out swamps) and then _Less spectacularly to 46? in 1984. The increase of 193 large animals o_ver a perioil of 6 Years -in spite of tbe fosses referred to above- again h-lghlights the exceflence anal importance of the tidal sistems in t;e Alfiqator Region. anal especialty of their associated freshwater complexes - 4. The ratio of (3-6') to large animals sighted decreased from 1.33 for 1978 to 0.92 for 19?9 and then increased to 1.18 for the 1984 survev. Holrever this latter ratio is a somewhat artiflcial one, in the present instance, because the figure of 549 for the num;er of animals sighted in the (3-6') size cfasses is inflated bv at least an additional 141 (3-4') aninals, nany of which itill not reach the (4-5') size class anal are likely to have allsappear€d within a year. Furthermore, the figure of 461 for the number of animals sighted in the lalge size classes is altificially low because of the heaw losses of large aninals tbrough drowning' 322 5. The minimum exclusion anal/or loss factor calculation for the (3-6') Eize classes shows for 197A-I9A4, a ]oss factor of 112/365 or 47* and for 19'79-t984, a factor of 304/369 or g2t . These percentages require careful interpretation for included in them are not only the exclusions and/or fosses in the (3-6') size classes but also the Iosses alue to drownino of manv of the large animals. one must afso continue to beir in mi;d that each of the tialal waterways in the Alligator Region has fresh\rater complexes associateal with it and thaa there is substantial movement of animals betlreen the waterways and its complexes. 6- The relatively 1ow hatchfing recruitment rate orl the tidal waterways in the Alfiqator Region -only some 9g conpared to an average of 27% for all TypE 1 systens -supports our contention that substantial recruitment of animafs in all size classes occurs in the freshwater complexes associated lrith the TypE I tidal systems of the Alligator Reqion. Furthermore, a study of the distributionaf aliagrams for the animals on each the ststems rn the Region (appearinq in Monograph 19) shows an atypical distribution with most of the large animats atistributed on the extreme upstream sections of the waterways rather than on the brackish midstream sections (chapters 6 and 9 Monograph 1). This again supports our contention that a substantiaf fraction of the animals sighted on the tidal waterways of the Alligator Region are deriveal fron the freshwater complexes associateat with these The relatively-hiqh fiqures for the number of l2-3'\ and (3-4,) aninals sighted (145 ar]i 229 respectivety) during the 1984 probably reflects high recruitnrent durinq the ,dry wets, of 1981- 1982 and 1982-1983 as it did on the liverpool-Torikinson and Blyth-Cadelf Rivers Systems (see Tabte 1, paoes 114 anal 115 Monograph 18) . COBOURGCOMPLEX AND SALTWATER CREEK (Tigs. 1 and 4 to 6) Sallwater Ci_eek {4 km from the nouth of important anat excetlent Murgenefla Creek) and the Cobourg Complex, consisting of the Mlnimini and Ilamaryi Complexes were first surveyed in 19?9 (Monoqraph 14). These waterways coilstitute +,be largest assembfage (275.1km) of 1'YPE 3 \{aterwats in northern Austratia anal provicle rearlng stockyards for g. pggs_Ug excluded from TypE I breedinq systems in the area -probably, fargely for animats exctuded throuqh the mouths of the tidal lraterwa-/s of the Alligator Region- thouqh it means sea journeys of at least 40 km for s,rch arlimals. For corpfeteness sake aDd because these Conjplexes were unfikely '.o be resurveyed again in the foreseeable future, it was decideal to resurvey them in July 1984, though tbe uDdertaking was one of considerable complexity. The results from these resurveys are shown in Tables 1 and 2 and the hiqhliohts are: 323 1. On Saltwater Creek (Figs. I and 4), the nuniber of non- hatchfing g. porosuq sighted alecreased from 29 on the 1979 sulvey to 19 for the 1984 one, Furthermore, whereas no hatchung were sighteal during the 1979 survey of thls hypersaline creek, on the present survey, 6 were sighteal, again sho!,ring that €poradic nesting can and does occur on I'YPE 3 watenrays. Because of the sigtrificant increase in both the nuhber of (3-6') and large animals sighteal on Murgenella creek, one night have expected to sight on Saltwater Creek an increased number of (3-6') and farge anirnals -aDinals exclualed for Murgenella creek- but as shown in Table 2, this was not the case. The nuniber of (3-6') aninals remalned afmost constant, 12 wexe sighteal tluring the 1979 survey, when many animals had been concentrateal back into the tidal wateffays. anal 11 during the 1984 survey. on the other hand the nur.ber of large animals alecreased fron 16 to I for the same surveys and this decrease might be relateal to the fact that breealing occurreal on the creek during the 1983-1984 wet season. This sort of variation appears typical for TYPE 3 systems, which act largely as rearing stockyarals, and there appears to be a continual flow of animals back and forth between them and rYPE 1 and,/or orther TYPE 3 systems (page 121, Table 6 Monograph 18 anat MoDographs 5 and 6). 2. The 1984 resurvey of the three bypersaline tidal waterways inclualed in the Minimlni complex -Minj.mini creek, !'litldle Arm and Iwalg Creek (Figs- 1, 4 and 5)- revealed an increase, from 21 to 44 i^ the nunber of (3-6') and large aninals sighted with the major increase occurring in the large size classes- whereas onLy 9 large animals were sighteal on the 125.8 km Cornplex during the 19?9 survey, the 1984 survey revealed 21 (Table 2) ' Perhaps because breealing alial occur on saftwater creek during the last wet season, some of the imnature large animals may have been excludetl from it and these then entered the Minimini cornplex Just to the nolth of it. 3. on the llanaryi compfex (Figs. 1, 4 anal 6) consisting of coasi:al Arms A, B, C, D and the Ilamaryi River, and encompassing 135.2 kn of slightly hypersaline, clear tiatal aterways, a decreased number of (3-6') aninals -20 i^ 19'79' 8 in 1984- were sighteal. On the other hanal the nuhber of large animals si.gbteal increaseal slightly. fron 20 in L979 to 24 for the 1984 resurvey- 4. consialering the two interlinkeal complexes together -known as the Cobourg cotnplex- shows that the total nunber of g.Dorosus sighted on the 261.0 km of waterways increaseal from 67 for the 1979 survey to 76 for the 1984 one. This increase is not stati"stically significant and the density figure for the complex increaseal from o.26/km to 0.29lkm only. 5. Careful note shoufd be maale of the size structure of the crocotliles sighteal on both the Miniminl anal rlamaryi complexes. on the Mlnihini complex not a single hatchling or (2-3') aninal was sightedr a1l animals were in size classes (3-4'). This was afso the case for the 1979 survey. The same corunent appfj,es ro the Ilaniaryi Compler<. bowever in this case no (3_ ,) ;i;;d animals were observed either, al1 lrere tn size ala""."_-ie_s ,l . It is apparent that no breeding of g. porosus ii," cobourg complex anat that atf animal; sllh-IEE-have""""i"-i" tn. Complex from elsewhete. ""t"i"a 6-. Interestlngty, - there has been a consialerable change srnce the 19?9 survey. in the size scructure of the animals siqhteat. During^the 19?9 survey the rario or (3_6,),ztarS; *u.-f.li, t", the 1984 resurvey this ratio dropped to O.bg, i.ff."ti"i-tn" nudber-of rarge animal; siqhted (45 ."Jn;.."a--i" ZSI anol::.::""q rne decreased number of (3_5.) animals observad (31 compared to 38) - 7,. If_one ()3.) adds the animals sighteat on Saltwater Creek Enose to ot-the Cobourg Complex? tben one finds that the number stghted during the 1979 survey was 50 (3_6,) and larqe 45 or a total of 95 (>3,), whereas for the 1984 survey tf,. 42.13-6t) and s3 larse. for a total or ss 11111-;;.;;:-;-""i1". "", coiDcial€nceof nuniber-or is it possibfe tfrat aniiafs laa neen concentrated into the Complex in l9?9 as they had elsewhere arrer and rhe norna.L wet seasoh of 1979_1980 they had returneat from where they cane? This \ras then followed uy i .i""-in..".". to the o""r nunibers siqtrted on the 19?9 survey._w" answer tlis question, bui considteriDs trre popr:r'aiion iil.J"J!l-"".,"." "n"li"_io past years, ti," 5 in the TypE l systems- o? ttre atliqatoi R;si;,. ,. ls surprising thar we did not find a proportioniie i";;;;;" the 275.1 km of ?ypE 3 waterways resurveyed. "" ADELAIDE RIVER SYSTEM (Fig. 7) Scenic-wise anil crocodile-wise. this 231.6 km {aterway with-1".t i.ts few, remaining freshwater complexes nrust rank ii' tii! or oe amohgst , the very best, in horthern Austrafia."" "ii We have often wonoereo why so mahy people flock to the r"raterwavs of Kakddu Nalional Park.when the Adelaide River is only I irour's alrive trom Darwin, is a far prettier waterway than any 1" tf," p".t,-""a cert_ainly has more large crocoalilas on it. In fgft ind-'igie we rought strong]y to have its waters closed to alf commercial net fishing and to have the overall system inctualed i" -reserve. We altnost succeeded, but seff government came" ",if6iir" to the Northern Terrirory at about the sarde tiie and il-.ii" driving determination to discard _with gfee_ every"iii ii"",_ o""a" bad. which had been proposed previouslyi ". Because of the lmportahce of the Adelaiate River System, the university of Sldney had estabfished its maid fieia station rn northern Austrafia at Beatrice Hifl, obly a few away fi"r-tn" Adelaide River Eridse, with the view of ;arryins i;a;"=r"" studies on the System. such intelfectuat enalav6ui ";l ;.; ;;-- _anathema to the new government and we were soon hounied out of Beatrice Hill- one of the major factors mj.litatirrq uq.ir,"t tfr" Adelaide River System today is its closeness to Oar.ii n yet thrs very fact could act ilr its favour and provide the people of Darwin with a tourist attraction of worfb reknown- Each of the four surveys of the Adelalale River System vere made Dlior to the breealing season aDd should be comparable. However, ioain, it must be remerhbereal that the 1979 survey was calrie'l or]t after the rdriest wett on recoral anal ftost of the animals inhabitj"ng the freshwater complexes as6ociated with the upstleam sections 6f various creeks of the System would have been concentrateal back into it (Aatttendum, Monograph 1). Examination of Tables 1 and 2 reveals tlat: 1. The nuniber of non-hatdrling g.Dorosus sighte'l during the Ig'la, 19?9 and 1984 survevs was 369, 319, 321 and 542 1971, j.ncrease'I respectively. Thus the non-hatchfiDg nunibers have sioirif-icantty and dramatically since the 197?-19?9 surveys -eipecially ihen compareil with tbe results for tidal systems in the- MaDing;ida area of Arnhem LanCI (llonographs l and 18)'. Purthermo;e this najor increase is not predominantly 'lue to incleases in the (2-3') and (3-4') size classes. comparing the 19?? survey results with those for 1984 (Table 1) shows that the increa;e r,tas only 12 for the (2-3') and some 1? for the (3-4') size classes. rmportantly the maJor increases, durlng the ? year interval. occurred in the large size classes, going from 81 to 228 (Tab1e 2). 2. fhus the increase in the density of non_hatchling sighted irom 1,6,/kn in 197? to 2.3/km in 1984 is important an'l signifies that an excellent anal sustainable recovery is unalerway on this 3. Note also (aable 2) that the nunJcer of crocodiles sightea i" tir" tg-e't size classes aluring the survevs of 19'17' 1918' i9?9 and 1984 was 264, 21?, 190 and 2?8 respectively and in the plr-r" (5-6') size classes (Tab1e 1) it was 163, 133, 133 ia-S') (3-6') ana fif'respectively- Not that the figure of 278 animals contains at least 105 (3-{') crocodiles and as mentioned iieviousfv most of these could be expecteal to be lost' Again ihey uere_derived from the excellent breeding season during tbe (5-5') iaii *.t' of 1981-1982. The constancy of the (4-5') plus tiq_ures again highlights the bottleneck which occurs for these size classes. 4. T'he filinimum exclusioD and/or loss factor calculatlon for ifre (:-e') size classes shows for the 1977-1984, 1978-1984 and iil'ig-iseE surveys, exclusion anal/or loss factors of \17/264' 61/217 znd 85,/190 or 44%, 31x and 452 respectivelv' The relative ;";;i"";t anal size of these factors makes us suspect that most of ine.e roise" are natural anal that only a snafl fraction are due to causes relateal to netting anal poaching' During our JuIy 1984 survey not a single barramunali fishinq boat was sigbted on the Ld"1"id. River -;o different fron former tines. Apparently the river has been well anal truly netted out an'l barranundi have become a refatively scarce corrunodity on it. Hoirever, it appears that g. pglgSq still manages to obtain sufficient food' During *oveme"t-"f "nt" shiralee" upstream, we sighted a verv Iarge crocodile at km 41, alragging a dead bloate'I feral water buffalo i.i"r" tit. rlver. ihe cio."aif" was mialstream when we sighte'l 326 it, at a,hich time it diveat with the buffalo and sl'am he.ld in its ,a."ahouth underwater sone 20.ro_ 30 m. rhi;-;w;-ii"niriii-;;e-;;;;ii",rl". of strength had to be seen to be berie";a. trle largest. ever seen bv HM aluring tis in yeais ii-iJj!I..n-.. the tidal_waterways ;orthern on _of Austrafia i"a-.". i ii.*i.o t" oe 1n excess of 20 feet in length. we the laa excetieni-"i"r'" .t animal's head and estimate; it to be .;--i;;;;";";-;:;r" _Length. A few ," rreirrry days Iater we . capturei';;i-:;;;ni:;;'IEi i,ti."t'*3;.nt:t n*u.:i.n ::r:ggl:d ft:lg.ry. ana kep[ wrappins rrs bodt "i""na^-ir,!-n".a :,'.iff,'i:'?i:i"_;?:i;: :3=::ii:; -.i,".i]--"., when we witnessed :1."il:";3;*"ljj:.j,t*,". a 1arge crocodile . ""it,i." We believe that the relatively fow loss factors Aalelaide River founal foi the are related not onfy to the f"*_..."iri"J- freshwater comptexes(most have u.!" J"ili"vJi buffalo) ii"'ijilir*"... associated with the ars-oimportantrv to t''"tire a"*n"t.J.i-";;;;"ror'e km-oi-."J.i"'i"ii"'Illlil-^;;".;."i:il::::J:TH.:n;:l.u::i""""." ?Yt refuse for many of Lhe (3_6,) ;;d i;;;"";;;r;;" our.Lng:::::: the9,f hiqhly inCeractive Dreedrng season ahd thus decrease the heed for rhem ro reave rhe ridal;y"a;;-;";-;";;-ill-*.", dangers of sea travef. The situation f,i." i" *".h-iixJ"ir,.t found on the Kalarv.oi River Sysrem-in Monograph ze 10) and coufd be e: tl.llt"""xirsi"*"""y"ipjs! the ross ractor consrcrerably.Apparentry . nr joi5'if,. ratio (3-6') :. Th9 of to farge animals sighteil, decreaseat--".'". from 3.26 ror 79'7'7,to r.22 for the r9ea "rii.ji-, 6. Examihation of the hatchting and {2_3,) numbers siohteal for each of the four surveys indicate. .r,.t'r.iriii..ii'"i animals nrust also be occurring on the fr"rrr""i"i-".r""i""J. associated with the adefaide niver system.-(rl;i-;;;'ij_;',') il;i;.;;;;,1;. relarively hish fisures fo.r the nu,nb;r of rerrects rriqh re"."i.*."i"a,liri" :l:'?l:__.ig1'r:d,-pf9!:bly re81-rs82 ;lit":i:,-F:;;";r. andre82-Is83 t'" it aia-i"-ii" The distributional 1: diagran for C. porosus on the Rtver system (see Adelaide MonooraDh-l f". rh; r;]J-;;; i;?; ;i;;;;., Y::::::nl^]8-_f :'_the r6?s-one, Monosraphrs .""i.ii'iil" ]y64 survey) is quite different"iri ;::"::,-':::_.:,=.yury ;i:".;":i::1:#,:i.:":.i::i3i*."1:fl';l.I:';1"to those peak_ofr::':i.i::i:i the distribution does hoc occur on the-o;-';il';";5;"y" extrene upstream tidal sections of rhe waterway as i" tr,e-"ase in tbe. AlIigator Region, but occurs on the middte Thus the. distriburiohat diagram for the Adelaide sr"i"*""i."".tion".'i"'Jna' very much like those for th; Btyrh_cao.ri reool -romkj ir,a"r"q..i,i r ef 'ine_rew nson {Monosraphs7 and ral ni".-." :Ir9 | I lreremaining iy!i!*". freshwater complexes assocjated with the which haveD,t been 19:-l?t9:, "t":.-9ysrem, totarry aesiroyJa oy ::':i":i:"5.:i.','ij'ii;"Tij'*"illi:.:*i3:".fr :H:llj;jiia"";",., 327 survey of the Ade1al'le system we recor'red 8. During the 19?? johngloni for the first time, of a 9' in bractish ;;" 3) ' *"i"r-iittt"i;;;;;q. i measured salinitv of ?0/00-(page 39 Monograph ;i;;; itr;a iime we have siqhted g' iohnsloni on the^ti'lal.sectioDs i.t"t".vs in northirn Australia (Monosraph2'3'a'L2'13 li"ii"t Monosraph lia'iil ].J-"p.-.i.irv p.s" 4se Monosraph 1) and in i::tl'3r"3":t i:.x:*+,:u=:iguliq*::=irisca the tine that the Previous :#*ffi::c5,'*:than an ii'tia'ii .i"e." t.^rr".t exclusion bv g' p9!-99.!E-tather, saline con-difiois ' Recent work be webb iitiii" -i;.;;;a;ti.- i"t.i"ii"." tends ;;"'.i. i; Aust."r wildr' Res' 1e83' 10' 63e-50) tshis view as does the discovery by Taplin and- i" or finsuar-salt slands.in iiii"e)"iiiiii""-::g_c,_f+-"it;iiii"'ii"i.t"!-igei,""oo"tti zrz':ons-m47) system (Monograpn r6, lH:iH,:5i3ll,iilii",3''"' e:";;;;.;;i^;;Adelaide ir. ll ??.:-'il;:,:il:';:.:"::;.y?i3il"531".o" durinq our 1944 survey 1r 9. - rt 2- ind g-on-Tlf-km gl' ?- I 1?' 0 section' ii' ig']o-si. g' iohnstoni would be interesting"..tion to see whether the nurdber of Rlver continue to ;i;;"a-";-irt" -;;. tia"i-iumler sections of the A'lelaide of g' Dorosus increases' Both webb et al's ;::;";""-;" data afrows a ;i.-;;; o,r.i t.ta to sussEst'Tlli-Eut neither flrm concluslon on this Point' (Fig' l) COI{BINEDwATERwAYs OF vAN DIEMENGULF prevails f9t g'pslgsCg Because of the very ilynamic-certain situation which duriiq seasons of a sisnificant fraction 1;;;;";.;a dispersed titlal of the aninals ithin a i"a between wi'Iely "vtt"^repeatedlv (chapter e 1' ;";;":;;il";-..pr'""i,ia Y:l:s:3!hstatus an'l &"rI". a oa"""qi"!i'' re) ti'" i^iottttttl' for S' P9:g+ str:di5s,_of not considering, lust a portlon^ot^,4 i..!""iv possible oNE sHouLD ;;;;;;i or even a sinsle v ate rwav' wt'en""er ", m:p REsuRvEYil't' tsp trpnr, sllr .io""rioi,r-to-iinop suevev Yi-wlTHrNTfMx oF GE.GRAPHTCAREA AND RoucHLY NEAR THE 'AME- a oivi" arise-in the flra* iilr,_ atibiguitj_es could easily "ln"."ise;i- it . '"i"rt'' For instance the tidal waten'aYs i;;.;;;;i"ii;;- during october 19?7 of the AIligator Regron were iii=t =urveyea in June 19?8. August 19?9 an'l JuIv 1984'one I"a-ift."-."3t.".yed october 1977-results i"!t-ir"--""iv cauiloos wt'en comparing-the other : survivs for we rnow that the breedinq iiiii ir'"."-i'r';;"*;;""; the (3-6') an9 irunature ::;:'"; around october- an't that manv sections of ;;;;;"";i;;1" are exclualed from the breedins .tlte ti*' (see point 13 in 'he rntrod'ction) ' til$ ;;;;;;.Jir,ul one studv of the resulls in rable 2 shows that ;;;i;";;;", of g' p9!99!q if one mioht qaln erroneous prtt:lrt"'"U""t the status ine iesurts ]tr *re west Al-Lisator svsten rather ii3il.a"i"i"ii- .l- remarks the other svstens nearbv as vrerl' The same ;;;;-i"; if one iiiiiy'*i.i' s...t.' -to"" -monitors::]LrlTir"d ldJ ' of ""."a waterwav (pages 130 and 131 Monograpn "2rltio"" f'or tlte tidal anal 2 we have cornbined the results In Tabl.es 1 cobourg !ur.rev"a, from the Ilmarayi River on-the i'jt"i*."" Bav- rhe varrous ;;;;;:;i; io-tir! eieraia" River ln Adans 324 conbihations shown allow one to view the results fron a ntllnber. of different angles and to assess ttre porosus recoveiv of C. in this broad geographical area of northern a"'"ti.fii. 1. One point which stands out strongly, for each of the combinations shown, is the inftateat ruly "u.i,;r "f g-":ilg,:b:. 1e84 survey in the (3_4,) ""i..i".i_""- triii."i"f,t"a D ano rnat thrs in turn has j.nflated the (3_6,)"i," size (3-6')/larse class nrhber 99utl!.un9 the_ ratio (Table 2). These .r,i."i" in tr,. {r-q , slze class are the result of the excellent ,dry breeding season during the wet, of 19Bt-1992 ana as afreiav-oor.rt.a out -several tines previously, a large fraction of lire_m-aie untrKe-Ly ro enter the (4_5,) and (5_6,) size classes. Exclualing :::l- !I::.Y:.I gl's, which appear to revel our .uir,"i qui.ity, u]" numDer ot.(J-6') aninals sighted normally remains fairlv consrant (see Tabfes 2 and 5, pages 116 and 120 Monoqra;h-}r"!__U"""*" 18). However as r"re have accumulated more anal hore a"t" i"-"iiilr,- clear that it is the (4-5,) and (5_d,) size crasses provioe most of tbe bottleneck and that the neck size appears to."*"r. surprisingly constant for a given tidal system. 2- Examining the results in Table 1 for the Alligator plus Regron Cobourg Conpfex and Saltwater _629.5 km_ showi that tne nulb:I of {4-5,) plus (5_6,) animats siqhted durinq th; 1t79 and 1984 surveys were 252 and 26L""peEtiv"Iy. r"i..".ti"qty the humber (6-?,) of animats positively identified was 164 on each survey. For the_'Adelaide plus Al]igator Region with Wildman, _596.r km_ the {4-5') plus (5-6') counrs for lij9, t9.tg and 19g4 *"i. :o+, 343 and 3?6 respectively. considering the errors -"fup lo or,. srze ctass- whrch can easily arise in size cfass estin;tion, Enls ts an amazing constancy. If one then adds in the resufts for the cobours Comp.lex anat (4-5,) SafLwater, the plus (5_6,) counts for f6Ze a;a rSS become- 385- and 404 respectivety _again surprisingly const;nt for the 861.2 km of tidaf waterways surveyeat- 3. ?hough the nunber count for rhe (4-5,) plus {5_6,} size classes appears to remain ctosely constant fi". .ri.""v't"- equivafent survey, this is not the case for targe-th;i; aniirats. once the anitnals have passed through the bortteneck, ;;;".= appear to continue to increase _inspite of various anil ccrltrnuug Losses within their size cfasses as wetl (Table 2) 'AlI-igator For-the_ Reqion pfus Cobourg Compfex anal -ozy.b Saltwater, Km- the numbers of large animafs sighted on the 1979 survey was 447 while the 1984 survey yield;d 519 farge aninats. 'Adelaide F-or the plus Atligator Region }/ith Wildman' _586.1 km_ the.number of large animats sighted during the 1978, 1979 and 1984 surveys was 352. 525 and 695 respectively. and ii one-adds rn the cobollrg Complex and Saltwater creek, then the number of, rarge anrmats sighteal on tle 861-2 km of these tidal .rraterways during the 19?9 and 1984 surveys is 569 anct ?4? respectively. 329 'alry 4. As already pointed out previously, the wet' season of 19al-19a2 resultad in heavy hatchling recruitment and this in turn resufteal in a high (3-4') animal count during the July 1984 sur.vey. As has been shown during the course of our lengthy stu'ly on th; Blyth-cadeIl anal Liverpool-Tonikinsoh Rivers systenrs such fluctuati;ns are soon smoothed out (Monograph 1 and 18) ' The heavl' (3-4') animal count in turn inflated the (3-6') count wtrici in turn halted the alecreasing (3-6')/rarge ratio (Tabte 2) ' Furtherrnore, the very hea!ry losses of farge anrmals tbrough alrowning j.n barramunati nets set in the tidal waterways of Kakadu Nationai Park afso leads to an artificially high ratio. rf comriercial net fishi"nq $ras halted in the tidal waterways of National Park, one could be confident that the ratio would continue to fal1 over the long terrn. However only repeated, careful anal systematic surveys of the overall watervays in the area can proviale a long term check on this matter. 5. The alensity of non-hatchling crocodiles sighte'l during tbe (Table 1984 resurvey iicreaseil in each of the systems anCI areas 1)' F',or the overill 861.2 km of tidaf waterways resurveyed, the increase was fron 1.5,/km for 19'19 Lo 2.7 for 1984. This is Eignificant statisticatly at 992 tevel of confidence and (3-6') im;ortanttv the increase is not made up increases in the si'ze ctassis (8?O versus 610) only, but there was also a large increase in the nuniber of larqe aninals sighted (?47 versus 569)' Thus the present results support the view that a sustainable recovery in the 9. pgf9qlg population is in progress in tbe Adelaide niver systern ana in the tidal waterways of the Alligator RegioD. Furtherm;re this recovery is very nuch in accor'l.with Itr6 preaictions of ou! nrotlel, aliscusseal in the Introduction and lends further suPport for lt. Discuss ion In the Introduction, we sumnrarized the moalel which we have been g' aleriving over the past 5 years for the dYnamics of pg!.gElLg based 'upinp"p"fiti"n" in the tidaf iraterways of northern Austrafia, repeatea night-time spotfight surveys. The model is.able not onfi to account in a consistent fashion for the vast store of field observations and results lre have accumulated for some 1Oo tiaal aterways in northern Australia but has also been successful in predicting results to be expected on future surveys typis of tid;1 wateffavs (Monographs 1 and 18) ' "i-"i.i""" In points 7 and 8 of the model we atated: and at least 60-70X " Because of the 80% exclusion losses of sub-adul-t crocoaliles as tbey procee'l toward sexual rnaturitY, there has been no significant sustained increases in the ;on-hatchrinq g. pgrPSlE population on the-tidaf atefl,talEof our monitored area in northern Auslratta slnce the conrmencement of our systematic surveys,a period of ten years (Monograph 18)." and 330 Assr.r.rning the results from our monitored area apply elsewhere, any slgni-ficant sustaineil i;;;;.-"" E.ne non_harchllllg g. porosus poputations on the tialal warerways of northern Australia hust be measureil in decaates. Howevet, as discusseal ..., tie;i .y"t"r* .iti, freshwater complexes, the recovery could"" be e*iectea to be more rapid',. In. Table 3. we have extracted alata for 1979 and 1983 from 1..pase 114 Monosraph18, for the arr. s--i.-"i"tiiiir*r*ry. mon.ltoredlgble in the Maningrida area, which encompass ifr"-s'v"i.." Co(r*oa"r. llliil?"kT:tr"son., Bryth_ca.tetl an.l ctyde ni""i. r creeKs tn the area/ and presented these ""a sahe in the from as the resufts shown in Tabfes 1 Z. permi.ts iiii=-ti"" us.to compare surveys results for tr,e""a ^o"iloiei--iiaar waterways in the Maningrida area with those for the g6t.Z f(m or waEerways bordering Van Diemen cuff. Comparing Tables 2 and 3 hightishts inmedlat;ty and stronsly tr,. ti" i.i"if""=i-point" quoted above. The resufts derived from the present resurveys of 861.2 km of tidal systems bordering van Diemen Gulf, tasi resurrreyed in rrte, aEe very much in agreemeht with what we predict;d rhey provide for them. strons evid;nce for an tmportani ;;;;;;i";"s g. pgl$g on the tidal witerways of the niiisator Region::"9".'y ?f and on the excellent Adelaide aiver S!.stem. if,i"-i.""".ry is much strongei than that found for the tid;I *.t.r..y"-i" Maningrida tfr" area and the exptanaLion fot Lhe difference is s trar nght torward . Whereas the freshwater compfexes-i."" associated y]:l-tl: rYPE 1_waterways in the Mabiosrid" rlence most of the aninals excluded from the tidal "."-."i"i,systems rn""a the area had little choice but to _leave tr,e ,vsie.r- ianl-rate, endevour to return or ro be kirted if tr,"v .eiaineal process l-ii ti,t. the losses in the (3_6,) and targe si.ze cfasses-th.." are very high. On rhe other hand. in the Altigator a.Si"". are subsrantiat freshwater comprexes u"ro5t"t.a *iir,--ii,J"ivpe r and many of the excru.red an.inals take l.r"g" ," rnese::1:l :::":y:I.and they are used boLh as rearrhg stockyards and as breeding sustems. The fosses in this ca;e .o"Ia ;; (see .*o."i!o t" be lower poinLs S and 6 of the rntro;;;[io;i ;;5-i;;' recovery rate faster t})an on systens without associated freshwater complexes. For the overall waterways in the Alliqator Reoion we found_that- the exclus.ion and/or tois r."t"i,"iiJJ-t.t"JJi' nr dzn.. rnrs ."a tatter high figure can probably be attrib\rteal largely to the foss of crocodites through drolrni;g r" n"i"- w.."-ii f-or this, the figure would undoibtedly traie Ueen *".r.r-ioltr'!, ""t."a the recovery more spectacufar. For the Adelaide River sytem, two important factors apDear ro come p1ay. into Though nany of the forner freshwater .;.pi:;;;- associated_ witb the Systen have been destroyed Uy f!r"i wat". buffalo, the lraterway has in adalition systems of "n ""i.".i".-iiOi.i-t*t mostly TypE 3 watenrays on its alownstrean sections and hence when aninals are exctudeat?rom the ur."ai"g-";.iii"-in"y-a"-we-fra.,e can take refuge in these without leaving the Sysi".. seen, tbe exclusion and/or loss factor iot the_Adelaide Ststen 331 lle|s cnly between 31 and 452, compareal to the 80 to 90X or more. for th; waterways ln the l4aningriala area (pages 127'134 and 155 Monograpb 18). The increase from oDly 81 large animals sighte'I on tie idelaide during the ,Jufy 19?? survey to 228 Large anirEl's sighteal on the ifuly 1984 one is the consequence of these smaller lo;ses. clveD anothel decade or txto of protection, the Adelaide system may begin approaching its former self, crocodile-wise. we believe our results fo! the waterwaYs in the Alligator Region also indicate the potential for recovery, at a rate equal to or even better than that alreaaly found for the Aalelaide System. However, this wifl only be so lf conunercial net fishing for barramundi is halteal. Other than on the extreme upstream sections of the tidal {aterfl-ays there is so fittle to see on the tidal {aterways, a few feral water buffaloes, some birals and, of course, the crocodi les . Proper ly protecteal, g. porosus in large numbers could easily and quickly 6eco*e one of the most outstanding and spectacular tourist attractions in the Park -lYing with the best g. lrllqtlg.lrq attractichs of Africa, This whole natter raises an important issue- what is a National Park? Is it an area where iniligenous flora and fauna is to be preserveal and fully protected for posterity, or is it an area whici is closeal and protected from the ordinary citizen an'l yet left open to exploitation and alestruction by coNnercial fishing -interests? park Kakaalu Natj-onal Park is a very strange indeed' Does the Australian public know what is happening? In whose l"nterests are the crocodiles in the National Park being drowned? IIow are scoles of farge crocodiles being balanceal against a few barranundi? More importantly, when is it going to be halted? Not wlshing to withstand a further campaign of persec\rtion- for asking difiicult questions and exposing the truth, we shal1 abstain fron any further comnent. As far as we are concerne'I, this matter is now closed. our resufts have alenostrated that consialerable care must be taken when aliscussing the recoverY of g. Dorosus on the tidal waterways of northern Auatralia. For the tidal waterwals on the northern coast of Arnbem Lanal -from the Goomadeer River in the west to the clyale River ilr the east (Monograph 18), some 411.5 km of waterwavs- thlre are olrly scant signs that a recoverY is underway' on the basis of some 10 years of surveYs in the area, it appears that any signiflcant sustained increase in the non-hatchling q. pglqEgq pofulations. on those watervrays, may take decaales. For the waterwavs ;f_ the Alligator Region and the adelaide River system, a significant recovely is-alreaaly underway and must be encouraged further by naintai;ing fu1l piotection of the animal and halting commercial net fishing in the tlalal {aterways of tbe Region. on the basis of our 1983 and 1984 results, when we resurveyed some !272 kn of tialaf waterways, one would predict that a recovery is also underway on the mighty Roper River SYstem, for in many ways it is like tie Adelaide Systen. uowever. comnercial net fishing is permj.tted well upstream on this {aterways antl we know t}tat Iar-ge numbers of crocodiles are drowned annually in the nets' The waterway was surveyed in 1979 and it would be of interest to 332 it carefulfy and sysrehaticafly again, afrer perioat or::":.--l 6 years- Furthermore. a one would preaict-any reco".ri-;;=; i" ..ny in rhe.Kimrce;ry w;;i.;; :I:i:.:19.]De srmllar to "::.:,9y. i.ii .o that found in Lhe Manin;rid"..."."f ' ri,. iiiii " 1919I*.v" there are mosrty devoid ir""r,".i.. ., _consequence.however the clehelg and"r the pr.ince R;G;a';;"""^.""rpr.*JJ' ""v have extensive rypE 3 sysrems _ii,ii"i i"' ir,.'i"il"iio "ciior.*_ at their mouths anattheie misht l,"rp x".p ti.," foss factor -ii" down. we surve,"6 these'ti;;i "ili""i"i""iaZ".r 6i e and 1979 (w.A. Reports 24 :na ".i..".vr ruture cou.rdei*ou, r.,,*,"r-Ii'";i' j":": rafi hanoh+ ^r r! ;ff:i":I"':rlH ?::1".. ACKNOWIEDGE},INNTS We,are pleased to acknowledge the continuing suppott -eii"of the University of sydney and it; science r.""aiii""-i". w.ithout whose i"_ , helF, there coutd never have F.een u .-..""-r, the magnjtude, or scope and completeness oi tle piese-Ji_o-ne -' rfre Foundati.on has, over the past ru years? never rThe pursuit erred from irs motto of Oxclltence,, ana our lengthy austrafian -"pi"ri"";";t;;.; research effolt has provided ..pf. iiv'-t", pursulng it. If ever there was a '+:F:--rs:!+-qg9i-s!9gqb,', ,,surveysresearch ;."qr;*" .;;;; our oi riaur wutur"u,r.-.requir"o ,,, Ausrraria,,provided rhe pelfeat example- thei::.!:I" rr r,is support, eI'couraqement,breadt_h of vi"", r"ie"tiii"-.*p...r.", tenaciLv \dhich onrv a academic :::i;":iffr::: sreat instli'tion We wi.sh to give special thanks to John anat Marie Saltmatsh own who the "M.V. shiralee s,, anal tbeir son peter. if,"r-rr""id"a marvellous serv.ice on a orear litrte ship and d;a-;";;;h;;, could wish ," for to hetp ,n"X" surveys a success. peter even becane a navigator-reclrder "". for one of our survey boats. Many thanks aqain. Itnafly our srncere Lhdnks go to Wdlty cill, our tonq time yl: over U-e ye",. r,"" acted 1n ;;;;y-;;p;;;;y-i,!sr,,uure. l:1r::,''war.ty, you are a great cook, but a better boat irrver. Cneersr Surveysof TidalBiver Systems in the NorlhernTerritory of Australiaano ,i'eirCrocodile Populations lhc Noriieo monograph.,covcr,ng lhe .a! qableporlions ol lh-etidnl rrvcrs and creeksol A s€res ol q 1984 r"iioiv;"u"'"ihvno.''oipr" S/oanvArsralr r9 MONOGRAPH''-'-i " rheBylhc.d.rFtvcrssvslcmslldvandtheslalusorC/ocodfrus'o/osusnIdawarerwzvtorNorlh'rr ustaia porosls uiir,oo. to, a*v.s rnd dvn.frcs or ! nonur o' or c McsselH voncck GC wcrs AGandGrec'.WJ _? Ihe vclo.a and Fizmaurcc n,v.r Svslems r,r..*r i Gan3.C wcLs ^G Gre.n.wJ vonc'k GcandBr'nnan xG oav and Mov4 Hvcr: Lress.r I Gifi a 'r"u . /. ai rfa G:..r w J a Th.i l.rLqnidrtl..io. rnv.' sfi' rr ML;6m.iadd0.oo.l:jc'|.|:toljso!t]ai.wl!l Mc.;c H w.r'i ^ G rnd (it".rr w.' Al rlQh: cteek' 5 Tlrc Goomadccrand K'no Rvcj Svsremsand Maldrr' wutugoli" A G r" 'lr'd' \'l/ J - ro!o' rnr 0 c' i h tiav Lalio'r: j.r.io n'e' a"o;af ;o.i saiii iroei!iniI'n!a'!ocr!n!''d u or Mcrvre sri.d r',rlrrrr.na s.Lir c'..k5 ,. G'anl l.!^d Melser H Wcrs ,^ C rid Gie.. w.i 7 TrreLivcrDoo Tomki..o. r1\.i: 1Y5r'n Jf' Nuncbuqar C:r!r' Messcl.H. V/cls A G ar d ai'e{. w J rr ih! irrr oi carp!'larr a some Five:s and cr..ks o.1hc e.slc.'s1or A'nh(m Laid nosc n vc( Munrat (;r..k l1.nr!rv. wa t'r rnvL{in'j Koo'1o^! rdrn Messc H eilorl M wcls r\ G Greci \4 J and llJelran x G I d. wale,v/ays or C.sler.iQi Bav 3n' Hul'h'nrn a'd C'o' I Slri Ls 9 woot: Hlci ae..tr ort,ia r)a.a,La Drabui Nari'a'audi Crc'ks '!e thc rirv'( an' Mcsstr I vo, ccr (i c r,.rri ^ c a'd c e'n w J r0 I dar s/.r.,(.r. .r lnr.r'nAhrrr r'a lrr i'rrw uivr' tllck.oNarn Erna/. v/a;"'*' i*r r' i' rl'irr' nr{ s Ori r 'rrtl rrr'J'r'' i Yr ' r 1 Tr'la wa1.^{Ys o! A' lrr.rr lr.\ arrlfnl) r1'! ir ' Da,eJa,uno.rr.bo(.nl rJirdm'.r Goldrp' Coror'u'! CaLo Pc1{ 'rr lr': r.ics.. 'r- v.,'.;r . (i w{r' ^ a ar.dGr"n lv ' T'.rarwaic^!.vs rhn slurf\!.s[!n clasi 01r]' Gu! 01'aroenrlrl 12_ on r"" L,-i.- e'.ni';"*, tvcr5 N:rrar\p vilnqlrLf:iea ar?! Manok!rd!;unaL, an(l Y vrrtr' cr'x'ks ^ V.sac rl vdicc[ (i C w']r:r ^ G (irc(f w J 3fd rorrrs'^ ^. iol r'ro j. T,.a.,:rlns . C ' i L" I o _oa c c w.ls n G. Grecn w J add Johnso' n".i". r. v-r""t " 'n I 1i T asr vralc.wavs o1'"'''.,''', v.n D'erncn Pcr''c ' r^ trcii"t.ir vot."t dc wcis ^G"dGrcen wJ r5- ^o. v.=" /4 t' c o'ur ' t'suralF ta slrvcysolTidr w:ic{\,ivs oncat! ^ riLr w.rs ^G i'""'.tr'r c fr! fnrl c Fl w'rvc ' Lrnn(rror''n " 17 Oatw,nand BYno.I CC aroir M wers AGand(t"| wj Ulcare1979r9rj 'r3 Foprraronoyn.dL.3.r Lfo..4vr,spol'sls a'd slt's Min'ecnfrt and Fccov'rv G C 6rcc w J an'jon'J rr' ^pt,c' rl Lnnt snm! t. t AunrJ Jr G'vc 'n{ I v'r svsrcmsor rhe "r1h-wc DeorFsrr wi(i No24r so1r9i7) Mcss. ts Bu,b,d(. A A Wcrl, A (i r.d Gr..n V/ J fs ( mberL" cr i'.codr{ n rf' !rk{x!!: Pi 'c' t' :l'ilanJ Ord FivcrSvslc Ocnr F.f wLdl N.:tl r'lrr rllri1ll Sutb'dqe.A A .nd M6sc. I 334 TABLE I Number po_ros c"ii,a"iiig'.iiii:.i;:';;;,ii;iii of c. 5 siqhted \aithin,;ff!,:'::":lH'":l 'l;:"" mrdstrear.distance ;;til"l,i;#"1;o"i,Hl surveyedand density.of non_hatchling .iololii"r-.ignt"o on {aterwayn,me"6ris non-r,'iicrriid;-p;;;";i: shown,as are the 959"?;:'iii:".]lTlii,::i,:1""i':lT;t"?l.jl;c "u.t ats0. Eachof the {aterways i:1i1"" listed hadbeen last surveyeJS y"i"i ii"uior.fy, Size Class Numbers I4ONOGRAPH3 AoELATDE I July 77 | 417 566-644 Sept 78 I 3Bl 221.0 487-559 sept 79 | 374 231.6 490-562 July U 602 | 231..6 842-936 I1ONOGRAPH4(14 ]YURGENELLA I oct 77 e5 | I 1 8 33 13 6 1B 15 45.9 2.0 June 78 4B 1173 4 17 24 23 30 ll 44.9 2.8 183-227 Aus 7e 198 47 | 24 l2 22 24 27 26 16 45.6 3.3 223-273 ,July 236 U | 7 17 61 28 2l 3l 57 I4 45.6 5.0 346-406 ALLTGATOR IEAST oct 77 53 | l3r9 l8 37 57 41 40 38 I14.9 2.3 402-468 June 7e 39 I Pzs I4 63 51 42 31 51 38 118.9 442-510 Aus 7s 139353 30 44 58 28 5B 64 58 Itg.2 2-9 521-595 Juiy | 84 4r1 22 51 72 35 24 60 I00 119.2 3.3 598-673 SOUTHALLIGATOR oct 77 lr42 T2 24 24 25 31 113.8 r.2 209-257 July 78 lIsT 4 t4 43 24 38 tt3 -2 1.3 223-273 Aus 7e 1164 4 12 31 5I I14.0 1.4 237-287 July 84 | 279 17 1B 25 38 9t r14.02.1 363-425 WESTALLIGATOR oct 77 | 83 14 f4 15 t0 l0 42.2 1.8 104-138 July 78 85 | L2 9 I3 10 6 40.4 86-1r8 Aug 79 96 | t3 i4 7 12 14 42.2 120-156 June 84 1120 33 zt l8 6 42,2 149-189 335 TABLE (cc$n'D) Size ClassNumbers 1.9 91-L23 Sept 78 I 118 53 33.5 4.0 t97-243 Aug 79 | rs5 2l June 84 | 226 26 33.5 6.0 300-356 ALLIGATORREGION EXCL.!,ll LDI'IAN 1.8 895-991 oct 77 I 638 63 BB 316.8 2.0 980-1080 June 78 | 744 116 321.0 1151-1259 A,rg 79 I 85I 116 126 3.01514-163 July 84 11046 220 161 321.0 ALLI6ATORREGION !iITH I,{ILDMAN 2.01084-1190 June 78 54 13? 350.9 2.41366-1484 Aug 79 9B 186 354.5 1836-1972 July 84 145 233 SALT|/1ATER Aug 79 14.1 z-t 37- 59 4A July 84 1.3 22- 14IN.llNt Aug 79 43.8 0.3 July U 43.8 0.2 MIDDLEARM Aug 79 28.5 0.2 6 22 July 84 28.5 0.4 ra- Il/JALG Aug 53.5 0.2 10- 22 July 0.5 MINlMINI Aug 125.B 0.2 34-54 July 125.8 0.3 59-85 ARI'1A Au9 26.7 0.2 5 0.3 9 July 26.7 ARI'1B Aug 15.0 0.2 3 0.3 4 July l5 .0 336 TABLE I (covr'o) Size Class Numbers ARrlc I Aus 79 17 29.3 0.2 Jr.tly 84 | s 29.3 ARMD I Aus 79 19 19.8 0.5 9 July ul7 19.8 0.4 7 rLAr.lARYr I Aus 79 | 16 44.4 0.4 rB-34 July &| 7 44.4 0.2 7 ILAMARYICOI,1P LEX t35.2 0.3 s3-79 July | 32 U 0.2 COBOURGCOI.4P LEX Aug 79 | 67 10 ll1 ?61.0 0.3 94-126 July 84 | 76 21 112 261.0 0.3 107-143 COBOURGCOI1PLEX & SALTWATER Aus 7el%l It 19 t13 215.L 137-r77 July 64 ll0ll6l 27114 275.1 136-176 ALLIGATORREGION + COBOURGCOMPLEX & SALTWATER Aus 79 11102ll37 | 99 205[55 629.6 82L1645 Jury eahlz: hrz lrqs 260tl89 629.6 889?131 AOELAIDE+ ALLIGATOR RE6IONEXCL. l,{ILD[1AN July&oct7/ 45 11055lltl| 126t114 543.1 486t610 sept&June78 62 111251178I 1571107 538.4 891-1615 sept&Aue7e 72 1r225lr6e| 219 t149 552.6 6674797 July 84 116481145l12r 340 1221 552.6 4872543 ADELAIDE+ ALLIGATOR REGIONI{ITH |.iILDI"IAN sept&JuneTB 78 112431231I 164[16 57t.9 b964.724 sept&Aus/e 106 ll380l1e0I 250n65 586.1 B83?021 Jr.rly 84 118741I71ll81 353 1235 586.1 z ro2876 AEOVE+ COBOURGCOI,IPLEX & SALTWATER Sept&Aug79 114761190I 107 86r.2 a312r81 Jury 84 l1975ll77| rBI 861.2 a6411034 TABLE 2 This Table r{asprepared using the results given in Table I and groupsthe crocodiles sighted into the importantsize classes shown. 501of the E0 size classeswere distributed to the (3-6') size classes and the remaining50% to the (>6') size classes. This l{eightsthe distribution heav'ilyin favourof largei crocodiles, which are knownto nomally be the mostwary. l,{henthe E0 is an oddnumber, the bias is also given to the ('6'l size classes. Large Survey totats Hatchlings (2-3') {3-6') (:6' ) ADELAIDE July 77 4t7 48 ,4 1 264 81 3.26 Sept 78 3Bl 62 ,ol 2t7 78 2.78 sept 79 374 53 'l 190 r23 1.54 July 84 602 60 36 1 278 228 1.22 MURGENELLA I lct 77 95 I rl 61 32 1.91 June 78 t73 48 ';l 50 59 0.85 Aug 79 198 47 24 1 66 61 i.08 .-l July 84 236 7 tlt 95 1,23 EASTALLIGAT1 )R lct 77 31B 53 l8 154 93 1.66 June 78 329 39 t4 175 l0I 1.73 Aug 79 393 53 30 159 151 1.05 July 84 411 22 51 181 SOUTHALLIGA r0R oct 77 142 73 69 1.06 June 78 6 3 73 0.97 Aug 79 t64 4 I 5B 101 0.57 ,luly 84 279 39 t47 0.53 I,IESTALLIGAT R 1ct 77 B3 2 47 25 1.88 June 7t B5 5 37 20 1.85 Aug 79 96 12 9 4t 34 I .21 June 84 120 L7 2 17 24 3.21 IlILDTIAN sept 78 118 53 28 21 1.33 Aug 79 21 34 44 56 0.79 June84 226 26 60 96 44 2.tB 338 TABLE 2 (corr,p) jngs Larqe Totals Hatchl (2-3') {3-6',) (:6r ) ALLIGATORREGION EXCL.I,IILDMAN June 78 Aug 79 July 84 ALLI6ATORREGION I,IITHI,II LDI.IAN June 78 365 274 1.33 Aug 79 369 402 o,92 Jury 84 549 467 1.18 SALT|//ATER Aug 79 12 l6 0.75 y Jul 84 1l B 1.38 i\,IINI14IN] Aug 79 8 3 2.67 July a4 6 3 2,00 I,4IDDLEARI4 Ar/g 79 5 I 5.00 July 84 6 4 1.50 Il/]ALG Aug 79 5 5 1.00 July 84 13 12 1.08 IIlINI14INICOI,IPLE X Aug 79 t8 9 2.00 July 84 23 2l 1.10 AR}1A Aug 79 3 2 1.50 July 84 I B 0.13 AR}48 Aug 79 I 2 0.50 July 84 4 0.00 ARI4C Aug 79 5 2 2.50 July 84 z 3 0.67 AR}4D Aug 79 2 7 0.29 July 84 2 5 0.40 TABLE 2 (cqvr'o) lotats Hatchlings (2-3') (3-6') Aug 79 | 16 July 84 I 1 ILMARYI COI"IPLEX Auo 79 | ,.:rive+ I COBOURGCOI1PLEX Aug 79 July 84 COBOURGCOMPLEX & SALTI,IATER Arg 79 | 96 July 84 | 101 ALLIGATORREGION + COBOURGCOMPLEX & SALTt,jATER Aug 79 July 84 ADELAIDE+ ALLI6ATOR REGIONEXCL. l/1ILDMAN July&oct77 Sept&JuneTB Sept&ALrg79 July 84 AOELAIOE+ ALLIGATOR REGIONI,JITH I,IILDMAN Sept&JuneTB| 1243 Sept&Aug79 July 84 ABOVE+ COBOURGCOI4PLEX & SALTWATER Sept&Aug7g| 1476 July 84 | 1975 340 TABLE 'Hl fifri'ffi:"ffj:"l"i,li!,"31,3l;fliil] :l: liJ;:'itJ;l:T-:ffi"il"l;i:l;:tiy, ffi*il1:;n'i6!:"'in:"1"1;itg":i:o:,:*"ks(oDiained;ii;s-iiui" i,"piil, rra u,""'rn'ir,"-i6., i,iiioi""i ,dryi""rx"iiltji:':#":["f::' il.]"t],5rt,i3o,nu, surveywas r,ude afier the rvet' of I98Z-1b$ ::"1I i3l;"1ill':i"J:f *i;".:::].,::,:n,:i;"Fi,:;lii"ili:rF"l"l:*". ana nenceinirnais l!r" Sjze C'lassNumbers June& July t979 411.9 July E July 1983 Large (3-6') 5urvey Totals Hatchlings (2-3') (3-6',) (:6' ) Lar9e June& July 1979 1253 487 125 450 191 2.36 July & July 1983 1199 345 198 492 164 3.00 '. nl3dN3 z *--, a) .o ( '-- v8AH f E.-,* !?i I 7_\ a e. 5 i.\ $: > ?l o< q =1 22= vtnsN o3l o: 0Snoaoc =9 Foq NOI9NTSS! .LUOd == USAIU ;-E- t) g* E2 iE3 tz ;5 E ao z> I 0 *!: \) c E9 z-- f,g3 5 2 342 SALTWATERCREEK VAN DIEMEN GULF lt"53s MURGET{ETLACREEK 132"16,E 48 12"5S COOPERSCR€EK EASTALLIGATOR RIVER MAGELA CREEK M.p of Mulg.n.llacr..l, c6r.rs crdk rid th. E n AltisaiorRiv.r. Dji.nes in lh tr e F. g a ? 'a -l 2 o t{s z E = = = 2 :l= COBOURGPENINSULA WILDLIFESANCTUARY VALENCIA AND FLORAAND FAUNA ARAFURASEA ISLAND RESERVE ILAMARYI RIVER MOUNTNORRISSAY o COPELAND ISLANO ARNHEM LAND ABORIGINAL RESERVE u- !WALG CREEK ENDYALGOUT ISLAND ul MINIMINICREEK MURGENELLA lJ- WILDLIFE SANCTUABY SALTWATER CREEK VAN DIEMEN '51'S GULF 11 MUBGENELLACREEK KILOMETFI€S cd.ral a.!. maprhorins rh. rivcr andcrcekl on rhcCoborrs p.ninn,tr Dnranccsin km shorn for Sahs.r., C.Fk 345 a< E- a z a B 6 a 2 =x E =3 I 6 4. ;qH i :r ct I .it E f< :< ' >! ..j a F r:*: iE 5irt*; PP;Ii? ( D COBOUFGPENINSULA 8| WILDLIFESANCTUARY AND FLORAAND FAUNARESERVE 8,8MAINSTR€AM ILAMARYI RIVER CHANNE! E 11.6 11'29S ; 8.1 11 MAINSTFEAM CHANNEL o D 11'32',S 66 11MAINST c t 1'32',S MC \ i: rl CHANNEL \9 //.'-rD tg CIIANNEL B 11"34s AFMA J MAINS 11"35S / DIEMEN GULF IWALG (sEEFtG. 14 3) 012345 KILoMETRES MURGENELLA\wrLo-rFEsANcruAFy Iic 6 rrtAhl A, D, ( rnd t). t)nkn{e\ in l 347 VERNONI SLANDS o Mi CHAI4BERSBAY ADAH BAY 12'U, q',S SHIRECREEK CREEKA REEKC CREEKD I4ELACCACREEK CREEK Rr425 CREEKG rn50 DARWIN ADE LA I DE R I VE R COASTALPLAI NS RESEARCHSTATION E HUI4PTYDOO BEATRICEHIL NHEI,4HIGHWAY CREEK H CREEK STUAR-THIGHWAY I,lARRAKAI EATRI CE CREEK CREEKJ K I LOI4ETRES KATHERINE rm11/ FIGURE7 mnpoF THEADELAIDE RIIIR COI.{MENTSON INDOPACIFIC CROCODII,E DISTRIBUTIONS charfes A. Ross Department of Vertebrate Zoolocrv National Museum of llatural nist6-rv Smithsonian Institution Washington, D. c.20560 Iptroaluction The systefiratics and distrj.bution of Indopacific crocoaliles are confused and in part. unkno\,rn. Individual and geographic variation have- been inadequately studied, insuif i6i";rt rnur"urr, nororngs and the extinction of some popufations ensure tha! basic questions of recent Tndopacific Crocodvlus speciation will remain only partfy answered, ttrEliiistr-ib,rtior]" poorfy documented. This is particularly""a, true for the numerous rsland populaLions of palustrine or ,.freshwater,, Crocoalylus wh.Lchseemingly exhibiL a high Ievel of endemiam ln co"trast to the widely alistrrbuted fndopacific crocodile (crocoaivlus porosusl / \rith which most, if not a1f, are .ympat.i-- The distribution of the philippine Crocodite (Crocoatvlus mindorensis) was reviewed recently and shown t;-i;;1G;-th" islands of luzon, Mindoro, Busuanqa, Masbate, Sainar, Negros. Mindanao and Jolo ln the philippine Archipelago (noss aid Afcala. 1983). In this note I continue to review Inalopacific crocodile distributions by presentlng data that indic:te that New cuinea freshwater crocodiles are restricted to the istanal of New cuinea and map thei! known distribution. In adalition island records of the hdonesian pafustrine Crocoatylus, referreat 99-91 "c.rqsgdlltrg siamensis', in this nore rorrowins+lurrer HeIlmich (Hooijer, {1923), 1972) and Wermurh anal M;rrens (1977) . are surunarized briefty and the need for addltional records anal/or specimens is emphasized. New Guinea I'reshwater Crocodifes New cuinea fieshwater crocodites remain retativefy abundlant, Morpbological analysis of a targe sampfe shows that two disjunct and distinct New cuinea freshwater crocoalite poputations separated by the Oi{en stantey, central, and wanatanunen i,oirn""r, ranges exist (Hall, in prep.r Ross, in prep-). The northenr. Sepik River, popularion was alescribed bi S;hmidt (192SI; wtrereas the other, restricted to the southern towlands, is undescrtbed. The and northern -southern populations can be distinquished by olraerences oI cranial morphology and squarnation: genetic exchange between these two folms seems unlikely o!| the basis of distribution data. The description of the soutirern populitron must be postponed pending examination of Irian Jayai l= ssrl.rD na.rl ot asland of New cuinea) material at the Rijksnuseun van Natuurlijke Historie, Leiden - 349 Crocodiles have been reported fron most of the islands surtolrlding New cuinea. In most instances, these locatitY recorals have been assigned to .q. p-9l9Elt9. Neill (1956, 19?1) suggesteal that a palu;trine crocodvlus, either g. novaesuineae or a close relative of it, may occur in upland lakes on the island of New Britain. whitaker lfseOa) surveyea crocodiles anal crocodile habitats of the island provinces of Papua New Guinea. He founal from personal observation, skin dealer records and interviews with crocodile hunters "that q. porosus is tbe only species present". Crocodvfus p.Slgglq is known to occur in freshwater lakes, rnarsfresl"a inland rivers of maintand New Guinea and elsewhere (Dubois, 1896/97; whitaker, 1980b; Ross and Alcala, 1983). Nei1l baseat his specles identification merely on the basis of habitat anCI such an association is known to be unreliable. wermuth and Mertens (19??) anat Groonbridge (1982) included the aru Islands SsW of New Guinea in the range of q. novaeouineae. This locality recold is based on specimen number 8115, a preserved young crocodile in senckenberische Naturforschende Gesellschaft' Examination of photographs of this specimen clearly shows it to be a specimen of g. pglgg.gE - The following comparisons are the basis for this reidenti fication: 1. It has 30 traDsverse ventral scale rows whereas New Guinea freshwater crocodifes have 22 to 2'l (N = 2091 Ross, unpubl' 'lata) and is within tbe observed lange of variation of this scale count for g- p9!9E!g, 29 to 35 (N = 6Ot Ross, unpubl- data). 2. IE has a reduced nunber of post-occipital scales, i.e., less than 4, as observed in all g. Dorosus examined (N = 72) and only 2.4% of 24? New Guinea freshwater clocodiles examined (Ross, unpubl. data). 1 rr lr.Ls the ehlarded, often ossifieal, lateral scales and distinct tlark caualal banding found iD New Guinea freshwater crocodiles. These are typically absent in 9. Dorosus where the fateral boaly squamation is composed of regular subequal scales, and the tail iJ spotted or bfotched but rarefv has solid bands' whitaker (1980b) reviewed the alistribution of the freshwater crocodiles in Papua Ne\"t Guinea but failed to note that g' novaeouineae occurs in the viclnity of Madang (based on a five 1977. J'-rvEnii trre Moitaka crocodile Farm, Port Moresbv. in marked by J. l,ever as originating in Madang. and exandned by me) and mistikenly attributeal the southern Highfands Province, Kiriowi lsland (Kikori River) freshwater crocodile locality recor'l to a specinen at the Nationat Museum of Natural History, smithsonian Institution. Actuatly the record is based on a photograph of a crocodile captured by me and later left at the Kikori crocodile I'arm. NeilI (19?1) and Groorbrialg (1982) maintained that the 'Listrit'utlcn of New Guinea freshwater crocodiles in Irian Jaya is poorlY known' Actual1y. their distribution in Irian Jaya is well documented' These authors failed to note papers bY Brongersma (1958a and b, 1961' 1962) and the extensive collections of lrian Jayan crocodvlus of the Rijksnuseum van NatuurliJke Historie Leialen. Available records 350 indicate that freshwater crocoaliles occur throughout suitable habitat in Irian Jaya. The-locality records presented by Whitaker (19gob) (1968a , Bronqersna and b, 1961, 1962) museumcottectio"" ana iirir;;i", sumnarized in Map 1. "." No evidence exists that New cuiaea freshvrater crocodiles occur outside of New cuinea {with the possibte exception oi introaucea populations palaus). in tbe on the island of wew cuinea ihey nave a wide distrib\rtion, occurring in aft areas },"ott"t from Fak lak to Abau in the southern fo\"rtanals,"t ""iiil'i. i;;__ Maniberambo to Lae in the northern Towfands, They";;; are tnown trom Oransbari-in peninsuta the Vogelkop (Bernice p. Sishop Museum nulnbers 3942 and 5842) - There are no records of fresh;ater crocodiles from Milne Bay in eastern papua Ne1"Icuinea. Indonesian I.reshwater Crocodifes " CfocofllllE siarnensis', was apparently widespreaat in the Indonesian ls.rands. IL is easjly confused with g. porosus owrng to simil arjty of coloration, often reduced post_ocaipiT;-squ.*"ti"", u similar nurirer of transverse ventral scale ro;s- There in"na consialerable inter-lsland variation, and at present. insufflcient materiaf availabte to differentiate att isla;d popuiatlons. These crocodiles can be diffelentiated from g. porosui ;y a comblnation of craniat and squamation cnaracter;stfcs-]I6Ei ii p.ep,j rn"v are distinct from crocodvtus siamensis of mainlanat S'outieast esra on the bas!s of t.hroat squanatLon (Ross, rn prep.). ,,9. Distribution of Indonesian siamensis,, is now known to inctude s-umatra-, Bangka rsland, Java; aorneo and- celebes. speclmens on which these island records are based are in the coliections of the Rijkamuselm van Natuurlljke Histo.ie, r,"ia.n is"*iiii, e.nqr" .Lsrandl; senckenberische Naturforschende ceselfschaft (Java), the Museum of conpararive zoolosy. Harvar.l, ;;;i";;-M""""* of Natural york History. Ne1^l (Borneo); and the";a National Museum of Natural History, Smithsonlan Institution (Cetebes), Examination of additional material in Indonesian anat European museum coffections wi1] likeIy show t}at Indonesian ,,C. siamensts,, is found on other isfands in this region. es trre rei a&ti ri c-ition of existing museum specimens or the ;xanination of remaining wifat populations increases the sampte of islanal populations of freshwater crocodiles, it is Iikely that 1n_di;idua] islana popurations will merit nomenclaruraf recognition (Dubois, 1908, Br;;;;r".", 1941; Ross, pers - obs-). Discussi on The stuaiy of hdopacific crocodifes inalicates that many islands in Ene reglon harbored endemrc Crocodvlus that differ fron the wide_ p-orosus. :?,lgr"g e. in morprrorosy, size, anat pertaps (prior ro olsturD€nce by man) habitat. Any past ecotogical sepaiation palus!rane of crocodiles and e. .p-qr,9E!g in unknown. faity accounts or .(ndopacific crocodiles did not differentiate betwe;n specres, 351 but centereal on crocoalile plealation on man. As eally as 17?9, bountles were paial for crocodiles killed in estuarine or riverine habitats ln southeast Asia (Koenig, 1984) and even Dyak tribsemen in Borneo who normally did not kill crocodiles owing to local superstitions, would slaughter large.nunibels of. crocodlles when a ;rocodife took one of their group (Roth. 1896) . The behavior anal ecology of crocodilians is known to be influenced by hunting and habitit disturbance (Bustard, 1968; Meden, 19?1; Ross, pers' obs.) ancl, as such, any ecological or habitat differentiation is now maskeal. The vicariant speciation observed in Inalopacific palustrine crocoaliles, which bas resulted in numerous endemic but ;losefy related species, can not be explained simply by- geographic isotation. It is likelY ttrat tbeir distribution was inffuenced bY tlre occurrence of g. porosus in estuarine and coastal habitat wlrere g. pglgslg might act as a barrler to their dispersal' fnterspeclfic aggression nay have had an influence on their distribution and subsequent speciation- Literature Cited Brongersna, L.D. 1941. Age variations in the skulls of croco'Iiles' Arch. Neerlandaises zoo1. 5(4) : 505. Prongersma, L.f. l.958a.over het voorkoFen van crocodvlgs- novaeo'dneae in Nederlands Nieuw-Guinea- Lacerta 17(1-2): 3-5- Rrongersna, L.D. 1958b, The Aninal lrorld of Netherlands lle1.tGDinea' J.P. HoIteis, Cro!- jqen. Brongersna, L.f. 1961. Zoological exploration of Netherlands tr"ew Guinea. Porc. 9th laclfic Sci. congr. (Bangkok) 19' 6A-'71' Brongersma, L.D. and G-F. Venema, 1962. To the lrountains of tle stars- Iiooder and Stouqhton, London. Bustaral, H.R- 1969. Rapid learning in wifd crocodiles' (Crocodvlus porosus). Ilerpetologica 24(2) | I'13-1'75- Dubois, E. 1896/91 - o^ the occurrence of .g-r.9.S-9-d:C-I!g@ far above the tideway in a Sumatran River. Notes Leyden Mus' le(2/3'). 134- Dubois, E. 1980- Das qeologische alter der kendengoder Trinil-fauna' Nederlandsch Aardrijkunding genootscbap, Amster'lan. Tijdsschrife' ser,2,25t L235-1210. Gloohbridge,B- 1982. The IUcN Anphibia-Reptilia -real ilata book" Pari 1, Testudines, crocodylia, Rhynchocephalia' lucN' Glan'l' Hooijer, D.A. 1972. Pleistocene vertevrate from celebes. xTv' Additions to the AlguliLgl9.da!-celebochoerus fauna. Zool' Mededef. 46 (1) : 1-16. Koenig. J-c. 1894. Journal of a voyage from India to sram and Malacca in 1?79. Translated flom his nranuscripts in the British Museum. J. straits Br. RoY- Asiatic Soc. (26): s8-201, aod (2'tJ . 5't-133- t52 Meden, F. 1971. Bioloqical isolation of synpatric species of South American Crocodilia. fn: Crocodiles. IUCN publ,, New Ser-, Suppl. Pap- 12t 152-I5A. Mulfer, L. 1923. crocodilus slamensis schneid. und Crocodilus ossifraous Dubois. Palaeont. Hungar. 1r 1O9-122. Nei11, W.T. 1956. The possibility of an undescribed crocodile on New Britain. Herpetologica 12(3)t I74-I16. Neifl. W.T. 19?1. The last of tle rufing relfiles. A.Ifiqators, crocodiles, and their kin. cofumbia univ. press, New york and london. Ross, C.A. anal A.C. Alcala. 1983. Distribution and status of the Philippine Crocodile (Crocodvlus nnindorensis). Kalikasan. Phif. J- Biol. 12(1-2). 169-l'73. Roth, H.L. 1896. The natives of Sarawak and British North Borneo. Truslove and Combe, New York. Schriidt, K.P. 1928. A net,, crocodile from New Guinea. Field Mus- Nat- Hist. Pub1., zool- Ser., 12t14) | 177-tql- Wermuth, H. anal R. Mertens. 19??. Das Tierreich. Liste der rezenten Anphibien und Reptilien. 100. Testudines. Crocodylia, Rhydch ocephali a. Wafter de cruyter, Berfin anal New York. Whitaker, R- 1980a. A preliminary survey of the crocodile resource in the Island Provinces of PNG. Wildl. Div- Publ,, 80,/11. Whitaker, R. 1980b- The status and distribution of crocodiles in Papua New Guinea. FAo Ass. croc. skin rnd. PNG, Fielc r'oc. (1) 353 .n; E // t{ 354 INDIA: STATUS OF WII,D CRoCODILES 1) L. A. R, Singh-, S. Kar- and B. C. chauathury- -covernment1 of India, Crocodife Research Centre Camp: Nat.ional Chahbal Sanctuary. post Box tl Morena 476001, Madhya pradesh -Government of Orissa, Crocodile ProJect,Camp: : cbandabali, Balasore, orissa -covernment of Inalia, Crocodile Research Centre of Wildlife Institute of India, Bahadurpura, Hyalerabad 500264, Andhra pradesh Introduction At the First Working Meeting of tbe Crocoatile Speciatists Group in 1971 the following were the status given to the hdian crocodilians (Honegqer, I97I) . l. charial (cavialis oanoeticus): ,'Extremely rare" (baseal on . Seshadri, 1969) . 2. Saltwater crocodife (crocoalvfus porosus): No mention, apparently thought to be fairly safe. 3. Mugger (Crocodvlus palustris): "Exterminated in most areas of its range" (Daniel, 19?0). Extrenely rare (Seshadri,1969) . By the Fifth meeting in 1980 reports on the status were more clear and approxirnate nuniber of crocodilians in the wild were know in most cases (whitaker, 1982) - The IUCN Red Date Book (1982) stated the status of Indian crocodilians as follows: 1. g. oanoet.icus: Fndangered, exl!eme1y dep-Leted. 2. g. p.g!.gClLC,Endangered, now seriously depleted and rale or extinct in most of its former ranges .in India. 3- g. palustris: vulnerable, no'!r heavily depleted throughout the range. At the last Working Meeting in 1982, the situations were accepteat to be as before. The present paper provides updated information on the three species as regards their status before any release,/ re}labilitation took pface through the covernment ' s conservation management progrannne. Also given are the accepted population figures and the present locations of breeding populations. Present status of: cavialis danoeticus (GMELIN) T. ],EGA], STATUS: INDIA: 1. wildlife (Protection) Acr". 19'72r Schedule I (Total Protection). 2. Export I Instruction Nt 46/13r Export of animals and their products probibiteal- 3. Instructlon Ne 5'7/'75r Protection as religious symbol INTERNATIONAL: 1- CITES: Appendix I (Tndia is a party) 2. IUCN Red Data Book: Endangered II. PRE_RELEASEPOPUI,ATIONS: River_ State Adult Jul,Enile Tttal Source 1. BralnEtr tra Artr]adal ? 50 l,bbanta, !{., 1981 clrcu&rurt' . 1983 2. cltanbal RajastlFn 40 81 121 Fao,19?4, AnqI, 1976t l'lhital€r ard fErdel, 198ot Singh, V.B., 1978rIJG{,1982t Whitaker ard Basu. 1983 Girwa uttar kaahsh 9 19 28 RanEnard and Jchri, 1982 lrel1) Ken (1989) l4adbra Pradesh 1 0 I Ancn.,19?6; Singh. 1990 l.bhanadi Orissa 4 I Bustard arrl Singb, 1982 Raqarqa uttar kadesh 0 4 4 Ancn, 1975 (?) 7- Sci) (1984) lradb'a Pradesh 18 0 18 Pandey, 1984 Ib'tal p.putaticn: 230 inclucing 72+ adults- Aftlouqh tlle above fi$rres are in()ro\rensrts over Bustard. 1982 (60-?0 nG) and r,{hitaker, 1982 (less than 50 adufts), the overall status rslgins t}F sare, 'endangered' . III. BREEDINGPOPULATIONS { 1984) 1. River chalribal: (Places vs- average number of nests as oflL9a2- 1984) Baroli- ?, Bharrah- 7t Tigri-Rithaure- 2t Pureini- l0t G)ranpura- 2: Total = 28 2. Rlver Girwa: within a stretch of about 12 km up to six nests. 3. River Mahanadi: Last successful breeding: 19?4t recommenceal: 1984; nrnnber of nests: one with 24 eggs at Majhipada. 4. Brahnaputra: Reports of breealing in the fo]lo1'ting tributaries are available but Lhe exacl status is unknown- 5. Ramgahga: Uncertain. IV. TOTAI, POPUI,ATION ( 1984) Natural crarlil* Population River Adult Other Total Released Total trend 50 50 Brahnaputra ? 0 Iriclo^Tr Chahbal 5; t92 245 972 1157 fncreasing 85 Gi rwa 9 19 2a 113 Increasing Ken 1 I 3 4 Stable Mahanadi 6 2 I 150 lncleasihg Ramganga 4 4 12 Ihlc|d^ttl Son 18 18 2 20 Stable (no nE-te) * IOTAIJ r47 273 1164 1518* Increasing +. without cohsidering losses among released gharial " and captive poputationabout one thousand Present status of: Crocodvfus porosus Schneider I. LEGAL STATUS: INDIA: As for Ghariat TNTERNATIONAL: As for charial II- PRE_RELEASEPOPULATTONS: Iacatiqr State Adult Jlx€rlite lbtal Sourclg 1. Bhitarkanika Orissa 34 64 95 ?iar ahd Brstard,1982 | \9'7't) 2- Sunalarbans W.Bengal 96 100 rrail,l.€alras ( 1978) 127 Jan., 197A1 3. Andaman and Nicobar rlp to Whitaker ard Whitaker, 1978 North A. 50 150 100-200 Middfe A- 20 80 50-100 South A. 10 20 20-30 Nicobar 20-25 (Bbaskara, 1979) Total population: up to 5S0 incl\rding 125 adufts. III. BREEDINGPOPULATIONS (1984) 1. Bhitarkanika: over an area of 176 sq.kn. up to eight nests. 2. sunclarbans: A total of two nests every year. 3. Analamans: Most of the Dests are prealated in this wild (Choundhury anal Bustaral, 1980). Exact extents of reproaluctive ef fort uncertain- 4. Goa: Existence of viable populatlon reported. Exact position unknown. IV. TOTAL POPULATION (1984) Total Grand, Population Locatron Adult Other TotaI Refeaseal Total trend Bhitarkanika 38 130 168 350 518 Increasing sundarban 96 100 165 Tncreasing andamans 80 up to 0 330 unknown 250 330 Goa ? 0 ? unknown TOTAL 118+ 480+ 598+ 1013€* INCREASING * without considering losses among released crocodifes r* and captive popuLation about 700 TOTAI POPULATION IN TtlE COUNTRY: 1713+ Present statu6 of: crocodvlus Pql]lqlrilg Iresson I, IEGA], STATUS: INDIA: As for gharial INTERNATIONA],: 1. CITES: Appendix I 2- IUCN Red Data Book: Vulnerable II. PRE-REIEASE POPULATIONS: Excepting the Dorthern states of Jammu and Kashmir, Himachal pradEsh ind sikkim, mugger are reported to have cocurred in all the other states during early 1970. Although no detaileal census were conducteal an accepted approxiirate population figure was around 10OO with a population trend "depleting faster thaD it coutat reproaluce" (FAo, 19?4) - Based on the number of wild mugger some of the gooal states were in the order of Tamilnadu, Gularat, Ralasthan. Analhra Praalesh, Karnataka and Maharastra. 358 III. MJ\IN BREEDINGPOPUI,ATIONS (1984) Tamilnadu: Amaravati.Sathanur,Hogekkakal,Chialanrbaram, Kullikudu, Mettur, Mundanthurai. Totat approx. cularat: Hiran and other lakes (cir). Total approx. 12 Andhra Pradesh: Ethipotha 1a,/Nagarj una Sagar Sirisailan (Krishtrla), Kinbersani, LanJamaalugu, ManJira, Sileru. Total approx. 12 nests. Karnataka: Cauvery.river at Ranganthitu-Sri Rangapatan, Tungabhadra and Bhima rivers. Totat approx. 4 Maharastra: ?adoba National Park. powai Lake (Bonrbay).Total up to six nests- Bihar: Bber river (Mutta), Rainur Sanctuary,. Damodar Vafley. Total up to 6 nests- Ranthar.ibhore, Pushkar Lake. Total up to 8 nests. Madhya Pradesh: Ranga!,ra Dam (Panna) , Bandhavgarh. Totaf up to 5 Uttar Pradesh: Corbett, Dudh$,a, cirwa (Katerniyaqhat) . Totat up to 5 nests. Charibal river: (Madhya Pradesh/Raj asthan/uttar pradesh). Up to 12 nests. Haryana: Kurukshet!a. Kerala: Neyaar, Parambioulum- UI) to 3 nests. Orissa: Koraput (Batimela Dam project), cranjan (BlEnjanaqEr)- North-east rivers: (Arunachal Pradesh, Assam, Nagaland and West Bengal). occurrences reported but exact locations of breeding population not available. IV. TOTAL POPUT,ATTON(1984) Natural Approx. 1000 all sizes Released: 600 (afl from wild-collected eggs) !'rom wild-colfecteal eggs- 3000. By captive breealing- 2500 Total: 7100 Trend: Increasing. (Extensive captive breealing in at least twelve centres) - 359 Anon 1975 . Gharial Survey. Maalras snake Park Tfust. anon 19?6 . |4adhya Praalesh Gharial survey. Newsletter of the Madras snake Park 1(2): 2-3. Bhaskara. s. 1981 Travels in the andamans anal Nicobars' Hanaalryaal 6(1): 2-8. Bustalal, H.R- and singh, l.A.K. 1982. Status of gharial in (1982) orissa, !! singh, L.A.K. and choualhury, B'c' ' Indian c;codiles - conservation and Research. Folum of crocoalile Researchers, India, P. 7. Chounalhury, B.c. 1983. Pers.lnform- from Arunachal Pra'Iesh' anal Bustard, H.R. 1980 Prealation in natural nests of the sal-twater crocoalile (crocoalvfus Dolosus schneider) on north Analaman isfand with notes on the cloco'Iile population' J- Bonibavnat. Hist. soc. 76 (2): 311-323. Daniel, J.C. 19?0. A review of the Present Status and posltion oi enaanqered species of Inalian reptiles. rucN Publ' (N-S') N! l8: ?5-76- F.A.O. 19?9. India. A Preliminary Survey of the prospects for crocoalile farming. (Baseal oi the work of Dr' H'R'Bustard) ' Fo:IND/71,/033, october 1974, 1-65 pps. crocodilian Honegger,-ipecies R.E. 19?1, The Status of four Tlreatanded of Asia. IUCN supplementary paper 33 (1): 44-53' IUCN 1982 a. I(eal Data Book- Amphibia and Reptilia' IUCN 1982 b. Crocoaliles. Proc. 5th workino neetino of the CSG/SSC' IUCN. Kar,---' S.K. anal Bustaral, H.R. 1982. Status of saltwater crocodile (Ed') lndian in Orissa- I! !.:-!-d, L.A.K. and choudhury, B'c' crocoililes _ conservation and Research, Porum of crocodife Researchers, fndia. Mohanata, H.K. 1981. Pers. conunu _ to LAKS Pandey, S-P. 1984. !9lq5,--g9gq!g - to LAKS of the Ramanaal,- S.P. anal Johri, v.K. 1982. Results of a census ocBMTr Trainees in tlariaf in Katernil'aghat sanctualy by ierg. r", (Ed.) sinqfr, L.A.K. analchoudhurv, B'c' (1982): lnilian crocoaliles - conservation and Research' Foium of crocoalile Researchers, India- seshadri, B. 1969. rhe twilight of lndla's wildlife' London' Ken River' Madhya Sinqh,- L.A.K. 1980. Crocoalile survey in iradesh. Report to Forest Dept', Madhya Pradesh' 360 Singh, V.B. 1978. Status of the gharial in Uttar Pradesh aDal lts rehabilitation. J. Bonbav Nat. Hist. Soc. 75 {3) : 668-683. Whitaker, R, 1982. Status of Asian Crocoditians- I!: IucN (1982 b) Whitaker, R. and Basu, D. 1983. Ghariaf: A review. it. Bonibav Nat. Hist. Soc. gq Whitaker, R. and Daniel. J.C. 1980. The Status of fndian Crocodilians. J. BonibavNat. Hist. Soc. 75: I23A-124a Whitaker, R. and Whi.taker, Z. 19'78. A preliminary survey of the saltwater crocodife (crocoalvlus pqEql€) in the '75 Analahan islands. q. Boribav Nat. Hist. Soc. lllt 43-49. 36i INDIAN CROCODILIANS: A 1O_YEAR REVIEW OF MANAGEMENT 't)ll L.A.K.sinoh'. S.Kar', & a. c. Choudhurv- 1. covt. of Indj.a, crocodite Research centre of wildlife Institute of hdia- cam:Nationaf chahbal Sanctuary, Post Box-11, Morena-476 001 2. Govt. of orissa, Crocodile Project, camptChandbali, Balasore, Orissa 3. Government of India, crocodile Research Centre of wildlife rnstitute of rndia, BahadurPura. Hytlerabaal 500 264, Andhara Pradesh Introaluction Inalian crocoalilians (Gavialis oanoeticus, crocodvlus pglgEgq and Crocodvlus palustris) are known to have close association with the fndian culture as refigious syntbols and use in inaligenous meaiicines. crocodifians were also useal as exbibits anal even maintained as imperail executioner. Huntlng of crocodilians as a sport was popular only among a few lnatian sport-hunters an'l altl,ough .p"iaal" commercial bunting for the luxury ]eather trade did occur such killinqs are considered as only one among the various other more serious causes that wele responsible for the depletion of the populations during the post_inalependence era- One of the major causes was the introduction of nylon gifl netting anal the perjudice against crocodilians as the enemy of fisheries. other causes were the construction of dams and barrages and increased nunicer of human habitation near cradilian habitats with better net-work of approach roads. These developments are reflected in a shrinkage or total loss of crocodilian habitats - After the establishment of the Indian Board for wildlife in 1952 efforts by sorie indivialual Forest officers and naturalist are 'piotection' know to have been made for the of croco'Iilian jurisdiction- proposal was _un-derDoDulations in areas unde! their A consideration during 1971 to start corunercial farning of crocoaliles but by 1974 it had been realiseal that Indian croccdifian resources were so depleted that tbey were not a position to support the connnercial exploitation. This was the perio'l when UN-DP,/FAocolfaborations in the form of technical expertise, soon followeal with financial assitance, was made available to the covernment of India to conmence and promote the crocodile breeding and management programlre in different states- Manaoement Goals {1974-?5) And Acbievements 1- Plotection to remaini objective: Location of aI1 the best crocodilian areas and creatlon of a few speclal crocodile sanctuaries for habitat an'] species management. 362 Afl irnportant habitats for the different species bave been identified and if these were not already within a Sanctuary of Natlonal Park, were formally declared as Crocodilian Sanctuaries. Some of these protected areas have been identified for introaluction or reintroduction. Two such sanctuaries are in Andhra Pradesh, one for the saltwater crocodile (Corinqa sanctuary: reintroduction) anal the other for the gharial ( Papikonda : probably reintroduction since the species is no}r known to have occurred in the Godavari Bustard and Choudhury 1982) - Ths nurnber of areas in i"rhich active protection is given to cro.oalilian is 34 {20399 sq- km) and the humber of specially created Crocodilian Sanctuaries is l3 (8346 sq. km +) (Tabfe 1, Fig. 1). Although no special law or regulations wele enacteal since 1974, inplementation of the existing regulations was vigorous. The best example of the present state of protection and management of sanctuaries is the resunption of breeding by the wild population of the gharial after a lapse of ten years. (Satkoshia corge Sanctuary, 1984). Regeneration of mangroves, especiall1' seen ln the Bhitarkanika Sanctuary, is yet another example of rehabilitation through protection. 2. Rebuilal latural popufations Objetive: To realuce natural losses through 'management'. The technique adopteal was 'grow and release'.Tbis involves colfection of wild-laid esgs , in cuh,ati on of egg in hatcheries, rearing, of the young crocodilians upto a 'releaseable' size (over a meLre length) and release of the juvenifes in sanctuaries or other protecteal viable habitats - The totaf nunber- of eggs handled so far is, charial: 9.6000t Mugger: g. 9000, Saftwater crocodiles: 2500. Tle total number of hatchlings hanalfed is, Gharial: 9- 1700 and the total number releaseal is chariat: 1164; Mugger: .9. 6Cr0; Saflwater crocodile: 415. Tbe releaseal Gharials are expected to conmence breeding in 1985/86. Mugger breeding comnercial with the population in Ethipothala in 1981 and Saltwater crocodiles are expecteal to conmence breeding in 79A5/a6 - The post release nonitor has been satisfactory. Recently, radio- tracking was useal to monitor the movement and habitat preference in sanpfe populations including the released Juveniles. Based on these studies species-wise recommendations have been made on restocking sites and seasons and to extenal the limits of the sanctuaries into certain tributaries that are used during rnonsoon. Whife Gharial and I'lugger have responded fairly well \rithout causing any public concern stray incidents have come to notice hrhere q. porosus juvenifes have entered village ponds. In response to compfaints prompt actio!1 has been taken to shift such juveniles ej.ther back to captivity or to a alifferent point for release. Studies are in progress in sefected sanctuaries to a determine the average survivaf anong releaseal crocodifians. The indications have 363 been very cfear that the habitats have accepted the refeased Juveniles and there are increasing trenals in the poputations, It is, ho evef, feft palticularly in the case of ghariaf that ih the near future, as the recruitment into the aalult group steadj.ly increases, nolr areas may have to be aleveloped to attract sub- atlufts to settle to form breeding groups. Studies are unaler progress to identify such potential areas anal the extent of management requirejients. The public reaction has been inclifferent to releases. Several local people have been provialed enpfoyment under the schemes as boatrnan. crocoalile/sanctuary guards, husbanalry attendants, fish- suppliels and other generaf help fot the upkeep of the centres and camps in the sanctuaries, The sanctuaries have attracted visitors from which the Iocal people have definitely experienceal an economic upfift (Singh 1980) - 3. Promotion of captive breealino objective: To breeal under simulated natural surroundings the available adults in certain zoos and similar organisations. Mugget have responded the best to captive breeding attempts (Table 2, t.ig. 2). At feast:15 centres are being set up. Gharial being a very specialiseal species in lts breecling habitat requirements, has seta record by breealirig in the Nandankanan Biologicaf Park, Orissa since 1980- A special breeding pool holding 2.7 milfion fitres of water has been used for breeding. The maximum depth of the pool is 10 metres. Saltwater crocodile have bred in captivity at the Bhagabatpur centre and at the Madras crocodile Bank (a tlon-covt, Trust) (1983) - 4. Research Objective: ?o take up studies that will improve the ongoing management progranune. The aspects that were imnealiately relevant to the grow and release techniques and the manaqement of the Sanctuaries were given priority. This has overlooked several biochenical or enbryological stutties which nay invofve or require to sacrifice eggs or young or both- Some of the important aspects that were studied are: - interpretation of the various types of data collected during survey and census - - determinatlon of parameters for maximum hatching success; (This had overlooked the rofe of temperature on sex differentiation, an aspect that is now being studied) - - husbanalry of young crocodilians including feeding prescriptron, fooal converslon and growth. 364 oIosy incrudi!rs reproalucrton. thermoresufaElon, reeorhg,;^5k:t":::], f l orientation, locomotion, and reproductionr an; - habitat features and populaEron scructures. 5. Build ut] levels of tralneal personnel Obj€ctive:. On the spot research/trarning guided throuqh-o".1i,"'.poa FAO expertise in collaboration vrith ]ocal U"i""."itr."- -i""iit,lii"".r trainins ro persons ltr Aspect Prior 19?4 1984 1. Population status Endangereal and Endangered of and alf species depleting increasing 2. Status of conservation Localised and Definite country- dependent on wide prograftne individuals 3. Legal protection Provided Same but strongly endorsed Kiflings in the wifd Sporadic Stopped 5. Number of speciaf Thirteen crocodile sanctuaries 6. Surveys conducted Few,not in detail '7- Public attitude Religious, or ReIigious, most favour indifferent conservation, others toward conservation in the process of being weahed away from a negative attitude 8. Pubfic media Curious toward Constructive 'accidents' and explanatlon to sport kilfinqs accidents, promote conservation need and progianune 9. Crog,Fish relation WideIy misunder- Studies under progress towaral a better unde r-stanaliig 10. captive rearing Zoos as exhibits 23 special unit for 16 (all species) 11- captive breealing 3 zoos (a11 nuqger) 9 other Places making serious breealing attempts 12. Knowlealgeof ecology very limited Much better unalerstood I\ture Priorities The folfowing priority progranmes are suggested: 1- SANCTUARYMANAGEMENT: (a) DeveloP more atluft zones (b) continue the search to ialentify other places where natural Populations can be built uP- (c) orient management on eco-system basis (Extend the efforts to other flora and fauna, e-g- turtles, aquatic mamhals and birds ) . 2. CAPTIYE HUSBANDRY: (a) Proaluce appropriate number of crocodilians of either sexes anal try restore a balanced ratio among the released populations. (b) study stress factors and maximise captive breetling pro'luctsicns' 3- RESEARCH: (a) continue as neealed in sanctuary an'l captive managements' 4. TRAINTNG: (a) Extend speciatised courses to persons already receiving general wildlife training. (b) Buj.1d up expertise to permanently man each crocodilian sanctuary. 5, FARM]NG: Corunence the experinentat pilot project with captive mugger' Other Efforts The Bombay Natural History Society bave un'lertaken or supported extensive_ surveys of Crocoalilian habitats ' The society have also remaj.neal as the- only international organisation with a very strong appeal for Conservation Programmes in India- The Curator of tn6 society, Mr.J.c- Daniel, was the first rn'lian representatlve at the ssc,/Crocodife speciatist Group. 366 Another non-government organisation that has coDtributed to the cause of Crocodife Conservation in India is the Maalras Snake Park park antl Crocotlile Bank. The have not only breal muqqer anal saltwater crocoatiles, but have also supp.lied sLveral crl-coaifes to alifferent States for restocking in the wi1d, rtre paii no, aims to become an InternatioDaf cantre for breeati.ng .ii of Crocodilians. "f."r.". Acknowledoements ,l The authors are gratefut to Shri Samar Sinqh, Joint Secreta_ry and Director (wild]ife) to covt. of Jndia, shri v.v. sabaria, (Wifdlife Directol Instt. of Tndia) and Shri J,C. Daniel, curator (Bombay Nat. Hist. soc.) for their critical reaainq ihiouqlr the manuscripts and suggestions for implovements. rqr. t. wf,itii." provided information on the Madras snake park anat crocoalile Bank. References Bustard, -H.R. anal Choudhury, B.C. 1q82. Occurrences of gharial in Andhra Pradesh. In Singh, L-A.K. and Choualhury, B.C. (Ed.) Indian Crocodifes - Conservation and Research: lorum of ciocodile Researchers, India. Singh. L.A-K. 1980. Sanctuary management as a tool in rura: development- paper presenteal at a Symposium on ,Witd]ife Resources for Rural Devetopment, Irald at Hydeiabad, tndia, 7-11 July, 1980. I JosA'/argas (Divisi6n de Orencas e Hidologia, EDfl,CA) kindly ie&ew figures 1 arlC 2. 367 Table 1. crocodilian Sanctuaries (**) and other areas offering active protection to crocodilians. 1984. S,sanctuary; NP, national park, Gh. gharial; Mg, mugger; swc.salt - water crocodile Area Year StrEcie.s Nu$er sq.kn. cqfislc€d nlarlaged released s1.N4 lrs 1. Bandovgarh NP l4adhl'a Pradesh 437 sl,tc 350 Bhitarkarika S, Orissa 1975 3.** ctlalrbaf, Naticnal S. l6&rya 1500atrI'rox. Pradesh^aj astllan, t ttar Praabsh 1978 (*l (Ms) 912 (10) 4. corbett NP,Lrttar Pradesh cl, (l's) 12, (rlil) Coringa S, ,Andhra Pr€desh 236 1974 sI{c 3 6. Gir NP, cujarat t4t2 1915 w Hadgarh S, orissa 191 19?8 L HoqEenakal , Tanilnadu !s 46 Ja^'alFrsagar s, Rajasthan 100 19'75 Gr 21 10. Kaimrr S, Bihar 1342 1969 l4s Iiatemiyaqhat S, U. Pradesh 400alDrox. 1976 (ir (t€) 85 L2.** Ken S, f4adhya Pradesh 45 1982 el $s) 3 13. Kinnersani. Andhra Pradesh Ms 33 14. Kiishnaqdri, Tarnilnadu Ms 130 15-** Innj anoduqru, lnalhra Pradesh 20 \97a I,g Ltlli an S, West BenqBf 38 s'V,Ic 24 !.:anj ira s, l,rldhra Pradesh 20 19'74 rg !tudr&alai s, Tanilnadu 321 1940 !s 6 19. Mrmdantiorai. Tarnilnadu 149 2T 20. l\,luba s, Biha.r 5 Propo6ed i'q 2t-*, Nagerjlma Sacar s, a. Pradesh 3588 r9'78 rt 1"54 22. Ne'1'ar, Korala 270 1958 I,ls Pald€l S. in&)ra Pradesh 850 t952 l4s 24.** Papikcnda S, Ar&tra Pradesh s91 t9'78 G1 25. Parad)ikufui, Kerala 245 19"7e }b Renganthitu S, KaraatalG 26 Fenth.fibhore Tj-ger R-, Rajasthac 392 1959 tq '796 24.'* Sat-] 368 Captive fearing,4reeding schemes, 1984. *+Successful breeding *successful commenced, breeallng attemptedr Gh, gharial; Mg, muggerr SWCr Saltwater crocodile State and U.T. SI.no. Lcation Yea-r SIEcies Andaman Nicobar 1. Port Blair 197 9 swc Andhra Praalesh 2. Ilyderabad 1916 Gh,sWX, Mg** 3. Nagarjmasagar 1979 Mg Bihar 4 - Nl,rtta 1976 Mg* GuJarat 5- sascn cir 1976 Mg Karnataka 5. BarErghatta 1980 Mg** , ch* Kerala ?. Iilel,zar 19a2 Mg 8. Peruvaruraruzhy t9 82 Mg MaCIhya Pradesch 9 - Deori 1981 Maharastra 10 - Tadcba 1971 l4g* Oris6a 11. DBnqanBl 1975 swc* 12- NandartGnan 1916 Glr**" Mg**, swc* 13. Rarlatirtna 19'79 Mg Ral asthan 14. TikerlEda 197 5 ch, Mg** Tamilnadu 15. Kota 1975 Gh, Mq 16. lrrErc,\rati 1976 !7. Hoqglnal 369 Figurel: Crocodilian sanctuariesano other areasofferi nq active Drotectionto crocodilians, .1984.Numbers as in Table 1. 23 ie. tt tl t9 Fi$ure2: Caotjverearjno/breedjnq schemes, 1984. Numbers as jn Table2. I, States that are interested in corirnencinqschemes soon. 371 STATUS OF AFRTCAN CROCODYLUSNII,OTICUS POPUI,ATIONS (BOTSWANA, MAI,AWI AND MOZA.I4BIQUE) Kevin van iraarsveldt Binga Products, P.O. Box 2569, Harare, Zinbabwe Following the 1984 CITES conference in Botswana anal the Technical committee neeting of cITEs, in Brussels in late 'f,unte 1984, twenty four African countries are known to have or are Preparing to petition the dolrnlisting from Appendix I to Appendix II their 9. niloticus populations either as individual countries or collectively. This report intends to present to thls CrocodiLe speclalist Group some known facts of the position of wild crocodYlus niloticus population, wild life authorities' management pollcies anal comrnercial activites in BotsNana, Malawi anal Mozambique. The task at hantt however is to cormrent on the 24 Aflican countrles intentions to have. their q. niloticus populations transferred from Appendix I to Appendix 11. The statement presented by Malawi is a si)ni1ar argument used by the Crocodile farners Association of Zimbabwe in their meeting held in conjunction with the last crocodile speciafist Group meetiDg in Victoria Ealls. Zimbabwe in 1982. Zimbabwe however were able to back many of its claims with hard facts after numerous years of serial and niqht surveys of selected population densities and twenty years of commercial ranching activitles. The problems facihg Malawi anal the other 23 African countries are familiar anal in many cases true. 'Ihe rrBerne Criteria" nakes it very difflcult for African countries to meet the positive scientific evidence required. Some of the facts mentioned in lhis report in regard to conffict between human and livestock and loss of fishing grounds may welf be the case in Malawi. However it can hardfy be the case in all the 23 petltioning Further consideration shoufd be given to the reason why these respective countries are applying to downlist their g. nlloticus populations. The nain reason is conrmercialt for the sale of wet safteal or partly processed belly skins in return for foreign currency (foreiqn exchanqe is in short supply in most Southern African countries) . This would be achieved by the following: offering annual culfing quotas b) sale of hides from farining operations ?ou!isn 372 The author vielrs anbual culltng.quotas as a contradiction to neaningfut conservarion trebds (diving ."".iJ"r.iiJi".i";".,.r"g, ranchins possibif tties) . rhis cuitins-h,""ia-i;;i;;;-r;;,.,i" of rarge breedins 1.gltlr9r. crocodiles 1r,""t!i" .r"-!!i"rarry--- .-" "rrru serectrve, reductng the ]arger crocoatiles firsti- T:: l::11!I 9l lh.:: farser skins is not of the hishest desres ano-experrence in the sale of hunted crocodi.le-iirJt-qi;d"-;ii quatity selectioD ,Lii.-iiai."t." to be approximatetv soz sox second and third grade sk-iirs - accepted lgji:13:i,lll internarionar market contracts atfow f,or z:x recluctron in second grade skin prices and Sox reauciion :.n third grade skin prices - one acceprs a heatthy poputation to be s0,/60 0oo ::::*:,::=yTl"g (as was conservatively- estimated by Zinlbabwe Management Authorities afLer 7 years or population "r.,.,.o., skrns could i:' n,*;; or be tanned ihto sateable :eather";.";i. bv th.;;;"';;."" tanherles-in France onry {excruatn! i;;i;;-w;;t";..*1i",..!.p.n the unired Kindgdonr) within 60 aayj or r6"e tvins-ih;-;1i"ir", . "no larse crocodire skins has changed oemandTl:-:.."!i:lsituatioh due to suDDtv an.l and the fashion.roday is ;", ioZeo.^-u5iii.-".' .iii". of hish quatiLy. (Maindemanal 25llscm-berry ;k;";i:-'" ?he sale of hides form farming operations affords the-iio*-J,i."int wj.ld population good protection, popurations. in that eggs iui"n-i" -ir]J- ll {Hatchins success in zin*jiuwe"r" i" i'ijx-1...- ."o to sate size (2 t,/2 years ifil, i.".t"n /4 is se;er"ity in-tl,e zoz Tj^:1. _::l:t 9".: wifd barchins percentases are no more rhan r0z lnost cases as 1or,ras 3z i"n areas of co;flict wiiir rrum"i._""a wild life predators) . Alfowance should be made in farndng permits wild.seni for the return to the mature (three year old) ;.;.;;i;.-;; ii.,i""".iil, require re-stockinq. .n.. ,,nuisance crocodiles causing a factor,, shoufd wnere.L-arge possibfe be caDtured and used in breeding banks withi; to. supplement ;;rui;.-i:-t t..*" eggs coltecting. numl5rs. with il"g t-e;."*p1."i, total depenalance on internal breeolng. "" The establishment of crocoali fe is long term anal capital hor"/ever the _farms It:":ly", author ree-rs very strongly, is the onfy rolrg terh guarantees for Soutl popuLations. aL the same .in.t:::"lfti:."'s-e' lilotlcu= "ti ri,.ri.,' giiiii-i i-,,.r"j"'!,"ii;::T":";.q"; r-#+ff"*::ilH;i :: ]" Toulism offers good foreigtl and local ar-eas frequenred currency returns in those by inter;ationar tour.ists iirr a-Ltays offer arr attraction - ""i "i"""iir!. 373 cperatid)s the high costs of establishiDg crocodile farnLing Owing to wifal populatlon ii,e iorrowins c6mprornise nay be considered: Realistic ;;;.;-;;;;id be iaken ana verv conservative-quot" :v:l:Tt- ir'. of hirnted skins' (skins remove'l onlv iipii..i.i-ii.- is genuine unier wilalife authorities"*pott supervision' where there ' i"iiir.l-u.L.." crocoilires. nan and his livestock) conclusion g' populatiolrs The question regaraling the downlistinq of niloticus ab'l complex in twentvfour Afrrcan countrles is a aifficult Problem i"a fr""ifv not possible collectively' (not those. views The author,s views in this matter necessarifY rather be i"iaE--iit"- csci are that these petitions should dealt with indiviiiually. Botswana are both countries that' given the right Malawi and in time anal tlocumented evi'lence' could be successtul strensth or il:i;-;;;;;.:llev-stoura""iJ"ii".t, not however relv on the population figures ' irr.i. """"" g.niloticus" wild "a with the stronger Recofiunenalations shoufd be nade to the countries for an ;;;;;;-i;k; aalvantase of the EEc offer of fundins lheir populations whict' wourd strenstlen ;;;;;";-";;;y-;i -wild have been i;;;;;";; wiitr ctres arter itr3 followins sui'lerines and respective 1) Total national 9. niloticus populatlon figures dlensitY. geographical areas ' with 2) Plan aleas for totaf protection ' in conjunction National Parks and protected wild life areas ' sustainable popufation areas for 3) Recognise :l:.ll.itti"t 1n anal ictive support of conmercial farning activltres' ' conlunction *ilh f"nq term water an'I feetl supplies S' 4) Pfan harvest or capture Prosrammes in-tbose :::':--11"'"humans niloticus populations are causing confLict v/atn and fivestock. safari hunting 5) Plan cropping quotas to support comercial antl resialent huDting operatlons ' above mentioned 5)-' Provide basls tor research into effect of on knovm wild popufation nunbers ' ".tl.titi.. manpower' of this size are expensive an'I lengthy' however if surveys in eouioirent anal finaDce is available it nust be 'lone correctly pi..". where possibre' the samemethoq:1, ii;-il;;i aircraft' ;;i";i;;j-";; a,'it ".i"gi,,aiiiauars. (Pilot, spotters' recor'lers' etc. ) - 374 the openins parasraph of crrEs docurnenrconf- Tl(f.1r- f+ri:ll:g r9l6) 1S refevant_ 1.2 "Resolves that the defetion of a ptant or animaf taxon fronr Appendix r or rr or the reduction or protection taxon by transfer si";"-'ti-iirr." from Appendtix r to ippendix II-i;-; ;;ri.r" matter and should be appioached wrtfr caution,,- The auth_or states that with many unknolrn quantities anal p"""":t=d facts, this meeting cannot supp;rt the aowniist trom Appendixrr or anvarricai' counirieJ-"iii-i. i:i:l:ii.i":" nuoti.o" STATUS OT ASIAN CROCODILIANS: AN UPDATE Ronulus l{hitaker Madras Crocodlle Bank Trust vadanenunefi village Perur P. o. MahabaliPuram InaIia Introiluction of a mole complete status rePort is given iDthe cscProceedings the Gainesville Meetinq (1980) - The followiDg report surunarlzes in conservation anil managernent activities concerning crocodiles asia since 1980. Current Status bv Countrv IRAN: No change. No conservation action repolte'I' PARISTAN: currently interests being shown to start a conservation/ managenent progranune. qharial the INDIA: The State ProJects continue. Release of -in totaf of over iitirnUaf. cirwa and_otier iivers continue with a studY iiioti."i"i".a so far and 2500 nore beins reare'l' A longterm tl".t:i::!?l: has begun in the most important gharial abode-: ,- Nation:1 chambal Gharial sanctuary- captive thariaJ_ breedrng 1s only taking place at Nanalankanan Biological Parkr.n orissa' RestockirxE of mugger has nearly stopped and considerable resistabce In j,s building up by fisherles people against further reLeases -""_a". about i"".i.roit" their control' State projects are rearing ."gg"t anal the Maalras crocodife Bank about 1100- successful iOOO in iuooer iiptive breeding is taking place at about 10 centres the i;;i;. i# ="it".t.. ciocodi.le ii under habitat pressure in particularly so !""a"iui"" and Bbitarkanika on the mainlanil an'l clearance' Ii--irt" a"a.t"". alue to iltegal encroachment and forest iso l"a u"".' rel6ased in Bhitarkanika sanctuarv and iiri--isCi, at iOo being reared. captive breeding has been successful Bank' iit. ".t"i""a".u"i. r'orest DePt. projectand at Madras crocodile contry's SRI l,ANtrA: No change.In spite of the importance of.this .ugqer ana saf ti'ratar crocoalile populations' t! l:. !": dwlnoilng1::. ::tp" lavi ueen taken to protect or manage the raprclly pap"f"ii""" outsiale^ thetwo main Naaional Park of Yala End wilpattu' chitawan NEPAL: Rearing anal leLease of gharial is coDtinuing at National Park. BHUTAN: No change. BANGLADESH: The crocottitians were surveyed by wjhitaker -(1982) population anal the position is sununarizeal thus: small breeding (Padma Rivers) ii-qh;ii-.i survive ln Rajahahi District and Jamuna 316 but elsewhere it has disappeard. The nugger has similarly vanishedl fron Bangfadesh except for about ten individEal! at U)e Khan .Tahan Ali shrine in Khulna District. The saltwaEer crocodile survives in small numbers in tbe Sunderbans trlorest Divisi.on (3800 krn2 of mangrove forest lrith 12OO km2 of waterways). BURMA: No change. A proposed UNDP assiteal crocodile project was cancelfed for lack of funds. Tbe existing project in the Irrawaddy is ln need of technical arld alevelopmental assistance. IHAII,AND: No change. Restocking 9. siamensis in protectect areas fron captive bred stock continues to be a desirable priority. KAI4PUCHEA: No change. no new infomation- VIE?NAM: No change, no nev information. LAOS: No change, no new informati,on. CHfNA: In 1983, 300 chinese alligators were hatched at the l\nhui- Province Alligator F.rm under a continuing programme to rehabititate the species. In 1984 a large natural enclosure is scheduleat for completion. TAIWAN: 30 flrms rear perhape 10-0OO crocodilian mainly ggllgg crocodilus for skin and meat. One large farm had about 8.500 aninals in 1983, The source of their stock is unknown as is tbe nunrber actually being bred in captivity. MAITAYSIA: No change. Whitaker (1984) did a two month survey in Sabah and reports: The Sabah crocodile population is severely depleteal from over-hunting anal aggavated by habitat destruction and alisturbance. 1146 km of river were crnverECin nlght survey work anal only 56 wild crocodiles seen. Extrapolated estimates indicate a population of 2600 crocodiles of all slzes in Sabah. Yearling crocoaliles were seen in most of the areas surveyed, indicating the continuation of breealing, albeit on a sma1l scafe. A recovery soheme, followed by managed ranching is unaler cEnsj,ibration by covernment. The survey confirrned that lglqlqLgng is not present ln sabah, nor, for geoqriphical reasons, I!-it li-iely ro have ever ocurred there, SARAWAK. Briefll' visited and it was found that, though depleted, breealing populations of saltwater crocoaliles are stilf present throughout most of the courltry. Tomistoma is also reporteatly present in most inland rivers and permanent swamps which rras encoulaging nelrs. A survey and management development proposal is under consideration - BRUNEI: In generaf, claims of breeding crocodites at the various tourist croc farms in Singapore can be discounted, though the occasional nest is produced. Young stock which are teareal for slaughter come from various parts of Indonesia including Kalimantan and Sumatra. ?he presence of New cuinea crocodiles in the collecti.ons shows that Irian Jaya is also a source. 3 77 It i6 unfortunate that these people cannot foresse the drying up of these wild supplies antl get into serious efforts to breeal. Equally unfortunate of course is the Si.ngapore Go\ternnent's fack of control on traale in species i,n neeal of protection such as !.g!t!E!@. The skin of thls species is not valuable but young ones ale still being killed and stuffed as curios for Lourists along with thousanals of hawkabill sea turtfes. INDONBSIA: No change. Crocoaliles are protected but exploiteal at all age classes noderatefy to heavily in most parts of Indonesia. Irlan Jaya Province is planning a rnanagement progtaftrne baseal on ranching. The status of !.@is!.94e in Ralinantan (Borneo) is ubknown and deserves urqent investigation. PHILIPPINESS: The Silliman Universily project continues ' following exteDsive surveys by C.A. Ross. The Philippine freshwatel crocodife was successfully bred this year. Brazaitis, Peter and Myrna watanabe, rucN/ssc crocodile Group Newsletter. Vo1s. 2 and 3. 1983-84. Whitaker. R. Review of crocodile nanagement options and practices in Asj.a. Proceedings Crocodlle Specialist Group Meeting,1980. Whitaker, R. Preliminary survey of crocoaliles in Sabah. sabah Forest Dept. anat world wifdlife Fund-Malaysia. sanalakan.1984. Whitaker, R. Export prospects from conmelcial crocoalile farms in Banglaalesh. ITc/uNcTAD, Geneva, 1982. 378 AN ASSESSMEN?OI'THE CURRENT CROCODIITAN HIDE AND PRODUCTMARKET IN THE UNITED STATES peter Brazaitis New york Zoological Society Bronx, New york 10460 USA At the sixth working heeting of the IUCN crocoalilie specialists Group, the report on the U.S. market in crocodifian hides and products (Brazaj.tis, 1982), based on market and manufacturing surveys, indicatetl a depressed U.S. market for crocoalilian hiales anal products. Only three U.S. tanneties existeal which coulal tan raw crocodilian skins. so U.S- importers and fabricators were largely dependent on foreign tanneries for materiafs at hioh pri ces , . Importers experienceal fosses anal penalties when go;ds were seized by nifdlife agencies. l{anufactured crocoililian products retailed at prices out of reach of the general buying public - Prices paid fox American alligator skins at that time, a oood indicator for buying trends in classic skins with buyers ;rom two completely Clifferent cohsumer interests (Japan and Europe), haal fallen to between usg?.00-us l0.OO per foot. Subsequent reports from Papua New cuinea indicated tbat prices had fatlen tj:ere as well. threatening the continuation of farndng prograns. U.S. retail shops, lrhi fe officialty citing a ,'great" buying season in Deceniber 1982. indepenclently confideat that relait sales were off, that the U.s- consuner was largely buying usefuf qxality items, and that t}ley were ,,bargain hunting,,- We ieara the same retail reports in 1983. Classic crocodilian DroducEs were pretty much exclualeal from generat consumer inter;st.Fashion trends had also been diverted awat from crocodilian proalucts by the U-S. industry -- it promoteal snake and lizaral sk-ln itens and reptile skin prints on donestic leathers. There were other factors at work as weft in 1993 and 19e4. with tightening internationat and nationat regulations, and the strengthing of the U.S. dotlar, prices paid for classic raw ,,shortage. stins rose s1iqht1y. A of raw haterials l.las voiceal by some manufacturers and importers. Whether tbe shortage was real or not, contrj.ved by European tanners to dr;ve up itre prlce and create a demanal for caiman skins, or perhap-s ,:eflected baal hatching orcollecting se as ons .remai.ns speculativ-. et ttre ,'shortage,, same time 1983 saw a of cfassic crocoalilian ,,dumping,, hides, anal a related of stockeat finished Caiman crocodilus flanks on the narket, perhaps in anti.cipation ot tf- lmptementation ot CITES by the European CommonMarket, as of 1 Jan 1994- The effect appeard to be the utilization of cheaper caiman ffanks in the manufacture of high quality shoes anCI be-lts, anal \"rhote cai.man skins for hanalbags, wlich solal retail at classic skin prices. These replaced much of t}re classic crocodi-fian skins i; manufactured goods imported into tbe united States. 379 ltre Reptile skin Inalustry Trade Association petitioned the u-s- Fish and wildlife service to remove caiman crocotlilus vacare, the mainstay of the crocodilian leather industry, from the U.S. entlangered species list, in order to imPort directly from the main tanneries iB Bolivia. This petition was alelried for the tirne being- Imports originatinq from Bolivia antl Paraguay remain forbidden from entry into the U.S. Responsable for: the ban. were numerous altered, misrepleseDted and illegally issueal export documents bearing :improper or fictitious species names and originations. such as caiman crocodilus fgglg from trfarms" in Bolivia. Citatj"ons for ggllg! latirostris originally imported from Coloribia and "farnred" in Itafy only served to reinforce the neeal for restrictions. A rnajor central South American study of the status and systematics of caiman was inltiateal to adalress some of the systematic anal populational problems- Major sources of confusion to both the industry, trying to fulfi11 import requirements, and wiftllife enforcement agencies, are the nurnerous old synonyms and new scientific names nhich have been coined for populations of caiman crocoalilus crocodifus, caiman crocoalilus vacare, and for crocoalvlus niloticus, in industry trade journals anal European scientific publications (Iruchs, 1974; wermuth and i'uchs. 1978, wermuth and Mertens, l9?7) - T}le confusion wilf further be exacerbated by the inclusion of scientificallY unclefined subspecific names such as Cainan crocodilus matoorossiensiE, caiman crocoalilus paraouavensis / Crocodvlus nifoticus africanus, Crocodylus niloticus chamses, crocodvlus nifoticus cowiei, Crocodvlus niloticus madaoascarj-ens 1s , crocodvfus niloticus pauciscutatus and glgqgdJa]l]E niloticus€lghUg in the 1983 crTES identificatioD manual. These taxa, basetl on commercial hicles, largely ignored the authoratative works of South tunerican anal u.s. herpetologlsts, and in many instances refuteal the years of study and conclusive works eminent European scientists (Brazaitis, 19?3; King and Brazaitis, 1971; Mealem,1981, 1983; Wernuth, 1953, Wermuth and Merte$s, 1961; Mertens, 1943). Some of these authors pubfished widely accepteal and corroborated conclusions prior to conducting studies in cooperation with comrrercial lnterests (Wermuth and Fuchs, 1978; Wermuth and Mertens, 1977), which 1ed to the extensive subjective subspeciation of gg-494 crocodilus and Crocodvlus niloticus baseal on commercial hiates. The infusion of these taxa. wbich lack scientific basis, into the literature, has been the subject of much criticaf review (Frair and Behler, 1983t Medem, 1983). The result has been to present even greater alifficulties for importers anal brokers wbo must present alocumentation, and ma;ufacturers and rnerchants who find themslves with goods seized based on improper citations taken from industry publications. A major case brouqht by the U.S. Iish and Wildlife Service against MEG Import Corp., in 1984 made the U.S. industry even more acutely aware of the problems inherent in deafing with crocoalilian hides anal products. The u.S- owners of the companY, highly respected by their peers as eminent mefiibers of the Reptile Skin lndustly Trade Association, !,/ere convicted on 14 couhts each of violations of the Endangereal Species Act- The 38e company itseff was found quilty on 14 counts. It was aiisclosed EnaE cne company was owned in part by curtiembre ,,AIligator_, :.?:11i:l :annerv. MEGrmporta had ionspired t" aeiiuEiat"rv clrcumvent CITES regulations and the u.s. EsA, and had arranged tbe sale or engaged in the sale of over 2000 MelBlrosuchqs nioer skins from 1975 to 1983, invoicing -penatttesthehides as those of qainlan g. fuscus or cainan tronr gotivia. were reported to include a fihe of S75,OOO and a possible prison term for at _Ieast one olrner as a second offenaler. Fines ix excess of $300.000 and a one year or more prlson term could have been _imposed. Three seizures of over 2OO0 frnished Caiman crocoalitus vacare ffanks from zolfo co., owned by tt" piEliEEnt-6E-TtE-eitire'""".t Skin IDdustry Trade Association, resultea in an out settlernent incfualing fines and loss of merchandf".. Z"fi"-c"."i was not convicted of any wrongdoing. The company decided no! to contest the seizure after attending, i^,ith it_s . presentation on caiman identification. sponsored"ito.r1"y=, by tie U.s. I'ish and Wildtife Service anal qiven by CbC crrairmai r. w"i"" King anal Peter Brazaltis. Owners cited the European supptier with sendinq endangereal species contrary to tehir p,.r..ir_."" confusion ln the use of proper scientific names, citations of ttctltrous coLrnLries of origins of skins by European suppliers and changing national regulatjons in b.id; prooucrng.manufacturers, countrles, and the impfementation anal enforcement of CfTES, the ESA, and greater penalties for violators of the u.s. Lacey Act, all have served to undermi.ne the willingness of U.s- importers and merchants to deat in volume with products. Some inporters complained that they were"r"i"aifi"" teio! torced to accept caiman flank shipments from overseas suppliera, if they v,ere goinq to receive Iizard and snake sl In 1982 throuqh 1984. the exotic reptile products nsafer" traale turneal to skins and merchandlse, and was again ,'burned,,. The industry turned to snake and lizard skins, wrrich were cneaper to buy, were available in great quantity, and appeard to bL wrrnout rnport restrictions of any consequence. A fashion promotlon was mounted that equaled the crocodilian prottuct promotions of 1980. In 1984, the U-S. Fish and wilcliife Service. based on tbe prohibition from export, by India, of most of the conunon species of snakes utifized conrnercialty, began seizrng or refusing to allow the entry of snal 381 inaliscriminately mixed with evely species imaginablet and again various nanes were made up by suppliers in Europe aDd Asia. Importers were again shaken by having spent mllfions of dollars in promotions, created a fashion, naale sales anal contracts, anCI now find tbe sahe problems they experienced with crocoalilian products again upon them. Tbe effect has been a tlegree of disenchantment ith exotic Ieathers. It is no wonder that the snake and lizard skin trend also has peaked, arld appears to LJe wanlng. Some farsighted alesigners took a different approach beginning in 1982, and have further explored consumer interest in the leather market in 1983 and 1984. They began to use domestic leathers once again, in new anal "exotic" ways. Exquj.site dohe6tic calf leather became fashionable in 1983, followed by woven ]eathers in 1984. New antl exciting permaneDtly p.inteal domestic leathers depicting animals in natutal poses are on the fashion design tables. The unusual honeYcomb pattern of the stomach linings of sheep has been tanned to an interesting extremely soft pleasing sueale, antl nay soon appear. Products natle from coalfisb and eel skin appeared on the market, but have not "caught onrr with cons uners or manufacturers. Manufacturers anal merchandisers ale a very conservative group, with few major houses illing to take the lead, and the financial clrances by introducing promotions for unusual and unique leathers. The demand for some exotic reptile leather will always be there in the luxury market. New or revitalized fashions, such as those in products made flom crocodilian skins, are not generated j.s by the consumer but are maintained by the consumer. ft the d6siqners, promoters, manufacturers and rnerchandisers of fashion who create it. However, merchadts and lmporters will probably not broaden tbe present U-S- minimal demanal witb new ptomotions unless they can be assured that the raw materials are going to be available on a long term basis, that the skins or proalucts are absolutely legitinate and without import problems. and that there is a sufficient quantity of raw materials at a price wher:e products can be manufactureal both on a hlgh quality luxury basis and on a moderately priced volume basis. The near future for the market in crocodiliah hides and proalucts will be an interestj.ng one. Dozens of countries are racing to aleregulate crocoalilian species in order to capitalize on this natural resource in the from of firuch needed foreign exchange. Farms antl ranches are springing up all over the world, Iargely proalucing classic skins for the luxury market which many fashion Lonscious consumers may not be alisposed to buy. Taiwan is alrea'ly farming caimans for meat and hides, at present for donestic us€' New ta;ning practices, based on modern biotechnology and computeriz;A pr.ocedures may mean that skins can be tanne'l more cheaply, lrith consistant quality, and perhaps by any country that- chooses to nake the investments. New forensic identification techniques may ensure the accuarate decfaration of species an'l their origins in trade. 382 Tlre.ade-q ',safe,, tate supply of leqatly and acceptable raw naterials proouceo Dy accredrted private or governjnent sanctioned farms anal rancnes, comblnecl wrth conservation programs to manage and ensure the continuation and increase of wild p;pulati""; ;"-; renewanre national resource, is essentiat, if thi legat rrade i; c;codilian hi des ahd . -products is to grow, anal endangeied spe"ies are to oe excruoed trom exD-Loitation - llhat of the 1985-1986 narket? Nob much different from righE now, with more emphasis on pronoting new looks in aomesiic f.iln"r.. Nineteen eighty six anat beyond? I think that aepends on t1e cooperation between industry. farmers, .conservJionist, anat governments in recognizing the problems anal moving ahead together. Referencies Brazaitis, Peter. 1973. T}le identification of living crocoalilians - Zoologica 58: 59-101. Brazaitis, Peter. 1982. u.s. trade in crocoalilian hides and pioducts: a current perspective. 6th Working Meeting; rucN, Crocodile Specialists croup, Victoria latls; Zinbab;e- (In press). Frair, Wayne and John L. Behter. 1983. Book review: Iriste Der .restudines, B-gz-qllelt Amnnibren Uld Reptilren. crEE66-vfi u, Rhynchocephalla by E. Wermuth R. M"rteb.. l,gn-- Herpetological Revieh,, 14: 23_2S""d- Fuchs, Karljeinz. f974. Dlg Krokodithaut. Eatuaral Roether Verlag, Darmstaalt. 183. pp. King, !'. Wayre and Peter Brazaitis. 19?1. Species identificarlon of conunerciat crocodilian skins. Zooloqica 56: 15-70. Meden, Fealerico-. 1981. &q Crocoalvlia dC EgI America, Volumen l. leg Crocodvlia @ Coloncia. Colciencias, Aoqoti, 354 pp- 1983. !9q Crocodvlia d9 SIl! Anerica. volumen 2- cotciencias, Bogota- 270 pp. Mertens, Robert. 1943. Dle resenten Krokodile dgg natur_Museums Senckenbero. Senckenbergiana 26t 252_312- Wermuth, H. 1953. Sr/stematik qg! Rezentep Krokoatile. Mitt. Zoo1. Mus. Berlin 29.: 3'7A-5I4. and K. I'uchs. 1978. Bestimmen von Krokoclilen und ibrer Haute. custav Fischer Verl., Stuttgart, New york, IOO pp. and Mextens,, R- 1961. Schildkroten, Krokodi 1e . Bruckene chsen. custav Fischer Verl., Jerla- 422 pp. , 1977._Liste dq! rezenten Amphibien g4q Repti lien . Testuilj.nes , crocodylia, Rhvnchocepha 1i a - oas rieffictr- 1O0: t:31151. 383 BIOCHEMICAL TECHNIQUES: NEW ToOLS FOR THE FORENSIC IDENTIFICATIoN CT CBOCODILIAN I]IDES AND PRODUCTS Peter Brazaitis Department of Herpetology New York zoological Park Bronx, New York 10460 USA The effective conservation of a crocotlilian gpecies is often based upon the ability to ateternine the ialentification of living individuals, as well as those parts of the animal which are utilized co nercially. Tbe comrnercial use of meat, raw skins, hldes at various stages of processing, tanned and finished products, bones, teeth an'I cfaws, all pose special lalentif ication problems for governrents, regulatory agencies and vrifdfife law enforcenent officers- The effective prosecution of violatorsof wildlife protective regulations is contingent upon conclusive proof that the artifact in question is in'Iee'I t;re species which the law seeks to protect. Too often, there is not a sufficient sample upon which a determination can be ma'Ie utilizj.ng morphological characteristics alone, or the sanrple is not fro; the part of the animal's body which displays 'lefinitive characteristics (King and Brazaitis, 1971) - In recent years, new biochemical techniques and technologies have been developed which nay be adapteal to aial in forensic ialentifications. Sor0e of these techniques are being utilized both in the forensic examination of human anCI animal parts,and in general taxonomic work (Avise, 1974t Densdore, 1983; Harrap and wooals, 1966r shi et al-, 1984; wolf 1984). The results of biochemical assays of hunan blood, semen, skin and other tissues, have long ago been established as rleighty reliable evidence in the prosecution of offenders in criminaf cases' Protein electrophoresis is a technique developed nearly 20 years ago, which is currently used in taxononic studies to deternine tie relationship between species. It is based on the principle that proteins in a buffer separate accoraling to their net elect;ical charge anal size in the presence of an electric curreDt- onty a minute sample of protein is required, often as little as five to ten nicrograms is suffj.cient. There are a variety of recentlY developed electrophoretic techniques, each ktith its advantages and disadvantages in specific applications ' In a basic method (FiS. A), a prepareal protein sample is applied to a strach gef or polyacrylamide gel plate' A direct c^uirent is applied aaross the qel plate. The most negatively charged proteins migrate most rapidlY through the plate towards the anod! or negative side- The porositv of the qet mav a-lso separate proteins by the size of molecules. Each piotein has it; own characteristic pattern of migration. The resulting electrophoretogran or rrfingerprint" may be used to identify a particu-1ar speaies- Most of the work using this techinique has ;tilized blood serum as the source of protein (Scopes, 1982) ' The work of Densmore (1983) on crocodilian species relationships is a malor contribution - 384 A simple innuDoaliffusion tecbnique has also proven useful. If lre take a protein cohtaining sample, such as se-rwn fron otle species (e.-9., a caiman), arld inject it into a totally alifferent species, such as rabbit, the second species will produ:e antiboalies to those proteins- The antibodies wilt best ,,recognize" the specific proteins they were proaluced against. and will recoghize to a lesser degree proteins of a sj.milar but Irecognitiontr not exact f6rh. This takes the form of a precipitant between the antibody and the.antigen it recognizes. rf i varlety of antlgens are placed ln a series of weffs in a agar ptate. surroudins a well containinq a specific antiboaly, a tine of precipitatio; wlfl be formed only between the antibody ana the antige-n of tlre species it recognizes. The same technique rnay be applied to the dete;mination of proteins of different species of repliles (Chen et al., 1983) including crocodilians (Densmore. 1983; chen et af., 1983). Conbi.nations of electrophoretic anal ilnlnunoali ffus i on technj-oues nav prove even more useful (Chen et at-, 19e3). Recent advances in the use of DNA probes which have been de\,€lolEd to identify specific genes, infectj.ous agente and human genetic aliseases may possibfy be used for species or poputationai determinations. The strands of DNA from a gene ao be ialentlfieal are separated, cut into fraqments by restrictiorl enzunes, hybridized and tagged with heavy metal, radioi6otopes or enzymes. These tagged DNA fragments wilt reassociate onfy wittr the precrse sequence of nucleotides ib the DNA of the gene from which they were originally hybridized. At present, only living or frozen fresh samples have been used to develop nucleic acid probe techniques, and many problens in probe and sample prelaration remain (Kingsley, 1984) . Wbenever new biochenrical assay techniques have been alevelopecl, the development of corunercial test kits has soon followed in order to make the assay more readily avaifabte, standaralize the technique and simptify its use, ENZOBiochem, Inc., N-y.,recently announced the marketing of a tissue origin identification kit- The kit utilizes monoclonal antibodies (antiboalies of a predetermined speciflcity) to recognize especific protei ns , including some keratins. Theie are considerable advantages in developing iatentificatlon techniques based on biochemical assays. Most significant is tbat the size of the sample need not be 1arge. Often: a sample barely a few milfimeters in diameter or mtcrograms in weight is sufficient. In the case of a costfy product, the sanple requiredl rnay be inconsequential and not result in unnecessary damage and loss of value. A cornprehenslve resource librarv of ltanaaia sampfes ma1r occupl a fer"/ shetves in the storaq; Lrnit of a forensic laboratory, anal may be duplicaled in other la6oratories as neealeal, in a minute fraction of the space required for a comparative nusseum collectlon. Samples for assay stanalarals nay be taken from living as welf as aleail specimens, and need not require the sacrifice of the donor, an inportant consideratio; in the case of endangered species. 385 There are some initial disatlvantages. ?he cost of developing bj.ochemical techniques is considerable, often in the hundreds of thousands or even millions of dollars. on the plus siale, techniques borroweal from human mealical research. which is often elaborately funded, may be noalified at a minimal cost- Laboratories running biochemical assays may require specializeal trained technicians or costly equipment. Howevef, once the stanalards of assay are established, the equipment anal technicians found in most modern comrnerciaf and police crime laboratories may be adequate, wj.th a minimum of upgrading and j.nvested capitaf. There are also advantages for the industrial private sector in developing biochemical techniques for identification purposes. Assay standards coulal be establisbed by 1^'hich crocodilian skins could be pretesteal and certified by the exporter, in accordance rith CTTES accepted protocols, before shipmebt to a buyer in another country. Commercially alevelopeal "test kits" may make such testj.ng econonrically acceptable. It may also make the untletecteal trade in protecteal species a thinq of the past. In the United States in 1980, approximately 32 states reporteal useinqf some form of:rununoassay technique to establish the identity of rneat or blood in wildfife related cases. only 15 reported the use of some method of protein electlophoresis - Most reported some dissatisfaction in the lack of research alata with to support their findings in court proceealings. Tests wele Iargely performed in state crime laboratories, and were directed at enalemic species (oates and Dent, 1980). In 1982, the U.S- Fish and Wildlife service entertained the concept of a national wildlife forensic laboratory. which would specialize in the motlern forensic ialentification of all types of wilalllfe, both native and exotic species. The concept is stlll under c\cnsiileratl canadian wildlife enforcenent agencies also concern themselves largefy with the determination of meat, blood or bair of protected frorn nonprotected or alomestic species. Most of the analysis is referreal to the crime faboratories of the Royal canaalian Mounted Police (Alberta EnergY anal Naturaf Resources, Fish and wildlife Division, 1982) . clearly, the application of nodern biochenical technology in the ideDtification of endangered species and their detection in illegal trade is stilt in its infancy. The potential for biochemical applications iD the conservation and management of crocoalilians is linited onty by our vision anal itrterest. Acknowledoments My thanks to Drs. Dennis curley, Myrna watanabe, anal the u-s- Fish and Wildlife Servlce. for providing information and help in the preparatj.on of this nanuscript. My thanks also goes to the New York Zoological Society for its continued support anal 386 References Alberta Energy and Natural Resources, Fish anil Wildlife Div., Enforcement, Liaison aEd Standarals. 1982. A su;;;v ;f'' forenisic research capabilities, technique; .;J--- requirements of the members of the Westarn Associ.ation of Ftsh and wildtife Asencies. Edmonton, Atberta;a;;:-3t- pp. Avr-se, John C.,19?4. systematic value of electrophoretic alata. syst. 2o11. 23: 465_481. Chen Yuancheng, Wu Xi_angfu and Zhao Ermi. 1984. Classification of Aqkistroaton species in china. Toxicon ,r, ta_;i:--' Densnore, I,lewellyn D- III- 1983. Biocbenical and immunological systematics of the Order Crocoatilia. Irl, Evolutionary Biology, vo. 16, eds. l4ax K. Hecht, Bruce Wallace and chillean T. prance. pp. 392_465. Harrap, B-S. and E.F. Wooats. 1967. Species differences in proteins the of feathers - Colnp. Biochem. pbysiot. 2O: 449_460. King, p. F- Wayne and Brazaltia. 1971. Identification of commercial crocodilian skins- Zoologica 56: 1S70. Kingsbury, David T. 1984. DNA probes-t})eir role in aliagnostics and research. presented at BIOTECH ,84 USA, Ontin; Publications. pinner, UK, pp.629_638. Oates, Davial W. antl Nancy L. Dent. 1980, A survey of technrques usecl by state fish anal game agencies for bllod and tissue identification. ltebraski came anat parks Conm. 19 pp. Scopes, protein purification: Robert- 1982- priI1ciples and Practice. Springerverfag, Ny. 292. pp. chi Y-i-ngxian, Li shlpeng, cao eingsheng, Huanq Zhujian, cao Yuru, Liu Weixin, Ma Lianke, and Cfren r,iJonq._t9gi- comparative stualies on serum proteio, hemogiobin and LDH Eetween Alliqator sinelsis anat A. mississippiensis. Acta Herpetologica sinica 3t 21_24- (ChiG;-;I;h- Dnglish abst). wilson, Michaef, ed. 1978. Bibliography of forensic science ilr wlldlife tar"r enfoi.cement. Suppt. to proc. forensic sciences Symp-, calgary, Alberta, April 13_15, t9??. parks Alberta Recreation, and wifdli{e, Fis; and Wildiife oiv, rzr pp. Wolfe, James R. 1984. Enzyme phenotyping of Alaskan bears for wifdlife law enforcement. J. Forensic Sci- 29: 910-914- o ] : z I l. tl It,t!l ffi "o; a.: rl tl .2i L' ll l. tl *-l llril It rl tl \ ,ltllllt I i'-ii; o ;:T o z tnl\ .r az a : z z o .z 388 I,IANAGEMENT.REPRODUCTION, AND yacareAr rrE NEWyoRPRtSSloSf"o**@*" "o"*@ Peter J. Brazaitis Department of Herpetolooy Eew York zooloqical pari_ Bronx, New york 10460 usA Introductlon ciocggirys 9+-4+ vacare, often-ca-Iled the paraguayaD or yacare carman, is the targest menrberof the sF,ecies gg!4qg crocoditus, and frequently attains lengtns In excess of 2 m. The species is fouhd throushout east.r. g5livia ."d ;;;.;;";, ;";;;";il;;" Brazil borderj.ng Bolivia and-paraguay ana-noiihei"t.i"-arg""t."". Because-of -.".p;";i' its harge size and wiae tiant ."si";" -}ri"torr..fty round. largefy unkeeled scales, the yacare iaima4 f]"i "f been unaler intense conunercial huntina p.u"=lri- iir.""Ji,""i range. It" Trade_in the species is requt;t;d lpp"ndi*-ir-lir.-ir. crTEs, and ""ae. the species is lisreat is endangered s"r . Endangered Species Act,and is prohibited i.". tiia"-i"--ifri"ii.i united states (croombridge, 1942) . some in"".tig"ii"i;-i"--tr,"lira i"ou rr".r, done on the reproductive biology of yacare (craswhaw and Schaller, t9?9). m1ile r"proa,].iio.,""i^i" r,." conditions ar rhe"o." st. 9:.".."d-(Anon., 9199f-:aptive Louis zoo i; the u.s. 1981/82), little is known about the growih, i"p.oa,_r"ti.," biology ahd maflagemenLof the species under 6aptive No -e .o^nOiiion=.-," data are available on the gr;wth or trre speiies iii,li wilal or in captivity. tr," For: many years, the New york Zoologicat Society has i been nterested both in the starus of this species i" if1.-"iia rtraswnaw and Schafler/ 1c?9) and irl its captive propagation as an. endangered species- Although caiman g. l,ica." :" ;;ii other ." calman species have rristoricarty u_eel,,"".-repre.enieJ-ii -N"* tne collectlons of the Department of Herp;tology ylrx park, tf," zoolosicat it w-asnot untir rg:r, wiiir tr,"-.q"i!itiJ""i 10 youns ot indivlduals, rhat a potentiaf lr..Ji"!-siJii-.""ia U" prior artempts ro breeal arriqator .considered- park ;!G!;iq-Ji-the N.y. Zoofogical had been unsuccessfuf. a"a it futile iEJ consialereat to pursue-the breedlng of tropicat ir"""aiii""" iil."." rn a renperate climate. Most temperate cltnate zoolooical institutions _are tindted by tack of space, trre f,iqh-iosi-ot ro provide ::e:9l-i::ded adequare temperatures, aia a qenerat tack ot experaence with t}e territorial and reproductive !,rild-crocodi be;avior of fi ans . The data presenteal herl, reports iire=e-inftiaf ir- the caprive breedins a lnnovative:l!::.:l:.". .r,a ti. techniques employed in -olvins"r ".ocoiitian ail-";;";i..". ""*" "; 389 Manaoenent and Reprocluctlon Six male anal four femal-e Il4!!gg crocodilus yacare were acquireCl in september, 19?1, via the U.s- Fish and wiLtllife service. Their country of origj.n is unknoLm. on arrival, animals ranged in size from 5o'2 cm to 97'2 cn in total length' an'l were estimatecl to be between two anal three years of age. These animafs were irlitially houseal in large galvanizetl cattle tanks approximately 2 m 1ong, ?5 cnl wide and high, containing approxinately 20 cm of standing water contj.nually heateal to 27o to 30"c.1. No natural sunllght was available (A11 crocodilians at the New York zoological Park are naintaineal at all tines in inaloor facifities). Three to four tiines per week the animals were fed a readily available diet consisting larqely of frozen salt water fish, frozen rats and nice, anal on occasion, some fresh mice anCI chicks. The aliet was supplenented vith varying anounts of vitamin E and pealiatric multivitamins. Aninals were fed to satiation at regular feealings - As the anj.mals grew in size. and competitive interactions became apparent, they ere noved to larger quarters, and associated wittr animals of comparable size anal simifar feeding habits. In 19??, one of the females acquireal in 19?1 (NYzP#t14831). 145 cn long, and estimateal to be approximately 10 years of age was transferred to an exhibit pool measuring 3 m 1ong, by 1.5 m wide and o.?5 m deep- The exhibj.t contained only a shall basking area- Although other environnental conditions remaineal the same, lighting in this exhibit consisted entirelY of artifical fl,Iorescent light on a 12 hour photoperioal- The female laid a first clutch of 18 infertile eggs in May of the same year. Ten infertile eggs were tald in !4ay, 1979, foflowed by an unknown nunber of eggs which were laj.d in the pool water in April 1980- Diets were modified in late 19?9. Frozen salt ater fish were eliminated and replaced with fresh chicken parts. The renaj nder of the diet stayed the same. In 19?9, female NYZP H?1482 was transferred to the sane exhibit _grouppool containing female H?1483, with two males fron the 19?1 of about the same age and size, antl a large male approdfiately ta years ot age and measuring approxj.mately 1.6,m. Although water temleratures ;ere normally maintained at 27oto 30oc, the inslaflatlon suffered from occasional tehperatures as IoL as 25'C' oh 10 April, 1980. at 11 years of age anal a lenqth of 13? cm, fenale *?1482 laid four apparently fertile banded eggs (Fergusolr, 1979) in the poof $tater. This was the first crocodilian to successfully mate and produce fertile eqgs at the New York zoological Park. 390 Because of the low environmental temperatures which prevaileal tlre exhibit in at the time the eggs were laid, tfre femaie wa" removed from the exhibit oool ind was placeat i" tank containing a sofr sulsrrate or aai,peneJ ;;; "-iiiJ""fr-"rai"q;;i#-ier-uoay ;" breaking of-any esss durins- oviposirion. l::::i-t-:l:Eemperarure was gradualty increased to 30.under warning Iighls- One hundred-and fifty IU of oxytocin (Schein Inc-, port Washington, New york 11050) (Huff, 19?6), ;dminj.stered at i a"..i!-"r'""" ru per 100 q .ivas 9f lody neiqht, injected t"tra*".cuiaiiv -ir,J-r"","r.at tn" base of a hind 1imb. Approximately 30 mihutes t"f.., began lateral pelvic movements. anal elevated tf,e cioaca-oif the. ot substrate. The frrst eqg was laial one hour u"a jo-^ii".". post rnjectron; two additionaf eggs were laid at 3 hours and 15 injection ana ano r6i two minures iri.i-ti,It. egq Trl*::t r was ?:::fatd lour hours Dosr injection, followed by # 5 hours and 25 rninutes post inje;tion. The. female assurned a specific stance during egg aleposition: a posirion "tripod" with rhe front tegs Urac5a ii it."ai"S-t"Ju",jtt position, forhing two support point; to elevaie it." tl," suostrare. Ihe taif was exCended back and stiffened aqalns! the ground, providing a third support polnt, wt i"ir t.ee movement of the hind legs. The palms of the hind"iiowei-ior feet weie tnen [urneo rnward, pa-tm upwards towarals the clocaca. and cuppeat. Egg 6-was # latd wrthin the cuppeat palms. anal then ar"pp"a-"ii" tn" s,awdust suostrate, Laying was folloved by atternate scraping of the substrate tov/ards and under the body with Lhe hind limbs,in a mounding notion. The female did not appear to show concern for her surrounali.d< during ovipositioh- Egg d ? was laid ih the alrthor ,s ;;;;;;:; placeo ne hrs hand, patm up, in the cupped palms of the female. mounorng and scraping motions \"rere repeated between each layang. Eggs 8, 9 and 10 were sinilary laid i; the aurhor,s h;;;. Body arching anal laying coutd be induceat by lightly toucrrtnj irre cloaca. Oviposition enaled I hours post injection. Figure 1is-a radiograph taken at 10 M.A.S. 67 KV, showinq the female still retaining 15 eggs on the following aay. an aaOrticrnf -rcu ,LU or oxytocln was administered, and Eesutled in the laying of-6 additional eggs within three hours after in.1e"tion. rire tr'oflowing alay the female was again radioqrapbed, reveafinq 8 whofe and one broken egg. lro additional oxyiocin .ani"i-.t"."a wnl.te.the anrma-t was hydrated. An additional I5O "u.TU of oxytocin were injected on the fourth day, resulting j.n the layinq ;f two eggs one bour anal 45 minutes 1ater. No additionat .g!" i.." forthcoming._oxytocin injecrions of 150 and :OO ru i;ie gi.,"., o., lott days :,f9 Yth :ld respectivety/ without resulr. Atth;uqh a chlrd ractiograph sho ed the female stiIl retained five eqgi. she was returned to a warnr water pool. These eggs were never-6xpeIted and it is assumed that they were reabsorbed. 391 In totaf. 20 eggs were faid, of r'thich 17 were incubate'I' The i"^ii"a"i eithJi were crusheal or badly alamage'I 'Iuring- laying' with ;;;;i;g;u" not noted on all egss, but-a]l esgs were.Iaid a mucui llke clear covering. Thirteen days after laylng' eggs *"it"i"a 61 llun to ?4 mnr in tength by 39 fttr to 42 rffn in-width' g' eggs ana welghea 52.5 Lo 70.4 g. Average weight was 6I'9 AII i"iti.frv incubateat in a covered pan containing moistene'I 3ooto 31'C' and a humi'lity of ".r"^go't"baDer toltels, at a temperature of go percent. Tvenly four days after laying, all eggs vrere transferred Lo dampened moss at the same temperature ano hunddity. Eggs were sprayett Periotlically with arm water' on day 44 of incubation, several eggs were selected' ul9 y:t" experimentally exanined using computerized axiaf tomograpn)' (ci scan) to determine if this technique cou_Ld be . ":to-:" 13 and i""r".i"'tir" viability of aleveroping ess: 4' 5'. 10' "ss!' emDryos 15 contained w}|at appeard to be develope'l but dead iir".'zi. Fiqure 3.-;hows the undeveloped yolk containecl in ii;;; ;;;.;a;i;; parustris esss or approxinatelv the sameaee for compals 1on. days Flakinq of the outer calcareous sbell was noted in the 8 July' 1984' it*"aiit"fy preceding emergence of the enbryo' on afte; 82 davs of incubation' Esss 4' 6' 10' -pt""ioustvtratcne6 fu1l- l5l-.ta'ii,";;-3-;;;'t'z exami-nedbt cr scan' contai ned-nearlv dead emlryos. seven eggs app-ard to have been infertife' or iernr tnree not develop beyonat the initial stages' The renarnrng did of .pp..tb to have perisbeat within the first 30 days the embryos "rnbruo"t""ri.tr"-"] fisea the minimal development of (Ferguson, 1981). "" a nale' Hatchling (egg 3: 70 nfil x 39 run. 61'3 g) NYZP #800199' "ti* an'l weighed 42 g' ri"."."6-zjo total length, 113 nun snout vent' ii""-ii-ioa nunx 4r nwr.62:2 q) also a male' NYZPH80o198'. iEl""."i-j:i t totat tengtlt, 120 rrunsnout vent' an'l weighed 44 s' on hatching. con'litions Beolnninq in 1981, the dtiets and some environmental ri were nrodlfied. lrom that time onwar'l' voung i"i- (c?rassius.asratus) ;;;.;iii;;;"i".6ai have"". been fed livins sordfish ano.aour! anll smalI or neonate mice (Mus)' Larger aDrma-Ls domestic chiaks :;;";aiiiJ; trave been real fres)lv *itrea piseons' vltamrn anil smalf marunals. All frozeh foods and fish' anct were eliminated from the diets' The effect was a dramatic""ppf...tt., increase rn reproouction in the crocodilian collection' siamensis' q' i;;i;i"s the successfu-l breeding of er9.gqdrllE rhornbi fer and AlUgSlg! sinensts. protocol for rearing Young fast grol,.,ing. cro'odi I lans The managenenl the ^"diiila in 1980 to inc)ude expoiure to black lishr-in at least 12 "".i!-u--"ili."i range of 310 to 400 nanoneters for per alay,"r.t on an experimental basis (Jay cole' personal hours 1982) ' communication, 197E: Townsend, 19?9; Mccrystaf and Behler' 392 Changes in aiet and exposure to black light have appearal to be beneficial_ in the rearing hanagement of toung ana has had a beneficial effect on thei. gro th, inclualing"roc_ohiiians, the gro\^rtb of cainan crocodilus vacare NyZp *,s eOO19e a"6 gOOtgg. Flgure 4- indicates the weiq:ht to totat length relationship of gajinen c- vacare # 800198 anC * BOO199 rais;d under exDosure to bfack light anal fed a fresh food diet froh hatching. Fiqure 5 shows the age,/grov?Lh rate relationship of both animafs ]inaicattng and average rate of growth of 3.33 ch per nonth for the iirst tour years. Acknowfedoments I would like to take this opportunity to thank the staff of the New York Zoologicaf Fark, anal the New york Zoological Society for support anil assistance. Thanks particularly to B;uce Foster anat Bob BraDalner who handleal the animals for t;e collection oi a.t.. Special recognition goes to Dr. Hefen Morehouse of the staff of A1bert Einstein Coflege of Mealicine for enabling the cy scan ro be done, anal for her expertise anal many lnnovative ialeas, anal to my wife Myrha Watanabe: without her help, nothing woulal get ttone. Photos of yacare cairnan hatchihg were tiken Uy ailf Aofmierom, and I thank him for thelt use. !ootnotes 1.. Water frorn the municipal water suppy is used for changing ano cieanlng, and was introduced at comparable temperature. Municipal waterqis treated with chlorine and fluolicle for human consurnption. 'I'he po rarefy deviates more than one or two tenths of a point frorr ?-0, and tbe water usually contains fess than 50 ppm dis'solved nineral. solids and less tlraD 10 ppm suspended solihs. References Anon. 1981:82. Reptil€' reproduction report. zudus (St.Louis Zoo) Dec.8l/Jan 82: S6. Crawshaw, Peter cransden, ,rr.. and George B. Schaller, 1979, Nestlng of Paraguayan ciaman (gEE@ yegglC) in Brazil. Repor to IBDF 11: 1-1?. Ferguso!, M.W-J. 1979. A macroscopic, SEM and EDAX stualy of the eggebell and er,bryonic meribranes of Affiqator F.issiasj.xpiensis Ploc. Anat. soc. 6r. Britaln anat Ireland Oec. tgZg: ZS (atst). Groombridge, Brian, ed. 1982- Tte IUCN Anphibla_Reptilia Reat Data Book. Part l: ?estudines, crocodylia, Rhylrchocephalia. Species account, yacare Caiman. pp. 301_304. Huff, Thomas A. 1976- T}le use of oxytocin to induce tabour in a .Tamaicanboa. fnt. Zoo yb. 15: 82. Mccrystal, Hugh K- and John L, Behter. 1982- Husbanctry anal reproduction of captive gaint ameiva lizarals Aneiva amer-va the New York Zoological park. Int, Zoo ytt. ZZ.. tSg_tSZ. Townsend, C.R. 1979. Estabtishner]t and naintenance of cofonres of parthenogenetic whiprail lizards.Int-Zoo Yb. f9: g0_46. 393 A antellor Fig.1 Radroeraph of Tena-e carndn c. ydcdre rllrr"rinJ ege.. ; Ar:ows indicate devsloped e,r'trFyo (C'r scan) within an egg of Fig. z Carnan c. Yacare. Arrolrs indica!e unCeveloped yol'( (cT Scan) wir-hin an egg Fi9,3 of crocodyflrs palustlis. 395 1.t q{ q rl !;; t3s 9;; dF F l-.0 I TEE I ar- E r! I q{ T n| o q{ o Pc :o -J9 e 4l al q a) qr (4 0\ do lo oa dt= q Sr I lo - qo ar al at .I a J t t a I o: o l! Fo!o'.r .ro€oo!€ (,.,r) THE CROCODILE SKIN TRADE SINCE 1979 by Ginette HemIeY TRAFPIC(U.S.A) 1601 Connecticut Ave, N-w. washington, D.c.20009 and John cafdvell wildlife Trade Monitoring unit 2L9c Huntingdon Road ca.rnbridge cB3 oDL united Kingdom fntrotluction Tbe international crocodile skin trade has clanged dramatically over the last three alecades. Peaking in the late 1950s and earlY 1960 r,rhen aD estimated 5 to 10 fiLillion skins a year rdere involve'l (rnskipp and wefls, 1979). world trade todav probablv amounts to ,'ro ro.i_ th.., 1.5 million skins annualty- The focus has generally .frift"a from the fargel and more valuabte species, nany of which are",t"y n_ow endangered. to smaller species -- particularly the spectacleai cainan lghgq crocodilus- Tn recent years national i'aws protecting crEEEEf f ian-ns have been impfemented around the worldl and all 21 species in the oraler crocodylia are affo)'ded il"g... of prot;ction by the convention on International rrade"o." ii Endanq;red specles of Wilai Eauna and r'lora (CITES) ' Iifteen crocodilian species and two subspecies are fiste'l on all iiTls appenaix r, whi;h generallv forbids convnercial trade*' i.."i"ii,'q species are incluaea on Appendix If and can be tratle'l comnerciallY through a pernit sYstem. To date 87 countries have become party to CITES, including most .i:ot and consuminq nations' Trade controls iii i*p.o.ri"q,"t"coair"-producins y3t over.tl enforcement anal implementation of the conveniion iJ eiratic- In central south American, for example' ' illegal caiman hunting and trade abound (Menqhi, pers' conun') producing countries., however' rhe iroblems are not iimited to the ii"qlp"r", a !f,ajor trade center for wildlife pro'lucts ' has Yet to iign the con;ention. France, one of tbe world's leading skin inporters, has not entirely fulfil1ed its crTES iepo.ting".o.oii1" obligat_ions. naking it difficult to ascertain the full promi nent sc'ope of-tfrat io,ltttry'. trade. Japan, an i ncreas ingly - couirtry in the crocoaile trade, shows siqns of not fullv inplementing the convention. CITES has become a prevalent force over its decade of existence' provides ."a a."pit" certaio compliance problems, it currently ;;; ;.ti available mechanism for tracking the overall croco'Ii1e 398 skin-trade. This report presents an analysjs of CITES_reported world trade in crocodilian skins from tgig t" ige2,-i";;5;ng what on appear to be the host important t."a. ;iii;".". caiman crocedi tus. crocodyius"f."i.!, *-:++?++€+++,urococrytus cata;EFct..,s, -nirotlcus, crocodyf us a;a@ porosus. Additional ryV3egUjlc3e, Lrade infonnation from sources 6i-h.r tnan CITES 1s also inctuded. Methods Most of the data inclualed in this report come from annual reports supplied by crrEs parties. Tire inrormation h;;-;;."... lnnerenr,Lthrtations : f or example, many crocoalile_ptoalucing countries have never issueat an annual ieport, whil; ;a;;;- h_ave.onfy recently become party to the c;nvention.-""ppiiJa-uy as a-iesurt.""""".r"s the trade data are based lirgely tr,. ,"p"ii. importtns nations. rn additi;n, uniLs"n #;;;;";;;i-;;; afways ;"r consistent in CITES reports. Unless"f otherwise-ana-.";i;;." noteai, this analysis covers trade in lrhole sr.r". transactions tlar were reported in unirs of""fi, - "r;ig;i;;--;;;; CITES reports are entered into a Wang VS computer by theWildlife ?rade Montoring unit at rucN's conse;varion it""ii"iinq--c.n.." ,n Cambridge. United Kingdom, under a consultancy contra;t with the CfTEs Secretari _ at. The data are analyzed i" t"" i) io calculate both gross anal net imports anat expor;s ".V", reported in trade. and 2) to compare importi of one"i-.fi'"""""rr". country with exports/re-exports of another couniry. ri,t, iir"}r.''irr" mrnimurn nuriber of s}(ins of each species eiter;nq traae eicir year to be estimated. The sources ot s: The trade data presented here should be iDtelpreteal with caution. not th"V T.y accuratety reffect originaf expo-rt patterns irom year to year and they do not distinguirl., 1.i.,."n' lo"i"i f.a skjns and recen r ly-h arves ted skins. Tr sbould b; ;;a;;-;;;l" tbe worldwide trade patterns for crocoditia; .*ir.."rv compfex, as skins nay move among severat intermeatiate"ii""-;;; countrres over a perlod of years before they are used for nranufacture. Results and Discussion IMPORTING COUNTRIES: We1l-aleve lopeat leather inalustries have made France and Italy the ]eading impo;ters of crocodifian st 399 EEc Regutatlon 3626,/82 becane effective 1 January 1984, and requires Italy and France (iDcluding overseas departnents) to cease importing Appendix I species on which they haalpreviously hefal reservations. According to the CITES Secretariat, only Italy has officiafly withdrawn its reservationst however, the Regulation aloes not require withdrawl antl contains no basls for naintai"ning reservations - For most of the period convered by tbis report, reservalions on Appendix T crocodilian species had entereal by the following cITEs Parties: Caiman latirostris: ItaIy Mefanosuchus 4!ggI: France crocoalvlus acutus : Switzerland (withdlawn 6/6,/81) (U.s. Population) crocoalvlus cataphractus: Austria.t'rance,rtaly,zaftbia Crococlvlus niloticus: Botswana,France,Italy.Sudan, zambia, zimbabwe crocodvlus porosus: austria,France,Italy,Japan, (exef.pwepopulation) swltzerland (withdrawDl/1/83) Osteolaemustetraspis: France Although all major crocoali I i an-importi ng countries except slngap6re are pirty to crTEs, calculating the precise nunber 6f ski;s in trade remains problematric. This is partly because I'rance, a major traaler, includes few imports in its annuaf reports, so analysis of its consumptlon is based largely on reporteal re- exports. cLearly, no refiabfe estinate can be made for consumption of skins within France. In addition, ;rapan lists most trade in Appendix II crocodilians simply as "crocodylidae spp. "or ,,Afliqatoridae spp-", therefore the only clue of species involveal is the reported country of origin. The total aleclarea value of u.S. crocoalilian skin itnports in 1982 was Just over $2 million. rn Japan, the totaL declareal val'ue of imported crocoalile anal alligator skins anal leather amounteal to th; equivalent of $?.1 million in 1982, and $6.2 nillj.on in 1983- MAJOR SPECIES IN TRADE: Allidator miss issiDpiens is (American AIIigator) The range of A-LLLS.e!-S!mississippiensis exlends across the southea;tern unitea stat"" fxom Nolth carolua to Florida an'l Texas. 'fhe largest Dunibers occur in Louisiana, while populations continue to recover from previously reduced nuabers in other areas, notably lforida and Texas. The species was transferred from CITES Appendii I to Appendix II in 19?9 and revisions of U.s_ Enclangered Species Act protections alfow a state-managed harvest in roiisiaDa. Linited hunting of "nuisance" afligators is allowe'l in Florida anat the status of the Texas population was recently changecl, allowing for sorne controlled hunting. The same status change may be applied to Florida alfigators in the near future' 400 fn 1979, after A. mi ss iss ippi.ens is was transferreal to Appenalix TI, a total of 5.404 skins were exported from the Uniteal States. During the following three years the net nunber of skins enterinq trade from the U.S. increased to 28,400 in 1981, decreasino sliqhtly to less than 26,OOOskins in 1982 (Tabfe t) - Table 1: U. S. Exports of Allisator mississipoiensis Skins 1979 1980 1981 1982 Total 5 ,404 13,0 87 2a , 400 25,835 72,726 Source: Annual reports by CITES Parties The avelage nuniber of alligator skins exported annually fron 1979 to 1982 (18,182 skins per year) is slightty more than the average duniber of alligators taken annually under lJouisiana,s harvest program (16,501 alligators per year, Table 2)- Total U.S. exports incluale sone stockpiled skins as well as afllgator skins fron Florlala, where 1,500 to 2000 alligators were taken anmElly fror 1979 to 1982 as "nlrsance" animals. A snBll nlmt)er of skins frcm atliqators raised on farnB are also e)eorted. Table 2: Results of the Alliqator rian€st lbcgrdr in Lcoisiana, 19'79 to 19a2 Ne lbSs Price Paid Year Issr€d N! Sold for Skins (o.3 n') 1919 17,516 16,300 L4,955 91,711,s00 915.00 1980 19,134 11 L7,592 13,00 ,692 't-4,442 11,609,972 s 1981 15,s34 14,8?0 ir ,'7'74,045 $17.50 BA2 18,188 11,142 16,000* s1,512,000* $13-s0 Source: Office of tlle scierti-fic Authority, u.s. Fish and wildlife Ser\dce. Tbe major importer of these skins was I'rance, followed by lta1y antl Japan. Japanese bul'ers are apparently beconing increasingly competitive in the alligator skin market (Brazaitis, 1984). The U.S. re-inported approximately 30,000 tanned alligator hides during the four years. caiman crocodilus (Spectacleal Caiman) over the fast decade caiman crocoalilus has ernerged as the dominant crocodilian in the skin trade. The specles is extant throughout much of South and central American to Mexico and in Trinialad and Tobago (Groombrj.dge, 1983). The subspecies g. g. apaporiensis from southeastern Colombia is listed on CITES Appendix Ir all other subspecies are on Appendix II. _g-.q- Iqq3lg is listed as "endangeredi' by the U.s- Endangered Species Act. In addition, C. crocodilus is afforded some alegree of protection in most ot the countries .in which it occurs. 401 some alisagreement ana confusion exi,st over the taxonomy of the g. crocotlilus complex, adding to a variety of reporting discrepancies at the subspecies level- }'or example, in 1981 more than 65,000 skihs of g. g.crocodilus were imported into the U-S- listeal as orlginating in Bolivia or Paraguay (Roeper & Helllley. 1982). This subspecies reportedfy does not occur in conunerciafly-exploitable quantities in Bofivia. and theae lmports were most probably 9- g. vacare (Brazaitis. pers. comm) Investigation into the range and status of the various q- crocodilus subspecies is seriously needed. t'or simplicity, this analysis atldresses trade only as g. crocodilus (Table 3). Table 3: Minimum world Trade in Caiman crocodilus Sklns' lg3! Gloss N.eg 423,766 t9't9 528, 986 '745 1980 1,264 ,'750 ,61'7 1981 1,2rt,'109 6'77,329 t982 a92,158 537,400 * Incluttes imports into Japad of "Alligatoridae 6pp.'! fron South American countries. Source: Annuaf reports of CITES Parties Over the foul years L9'79 1.o I9a2 a minimum of 2-4 million g. crocoalilus skins entered internationaf trade, according to cITEs reports, It appears tbat worfd trade peaked in 1980 when at least 785,000 skins were traaled, dropping to a ninimum of 53?,000 skins in 1982. ln addition, 3,595 sides or flanks, 38,145 kq of skins, and 139,177 sq ft of skins were reported in trade. some of the trade reported in units of weight or area probably overlaps with the trade reported as skins or sides, as an importer anal exporter may report the same shipment alifferently- The primary countries of orlgin of g. 9-f.9.9-9.di-ICgskins reported in trade from 1979 to 1982 are, in order of importance; Paraguay, colombia, Panama, and Bolivia (Table 4). of these, ParaguaY is the reported source of about one-third of all skins enteting trade. in spite of national legislation (Decreto Nc 18.?96 of 19?5) prohibiting tbe cofiunercial hunting and export of g.crocodilus. Tbe ban on commercial trade was officiafly reaffirmed in 1981 and the Paraguayan CITES Management Authority has stated that the law aloes not alloar import or re-export oflrildlife (Fuller & swift, 1984) - However, siqnificant trade apDarentlv continues today and much of what is leavinq Paraquav probablY oriqinates in BraziI (Menqhi, pers- corur.; Finq, Ders. cornm-). 402 fable 4: Origin of e.ql!!ar! clec_gdllus Skins* 19?9 1980 1981 L9A2 "otal Argentina 140 L5,944 632 547 L'7,263 Bolivia 36,509 160,183 1'77,179 72,A36 446,64'7 Brasif 4 Cdj|nED Is. 2,UO 2,800 Oolarbia a,2t1 t'tt,766 ros,ssi ze,rel 512,n6 trY. Guiana 4,079 ?,810 37,266 Gqtana "":* 2,\36 Hcrduras 2,62, 2,93r Nicaragua 224 I a.ooo. 4,22a* PanaIIE ztn,i, 124,400 t27,954 510,816 Paraquay 19,752 224.919 a3,a'70 266,931 809,538 Feru 3,000 6,351 Ver,eaEla 30, 155 44,322 74,41'7 Total 40t,204 es6,55r ?16.658 513,336,, 2,389,753* * Includes illl)orts into Jap€n of ,'Alligatorida spp. ,'frxn t€tin A€rican cqirrtries. Source: An El. reports of CnES Pafties Colombi.a was the reported origin of 26a,2IL g. lrggglllgg skins in 1979, but the nuniber decreased steadity to 26,'765 by 1982- During 1980 and 1981 over 110.000 additional caiman skins iiere imported into Colombia from panarna and subsequently re-exportea, presumably under the so-called ,'plaD Vaftejo', which was established to stirnulate foreign traale and exchange. Atthough a general commef_cial lrild1ife trade ban has been enacteal (Decreto Ley Ne 2811 (1974, /Decreto N.r 1608 (1978) , export of inventoried stocks of cai,nan skins has been a.I-lo\.fealto continue. Stilf, controls have been weak: CITES reports show that over 105,000 q. crocodilus skins entered tratle fron Colombia in 1981, although INDERENA (lnstituto de Recursos Naturales y del Arbiente) and INCOMEX (Colombian Institute for Foreign Trade) report no exports of g. clocodilus during that year (Meden. 1982). In addition, Pfan vatlelo has apparently been nuch abused. anal in the past caiman skins originally frorn Colonbia were re-importeat into Colombia from Panama with Panamanian certifi.cates of origin (Donadio, 1982). At this point Colonbia reports to have depleted nearll af1 the stocks of C- crocodilus skins inventoried when the general trade ban came into effect, anal authorities there say that only two firms, Mendal_ llermanos and prodeltir Limitada, are authorized to export the remaining hiates (puller & Swift. 1984). Panama is reported as the source of at least 510,000 g, crocodifus skins traaled between 1979 and 1982. In spite of Resolucion NoO02 of 1980 prohibiting the corunercial hunting of g. S. lfuESUEr the only subspecies reporteal to occur in the country, an annual average of 160,220 9. crocoalilus skins left panama in the three years since the law canre into force. 403 trtore than 446,00O g- crocodifus skirls were reportedly exporteal from Bolivia bet\,.een 1979 and 1982, with trade apparently reaching its highest level in 1981. Bolivian laws (Decreto Supreno 16605 (1979),/Resolucion Ministeriaf 14316-'14 ll974i apparently prohibit the export of skins of wild-caught caimans and untanneal hides (Fuller 6 Swjft, 1984) - As with Paraguay, many of the caiman skins exporteCl fron Bofivia probably originated in Brazil {Menghi. pers. conln. r King, pers. comm.). ft should be noted that ClTEs-reported figures Clo not give a complete picture of the trade in.q. q9-S.9dj-!.!.q. Accoraling to recent leports, large-scale caimah hunting continues in parts of South Anerica, primarily in Paraguay, southwestern Brazil., and eastern Bo1ivia, despite protective legislation. Most hides leaving the region are appaxently exported via Paraguay and Bolivj-a (Menghi. pers. comn.). It has been estimateal that this region supplies the world narket with at least 1.000.000 skins a year (Klng, pers. conm.). Most of this commerce is apparently i1legal. (See also irapanese Customs information below). crocoalvlus cataphlactus (Af rlcan slenaler-snouted erocodife) crocoalylus cataphractus is widespread thoughout west and central Africa fron senegal to Tanzania (Grooribridge, 1983). Distribution aDaI status of populations are in general poorfy known, but tle species has aleclined overall as a result of hide-hunting, habitat loss and local utifization for food. Although the hides of g. cataphractus are generally regaraled as cornmerciafly inferior, the species may be unaler increasing pressule as a result of the severe decline of many q- niloticus populations (eoc(tbridqe, 1982) . cITEs Parties holding a reservation on this Appendix r species are Austria and Zambia, and until l January 1984, France and lta1y. CITES alata show that a net minimun of 32,151 g- cataphractus skins entereil trade from 1979 to 1982, or an averacre of about 8.038 skins per yerar. The net mininlum trade apparently increasecl from about 3,700 skins in 1979 to over 9,000 skins in 1982 (Tbb]e 2) Table 5: Minimum worlal Trade of crocodylus gqlBpbIegllg Skins f€! Gross Nc! 19'79 3, 735 l9 80 tl,246 11,196 1981 4,420 4.192 1982 9. 105 9,021 Soulce: Annual reports of CITES Parties congo, the major source of g. cataphractus skins traded between 1979 and 1982 (Table 6), joined CITES in May 1983 and alid not enter a reservation for the species. The country reports exporting 4,870 skins to France during 1983, butftese exports may have occurred before congo accedetl to crTES or may have been regarded as pre- Convention stocks. 404 Table 6: Origin of Crocoalvf us cataphractus Skins 1979 1980 198r r9B2 lalsl Congo 9 ,209 6,509 6,663 25,546 cabon 811 r,612 585 3,008 l4al i : '7 980 980 Togo 571 79 4 _ 1, 354 zaire 249 616 905 Total, 3,'736 to,'799 4, 414 8,8 41 31, ?93 source: Annual ,eports of cITEs parties It shoulal be noted that both Togo and zaire have been Parties CITES since 1929 and since nei.ther enteredl a ,...i""ii!i sboutd tf,.y not be tradins g. cataphractus ."rr;;" i. i i;:' i;;i;;. cabon nor Mali are pi.TV t" .r" convention- Crocodvlus niloticus (Ni1e Crocodife) Croggalylus niloticus is widefy alistributed thr.oughout-"ii:liiiti, Africa south of the sahara, wirh rhe posstbte ."."pti"" cuinea, cuinea-Bissay, and Equ;toriat cr:inei. !. air"iiliJ i" or the most valuabfe crocodile skins in trade and-?6iF-producing"n. countries, Botswana, sudan, zanbia, and ztmtabwe, fli". i.J".".tron" on its cITEs Appendix r ltsting- France and Ital;, importing th; ;;;;. countries, borh had reservations -;;;" -iiio.."" rahuary 1e84, and it is Dossibel_that F."""; "rr".ii".;;; "nlii-r up to 100,000 skins in 1983 atone. .rne mrnrmLrmnunber trade of skins rn estimated from crrEs arara is wett below this i;";i-;;"""r" oJ the severe lirnitattons mentioned the above, particul;.fy-r"g.rafnq-i;;; fack of import data from rr"".. icira""i i; i' ii.;;: ,). Tab1e ?: Minimun Wortat Trade of CrocEdytus niloticus Skbs Gross NqL t9 79 3,706 1980 24,OA2 22,094 1981 30,003 22,253 7982 27,108 20,099 Source: Annuaf Reports of CITES parties 1:^1.":!.64,446 skins reportealfy entered traale between 1980 and rydz-wItn a country of orjgin listed for over 90 percent 'Ine rrgures of them. in Tab]e 8 sugqest that over 58 perce_nt or ine sxtns came from-lust two countr;es, Njgeria anat s"i"n, o-ut srgnrtlcant nunbers reported-export froh Mali. Togo,"itr,-".iif.. and Cameroon. T}tey further suggest rbat frorn Bots;ana; irt.it","c."g", cabon, -;;;"i; and somalia have declined in recent t;;;":-;t b" noteal_that Nigeria, Toso, anal zaire do g. not iave ,.""r""iiii" ro. 4iloticus, although they apparently exporteal nur,bers of skins from 1979 to 1982- "iq"ifi"i"i 405 Table 8: origin of glgqSdl|$. 4llqL&.ug Skins -19_qL 19.92 Total 6 3 2 11 cameroon r'74 1, ?81 1, ?18 3 ,6'73 834 442 65 1,341 Egypt 2 2 cabon 4'76 1,096 Liberia 230 143 3?3 tlaclagascar - 4 20 24 Mali t,745 2,'l8r 3, r3'7 7,703 Nigeria 5, 868 10, 304 3,541 t9 ,1t9 Somalia e4'7 2,lL3 sudan 1 ,520 2 ,784 15,323 Togo 1.806 818 2,417 zai.re 603 503 zinbabwe 689 2,3'71 t9 ,'750 23,4'77 16, 509 source: Annual Reports of cI?Es Parties cITEs The g. !ifq!!q!rs population of Zimbabwe waE transferred to Appe;dix II on 29 July 1983 in recogrlition of that countryi s ci:_ocodile conservation program and ranching operations' Data i;on cTTEs annuaL reporls indicate that lmports from zinibawe have lncrea"ed stead-ily to over 1,500 skins in 1982; this tt:en'l will no doubt continue ' crocodvlus novaeouineae (New Guinea crocodile) crococylus noYaequi[eae o-ccurs on the islan'l of New Guinea in tle Arv tsrancrs, ano 1n lne vhilippines (Groonibridge, 1983) _l'lhite g'mindorensis' ilq.ta Lhe Phitipptne from as a separate species liiis"l*. .J."gt ire. the L;o subspecies: g.novaeouineae novaequineae iiorn eapua-uell Guinea, Iisted on Appendix IL an'l q-lov-aequineae mindore-nsis from the PhilippiDes, included on Appendix I' Fron 19?9 to 1982 at least 114.OOO g. novaeouineae skins eDtered traale. Although the net number of skins trade'l averaged almost considerably Zg,eOO i.t y".t, exports appear to have decreased aluring tbe"f.i"t same Period (Table 9). T'eble 9: Mirfnnln World Trade of Gocodalus novaeqrineae Skins Ieg! cross N9! 1919 42,046 1980 21,6tO 1981 31,941 3t,286 19a2 13,463 t3,41',7 Source: Annual reports of CITES Partles 406 About three-quarters of a1f skins reported in traale had country of.origin fistedj of these, about 90 percent iro*-piiu. Guinea (Table t.* l0). Indonesia reportediy ."ppriJ-.1""'i"".. Si56o the :frl:: 9f remainins 29,ooo+ skihs, s"IIli'zi,ooo-*...-6iir"."a as orlginating in Singapore. Table 10: Origin of crocoalvlus novaequtneae Skins J3-L9 1e80 1s81 19_82 re!3l Intlonesia 1, 154 3,851 1,455 2,5A1 9,041 PNG 41,160 13,989 15,023 5,79I 75,963 Philippines 60 -60 Totals 42,3t4 I7 ,A40 16,538 8,312 A5,O64 * May include some skj-ns exporteal in l98O as pNG,s annual teport covered ilune 19?9_1990. Source: Ahnual reports of CfTES parties Papua New cuinea has not submitted a CITES annual report since mid-1980, thus the CITES data are incornplete- Tnform-ation recentfy received from the Departnent oi erlmary Inatustry in papua New cuinea, however, gives a 6ett"r iatea of papua New g..novqeouineae cuinea,s ?9!9.1 exports (TabIe 1t). Thi; i"r"r*-ii"" orrrers- srgnafrcantly from the cITEs data for both 198O and 1982, although the difference for 1981 is onry 2 skini. Tabfe 11: Declared Exports of Crocodvfus novaeoulneae- Skins from papua New cuinea* Source 1979 - 1980 1981 ]9A2 1983 wild 34.A36 27,249 14,29O 23.259 n,eo7 Ranched 646 460 131 L,474 1.304 35,4A2 2'7,709 15,O2I 24,',733 15,l1I * A snall humber of additional skins ( lX of total) may have been exported itlegatly. source: Hotfands, Lq l!E., 1984 Crocodvlus porosus (saltwater Crocoatile) pgf9ry has an extensive distribution, ranging from Sri Lanka and the East Inatian coast across Southeast .isi; to Papua New cuibea, Indonesia, northern Australia and the Solomon Islands. (Groonibridge. ri"i.a-."-di'iai-;;;;,;i;1983). A11 i:":i:':::'.:i:i!:,::"i:DoDul be vel']' seriously XX"":i::3i:' depleted. crTEs parties holdihq ;;s:!;;;;ons 447 on thj.s species were France anal Ttaly {until January 1, 1984), and Austria, tapan, and Thailand. g. Dorosus is the only crocodilian species for which ;rapan has a reservatlon. Table 12: Minimum Worlcl Trade in Crocodvlus Dorosus Skins Ie.3! GreCg NE! 1979 13,804 9, 188 1980 3,691 3,391 t9 8l- 1,196 t9 a2 2,\41 2,Ot1 source: Annual reports of CITES Parties The crTEs atata inalicate that net world trade in q' pglgEgg skins skins in i.if f."* Just over 9,000 skins in 19?9 to about 2,000 1982 (Tabre 12). of a total of alnost 20,000 skiDs reportect in liaae aurinq the four years. about ?5 percent ha'l the country of origin list;d (Table 13). Most of the remaining skins has sin5apore listed as the source country (some of these nray be for in the oriqinal reported exports) ' "".5u"t.a Table 13: origin of crocodvlus !9199!9 Skins 1979 1.9_g.q 1981 1982 Australia lnalonesia 1, 160 - Malaysia 264 7 r 3,0t2 640 12,464 PNG ,422 "o, '7 ,8'7L r,829 4, 358 666 14,124 Source: Annual reports of CITES Parties q' pqlgsllg skins CITES alata show that about 65 percent of all with g' iu."iaua in trade came from eapua New G]rlinea'However'- as the CITES data a;e incomplete because they lack Primarv iiiiiE."""""""i".u., lrlppr i.a by Papua New Guinea. The Departnent of p.6a""ti""- i'.. rurnisrea additj-onal infonnation which gives a Ne Guinea moie reafistic picture of g.Dorosus trade from Papua (Table 14) . Table 14: Declareal Exports of Sr9g-qdy-flfg pglpElg skins from Papua New Guinea: Soutce 1979 1980 1_9_St 1983 '7 wild ,442 3,926 Ranched 184 80 366 927 301 4,2Al 4,853 3.4s6 * A smal1 nuniber of additional skins ( 1z of total) tnay have been exported i llegalIY. 1984- source: Holfands, S !!1t., 408 MISCELIANEOUS TRADE: The follolring notes briefly surnrnarize CITES- reported trade in various crocodilian species during 1981 and 1982. caiman latirostris (Broad-nosed Caiman) In 1981, Italy apparently importeal 9.836 g. fatirostris sllns fron Palaguay, and 1,000 skins from Colombia. The foltowing year an additional 3,2f8 skins were importeal from Paraguay. Until January 11984. ltaly had taken a reservation on this Appendiz I species, although Colofiibia and Paraqlay have not. Melanosuchus qiggl (Black Caiman) U-S. fish and Wildlife Service enforcement officiafs seized a shipnent of 254 Melanosuchus nioer skins upon attempted inportation into the U.S.from Bolivia ln 1981. In addition, 162 skins nrere sent from Hong King officiafs to U.S. authorities in 1982 as patt of an on-going investigation which resufteal ln the June 1984 convictlon of two American citizens for violations of the U.S. Endangered Species Act- At least 13 separate commercial transactions of U. nioer reportedly occurred between l9?7 and 19?9 when the convicted indivialuals exported at least 2,692 black caiman skins from Bolivia to Switzerland, Italy, and Hong Kong (Anon., 1984). The offenders and their conpany were recently sent.enced with fibes totalling 976,000 and suspenaled sentences of one year eacb. Crocodvlus acutus (American Crocodi le) Over 8.300 skins of g. acutus were reported in trade in 1981, although some of tbese (4,505 skins) were declared to be frotn Paraguay where the species does not occur. The remaining skins apparently originated in Colonibia and Panama, and were traded by ltaly, Switzerland, and FR Germany*. In 1982, 420 skins were apparently traded in Europe; most of these w€re reporteally pre- convention skins imported by switzerland from Italy and France. Crocoalvfus siamensis (Siamese Crocodi fe) In 1981 and 1982, Japan reportealfy imported a total of 500 g. siamensis from ?hailand. Thailand, which joined CITES in April 1983, is the only country with a reservation on tlis Appendiz I species. Tlre Samutprakan farm reports exporting 1,500 crocodlle skins to Japab and 1,000 to France between 1980 and 1982 (Samutprakan, I! -l_fl!.). Most of these were probably q-siamensis, but it is possible that the shipments included some C. porosus skins - * THE U.S. POPULATION OF g. ACUTUS WAS TRANSFERRED TO CITES APPENDIX I IN 1979, WITH SWITZER],AND ENTERING A RESERVATION AGAINST THE LISTING, IN JUNE 1981, ALL OTHER POPUI,ATfONS WERE TRANSfERRED TO APPENDIX I AND SWITZERLAND WITHDREW ITS RESERVATION. 409 Osteoleamis tetraspis (West Afrlcan Dtarf Crocoalile) In 1981 a total of 273 skins of QSlC.Sl-eeEi€ tetraspis from Mali were re-exporteil by France to ltafy and spain. I'rance was the only country holdiDg a reservation on this species, ancl that became ineffective on 1 January of tbis year. spain and Mali are not party to cITEs. OTHER SOURCESOF TRADE DATA: For Japanese wildfife trade, customs statistics are often considered more reliable than tbe CITES figures recordeal in Japan's annual reports. Their use is limited, hor,rever. because commodities are groupeal into general categories. crocotlifian skin imports are reported in kilograms and divided into triro groups. "Alligator Skins and Crocoalile Skins" and "Alligator anal crocodile Leather" (Tables 15 and 16). Nevertheless. these statistics are useful for trend analysis not only because they include countries of origin but afso because occurred. Table 15: ,f,apanese Imports of "Alligator Skins and crocottile skins" (ln Ki lograms ) L9'79 !9-e.s 1981 1992 1983 1984 (thru 6/84) Be1g11In 944 colonibia t7 , 409 16,11a 6 ,290 6,111 571 Fr. Guiana 5,432 Indonesia 9,543 1,nz 9.55; rs,344 11,83; 1,000 Neth-Ant1ls. 1 ,080 '7 PNG L6,311 \7 ,462 20, 31; t4 , 2'74 2t,82',7 ,242 Panama 856 Paki stan 64 Paraguay 52,343 15,546 49,558 138,s76 158,676 52,9 35 Phlppns. !,479 110 193 54 sabah 342 62L 100 960 singapore 4,244 3,434 424 91 | ,'779 Solomon Is. ,: ,,? a74 tr? So.Africa at: Su!lnalre 29,87 o - Swt?lnd. 496 Thaifand 6.035 4,00 8 2 ,8e; | , 29; 1,65; u.s. 9,035 26,06; 2,O23 z inibabwe 4?0 L28 M M CAR* 24; r1; Totals 161,793 91,194 10s,416 188,309 233,564 49,592 * Marianas, Marshall and carofina Islands {U.S.) Source: Japanese published gobernment statistics. 410 The Customs alata reflect ilapan's growing involvernent in the crocotlile skin tratle. Apparently, ihports reached a peak in 1979 before ;rapan acceded to the Convention. After falfinq in 1980, imports increased steaalify to reach an all-time high tn 1983. Much of the trade other tban froh Latin America, the U.S., anal Papua New Guinea, while not aaldressed by species, probably involves Appendix I crocotlilians. over the last five years Japan's crocodifian impolts have apparently beeh doninateal by skins from one country -- Paraguay. Over half of all reported imports between 1979 and mid-1984,more than 497,000 kg of skins. came from Paraguay. Most skins from Asian sources came froh Indonesia, while, smaller quantities were reported from Thailanal and Malaysia. After Papua New cuinea, the largest quantity of skins fron Oceania were importeil from the Solonon Islandsr trade from that source appears to be increasing. Japanese customs statistics also Iist imports of ,'Alligator Leatber and Crocodile Leather" (Tabfe 16). The most important sources of what are presurnably tanned bides are Paraguay and BoIivia. 16: Japanese Imports of "Alligator anal Crocodile leather" "able (in Kilograms) 1979 1980 !9_g! L9A2 1983 1_9_&1 (thru 6/84) Argentina 168 ^ ^^: Bolivia 2 ,693 2,Aga 4'7A Cofombia 290 145 6 France ur"_ 426 'u. tr? 869 344 GermaDy, FR 230_ Hong Kong Indonesia 105 Itafy 4A 47 ,o: Mexico 50 : 2,66r 92 PNG Paraquay 73,912 7,349 g ,98; 2,O34 527 ..: Singapore 9'7 86 o: t7 145 Sudan 60 U.K. J u.s. ; 2'7t 31; Total 20,5ro 1t,574 13,119 4 ,836 2,979 1,809 Source: Japanese published government statistics. 41I Sunsnarv anal conclusion Sillce 1979 the international crocodile skin trade has l'ovolved prirErily six species, and probably no more than 1.5 milfior- skins total have entereal world commerce each year. A1 least three-quartera of this trade probably conslsted of Caiman crocodilus skins. C]TES reports suggest that the overall trade tapered off slightly in 1982 from higher levels in 1980 and 1981. According to ;fapanese custohs data, however, crocodile skin imports into that country increased steaalily untj.f 1984. A new EEC regulalion effective 1 January 1984 requres two other malor consumers, Italy and France, to curtall lmports of CITES Appendix I crocodilians for which they had previously helal reservations. CITES data show the foflowing average M]NIMUM nrnicer skins entering traale annually fron 1980 to 1082: Allioator mississippiensls -- 22,4OOt Caiman crocodilus -- 695,500, Crocodvlus cataphractus -- 9,300r Crocodvlus niloticus -- 19,900, Crocodvlus novaeouineae -- 25,100, Crocodvlus .p.e5gE]l€-- 5.400. These figures are incomplete, holreve!, as some countries trading crocoalile skins, such as Singapore, are not partl to the Convention. In aaldition, some CITES members, especially anong the producer nations, have not submitted annual reports, anal others. like France, report only a portion of their totaf CITES trade. It should be noted that a significant number of crocodi.lian skj.ns are apparently elrtering trade j.llegally each year. I'or example, recent reports suggest that, alespite plotections, at least one milLioD skins of g.q-iMll crocodilus feave south America each year, primarily from Paraguay, Bolivia, and Brazil. In addition, some CfTES parties (e.9. Inalonesia,. Nicpria, Togo and Zaire) appear to be exporting skins of AppeDdix I crocodilians cornmercially although reservations have not been entereal for those species. References Anon., 1984. TRAFI'IC (U.S.A.)Newsletter 5 ( ). p. 14. Brazaitis, P. 1984. IUCN/SSC Crocodile Syecialist croup Newsletter. February 1984. Calalwell, J. 1.984. NlIe crocodife STin Trade (1975-1982).Traffi.c Bulletin 6 {2). Donadio. A. 1982. wildlife Leqislation and Enforcenent in Colonbia. ARATFIC (U.s.A,) Nehrletter 4 (3 & 4)- Fuller, K. aDd B. Swift. 1984. Latin American Wildlife Trade Laws worl.d wildlife Fund-u. s.,/cITEs secretariat. Groombridge, B. 1982. @. Part 1. IUCN. Glanal, Switzerland. 1983. I@rld checklist of Thre Nature conservancy council of creat Britain. London. Inskipp, T- and S- welfs. 1979. @. Earthscan publication. IIED. Lonalon. Mealem, F. 1982. calman ?rade a "Tradition". TRAFI'IC (u.s.A.) Newsletter. Vof. 4, Nc 3 & 4- gnited R@IEr, N. ard G. ltFiey.lg82.CrocoAib ard aUicEtor Ttade bv ttE sie|!es.'IRAIT'IC (U-S.A.) relDrts. 4L2 A WORLD SURVEY OF CROCODIIIAN FARMING R.A. Lu).moore. ,J.c. Barzdo, S.R, Broad anal D.A- ;rones Wildlife Trade Monitoring Unit IUCN Conservation MonitorinoCentre 219c Huntrngdon Foad,canbrrdge, UK Introduction In the last few years great expansion has taken place in the farming of crocoalilians, both captive-bleeding and ranching,the rearing of wild-caught young or eggs. Economics factors have undoubtedly played a major part in this but CrTES restrictrons nrust also be implicated- The majority of crocodilians are on Appendix I of CITES, and commercial trade tn these is therefore only permitted for captive-bred populations - In addition tne transfer from Appendix I to Appendix II of populations that are no longer eEdangered and would benefit from ranchinq is allowed for under the terms of tbe Convention. It v/as largeiy the need to know what faming operations uere in progress, for the impfementation of CITES controls, that motivated a survey of crocodilian ranching and captive-breeding around the lror1d- In 1982 the CITES Secretariat sent a Notification to a1t CITES Management Authorities of the need to register comrercial captive_ breealing operatiorls invofvinq Appendix I species (Notificatlon Nc 233, 13 October) . At the fourti Meeting of the parties in Botswana in 1933 a resofution (Conf- 4.15) was adopted that trade in captive_ bred Appendix I species shoutd only be permitted from operations registered wirh the Secretariat in thls way- ?o date there 1s only registereal operation breeding crocoditians, this is in Maalagascar- One of the argunents fevefled against crocodile farms is that tlEy can be u,sed to conceal iltegal skin trade, and suspicions ha1,ie been ,'faunde.ed', expr€sseat tllat wil cauqht skins hale been thrpwh farTs. T is srlFr-y,i". 1""" urrr" to co.firm tlis but it is clearty a lrob,tem which requires crosei scrlriny".t in the future. Methods The survey was undertaken during 1983 and the early part of 1984. In addition to the Notification to parties sent by tbe CITES Secretariat, the Wifdlife Traale Monitoring Unit also approached the wifdlife management authorlties of non-CITES governments, Contact was made with members of the SSC Crocodite Specialist Group and with sent to the farms themselves reouestinq details of tleir stocks, breeding, wild capture, commerciaf prodiction and husbandry. The results presented in this paper are drawn fron the responses to these enquiries and also from published and unpubfisheal material and press reports. In the following section the results are arrangeal by country. 413 Results AUSTRALIA: crocoalile farning has been practiseCl in Australia 61nce 19?3. In 1982 there were farrns 1n the Northern Territory (Blshaw, (rever, !.u !!!!. 1984) and furthei two in Queensland iLI Mg. 1983; otti""s, 1982), The oldest farm, at Edward River, Queensfanal, run by Applied Ecology Pty Ltd, a Government-funaled organi sation , keeps onty- crocoavfus porosus (onions, f982), while the remainaler are privately ownea anai keep a mixture of q. Dorosus and g!999$tl!q johnsoni-. Ttre total stoaks held in 1983 were 5512 g. j9blsggl and 4351 q. pglgEl]g. The animals were obtained as Juvenifes anal from eggs Eotlectea in the wilal under licence, with the aaldition of a few "rogue" adults. The conservation commission of the Northern Territo;y has supervised the wild-capture of the aDimals in the state. Ttley have organised trials to quantify a sustainable level of annual trarvest wittrin specifieal rnanagement areas. A number of anirnals have been removed lirom areas in which they were cobsitlered a potentiaf hazard to the public. It is expected that annual haivests of g. l-gbls-qnj from the management areas wifl be composed of 3OZ eggs and ?OZ hatchlings, with a total annuaf harvest of 3500 uniii (Bishaw, i! litt. 1984)- A11 wild animals in the N'T- remain the property ot thE Co,r"rnment which retains complete control of the resource (Graham. j! litt- 1983). captive breeding was Dlanned at all farms (Bishaw, 1! l:!!. 1984, Lever,:! litt' 1983) lut by 1934 had only occurred at EalwaratRiver, which bred 769 g- porosus in 1983. conmercial skin proaluction at this farm was Eip;lGa to begin in 1984 and to rise to a target figure of 3000 sXins a year (onions, in litt- 1981) - The three farms in the Nortbern Territory wele plannintto start conunercial production in 1985 (Bishaw, !! fi!!. 1984) . a-ANGLADESq.:In 1982 Whitaker (1982b) proposed the establishnent of a Central crocodile Hatchery and Nursery and four moalel crocodile alemonstration rancbes. The main species involved would be crocodvlus porosus anal Gaviafis oanoeti-cus- Breeding would be carriea out ;n an experimentaf basis. The major part of the operation noulal involve takinq g. polosus eggs from the wild in the Sunalerbans and rearj-ng them to 1.5 m for skin trade and to 1n for release to the wild. crocoalylus palustris and 9. q3!gq!!S!q are considereal unsuitaUte for Ltris sort of ranching in Bangladesh because of their low populations. However, some q- pqlllq!4lg might be reareal from eggs c;ltected at Bagerhat. near Khulna, and some g. oanoeticus from eqqs collected at Rajshahi. It was proposed ahat tht system should be established by the sunalerbans I'orest Department with the central hatchery situated at Dhangmari, Sutar Kh-ali, chandpai antl the four model denostration farms at Khulna' pacca, Cbittigong and Syihet. The Demonstration farnnst eventual outDut woulal be 250 sl(ins a Year, plus a nwnber of Yearlings for res-tocking the Sunderbans (Whitaker, 198b). BOI,IVIA: ASICUSA,a group of four mealium-sized conpanies involveal especiafly in the tanning and processing of caiman skins in Boliva, established a crocodi,lian farm in 1975. A total of about 2000 animals were reporteal to be kept. of caiman crocodilus crocodilus, caiman crocoali lus vacare. {C-l3-!9qJeb-Ue liger and "another species 4I4 of Cainan'r (Bejarano, i_S !!E. 1983). Eurther confirmatlon of this farm is needeal. BOTSWANA: A crocodile farm was established in the Okavango Slramps iD ilanuary 1983. It holds ?0 adult breeding Crocodvlus niloticus; 802 of which are male. They were captured in iocal drought areas where they were thought to be unaler threat. It was anticipateat that in 1984 tbere woufd be another severe drought and facilities were belng built to cater for a larger number of crocodiles. The plan is to collect 2000 eggs a year over the next three sedsons. It is also pfanned to reinstate 5% of the l-n sized crocodifes j,n the wi]d. The cr'ocodiles have jus! started breeding. It is hoped that the breeding stock can be built up to 300 over the next three years (Seaman, rn lji!!. 1983) - BURMA: The People's Pearl and Fisheries Corporation established a crocodile far:m in 19?8. It had about 900 Crocodvlus p-ql9E!g in 1980 (Caughley, 1980). The main airn of the farm is to produce skins but it is thought that by 1983 no animals had reached marketable size (Salter, in litt. 1983). Young animals are taken as batchlings or yearlings from the eastern side of the Irrawaddy Delta where the PPFC has set up a number of coflection centres. ?here is evidence that the total recruitment of crocodiles was being taken by the PPIC in the Tawbaing chaung area (cauqhley, 1980) . From 1978 to 1983 an averaqe of 465 hatchlings were obtained from the wild each year (Salter. i! litt. 1983). The farm is intendeat to be self-sustaining !,rhen its breealing prograriJne is fully established- Successful breeding was expected by 1983 (cauqhley, 1980). The farm has recentfy been successful in inducing nesting but nost of the stock of hatchlings continues to come fron the remaining wilal poputation in the lrra!,/addy Delta (Salter, in litt. 1983) . The PPFC bas also proposed to turn Meinmahta Kyun, an island of some 50 square mifes in the Irrawaddy Delta, into a ,crocodile sanctuary' where re-introductions from the crocodile farm woulal supplement the remaining wifd population and provide tbe basis fot eventual sustained yietd harvest (salter. ;h titt. 1983) . CHAD: An experlmental programne to evaluate tbe possibifitles of crocodile farming (presumably Crocodylus nifoticus) was undertaken from 19'72 to 1973 under the auspices of the Centre Technique alu Cuir. Lyon (l,e Francois, 1974) - Although much valuabte information was obtalned during this experiment, it was not intended to be a conunercial proposition but lllerely to assess the possibilities of breeding crocodiles under controlletl conditions- It is understood that the experiment was discontinued in 19?3 (WaIlis. 1980) - CHINA: A substantial investment has been made in alligator ranching,/ farming by both national and local authorities in China. There is a growing number of operatlor)s, mainty intended as conservation measures, but there 1s considerabfe potential for sale of five animals or products alerived from them (Watanabe, in litt. 1983). There are unconfirmed reports that sales of alliqators may have taken place (Anon., 198c) - 415 lluang ChEchien names five operations managing Allioator sinensist Anhui Xuancheng farm, chekiang anchi farln. Chekiang Changhsing farm, chekiang Ningpo zoo, shanghai ?oo. The first of tbese was the only one operating on a large scale, having 100 adults and 380 juveniles (Huang chu-chien, l-S IiE. 1983). charoon Youngprapakorn of Samutprakan Crocoalile Farm. Thailanal, reports having given assitance in the establishment of a farm for Crocodylus siamensis catled the swato Crocodile Farm (Watanabe, i-S -li!g. 1983). The chinese Government is also reporteal to have expressed interest in establishing a farm for crocodvlus Dorosus in southern china (Anon., 1983c). cOloMBIA: No cornmercial crocodilian farming is konwn to occur in colombia, but there are at feast two crocodile breeding centres concerned with research ancl conservation. The flrst, Roberto Franco Station, operateal By INDERENA (Instituto de Recursos Natu- rafes y de1 Anbiente) . keeps 4 crocodYlus intermedius (Medem, 1980b) , 17 caiman crocodilus, 12 Paleosuchus palpebrosus and 5 eglegEUqbgg trioonatus. Caiman crocodilus and Pafeosuchus pgbgb!9glq have both breal several times at the station (Medem, !! litt. 1983). The second, Los cocos Breeding Station on Salamanca Islaod. also operatd by INDERENA, had 30 Crocodylus acutus in 1980 but had not had any breeallng success by that time (Medem, 1980a) - A third, Cienaga Grande Management Station, has now closed down (Medem. 1980a) - CUBA: The Ministerio de 1a Industria Pesquera runs a crocodile farm at laguna det Tesoro in the Zapata Swamp. It was established in 1955 (Harrison, 1981) and in 1981 had a total population of about looo adult crocodiles of ,rhich about 802 were g!999.4!I!g rhonbifer, 5Z were crocodvfus acutus and 15% hybrids of tbese two species. There were also about 5000 imnature crocodiles of a similar species composition (chabreck, 1982) - The main aim of the farm is conservation but there are reports that some of tbe ]arqe crocodiles have been sfaughtered for hiales (varona, 1980) and meat which is solal focally (Harrison, 1981) . The two species have inter-bred in the past, but recently attempts have been made to keep the two stocks apart. Most eggs are faial on islanals in the lagoons. up to 25 eggs are collecteal from each nest and hatched in incubators (Harrison, 1981) - In 1981 eggs were colfecteal from 600 nests. The hatching rate for all groups was similar and averaged 462- The total number of young hatched uas about 10,ooo (chabreck, 1982) . some of the q. rhombifer were moveal to another breeding centre at Tasajera, south-west of zapata, in 7g'7a ar 19'79 to breed pure individuals of the species (varona, 1980) It is hopecl to release pure-bred q. rhombifer into Zapata Swamp (Harrison, 1981) . INDIA: The Government of India initiateal a Crocodile Breeding and Management Project in 19?5 with prelininary survet s being undertaken in 19?4. The pr:oject operated on advice from a uN,/FAo chief Technicaf Adviser witb finance from UNDP (croombridge, 19e2l . Crocoalile rehabilitation stations have been established throughout the country and crocodiles have been released in 13 specially created sanctuaries and a furthe! 21 National Parks or other sanctuaries. Up until 1984 a total of 1185 GBILqIIS oanoeticus, 408 Crocodyfgs pglgElg and 500 Clocodvfus palustris had been neleased to the nild (singh qE 9I.1985). More than 2000 eggs a year are collected for captive hatching by alifferent state crocodife projects in Inalia. Captive breeding projects exist at Madras, Nanadankanan (Orissa), Bannergbatta National Park and Bangalore (croombridge, 1982) - Afthough it is not currently Government policy to promote commerciaf crocodile farms in India, the rehabilitation schemes ivhich have taken pface within India bave shown the potential of q. palustris as a subject for comroercial utllisation through farming or free range sustained yield exploitation (croombridge, 1982). INDONESIA: Crocodiles have been exploited in Irian Jaya for some time and there is evidence that the wilal populations have declineal through over-hunting (Petocz, in fitt. 1983) - r'arminq was started in 1976 but the covernment stopped further expansion untif the ability of wild stocks to support a farming industry haat been assessed. Tn 1980 there were 4000-5000 crocoaliles on farms in lrian Jaya. An indication of the species compositioo might be obtained from the skins exported to Singapore which are about 102 Crocodylus porosus and 902 Crocotlvlus novaeouineae (Lever, 1980) . Everywhere in the Mamberamo defta and along the river up to Kasonoweja (Picniersbivdk) local peopfe are repotted to keep crococliles in often very alirty enclosures fenced by corrugated iron. Skins of crocodiles reared by the viflagers are often bought by the loca1 Government employees who then se1l them to the large trading conpanies (King, gL Bf. 1979). The farms were reported to be of varying size and were, on the whole, poorly manageal and unecononic. Most of the farins started because the Government obliqed all conpanies wanting to export skins to operate a crocoalile farm. Therefore economics has not been of prime importance, rather the fa.rms have been established to comply with Government regufations- However, by 1980 it $ras realised that farms woufd have to be more efficient as the wild population woufd not support indiscriminate huntinq indefinitely- At that time it was forDd that management was poor on the existing farrns, pen design anal generaf health of the crocodiles was only fair and that there was a great need for nanagement training and advice (lever, 1980) - It is the aim of the Government to institute a farnring programme similar to that of Papua New cuinea (Boonsonq, 1981) - At present a project is being carried out unaler the title 'Crocodile conservation and inalustry alevelopment in Irian Jaya', involving a number of consultants, which started in October 1984 for an initial period of four months (Petocz, i!1 ll!!. 1984)- The purpose is to promote the conservation of crocodiles by utilizing their resources to benefit the indigenous comnunities. The prlmary aim is to establish the most suitable areas to set up collecting farns, determine the numbers of crocodiles that will need to be collected. investiqate the economics,and reconunend appropriate legislation. It is proposed that skin exporters wilI only be able to obtain five crocodiles fron collection farms. and that strict quotas wifl be set for the exploitation (An6n. 1984d) - Lever (1980) listed 13 farms operating in 1980 and a list of 15 registered crocodile farming companies was supplieal by the Director ceneral of Forest Pr:otection and Nature Conservation i,n 1984 (Rubni, in litt. 1984). No captive-breealing takes place in Irian Jaya (Petocz, ir litt. 1984). outside Irian Jaya there are also a few rearing farms in the vicinity of ,takarta, which are similarly depenalent on eggs and young taken from t)re wild (King, et al. 1979). The species kept are g. porosus, g. novaeouineae, and &Glqlgqq schleqe.Lii {Lever, jI Iitt. 1983). Farms have afso been established in Kalimantan but most of these were closed by the mid-1970s because the grolting rarity of the wild crocodiles made it difficult to secure the eggs and young needed (King, et al. 1979). ISRAEL: A crocodilian farm was set up at Harunat Gader Hot Springs in 1981. It held a stock of 302 Aflioator mississippiensis, 4 Crocoalvlus niloticus Elgb]lg and 3 Osteolaemus tetraspis 9S-b.94LL in in 1983. (Ben-Mosche, i.! litt. 1983) . At present iL is run so1ely for tourists but it is intended that live sales to zoos ani cornmercial operations will take place. The initial stock of A. mississippiensis \ras obtalned from farms in the USA (Perry, 1! IL!!. 1983). seven animals were obtained fron the University of TeI Aviv. 180 A. mississiopiensis were successfully hatched in 1983 (Ben- Mosche, i4 Il!. 1983). A second farm has started in 1984 with 205 9- niloticus (Ranot, Pers. conun.). ITALY: The compagnia Internzionaf Allevamento Animali Esotici (CU{AE) established a farm near Brindisi in 1980. It purchased 30OOcaiman latirostris reportedly from colombia but these suffered severe mortality owing to poor shipment conditions, low winter temperatures and alisease- The remaining 406 animals were still being kept in poor conalitions at the time the farm was surveyed in January 1981 and it was estimated that 100-150 were on the verge of death. It was suggesteal to tbe Managing Director of the firm to postpone the further order of caimans frorn Colombia (Pooley, !! Il!. r981). .q. latirostris is not native to colombia (Groonbridge, 1982) and no captive sources are known; it is therefore likely that the species was g. crocodilus- MRY COAST: It as reported in 1980 that there were plans for establishing crocodile farms for cornmercj-al production (Poo1ey, 1980) - JAPAN: The Atagawa Tropical carden and AlIigator Farm applied to export 8 crocodvlus moreletii from the usA in 1984 (Anon. 1984e). It is not known whether the export took place, nor whether the 'farm" has any commercial function other tban public disp]aY. KENYA: In 1977 Kenya passed a law forbidding t}le sale of most rvild animal proalucts in the country. This has prevented farms from operating cormercially but crocodile farming is being developeal for future production when al1owed. 478 A large crocoalile farm was starteal in 1983 by an Israeli-owenat conpaby in a 2o-acre (a.1 ha) disused quarry at Nya1i, north of Monibasa. It plans to calry a stock of 20,000 Ciocodvlus niloticus by 1986. r'ulf proaluction, once achieved, should be 3OOOskins a year with a value of about US$70,000- The oriqinal stock of 650 crocodiles was trapped atong the Tana River r; a three-month exercise (Anon., 1984a). An experimental operation is run by the Baobab Farm near taomodsa. The farm is primarily concerned with arable crops, alomestic stock and fish (tilapia) cufture. but experimental work began or- antefopes in 19?5 and on crocodiles in 1982 when it acquired 2OO eggs from i,rich 189 C. niloticus were successfully hatched (Hatler, !! ljl!-, 1983) . Future production would probably be based on skin sales. MADAGASCAR: Madagascar has one crocodile farm, estabtished in 1969 at Antsobolo; this is the only captive-breeding operation for crocodiles registered with the CITES Secretariat in accordance with CTTES Resolutlon Conf. 4.15.Commercial production started in 79'74- In April 1983 the farm held a total of 454 crocoalvfus niloticus (Berney, !! litt. 1983). Crocodiles are killed at aboul :-5 y"ar. of age. About half the skins are tanned in Madaqascar for use in the manufacture of goods. The remainder are used for taxialermv. None is exported by the farm (Anon., 1980), but the operation is self-financing from the sale of skins (De Lanessan, in litt. 1983). The original stock r.ras taken from the wild in the from of aninals less than one year old. These have been raised to form a captave breeding stock- In 1980 the capture of wild animals ceased (Berney, :! f!!!- 1983). It took about 10 years to produce rhe firsr capt.ive -.bred generation ln 1980 (De Lanessan, in titt. 1983) . About one hundred juveniles ire now born on the farm each vear and it is hoped that this figure will inprove as the breedinq stock continues to mature (Berney, l:! litt- 1983) . I4ALAYSIA: In Sabah eggs and young of g- poros\1s are talen fron the wild for rearlng in hide farms, but the witd poputations are so reduced that this trade has decreased in recent years (King, gg q!. 1979), and it is now ilfeqaf (Andau. in litt. 1984). one rea.ring farm, located just outside Sandakan, Sabah has been rearing g. porosus for export since about 19?0 (Anon-, 1980) . It had 1035 q. porosus in 1984 but no breeding had taken place (Andau, in 1itt. 1984). Rearing farms exist in Sarawak which raise wild q. porosus batchlinqs obtained fronr local fishermen. About 10 Tomistoma schleqelii are aLso thought Lo be present in the taii!, Ilfstins of which will probably eventually be sent to Singapole (crocnbridge, 1982) - MALAWI: Crocodifes were beinq trapped in 1984 on the Shire River for a proposed farm on Lake Malawi (Van Jaarsveldt, in litt- 1984). Seventy-two crocodiles were also supplied to South Aflica for a new farm in Natal in 1984 (pooley, in 1itr. 1984) - 419 I4ALI: A private company named MaIi Reptiles plans to operate a crocoalife farn near Banako, in Mali, involving Crocodvlus nilotio)s but the farm is not yet of conmercial status. A small pilot scale farm has been operated since 19?9 with 34 g. nlloticus captured from S€gou- The crocodiles are held in pods with feecling installaticrE anal provision for cleaning tbe water. Research carried out since 1980 with tr'AOco-operation has shor{n the project to be viable. Projected production is between 1000 to 3000 skins by 1986. The farm is financed by a private grant of MF90 000 000 put up by European partners (Sanogho, in litt. 1983) . MEXICO: The Mexican Government has established several farms for Crodoalvfus moreletii in Chiapas, Tabasco and Oaxaca. Other farns are planneal in Yucatan and ouintana Roo, the latter hoping to breeal crocodvlus acutus - Another farn is planned for both species in the Lacadon Jungle. chiapas. It is to be nanageal by the local people anal breeding for bot}1 conservation aod commercial purposes in pfanned { Lazcarno-B arrero, 1984) . MOZAMBIQLIE: In 1981 a small crocodile 'fram' was in operation in the Zanbezi wildlife utilization Area of Mozambique, situateal on the south bank of the zambezl River delta and convering approxinatefy 20,000 km2. rt was planned to expand this at a fater date, but no further details have been received (Te1Io, 1983) - The species -is presumably Crocodylus niloticus - NEPAL: A gbarial breealing farrn exists in the Royal chitwan National Park which has a stock of 255 gey-lqLlg qq!g9!!q99 (Maskey, in litt. 1983). It is not at present a conlrnercial operation, however future comnerce does not appear to bave been ruled out. Eggs are collected withiD Nepal and animals are subsequently returneal to the wild (croombridge, 1982) . PA(ISTAN: IGUANA. a leather company in Pakistan, stated the intention of setting up a cofinercial breeding prograrnnre involving crocoalvlus palustris and Gavialis sanoeticus, and that atlvice haal been sought from wwF headquarters. The farm was planned to fol]ow the pattern of Samutprakan, Thailand,but was not to be strated untll a similar project, of greater priority to the conpaDy, involving Varanus qriseus {desert monitor) had been established (Aftab Aram, in litt- t98o) - PAPUA NEw GUINEA: crocodile ranching has expanaled greatly in Papua New Guinea in recenl- years, fargely as a resuft of the covernment wildlife Division's newly-adopted National Policy on crocodile Farming. There were estimated to be about 21,000 gIqgglll|]l]E novaeouineae and 9000 crocodvlus _p.qf-g.qq.qon ranches in 1983- These range from small village pens, which might never hold more than 25 animals, to large corunerciaf ranches with up to 15,000 and which are still expanding. Tlre two such conunercial ranches, both established in 1979, now hold sorne two thirds of the total stock. There are at least 9 lntermediate-sized ranches each with 400-3000 aninals, and an unspecified number of village ranches, but the latter have declined in numbers since tbeir peak bet!,teen 1975 (Hol1ands, in Iitt. 1984) . 120 By. 1983 no breeding had occurreit atthough some was p.lanned future, and the entire for the stock derived f,;^ i;_;;;qf,;-J"iJ.,i r. , mostfy-in_the range of 50-90 cm total teDgth."i By c;ver;nenL " control of the price system it was ensured tnat'pii""es- oi ri"" animals l/ere. kept high enough to encourage f,rr"tei-. trme lo-.p!ia tfrei, to catch libe stock insteaal of Just-skins- rfr" animats collecred from the wifd are 3},""" i" iiui"-rl-'--""".i.i" "t Table L. crocodifes cotlecteal from the lri]al for farms in pN6 (HoUaDds. in litt- 1994) c. novaeguineae C. porosus Total 7919 3, 958 '7 9',74 4 ,932 1980 ,669 2, 14I 9,810 1981 8. 118 2, t78 IO t 296 1982 a ,602 11,401 1983 2,51e 1,901 4,419 TOTAL 30,865 40.858 Villagers are eDcourageClto collect young clocodiles and to sefl any that they do not require themsel;es io the -or ini.t'rnJJi"i._"r.r.o privarery_run farms. when ti,.." r,i".-"".ii]i"t"a :::.:ll.ntJuu-4uu surptus animals, representatives of one of-sf""iJiiy the condnerciaf T:l:hes.fly in by_tishr aircraft to coflect trl"nr- des.Lqnedcardboard rubes ahd boxes a11owthe effici;;i-i;";r.- ^, the animals, and their transport with extremefy f"* "' som_eof_the internrediate ran;hes derive th";; "ortaI;i;: such :"ai;" i;;Ji. ,.orlr sales of 1ive animats, while others .f"" .".i-..i".ilt". themsefves. rhe covernment is activety 'rmidi ,, ir,i-dii"r"p*."t of these -ranches ar abattojrs ;nd"".;;;";i;; fish the if"it" tr,ioogno.rt country. The two alreaaty established .t 1;;.ii;i;" rullnlng ... very successfullvt other- operations in"";h tbis-is8ti. category -"""' well on rocally run causht fish (Holra;ds; ra fi!!. Exports of farm-produced skins totalteal 301 C. porosus and 1304 e. n?yaeoriingae in 1e83 for narkers mainly ," (Goudie, j!! r;"ce ;n; tap.,, lltt. 1983). This compares \,/tth an anbuaf wild harvest ilurins the 1970s ahd eartv tqBOs rs _ iS,ooOi.-n'i.,..jiir,... =*rn., oorgsu:-skins. !r ill"t_:, ll:909 s. rhrs earne.r *re counTi-y approxiratery u-52 mrrrrorj a year- (Hol]ands, iI litt. 1984), Skin pr"aul.r"n was expecred to exceed 7,?00 an &84 for farns (co;aj;;-pJ.r- c"**f - PHII,IpPINES: A crocodile breedinq project, run by rhe Sittrman University. Marine was started on Negrol rsland ln conjunctton -Laboratory in tset with the Smithsonian Institute ;nd WWI. In i982 stock q4esedr]Js :!-!:9 ? of 17 nindorensis (rererrea to as LI(Jw!!y!€ novaeoulneae mindorensis porosus. in cITEs) and one crocodvlus The operation is an experrmenral project conservation irrveiffitrng-iji", techniques and the vrabilrtv irr io,nln"i.i there ng. i:--lr:::1. is _no corunercial produciion- rii "i "i-ii"-iro.oatt." :;i;"li;:":":i;"::,:::il.""i";]f"ii]'3i";,i!iill':g"T::"l.ili::"=. 42r h 1982 14 young were produceil by one female, the first known captive propagation of g. minalorensis (Anon., 1983b)- The ;rapan Crocoalile I'arming Institute in the Phitippines (Palawan) has submltted a proposal to start breeding q. Iqi!9gIglglq with an initial stock of 200. The aim of the project is to conserve the near-extinct crocodile population in the area, eventualfy to re-introaluce it to suitable aleas to prduce a sustainable yield of crocodile products - The Institute intenals to train ploject personnel anat focal resialents in crocodile farming techniques' the 6-year project is being lointlY negotiateal between the Japanese and Philippine Governments (Atlon., 1984b). There are also reports of a farm established in 1981 at san Ramon, Iroridablanca, Pampanga with a stock of 28 gr.s9.9dI\9 pqlaEllc (Alvarez, in litt. 1983) . SAMoA: According to a newspaper report in 1981 a west German proposed to build a crocoalile farm on the isfand (Anon., 183a) ' r,Io more has been heard of the proposal, but the Director of Agriculture and Forests declareal that there was no wildlife farming of any kind in 1983 (Reti. in fitt. 1983). SENEGAL: It was reported in 1983 that there was a proposal to establisb a crocoalite farm (presumabfy crocodvlus Di-!g!i!ffg) in in casamance anal that funds were being sought (Falf. iI 1itt.1983)' SINGAPORE: A survey of crocodile farming operations, carrie'I out by internationaler Repti 1lede r-verband E-v. established that there were theree crocodile farms in singapore {Diehl, in 1i!!.1983) The rirst, Tan Moh Hong Reptile skind and crocodile Farm, has a stock of about 600 clocoalvlus pgIgEUg and Tonistoma schleoefii (Anon., unalated). The second, Singapore crocodilarium Pte Ltd', has several hundred glqeg4]|bg p-glEgjil€ and a few dozen Tomistoma schleqelii (rnskipp, pers. comnr-). A third farm is reported to ir, .Si"gap"re whicb is operated by Leah Liang Joo- This farm started"*ist in 1t?O with 60 crocodiles and bv 1976 the stock had increased in size to 3OOO. Most of the crocodiles are probably g' Dorosus althouqh some are reported to have been obtaineal from S",rtr, lrn"ri"" iYounqblood, 19?6). There are reports that glggqVl]ll novaeouineae ana caiman crocodilus may also be farmed (chandler, in litt. 1983). It is reporteal that many other crocoalile skin businesses kept or have kept young wild crocodifes in back-yard enclosures, raising them unlil they are about tlto years o]d. some of these establistn€nts kept as many a; 4OO animals {singapore Trade, June f961,,Ejdq Anon', 19t9). acco;dinq to King qL 31. {19?9), a large number of rearing ffourish in Singapore by importing eggs and young from other Asian anal Pacific-areas. Stock is knovn to have been inporte'l froin Inalonesia, Malaysia, Papua New Guinea, Australia, and the Philippines. Some limiteal breeding is done on the farms' Output from ifrese farms is expected to decline as surrounaling stocks decline. Skin products are sotd in S and are.also exported to cermany, France, Japan and ]:9:3":t PR "r *'"''ri""-'p,t.;;5;;;;*"i:;:;"::":::'i;"iii::. rlllili"l;rilii crocodile meat-is also sold, noin ." . a"ii...i'..li,.ior,^.ai.irr.r use (Anon- , undated) - SOUTIi-AJ,-RICA: The first crocoalile farm in South Africa was established by ,I. Kuhlmann in pi.i".i.-iiir,'t4 (Kuhrmahn, 1968-outsiale ,,nulsance,, :I:"gi:1:" i! It!- tge:) - rr.,i" ;;;-;;;;;;, . h.. ouu--/uo,crgco-dvf us n i toti cus- (van..laarsveld navtng l, il-::t_g. i6 e: f , rromiszi bred ;;;;;.-":;.;:i';;:";";J"":::"iT.'lii,;"..**,;,il'ii; them reoularlv J couhtry, and in 1983 formed Lhenselves .inro rte souitr crocodj.le Farmers, iirrcan Association. rn 1983 there rn,"i"-iii iir a-totat stock of about *itr, 1q0o_c. 4itqricus, *".trv-j""."iils " ootarned rrom rarms in zimbab!./eana sou*r eJilii few adurt probtem ii.,uiiiiiin . animals (lrnora, 14 iitl.-is8-ji"iu, lii.!i1." "tr.", the caprivi strrp, Nambia (stowqrove, pers, *i;3':.:.:iit'*1.i"::,:;:,_'iu: comm.)- Another large i?-1extarl farms l;;iiF".!:"1l;;ii t]i:.:9-:: but so far, aparr fron KubtmaDn,s farm, has on-Lyoccurred at rwo, !,/irh ^ totat of St tr.t"f,r'irs in litt. re83.aond. ia ;r"au!"o i" rarms1l931tl.J1r"tu. obLajn iii;:'i;;3i:"ilj;y or the income from Lourists but n"ng-"x."pi t;;;r;;;." anLicjpaLes beinq abfe to sett skins unliI at iedsr. rbsd--rernoro, ln lita 1983), It is not clear whether the fatter has yet sone of the farms have sor.r live "i!"iiril",",, alone so. Kuhlmann, ."i..r.--ie"ii, iI !|qL. 19e3, poorey, pers. cofiun-). SPAIN: A company kno!,/nas Iberia Enterprises many Ltat- requestecl "as crocodiles as courd be supplied,, t'r". irr"-ll.i"i'iiii Republlc of South Africa. for unspecified purposes request was turned i" is;0. """ra,fi]" dowr (pootey, f! lfgq. iSa.Ol Tbe crrEs ManasementAurhority stated in :11_!^5o, no crocodile 1983-aitrroush thar ..1::"_y::" farms or rancrres in sri r,ant SURINAME: There is one conmerciaf crocodilian farm in Sunname, at croningen, Disrrict Saramacca, which is .epo.t-J-E.Jiil:;i"f#* a; ;;;- --..-^_ ror the_produ.tionor skrns.rr" ii.ii :I:.:gjt". is most :.: :It!. likely France, but possibly atso the Northerfahds and FR Germany(Reichart, r-q !!!!. t"'r.r. o"pi"i"-isisi.""' TAIWAN: There are 35 crocoditian farms in Taiwan, in^1e?6,.with the firsr ::::!li:Ed a torar stock €l:"""J aoorj-c"i*"" 5uu rndran "r crocod i te,, ( :cavia I i-s oanc'eticus) and 300 of ocher species."n..:; incruorng l3y:h"9 crocodylus po.rosus (Tsdr, tn l+t:. 1984). Totaf annuat pEooucrion with a value anounts to-50,666"kn''1, 12,500 kq of skins of NrSlomirt-ion^ (.u"S, = rqiSj-r), '*"iti'"rp *".", worth NrS12miIlion, anal7_soo_ks .r million. Most is sold within Taiwan bur"*l,:i'ii"i"ii" . iiiii.-i. "t" .'aptive-breedinsi. "*o".i"a I:I:.,::9_jig.l.zuuu Juvenlte crocodrles b-ing produced""J"it"r-",,"";;,ilfi;."r" eacb year--iach 2s_45esqs *ilt, mar-ure i:[:].r;;l;."o*t . r,.t"],i"q iiii'"i*iir.,.?r".i, i,, 423 Ltd" in 1983 had 5200 one of the l-arge! farlis, Taiwan Crocodile ?n3**ff'n roT+**,ff**-ft.ni,' q suc ce ss rate or-' i=i;.HifiH.i"3" -n. " :i"' ?"*1,i : :iii3 i 3 lll' *I i ?.i'.i"" :;;";i:; ;';";;-;;a weish.about :;:"9::?"":i;-"il::'.i:;'":: of the iaflr as weft as tkins 15 kg. Meat is an lmportant ptoJutt to purchase-1000'Iive hatchlinq (Fuchs, 1983) - Another totptny-"'tttita *:f t""tn Jiilliii,r i".' r'o^ ir'""r"i'i Parks-Board' Y?l'-:?t Africa,forrmporttot"''*'t':'"1"96'purposeunspecified(Poolew'""-.i ",i" in Il!. 19S0). $::;":}":il:"i",;;i':$"iu3;'i:::dfr;" I3i?l"iii."'l::""';":5 from the Ruvu-andRufiji Rivers' ,iiiiiiit". o"i""ls vere obtained been npiir 1e83 8o adurLs and^1400esss had +fi::ii;' r'or/ ' Laken from ";;;;-i"the wild (Katalihwa' rll lr'!l' bt The Samutprakan crocodile Farm an'l-zoo' -rnal:?ig. THAILAND:i*:F:,ir;t;t*::[i,;;1."1;;Sffiil#d:T i''13*:" 11, ?OO crocodvlus siamensis, - and Crocodvlus 49!lQ]l9! tuuw ",. thecrocodir ians-:'.,:'::"|"i,[E"li,il']i,!"i,liil* -to il3 ii",3,, o"i"g the.1ow. narket :3;:'i: i;:i"::i;",.i"-:;:".i;;;'i"l skins are Anon' , re?ea) ' sixtv percent of the iii L^i"i-.r.,'n'J-i whi le-the-other 40u analsold Iocatry' Inittlv'i'o i"tttitt"." orocessed (suvanakorn and YoungprapaKorn' i""'!"ii"a-l"a shipped ab;oad Thai tn. rtiln supptving 8Ox of the Unpublrshed). rn l9?4 "t" cr-ocodile skin trade ' c- Dorosu-s-and3600 g' Fron 1980 to 1982 approxrmately l2Oo :i;;";:;. "i,. -r'ut.l'!o_i"_"::i"l;U;.t1"ffi-.ffiT#i,l"lln'"'" .::;;;.;-;; i!"ii'"i (Anon" 1e ?b) ii.Xfl;il3; il.s;ni#i8ffi drops "s"'rto below "" 5? (suvanakorn alie in their first- year, tnen-rnoriafity ' ..ta y"uJ)qpt"p").or n , Unpublishe'l) nr-IgE*) croco.lrle tarnlns project rp'":Y"!ll roco: A future" !:":8gXtY:,in 1e8l (Dosbi -rom1' ;;";-p;"i;;-.; le set up-"in ir'" n"lr in ritt. 1983). in lhe USA started uNITED STATES oF AMERICA: Alligator "farming" purelv rasr-i"i-ir'ese ea'tv-v"ntures'were :i'i;";';;1";; "" ' It ;as not until 1964 that the purpose of"q"' attraclrng-;i s itors for and Fasheries began-research the Louisiana Department iiiailit ;:i:"::t:li*"##':t*#;"t :T?il":x:'iiT:::t:'i:"" rr,"""r",*" srewat a il,:i'.:;1ffi:- of 19?8 that alligator "9*farme ",i*r:.;i"?13.':J3"d:1", 424 laisetl skins. In 1980 tbere were five active alligator farrns in tloriala holding a total of 7000 aninals. Less than 152 of these were breeding stock, the remainder being at various stages of rearing- In Louisiana in 1980, there were eigbt alligator farms keeping a total of 13,000 aninals (Ashley, 1980). In 1983 there were 14 breeders in Louisiana and 12 in Florida (coodwin, in Iitt. 1983) . Only one farm had started selling skins i.n 1980 (Ashley, 1980). By 1982 at feast two farms were involved, one of which was afso selling meat (Boonsong, 1981r Kel1er, jq I!!. 1983). A fully operational fann produc:ing 10O marketable skins a year would have to naintain a stock of 3500 to 5000 animals- The Louisiana farm stocks ale being supplemented with wild-caught animals during their first five to seven years of operation to help them acquire breealing stock and expanal their operations. Tn !9'79 the Department of Wildlife and Fisheries provideal the Louisiana farms with about 1700 wild hatchlings unaler a rEnagsrent prolect designed to supplement new alligator farmers (Ashfey,1980). In 1980 the five active Florida farms were collectively proalucing about 2500 hatchlings a year. Many of the Louisiana farms are small arld ln 1980 were collectively only producing about 1500 hatchlings a year. The long tern goal of the Louisiana prografime at least is to become primarily orlentateal towards captive-bleeding (Ash]ey, 1980) . URUGUAY: A project involving tbe captive-breeding of gEhgq fatirostris for conservation purposes was planned in 1977 (Anon., 1977) but haal not been implementd by 1983 {Achaval, in 1itt.1983}. VENEZUELA: The Ministerj-o de1 Anbiente y ale los Recursos Naturales Renovables has recently proposed a possible multi-leve1 management scheme for wild g4h3! crocodifus. This includes ranching in whicb eggs would be collecteal from the wilal for incubation. The hatchlings would be kept tn 1 m by 3 m tanls and fed on sma1l fish, finely choppeal meat and insects. After one year they would be returned to semi-wilal conditions in the form of fenced-off natural lakes and rivers where again they would be feal on fish anal rneat. The animals would be harvested after three years for their skins, the meat being fed back to the younger stock (Anon., 1982b). ZAMBTA: There are two operational crocodile farrns in Zar,bria. the Kariba Crocodile and Fish Farm which has about 200 glggq1lllg nllotrcus (Parker, in litt. 1984), and another on Lake Tanganyika which has around 500 crocodiles (van Jaarsveldt, in li!!. 1984) - The first skins were expected to be reaaly for marlceting by the end of 1983 (Anon., 1982b) . A1r stock has been obtained from the wild, Eggs have been collected in zanbia under covernment licence and hatcbed at the farm. The Government controls the number of eggs alfowed to be taken anal tbe areas from which this cao be done. It then demands the release of 102 of the stock after two years.1417 eggs were hatcheal ln 1981 and 194 ir|, 19A2 (Parker, in litt. 1983). The first farn boped to be permitted to catch adult animals for breeding purposes in 1984 but no breeding has yet occurred (parker, in !!l!. ls84). 125 A thiral farm, Lauangwa crocodile and safaris, is not operational yei. 17/44), but hopes to collect about 5000 eggs to operate along the lines of the farhs in zimbabwe (Van Jaarsve1clt, in !:!!- 19e4). ZI|4BABWE: Nile crocodiles bave been ranched in Zinbabwe slnce 1965; there are nor,r five crocoalile rancbes in existence there.T'wo further ranches existed in the 1960s but were both short-lived (Blake, 1982). The five ranches held a total of nearly 26,000 crocodwlus niloticus in December 1982, comprising 10 350 hatchlings, 16 308 rearing stock and 227 brooalstoclc (cununinq. in Ii!!. 1983). Crocodile ranching 1ilas experimentally introduceal into Zinibabwe with the enphasis placed on collecting eggs fron good breeding population areas, artificialfy incubating then and rearing the hatchlings (Ashley, 1980) . Fron 1957 to 19?3 a Lotal, of 22 619 eggs were collected and 16 6?9 \,rere hatcheal, giving '73.62 a nrean hatching success rate of (Ashley, 1980). The stocks come from "government egg supplernentary programmes " anal each ranch is annualfy designateal an egg-collecting areas anal a quota of betlreen 2000 and 2500 eggs that may be collected (Van Jaarsvefalt, i4 litt. 1983) - The ranches have breeding facillties_ with d potentiaf production of 3000 eqgs in 1982 (Van Jaarsveldt, 1982). Actua1 hatchling production from captive- -bred eggs in the year was 1807 (Curuning, in litt. 1983). The hatching percentage and numbers are expecteal to increase significantly each year, but it wilf sti11 be necessary to supplement the breeding stocks with the collection of eggs from the wild to retain genetic viability (Van Jaarsveldt, r9a2) . ID 1981 season 2890 skins were produced for export from ranches in Zinbabwe. A1l skins are marked with nunbered tags and are currently exported through the Crocodile Farmers Association of Zinibabwer records are afso kept by Zifi.abwe Department of Nati.onal Parks and Wild Life Management (Van Jaarsveldt, 1982) . Crocodife farmers in Zimbabwe must provide the Department of National Parks anal Wild Life Management lrith a monthly return of stock on hand, hatchlings, deaths, ki1lings, eggs collected and hatches. Government policy requires that 5X of suitably-sizeal crocodiles be maale available for conservation purposes- This availability "is in the form of ctocodiles of a size suitable for restocking denuded habitats, augmenting wifd populations / research or the meeting of international obligations" (Van Jaarsveldt, 1982) . Discussion Corunercially-orientated crocodiflan farrns have been located in tyenty-two countries using eight main species of crocodilian- The numbers of each species are summarised in Table 3. Crocodylus nilotlcus is the most widespreaal with a total of about 33 000 being kept in ten different countries, folfoweal by grg-qSdyllg pglgsltg, sone 25 000 of which are kept in eight countries. These tsro species are the most highly valued by the leather industry. 8000 gg!!e4 crocodj.lus are kept in Tainan, but it seems that meat and other products may be the main incentive here as together they produce twice the value of rhF skiFs. 426 Crocodilian farning for skins is a relatlvely new industry, the oldest farm having starteal in 1950, and the majority i.n the last five years. Most farns are still building up their stocks, few have started conmercial skin proaluction, anal captive-breeding capacity is findteal by the lack of mature broodstock. ?his is reflected in the figures presented in Table 4, which sunmarise the most recent available data. Skin production from farms is iD the region of 7000 a year from a farm stock of some 142 0OO crocoalillans. Io full production this totat stock could potencially produce about 28 000-35 000 skins a year. Added to this most farms report planniDg to increase their stocks, anai so there is clearly considerable expansion to be expecteal. In spite of the early stage of development of captive-breeaing, the total number of hatchfings produceal on farms is about 14 0OO, whicb, if the fiqures are to be believed, represents over a third of the total numbers collected from the wild wach year. papua New Guinea, Zimbabwe and Australia are the nait] countries where farms rely on wild-caught stock, and of these zin cabwe anat Austratia both have substantial and expanding captive-breeding programnes. Acknowledoements This survey woufd have been inpossibte witbout the willinq assistance and co-operation of the numerous correspondent: who replieal to letters and filled in questionnaires. Their help has been cretlited wherever possible in the leferences, and the autbors would here like to express their gratitude. Funds for this survey were generously provided be the International Iur Trade Federatio4 and IUCN. Literature Cited Anon. 1977. Comprehensive action programme for the conservation of crocodifes- Draft Project 3: Conservation of gglIe4 fatirostris in Uruguay, Argentina and Southern Brazif. IUCN/SSC Crocodile Specialist croup. Anon. 1979a. Croc it to me. The Singapore Visitor February 17 - March 2- Anon- 1979b. The crocodile: a vanisling or a aleveloping resource, Leather (Aprit) : 63-66. Anon. 1980. IUCN Crocodile Specialist croup Newstetter N! 19, Gpp. Anon. 1982a. Aprovechamiento Racional ate 1a Baba o Babo (llgjllq3! crocodilus). Ministerio del Anbiente y de los Recursos Naturales Renovables, Venezuefa. Anon. 1982b. Zanrbia's crocodife firm. The Standard (Zambia) 2l May. Anon. 1983a- IUCN crocodile Specialist Group Newsletter 2(1): 8. 427 Anon. 1983b. Breeding success at crocodile farm. wWF Monthly Report. Septeriber- Anon. 1983c. Managinq tropical animaf resources - Crocodiles as a resource for the tropics. National Resealch Council. National Acaalemy Ptess, waslington D.c. Anon. 1984a, Kenya pfans a home for 2O,O00 crocodiles. New York Times. 4 May- Anon. 1984b. Asia-Pacific Forestry CotrunisioD country reports Philippines. Tigerpaper 11(2) : 1r-13. Anon. 1984c- Nang Fang Ribao (People's Republic of China) l0 April. Anoh. 1984d. USAID co-financing grant proposal. Crocodile conservation arld industry debelopment in Irian Jaya; preparatory phase I consuftancy, 8pp. AnoD. 1984e- Us Fish and Wildlife Service, Enalangered Specj.es Permit; receipt of applicatioDs. USA I'ealeral Register 49 (9r) | I9'74- Anon. unated. Tah Moh Hong Reptile Skin and crocodife Farm.Publicity brochure, 2pp- Ashley, J.D. 1980. crocodilian farming: past, present and future. Paper presented to the society for the Study of Amphibians anCI Reptiles (uSA) and to a meeting on crocodile conservation of the International union for Conservation of Nature anal Natural Resources, Gainesville, I'loriala, usa. Blake, D.K. 1982. crocoalile rancbing in zimbabwe, Tbe zinibabwe Science News 16 (9) - Boonsong Lekaguf 1981. wildlife resources for rural comrunity devefopnrent. Tigerpaper 8 (3) - caugbley, G. 1980. Crocodiles in Burna. FAo Report. chabreck. R.H- 1982. crocodile management prograntnes in Cuba- FAO------, -"p. ruchs, K.l{. 1983. crocodlle farming and ranching in Taiwan, IucN SSc crocodife Specialist Group Newsletter 2\2) | 13- croomlcridge, B. 1982- The IUCN anphibia - Reptilia Red Data Book, Part 1. lUcN. clanil, s!,/itzerland, 426pp. llarrison. G.H. 1981, Raising crocs, not cane. Animal Kinqdom (June/Jufy) : 27-29. King, F,W., Campbell, !{.W., Messel, H- and whitaker, R, 19?9. Review of the status of the estuarine or saltwater crocodile, crocodvlus .p.9S-UC. (Unpublished Report) . 42e Lazcano-Barrero, M.A. 1984- Area reports, Mexico. IUCN SSc Crocodile Specialist croup Newsletter 3(2): 9_10- IJe Francois, R. 1.974. Report- L'6levage du Crocodile du Nile. Centre Technique du Cuir. Lever, J- 1980- Crocodile conservation and industry atevetophent ln frian Jaya. Report on consultancy. spons;red by I,AO, prepared for the Directorate of Nature Conservation, Directorate General of !'orestry. Bogor, Inilonesia, 53pp. Medem, F. 1980. Caimans& crocodiles _ a tale of destruction. Olyx 15 (4) : 390-391. Medem. F. 1980. Sanctioned exportation of caiman hiales fron colombia. TRAFr,rc ( rnternatj.onat ) BuIletin 2(9&10): 95_96. Onions, J.T.V. 1982. Crocodile farm project- Edward River, oueensfand- Australia. proceedings of the 5th Working Meeting of the Crocodile Speciatist croup of the Species Survival Corunission of tbe hternational Union for Conservation of Nature anal Natural Resources conveneal at Florida State Museum. cainesvitle, Iloj:iata U.S.A. 12_15. august 1980. Pooley, A.C- 1980- The decfine of crocodiles in Africa. Traffic (lnterbational) Bultetin 11 (9&10): 94. Singh, !-A.K., Kar, S.,Choud B-C- 198? Indian crocodites: a 10 year revew of management. (This volume). Suvanakorn, P. and youngprapakorn, c. Undated- The breealino of crocodiles in captivity at Samutpralan, Thailand. Tello, J. L- 1983. Mozambique's cropplng scheme in the Zambezi Delta Area. Report presented to 59th SSC meetino of the Internatlonal Union for Conservation of Nature, Harare, Zimbabwe, 16 Aprif 1983. van Jaarsvefdt/ K-R. 1982. The present trade in skins of Crocoalvlus niloticus ranched and reared in Zimbabwe. paDer presenteal to synposiun on crocodile conservation anal utilisation, and the sixth working meetinf of the IUCN/SSC Speciafist Group l8130 Sept., Victoria Fatls, Zimbabwe. Varona, L.S. 1980. protection in Cuba. Oryx 15(3): 284- Walfis, B-E- 1980- Marketing assistance prograrme for agricutturat products from teast developed countries. Market ;rospects for reptile leathers. Ir'r.tCTAD/cA"TInternationaf iraale Cer1tre ITC/DIP/72. Wbitaker, R. 1982a. Crocodife conservation in India- The Zinbabwe Science News 16 (9) | 211-213. 429 whitaker, R. 198b. Export plospects from commercial crocodile farms in Bangl;desh- International Traale Centre/uNcTAD,/GATT ' DcC. ITC/DIP/63. Youngb]ooal,--_'' R. 19?6. Baby crocodiles become big business' Jakarta' oec.mUer. (rites of IucN wildlife Trade Monitoring unit) ' 430 Table 2. Species of crocodilian kept in different countries. KEY: F: farmeil on a farge scale, f: farned on a scale, c : conservatlon/research operations, s: rnainly conservation but some sales may take place, p: proposed operations, ?: status uncertain. ol ;l 9l eilillg. vl rrl Ol .il .:l ql ql s!l qc al El:1-l .,r 'r fil .r ot cl 'fit at .:l 9l 8i !l El il EI dl ,l 5t to! c/l Ol r{l ol il ,l ,i .it cl El ol ot Et ol !l !ls €til Hlct rjt ol ot dl cl ot rt Et El dl ol Ol dl Ol dl dl ol .cl dl -l El El cl etilililgil {rl Ei >l Sgel flil .jl ol crl ol ol ot Fi (,l Australia Bangladesh Bolivia Botswana Bruma Chaal p. China Colombi a cuba India pc Indonesia .F lsrael Italy Ivory Coast p. ,f,apan Kenya f Madagascar f I'4alays i a .I Mali .f Mexico p Mozambique Nepal Pakistan p PNG Phi llppines Samoa .p Singapore South Africa -.r Spain Sri Lanka Surinam f Taiwan I p .f Tanzania f Thailand Togo ; USA p. p Zambl a F zinbabwe F 43I Table 3. Approxirnate numbers of each species of crocodilian kept on conmercial farms in different colntries. "?" represents rDi EI ''{l -rl Lll !l r 2l Et fil il al flal sl 3l 3l !t €t ;l FI EI dt €l !l el 9l 9l qr c'i fl EE fl6l ql 3t fil tl €lH6l gg g8l 9l EI gt ul ,ll ,Jl gE| Austra 1i a - Bolivia ? io- Botswana - Burma soo+ - 4500 t:o Inalones ia _ I6rael 302 ftaly Kenya alg - 4s4 i a fO:S+ 10 Malays - Mafi 34+ Mozanibique - zrooo 9000 3600+ Singapore _ South Africa 1900 Surinam - ? Taiwan - 8000 _- 300 Tanzania 1200 I'bai land _ esiorrroo 88 uSA 20000 Zambi a 2500 Zimbabwe 26000 TOTAL 20302 10000 2000 6612 33001 25500 24236 Lr'700 123 432 Table 4. summary of most recent figures foi the stock, a'rrlual proaluction, breeding and wild-collection of ccllr€rcial crocodilian farrns in different counrrles. Aotal Current Tntake of Number crocodilian ptrduclicn eS$,/adufts FarlrFbrEd of farms stock of skins frcrn wild hatchlinqs '7 Aus tralia 10 963 0b 500 r 69 Bolivia 1 ? 0 Botswana I 70 0e 000. 0 Burma I 900 0b 465 ? Indonesia 000 ? 0 Israel I 309 :o 0 180 Italy 1 406 Kenya 2 839 0 189 Madagasca! 1 454 ? 0 100 9 600 2 0 Mali I 34 0d : 0 Mo?ambique I ? PNG 11 30 000 700 1I 400 o Singapore 3 3 600 ? South Africa 10 1 900 d" u: si Surinam 1 ? ? Taiwan 8 000 000 ooo Tanzania 1 I 204 0c 480 0 1 30 000 200 0 4 800 USA 26 20 000 200 I 700 4 000 Zambia 2 2 500 ?a t 4\7 + 0 Z imbabwe 5 26 000 890 9 421 + 807 TOTA]- 134 142 r?5 12 990 32 093 + 13 e96 Believed to occu!, nrmbers unknor/n No infornration Planned for 1983 b Planned for 1984 Planned for 1985 d Planneal for 1986 433 THE PECULIARITIES OF CROCODILIAN POPULATION DYNAMICS AND THEIR POSSIBLE IMPORT,ANCET'OR MANAGEMENTSTRATEGIES Wilfian E. Magnusson DepartflaenLo de Eco.Iogja, TnsLituto Nacional de Pesquisas da Amazonia calxa Postal 478, 69O00 Manaus, Amazonas,Brasil The concept of r- and K- selection has provialed a useful frarnework to compare life-history strategies (Pianka, 1970) - rt is possible to identify species that contain fong lived individuals aud which produce small nuribers of youno each of which recieves a large investment in terns of energY from the parent' Populations of these species are generally considered to be relatively stable and llmited by resources/ resufting in competition between juveniles (K-selected). species which are subjected to unpredictabfe conditions will not reach the carrying capacity of their habitat- .luveniles wilf suffer high mortality regardless of the investment by the parent so selection is for the production of large nuncers of inexpensive young which can disperse in search of favorable conditions (r-selectioh) . the uncritical use of r- anal K- sefection anil its various definitions have been criticized (Parry. 1981), but the concept is logical and groups which do not fit on the r-,/K- continuum deserve careful scrutiny. crocoalilians are one such group. Adult crocodilians are large {masses of adult fenales range from about lOkg.for Pafeosuchus to over 150k9 for g!9g9d11ltg) and are amongst the most long-lived vertebrates (Gibbons, 1976) . However, clutch sizes are large (ranging from about 15 for eglggsgelUq to over 60 for some species of Crocodylus) and neonate sizes are tiny in comparison to tbe motber.-T iE6iate of Paleosuchus triqonatus (a small species ith a smal1 clutch si?e) weighs only about O.5x as much as rits nother. larger species have relatively smaller neonates. This is the paraalox. The theory of r-/K-sefection says that Iarge. lonq-lived animals should invest their reproductive effort in few, large yo\rng. crocodilians are large and long-lived, but produce many young that are amongst the smallest relative to the mother, of any reptife. why crocodilians are different is of more than academic interest- The management strategies appropriate for r- and K-selected species are usually quite different, especially under exploitation. llere f lril1 try to synthesize what is known of a nunlcer of species of crocodilians from many different habitats in an attempt to identify pattelns anal indicate areas which are in need of more research. Attempts bave been made at moalelling the population alynamics of allioator mississrppiensis (Nichols et al ., 1976) and crocodvlus niloticus (Blonberg et al., 1982) - Those models have considereal the physicat factors affecting recruitnent (mainlY water fevels) and their interaction with one biological factor, non-selective density-dependent cannibalisn on the smallest size classes. Tbese models and other, less explicit, managenent sclemes (Bolton and 434 Laufa, 1982r Whitaker, 1982; Btake and l,overdige. 1975) assume that crocodilians proaluce an excess of "expendable,, youno whii,ch can be cropped \,rithout influencing adult populations lev;Is. Assuming that crocodilians diai not evolve this strategy purely for the beneflt of wildtife manaelers, there must tave-Eein selective advantage for females which produced many small young. Why-not produce a few, 1arge, competatively-superior young? Such young woulal be inrnune to attack by many oi ttre predators known to fake hatchting crocoditians- ihe loqical co-ncluslons are that t]tose predators are not important, or that ]arger young are not competatively superior. With whom woufd the vou;o crocoalilian be competing? Food ]imitation has not been sliown to be a major factor in crocodilian popufation dynamics (though it has been littfe studied) so the resources for hich the young compete would most probabty be space, mates, or both in the case of territorial species. Could a young strong indivialual in a poputation of crocoali:rlans displace on a old weak individual fron a territory as might occur in a population of inanunals? Alnrost certainly it could noi. Crocodi.lians continue to grow long after they reach sexua.l naturity. A recently mature aninal wilt atr..'aysbe at a critical weight disadvantage. It is very unlikely that it wilt survive, much fess \,/in, an encounter with an older individuat- Adult crocoalilians are long-fived and have few predators. Unhunted popufations of adufts probabty increase until they are limited by resources (food, space, mates) . under natural ;onalitions rhere is probably intense cornpetition for these resources and it rs the small. recently mature animafs which wiff tose out in this competition. The only chance a young adult has of estabfishing itself in the popllatlon is to find a ptace in which the resialent adult has died, which is a refativety rare occurrence. The crocodilian reproductive strategy can now be seen to be reasonable. In the absenie of any chance of making her young competatively superior when are seeking to enter the adutt population, the best strategy for a female is to produce targe number of smatl youlg, anal hence increase the chance that at l;ast some wilt happ;n upon a vacant area. It is the stability of t}le adutt populations that makes the environment unpredictable for young croc;diIrans. ?he itleas outlined above differ substantiatty from the nodefs of Nichols C! e!. (19?6) anal Btomberg e! gf. (1982) in which most mortafity due to conspecifics is thouqht to be a result of cannibalism on the very smallest size classes. What is the evidence? Canniballsn of hatchlings atoes occul, especialfy unaler conditions of extrerne crowalinq in zoos, but there is ampl; evidence that crocodilians haie complex behaviora.L repeiiotres wtricfr normafly resuft in the protection of sub-adutts by adults rather 1n cannibalism (e-g- Hunt, 197'7t pooley, L971 , 19e2). cErmibatism in the wil-d has been reported for gE;he4 crocoatifus (Staton and Dixon, 1975; Medem, 1981), Alfloaror missilFipotensts (ciles and Childs. 1949r Valentine et al.. 19?2), Crocodvlus niloticus (Cott, 1961; Pooley, 1969), crocodvtus porosus (worretr, Fs64; webb ana Messel, 19??) , crocoalyl-us gg.q!!g (schrnidt. 1924), Paleosuchus pafpebrosus and P. lEtgglqlE (Medem. 1981). However, these records tre comparatively rare consialering the nunber of detaileal studies that have not reveal-ed cannibalism. Grahan (1968) and Blomberg 11977) exanined 239 and 493 stonacbs. respectively, of q.4!-L9!&u9, rnany of which were atlufts. Neither author reported remains of crocodiles in the stomachs. Taylor (1979) found no evidence of cannibalism in 239 stotnachs of subaalult g. Dorosus, seijas and Ramos (1980) reported no canibals among the 49 9. elglgqlllg thev exanineal, and webb 9! 3!. (1982) founal no crocoalilian remains in the stomachs of 153 g, iohnstoni. clearly, members of their own species normally are not important items in the diets of ctbcodiliens' sizes of cannibals and their victims are rarely reported, but there is strong evidence that most canibalism is coincidental to social interactions between adults or between adults and alnost matule subadutts. c:iles and childs (1949) reporte a 45cm A. lqiEglsgtEigglg from the stomach of another individual. That is the only documented case of cannibalism of a small Juvenile bY a crocodilian in the wild that I have been able to focate- cott (1961) and Poo]ey {1969) report cases of g-a.Sg-qdllf.C-gniloticus about ln in length being eaten by individuals about 4m long- only 2 of 17 cannibals recoraled by Cott were less than 3m long. Schmidt (1924) repoits a 120-150cm 9. acutus that was eaten by a 3m conspecific. staton anal Dixon TlsrS) report two 40-50cm s\/L {80-10ocn total lenqth) g' crocoalifus that were apparently cannibalizeal. tledern (1981) reporteal ttre le"qtlrr anal sexes of two g. crocodilus, a 9. pgbgbll]€gg and a 9. trloonatus which cannibalized conspeciflcs. A11 were large ;du1t mates. carr (in foreward to the 1976 reprint of McrlhennY 1935) referring to a large female afligator resident on his property said: "Young alligators, her owD or others that wander in ironr tlrne to time, alwaYs disappear when tbey get to be five or six feet long"- webb and Messel (1977) reported bigher injurY rates of g. po;osus when they approach sexual maturity and report a 58cm sw-inaiviaual {about 115cn total length) that was apparentfy kilfed but noteetenby a larger conspecific. The evidence for fittle cannibalisn on very young animals, but intense social interactions between aalults and farge subadult young lttrich often fead to the aleaths, but not neceesarily cannibafisn. of the latter, is strong' Strangely the only population model of crocodifian population dynamics- to consiaei lhis aspect is that of Messel e! e!. (1981) - rtre modefs of Nichols e!.3!. (1976) and Blonibers e! d. (1982) include exactty the oppoiite process: cannibalism for the first 3 years and none thereafter - Hunting mortality (at reasonable 1evels) is conpensatory for natural mortality. rathe; than aalditive to it. for nrany species (Anderson anal Burnhan, 1976t Burnham et al. 1984). It is not kno{n whether hunting mortality is coropensatory or additive in crocodilian populaiions but the two models describe above differ in the alegree lo_which huoting mortality is tikety to be compensatory. If almost all natural mortatity occurs before the animals reach commercial size (the nodels of Nichols e! 4., 1916, and Blomberg et al., 1982), hunting mortafity nust be additive. If there is significant mortality of subaalults after they reach comnercial size (Messel C! Bl. 1981. this paper) hunting mortality nray be partfy compensatory. 436 Uost models of the populatiot) dynamics of huhted species assume tlat. mortatity is positivety relaLeal to p"p"f.ti""'a"".itv, rs thrs neccess€rily so for crocodifians? ?he evidence qiven above"". strongly suggests rhat many subadults die in conflict! wilrr -Larger tnctividuals, but the toferance of adult6 for conspecifics rs not fixed for a species, it varies with the experienc; of the animals. captive-raised alligators (Al Iioator misiisstprciensis) can be kepr at denslties ten tillles trigner rhan-;;;;;ts-:apturea fron the wild (;Ioanen and McNease, 1980) . over tonq p".ioi" tine the hinumum exclusive area demanded ly inalvi;u'afs witnin"f population the probabty contracts as simillr sizeal indivi.duats tar(e up areas within the territories of farge conspecifics that heve-died- The limit witl be determined ly ihe .."i"i... avaifable trood, nesting ponds etc.) . Hunting for extended periods (10_20 years) may severely affect the densities and size distributions of cro"odi_lian popufirrons. The few wary animals that survive rnay l"co.e i" tn" exclusive use of very Iarge areas (superterritorie.i."c"urton,ei at ["" cessation of hunting, reproduction sbould s\rpp]y recruits to the Dreeorng population but wifl the resident adults which are very l€rge (they have been growing throughout the perjod iruntr"gl , ano used to the exclusive use of large areas. aflo!, the"f large subadults to survive? In sone situatio.,. su"h as the tid;i rivers of northern Austrafia (Messet e! a1., IgBl) it ;;;;ar_ that they do not. Nonetleless, other spectes of cro.oaiiian, that were heavily hunted recuperated quickly (e.q. Atlioato! - patmisano mrssisstppiensis et a1., 1973). Tr ia fiket-v Chat the structure of rhe habirat intr""n"e, tir. ii ty-"i-i".g" animafs to maintain excfusive use of large areas."Ut in strnoie habitats such as rivers anct streams unr.it. ^ay patioi ltei. entlre territories in a signle night (of tfre oi.dlr of ltm of paleosuclus water_ course for trioonatus and possibly tens of kms or caca-L-rrvers tor Crocoalvlus porosus) . It would take rnuch more tlme/ and cost much more in terms of lost feeding opportuhities for. an.Allioalor mississippiensis to patrof .i."-Lr *"i"r, watn slmr-tar .Linear dimensions. The more complicated"" the habitat, the fess likely that attered sociat systems in hunted popoi.t.or," will inffuence the rate of recovery. carrick anat r,ano lfgZi, suggested that the difficu-tty of encounter'ing conspecifics in marsh habitat has fed to the evolution of calls as a major social signal in marsl crocodilians. Rlver and lake specles us6 visual signafs. The costs associated witb trying to miintain exclusive use of large areas probably iesulted in tittte selection fo! territoriality in species that live in marsh anal swamD systeru even before the aalvent of intensive huntihg. Another important difference between Atlioator ntssissippi.ensis and other species of crocodirians is the occurrEncE-ZE-I$ft.ac segregation between t}e sexes. If the hypothesis I presenteal at tbe beginning-of (that juvenlle _rhis-paper s"rviv"r'is r".gery lndependent of adult density in crocodilians) is true the ;ost efficient management strategies woufd aim at cropping before _luvenites the bottleneck wben they rry ro ehter the- ;duit-;o;;lati on, 437 and maximise aalult Clensities (e.9. management programs of zimbabwe (Blake and Loveridge, 1975) and Papua New Guinea (Bolton anal Laufa. 1982). conventional wilallife management wisdom that the maxinuin sustained yield is obtained at about half natural densities (caughley 19?7: 180) probably does not apply to crocodilj"ans - Harvesting adults of Allioator misslssipDiensis is efficlent onfy because hunting mortallty can be concentrated on rnales, anal hence has 1itt1e effect on recruitment (Palmisano et a1. 1973). Hunting reduces the nesting femafe cohort of crocodvlus nilotus to about 7U of equllibrium levels in the model of model of Blomberg e! ef- {1982) ' T}re mottel population is then unabfe to naintain sufficient recruitment to sustain commercial hunting. The authors suggesteal that egg collection and captive raising r^ras the only viable management alternative for this population, However. such schemes are costly anal like1y to involve techniques not suiteal to the technological abilities of the local people (Magnusson, 1984) . A different hunting systen concentrating on large subadults, that avoialeal mortality of adults or at least of adult females, coula well yield very different results. The initiaL effect of hunting on a species depends on the value of its skin, its population dynamics, and the ease of hunting the area. The rate of recovery after hunting may depend on behavioral- factors sucb as those outlined earlier- It is not possible to differentiate the effects of these factors lrith the alata presentfy available, but it is obvious that in concert they have resulteal in riverine crocoalifians suffering more from hunting than species in other habitats. A11 species of crocodilians that are intenslvely hunted are listed in the TUCN Red Data Book (Groombridge. 1982) as endangered, vufnerable or recovered (out of danger). "Endangereal" indicates that the species has suffered badly from hunting' "vulnerable" indicate that the hunting, although not presentfy endangering the species, is uncontrofled. "Recovereal' applies only to tbe Ameiican alligator. Tabfe 1 shows the status and habitats of crocodilian species important for the leather inalustry that are affected primarily by hunting- other species (AIlioator sinensis, caiman latirostris, crocodvfus mindorensis and g. rhombifer) listed in the Red Data Book, but for wbich it was not possibfe to alifferentiate the effects of hunting from habitat alestruction, were not included' crocodvlus niloticus may be considered to have as its primarl' habitat rivers. lakes, swanps or savannas depenali!1g on the population, anal some populations migrate between habitats (Pooley, 1982) - Likewise. the populatlons are variouslv endangered, vulnerable or recovered. As it was not possible to obtain reliable data for each population, thls species was not included in the table. ?he many subspecies of Calnan crocodilus occur in a !€rieLy of habitats, but most of the coromerce in the species is presently based on populations in savanna habitats, so it was included as primarily a savarlna specles. Species such as 9q!99!j1e!!q tetrasDis and crocodvlus cataohractus, listed in the Red Data Book ae "indeterminate" were not includeal. Designation of a particular habitat as the primary habitat for a species is subjective in 438 some cases, but the overall pattern is obvious. l4ost enalarrdarA/i spectes tive in rivers or takes, and most l;"4-;;;:---- resisteal the deleterlous effects of hunting "p..i",live in swa.ps or Rivers and lakes are relatively simple systems and are easity buhted, lrhereas hunting in swamps and marshes is nuch more difficult. Savanna habitat.s are easily hunted in tf]" ary-."""o", but the- t\,ro savanna species have comparatively low gradl skins. Nonetheless. these simple observations *ay nol be .o explain the slow natural recovery of some species ",iffi"i.r,.p."t".tt"" is enforced. We need to know more about the effects "i[.,of frunt,-^ ^- the social structures or populations in diffe;;;a;.;;t;;;:"'.-' popuratron models baseal on Altioator mississippiensis,-to-ti"coa:iii the best studied crocodifian, nay n"t t)e apprtc;;fe rr_t.^ ih other habitals. "". In stxrunary-: Indeterminate growth of adults may leaal to tow anat unpreorcrabre recruitment of Juveniles into aduft poputations of crocodilians. However, there is titrte evidence tr,irt'="ivl""r juvenifes, of up to the pornt that tlley are atmost .aiuie, .u dependent on adult densrties. Therefore huntinq strateqies that mi nimi ze _mortatity of adult females should maximise ,";;;i.."". .!iT.t: to_the juvenile :: and. porentlalty, ti,e r,u"iea- popur"ti on. of. adurLs on ll"_:-:,:::". rarse, afmost r.arure, subadurts appear so hunt.ing shoutd take ptace before Lhe luvenrfes reacn the size at which adults no tonger toferate them (aLout 1.0 _ 1.5. for most species) . More work neeals to be done on the effects of hunting and lrabit.ar on crocodifian social systems i" ;;;;; ." efficiently manage recovering stock of "ro"oai1i.r,.- Anderson, D.R. and K.p- Burnhan 1926. population ecology of the mallard: 6- The effecr of exploirarion on survivii- u-s. Fish Wild]. serv. Resour- publ. 128: 66pp. B]ake, D.K. and J-p. Loveriatqe 1975. The role of commercial crocodife farming in crocoalile conservatlon. Biot- Conserv. at 261,2'72. Bfomberg, c-E.D. 197?. Feealing ecology, nesting ecologt, and habitat preference of Okavango crocodifes- Botsw;na r,tot63 nec. Z: 131-139. pierre, Blomberg, G.E.D., B.c. st K.D- smitb, s.M. caatdell and s.R. Pett 1982. Simulated popufation dynamics of crocoaliles in the potswana. pp, Okavango River, 343_375 II D. Dletz. F.W. King and R.J- Bryant (eds) Crocodiles: proc. Sttr Workind Maar Croc. Spec. croup of the SSC/IUCN. Bolton, M. and M. Laufa 1982. The crocodile project in papua New Guinea. Biol. cons. 22: 169_189. 439 Burnham. K.P.. G.c. White and D.R. Anderson 1984- Estimating the effect of hunting on annuaf survival rates of adult mallarals. J. wiId1. Manage. 48(2): 350-361' CaughIey, G. 19?7. Analysis of vertebrate Populations' John wiley and Sons, London. ecology cott, H.B. 1951. scientific results of an inquiry into tbe and economic status of the Nile crocoalife {crocodvlus nifotus) in Uganila anal northern Rhodesia' Trans ' zool' soc' London 29 (4) : 211-356. Garrick.---- L.D. antl J.w- Lalrg 19?7. sociat signals and behaviors ;; adult alligators ind crocodiles' P'rner' zo11' l'7" 225-239 ' Gibbons, J.w. 19?6. Aginq phenomena in reptiles' Pp' 453-475 I! (eds)- M.F. Elias, B.E: Eleftheriou an't P'K' Elias special Harbour' i."i"".' Experinental Aging Research' EAR Inc" Bal "f the ciles, L-w. and v.L' childs 1949. Alligator management on Sabine National Refuge. J- wildl' Manage- 13: 16-28- (croco'lvfus niloticus craham, A. 1968. The Lake Rualolf crocodife Laurenti) population. Report to the Kenya Game Department bY Wildl. Services Ltd.: 146PP' - Book' Groonbridge, B. 1982. The IUCN Amphibia Reptilia Red Data Pari. 1- Testudines. Crocoalylia, Rhynchocepha li a ' IUCN' Gfand:426PP- crocodiles llunt, H.R. 19?7. Agressive be}lavror bY adult Morelet's "-'--' 33(2): iii"""ayr"s ioreleti) towaral voung' J' Herpetol' 195-201 . the American ;Ioanen, T, and 1,. McNease 1980. Reproductive biology-of alliqator in southwest l-ouisiana' Pp' 153-159 l! .J'B' Murphy iii-i-i. c"rri". (eds) Reproaluctive Biologv and Diseases of captive Reptiles ' SSAR, Lawrence' W.E. 1984. Economics, developing countries and-the Magnusson, ' 12' capt1ve p!opagatron o! crocodilians' wil'11' soc' Bull L94-197 . Facsimile McIlhenny, E'A. 19?6- The Alfrgator's Irfe bistory'. Re;rint bv the SocieLv f;r the studv of Amphlbians and n.itif." of tl. tglS ;dition pubfished by christopher lrriti"hittg tlouse, Boston: xvTrr = 1l?pp- Los crocodvlia Medem, F. 1981. Los Crocodylia de Sur America vol 1' de colombia. colciencias, Boqotd: 354pp' surveYs Messel. H.. G.c. vorlicek, A.G. Wells and w-J' Green 1981' of Tidal River Systens in the Northern Territory of Australia Blyth- anil Their crocoalile Populations' Monograpb 1' Tbe Dorosus cailell Rivers system studv and the status of 9r9q.99llqg in Tidal Water ays of Northern Australia' Methods lor g' Analysis, antt Dy;amics of a Populatlon of .p.S!gs!g' Pergamon Press, sYdneY: 463PP- 444 Nichols. ;I.D., L- Viehman, R.H. Cbabreck and B- Fenderson. 1975. Sinulation of a conunelcially harvested alligator population in Louisiana. Louisiana state univ. Agr. Exp. stali;n Butl. Palmisano, A.W,, T. Joanen and l- ltcNease 1973. An analysis of Louisiana,s 1972 experimental alllgator harvest piogram. Proc- Ann. Conf- SoutheasterD Assoc. Game f,ish Conrfi. 2?: la4-206. Parry,-c.D._1981. The meanings of r- and (-selection- Oecofogia 3at 260-264- Pianka, E-R. 1970. on r- and K-selection. An- Nat. 105: 592_597, pooley, A.C. 1959. preliminary studies on the breealjnq of the Nile crocodile Crocodv.Lus nrfoticus, in Zululan;. Lanunergeyer 3ll0) | 22-44. Pooley, A.C. 197?. Nest opening response of the Nile crocoalile Crocodvlus niloticus, J. Zoot. London t92t l'7_26 - Pooley, A-C. 1982. Discoveries of a crocodile man. wilfiam Col1ins, Lonclon: 213pp. Scbmidt, K.P. 1924. Notes on Centraf American crocodiles- Field Mus. Nat. Hist. publ., zoo1. Ser 12(6)t 19-92. Seijas, A.E. and S. Ranos 1980. Caracteristicas de La dieta ale la Baba (ggllgg crocodilus) durante la est.aci6n seca en fas sabanas modulas de Estado Apure, veoezuela. Acta Bio;. Venez. 10 (4) : 3?3-389. Staton, M.A. anal J.R, Dixon 1975. Studies on the dry season biofogy of Caiman crocodilus crocoalilus fron the Venezuelan Lfanos. Mem. Soc. ci. Nat. La salle 35(101): 23?_265. Taylor, ,J.A. 1979. Tbe foods and feeding hablts of subadult Crocodylus porosus Scbneider in Northern Australia- Aust- Wifd1, Res.6:347-359. Valentine, J.M., J.R. Walther, K.M. Mccartney and L.M. Ivy 1972- Alligator diets on the sabine National wildlife Refuoe. Louisr ana. J- Witdt. Manage. 36: 809-815. Webb, G.J-W. and H. Messel 1977. Abnormalities and injuries in the estuarine crocodile, Crocodylus porosus. Aust.Wildl. Res.4:311-319. Whitaker, R. 1982. Crocodile conservation in India, Zimbabwe Science Ne\,rs16 (9): 210-213. Worrell, E. 1964. The Reptiles of Australia. Angus and Robertson, Sydney:20?pp. a.. 3 err:p E5 axxxax s; P> ;.i 9;. 'i!o ol ! 9 -4 'it 9;.: ;:lXdu or 6l i f 9 cl il .il ol q _: - 3l al il dl ; ; "r,l ol ot ot ot o 6" = 4 it -Et!t :l dl i i i + .2 gl .rr ir dr.rl ! j ' I ; 6l ol bl b, d d rl ,l ,l rl !l > * - - r,l "1 ;l ;t ;l ;l ; -:; a !l ;l 442 6l Romufus whitaker Maalras Crocodile Bank Trust Vaalanemnefi Vi11age. Perur P. O. Mahabali.puram Road, Chinqleput Dist Madras-603 104 In 1975 the Maalras crocodile Bank was established under the management of a non-profit Trust with the support of the Madras snake Parl<, the Worlal Wildlife Fund and the Tamil Nadu coverrnent. The main objective of the Trust was conservation of India,s three crocodilians by captive bieeding for release and public education. These ongoing objectives are afso being carried out by several State and Central covernnent projects, originally sided by FAO,/ UNDP- The status of fndian crocodilians is not yet satisfactory but most of the \"rork to be alone now is habitat protection by the State tr'orest Departments. In 19?? the Trustees approveal a nove to establishing the Maalras Crocodile Bank as an international bank with the nain objective of estabfishing a gene pool of every species of crocodifian, The following year at the fUCN/SSC Crocodile Specialist croup meeting held at the Crocodile Bank the Group members also approved of the proposal. Tbe tropical clinlata ,feed and water avaitability and low overhead costs aff contribute to making Madras an ideal locality for the Crocodile Bank. The breeding records of three species (Tabfe t) indicate the suitab:lity of the Bank to establisb breeding qroups of the other crocoalilians. Already over 400 mugqer offspring have been supplied to State restocking and breeding projects in India (TabIe 2). while severaf countries are not, at present looking after their crocodile resource, it is always hoped that times wifl change and enlightened conservation/management policies implemented. At such a time, the value of a source of young crocodiles of the desired species for restocking protected habitats cannot be underestimated. The uftimate success of the Bank \rift depend on the co-oDeration and assistance of crocodile and zoo peopie world-wide. S_urplus, non-breeding animals are better used in a breeding programtie than as disDlavs - 443 z o a 4,4 ooo o ,+'oo0) 217i' oorrtrd o EA A tr EO zaa ooordfil o .-t!trrli 'ipEo6l!.cl!l! o EoOi!,Clolrd '!OCrrrDid!..1 F3 E6 o o o 7.t .dl rrl ol trl ol ol '.{l rrl cl ot ot ql ..al el ol ol ol F 444 ITUI,TIPLE CLUTCHING: CONSERVATTON AND COMMERCIAL TMPLICATIONS Romulus Whitaker Madras Crocodite Bank Trust Vadanerunli viltage, perur post Mahabalipuram Road. Madras-Oq3 !L! Among the reptiles some tlzards and turtles produce successive of esss- rhroughouL an extended breeiinq as: "!.h:: AjpAng_sp., chelonia !yge-g) or multiple clur;hes"."""n-i"""n per season {such as Pseudemvs sp., Chrvsemvs sp-), Unlike any ot.her crocoditian studied. mugger (Crocoalvlus pa.Lustris) at tbe Madras -to Crocodlf e Bank have demostr;Leat E-iEli.ity- ne.t twice in a single reproductive season. Eight femal;s in tro orrrerenr ehclosures (one at Madras snake park, 40 kn. north)lay a.second of eggs about 40 days afrer tr,! iir.l. li"t.t .l19 _clutch hatch_ing success is only s-fightty rower in ir,"-J""""a 3n9(see clutch rabre 1) and clutcb size ;.,r".;s"; .i. .i^ii.i-." tbose recorded in tlle wild- A single male is involved in both breeditrg pens but it is not yet..known whether- a srngle nating fertiliiei U"t}, cr"tcf,"r. as stlIt regutarly seen during and dfter the period ( first tavjh- February-March ) it is guesseat that the females are fertifized twice in the season. Factors hrhich nay ptomote the production of multiple ctutches mugger tn are not known but it is surmised that the;elativety hrgh year round temperature and abuDdance of fooat maale .""ii"Ui" t" the captive rnugger are impoj:tant. The double clutching phenomenon is beinq stualieat at Madras crocodile Bank and it is hoped to be abie t" q"."iir;-."d- sEanoardlze Lhe factors conLributing to Lhe doublil1g of the eSS annua-L Assuming that other rrave tfrJ same- capabrliLy,.ll:ld. "ro"odtlians rhe implicaLrol)s of doubling proau.it"n-.ri itu,ou. oorn ror conservation programmes, wherein numbers enoangered_a, of crocodilians urgently need buitding up and b) commercia_L usase_wherein the object ia to;roduce." *;;;;i.;i;.;;,'., possible. t+45 3 Io E ft, E *uz' 5tl 0 ql otr il ;I :t 1!oo k4 a e .o o gE F 446