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t - THIS DISSERTATION' LA TH~EA* ET~ HAS BEEN MICROFLMED . MICROFILMEE TE EXACTLY AS RECEIVED -NOUS L'AVONS THE SOUTH AUSTRALIAN-PRAWN SHBRY: A CASE'STUDI OF LIMITED
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t Name: * Jeffrey &* - - - ",-- --
"l 0 - - - 'i. kgrw: NY~tero-~-AL -- ' ------,Title of ~hei'is: The South Australian Prawn ish he;^: A Case Study of Limited Entr.y Regulation . 1
> Exami &pit tee : . a Chai r~ersdn: S. EastmJ
-- - - A A- --
P. Copes Y Senior Supervi sor
D. Maki
R. * ~rowh External *Examine Department of Ge 34 . raphy - -- PARTIAL COPYRIGHT LICENSE
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Title of Thesi s/Dissertation:
- The- S outh- Aus t raM pri-Pf-am--~Fis fteery :--X Case Stuay 3 F TimitedDatta -- / I I Regulation
Author : '(sigdaturG
Jeffrey L. Byme
19 December 1978 (date) li , . - d 5 1 B 8 ABSTRACT '1. / I?- 6 The prawn fishery in South Bustdralia has, .since its f inception in the late 196.08.s, been subject to limitep ?try.
reguzalion. It -has, as a resuft, avoidefthe orer&ioitatioq3 problems nor~allyassociqted witli coaman p . .
exploitation of the prawn stocks. In addition, the wealth and
L ------efficiency implications of the current practice of allowing operators 'to retain all resource rents have. not been fully ' I 4
considered. This thesis attempt& to shed sone light on each of % these rat*Frs, ' 3 - B'ionomic models for each stock in the fishery were -- - constructed based on the fitting cf surplus yield------functions to ob&rved catch and effort levels. This included development of nethods to stanaardise effort for changes in fishing unit characteristics and seasonal patterns of fishing. Analysis suigests that ad justaent bf 'the current number of licenced 0peIatQrs 'in each region is unlikely to signffieantly . . increase lave IS qf0,eoonomic rent, but that operator efficiency 1 and the rant levd in the Gulf st. Vincent region would be
operators at present appear to have an adverse effectkn
Y. ABSTRACTm.m.a*wm.m*wmmm ...... &...... iii LIST QF TABLES ~.,,4...... t..mvi~\- . LIST OF FIGURES ...... m...... m...... o...... viii~
INTRODUCTION om*mmo..l ...... - --up I ------BACKGROUND NOTES ON THE SQUTH AUSTRALIAN PRARN FISHERY...... 6 '.
% THE~JUSTIPICATIOBFOR REGULATION OF PISHERIES...... 7
- -.'tkvsic~asr~ OF ~ff~FIS WR~ ~TSREG~WATI~H.~ .\-c;-. .~r , BIIILOGY OF THE SPECIES...... m....m...... l9 . . THE *ISRING OPERATION AND STRUCTURE OF THE FLEET.. .22
SEASONALITY OF THE FISHERY* . . . a m6m 35 . THE IHPOBTAICE OF THE 49
THEORETICAL ASPECTS OF THE PLUS OF A FISHERY rn e3 5 - -- THE CCNCEPT OF ECONOHIC SURPLUS...... mm..m...... 56
THE YIELD PUNCTIONmm..m mm.mmmmm.~rnmm*mmam.e*.mm*m*mm~m*mmm61 \ THE ESTIMATION OF FISHING'EPPORTm.~m.mm..m..~.m...~'~m..m~..mm.71 .
A HODEL OF VESSEL PISHfNG POWEBmm.mmm-mmmo*mmm*mm*mmemm~~m72 ......
.I * STANDARDIZATION OF EFFORT FOR IISHING POY ER CHANGES...... a1 . - STANDARDIZATION 0 F EFFORT FOR I NTRA-YEAR DISTBIBUTIONAL CHANGESmmmm*...m.mmmm*m*mm*m*mmmemmmmm.mm.m~*m*.*m*m~m9O
- e ESTIHATION OF THE OPTIflBH LEVEL OF EXPLOITATION...... 95 - - - '9 b ESTIHATION OF RESOURCE RENT. . .e 0.. .I16 QUALIFYING CONSIDERATIOBSo.~..~m~m~m~e~ee~m~~m~~~~~~~~~~~l22 REGULATION OF PRAWN CAPTURE S'IZE...... -127 ALLOCAT~ONOF ACCESS RIGHTS AID DISTRIBUTION OF RESOURCE 1 c RENTS 133
- - ...... - * * ------THE CHOXCE OF THE ACCESS RIGHT UNIT...... I34 CLAIMANTS TO THE. RESOUBCE RENTS...... -145
AL~OCATIOII OF ACCESS RIGHTS...... h,. -167 5% I ITS ON ISSUE M4D FOR YEAltS 1968 TO 1977 ...... 16 . /- i I I AVERACE VESSEL LENGTH AND BEP MID PERCZRTAGE OP 4 VESSELS USING D~UBLERIG BY FLEET ErOR YEARS 1968.
TO 1977 m...... *...... c...r..*...... 26 ,
-..- XXI ------.4-swEB-.pI4lf.-wSfEfi FOR- eAmIFtEET------y IN YEdRS 1971 TO 1977 ...... i...... 33 . 1
IV BlWTELY BPFORT INDI$ES BY REGION FOR PEABS 1968 ..-% TO 1977 (AVERAGE MONTHLY ABUNDANCE,IN EACH YEAR-100).. 39 $?' ------\ V HDRTHLY ABUNDANCE INDICES BY-REGION FOR YEABg 1968- TO 1977 (AVEEUGEEIONTALY BFPORT IN EACH YEAW100).,... 41 P' P' PBAW FISHERY POp YWS1969/70 TO 1976177 ...... 50 "e 8 s F., - VII . ~T~LUTEDTOTAL VALUE OF AND VALUE OF AVERAGE CATC~~PEROPEBATOR BY YEARS 1969179 TO 1976/71 .r....+...... ,...... 51 h
cma. EFFORT AND CATCH PER UNIT OF ~RTBY~REGION FOR YEARS 4968 TO 1977...... 100 ESTIMT REGIoBsAL YIELD CURVES...... '...... 105 HYF'OTKETICAL RANGE AND OPTIMAL RESOUllCB \ RENT LEVELS FOR SP ...... 118 n - \ 6-- + pr1-~~~~~~~~~~~~~ FI8EING - t - . F4EET FOR YEARS 1968 'Nl 1977:...... t...... 139 -- - -- \ / XIV HYPOTEETICAL 'SP BATE SCALES FOR MCR-REGION AT 1977-78 LEVELS...... ,..;...... r.... 163 t
XV TY PAmSWHICII MDU~DHAVE BBK# Onom CAL ROYALTY BATE STRUCTURE BY OPERATORS IR THE YEARS 197 TO 1977-78.,.,...... 165 - )t er 1 'P C PBAW sJSHING REGIONS IN SOm AUSTRALU...... !\I0
I &TIVE PREQUENCY DIsTRI~TION!~ OF VESSEL LERGTIi POll WESq-COAST SPB((CER GULF KBBT...... y...... 24
AVERAGE mmy EFFORT INDEX LEVELS BY REGION odYEABS 1971 TO l977;...... ,.,...... ,...... 44 % AVERAGE mTRLY ABUNDANCE INDEX LEVELS...... ,.....8...... 46 - -- - b ------DYNAMICS OF AN EXPLOITED FISH STOCK...... ,... 62
RELCLTIOIOSRIP BETWEEN STOCKTOCKWEL, RECRUI'MENT AND SUSTAINABLE YI-...... 66 . 95% CONFIDENCE I~RVACSrn~ LOG(LE#GTII) ,~OEPFICIENTSUS~G OVERALL, EtBGIONAL ANTJ YEARLY DATA...... ;...... 84 . . 95% CONFIDENCE INTERVALS FOR U)G(BEP> COEFFICIEHTS USING OVERALL, REGIONAL AND YEARLY DATA...... 85
------95% COWFIDENCE INTERVALS FOB DOUBtE RIG COEFPICIHNTIJSIXG TOTAL, RBGIONAL AND YEARLY DATA...... 86
95% GOHFIDEHCE INTERVAL Pr)R LEAEN C0EqCIBW.C *USIS TOTU, ReGIORAL MID YEARLY DATA...... ;...... 87 YIELD, PBWWE rUlD COST CURVES FOR WE& COAST luoXoll...... lF1 \ ' YIgLD, REVENUE AND COST CURVES FOR SP~ERCULF REGION.. ... 102 I YIELD, RETENUE AND COST CURVES FOIL GULP ST. VIIBCKHT REGION. 103 The economic theory of'the exploitation*of colnmon property ,. fishery resources has become widely known since the subject was d first elaborated in seminal articles by Gordon (1954). Scott
, 0955) and Crutchfield (1956). It is now generally accepted that
i-r; -order -trubtai;n resarnrce-rent-s 3rld m --a fTS~~~~~~;~FCWS~~T---
stock must be caref ullp regulated. 1 NMost of the fisheries of the worJd have traditionally been B - - - = ------. open entry.' hence discussion to date has centred largely on ways to achieve effective management ccntqol, The move qf countries to a two hundred mile Exclusive Economic Zone (EEZ) has placed most fisheries within the juridiction of single cauntries, providing the mechanism for rational aanagement.2~However, there
I
are- - - -a- large- - nunber of socio-pcliti-ccl diff icultiesin -- 7 implementing' limited entry programs and reducing effort levels . .
in historically unregulated fisheries. Few such fisheries have yet reached*the poqition of yielding significant resource rents. In a fishery which has *been t'rad'iti~nall~open ~MW. fishing effort is normlly greater then that which wduld e mad~iseits economic surplus. For skch a fishery,the desirable ------lThe conventional outlined in Anderson (197733). ------=See, Copes (1977) and, Anderson (1977a) for a discussion of inqGLui-se-f +At~L~chtr&m~t KO hundred mile EEZ. direction of effort adjustment can therefore be deduced direckly i - .
from the fact that pntr ween+ - uqrestricted. ~dlicy *_Ii initiatives 'in this area can therefore precede :dbtaiJ& - *. - , 3 -- ' =. . - .consideration -of- the peculiarities of ths specific fishery.- Per estimates of the ielationship bet ween resource rent aria fishing effort for particular "fisheries have been iade.1 , f' ------A ------ti-tx~s-atteni-has~engivxiito %hi$esirab le / < distribution of the resouxe rents generated by ,an effective . . management prodan and how it cculd be - a~hieved.in practice. - - - ;F ------fl-z-yp ------P This is considered a giestion which' can .beappdaached after the goal of effort reduction has been realized. Bven Lthen it may be'
of -little consequence if the pcsaikle rats are s~a1~relati.w - 4 . to the costs of exploitation, Where rents have been generated, 9 they have been retained by fisherm& in the absence of. any . -7' -7' def inktecc2nsi_derat i~~~tbe_pcssibl~al&rnatives. : w The prawn fis6ery of Sooth Aua$ralfa did not fo116w the pattern "Z.- de.elopm-t re2er.d to mve. .~"o&h yearly , .; fishipg effort has increased con~inuouslysince the late 19601.s
when exploitaticn commenced, entry of vessels to the fishery has '--3 '--3 w?L-been restrictea at all times. The characteri~tics,of each vessel * have also been strictly regulated, As a rgsult, fishing effort- - ,--,-,,--,,..-v---3 /' . la large amount of resqarCh has been concerned with the nature - --- - ofofthe piela-eff ort rilationship Sor particular fisheries, - however this is only one of a number of inputs into a total - em-' e%* 7'- f vet0, % e (1 954). \ ',
+.
. - el. x;o thP"s extent, the .
I management of the resource-bas *beexi superior to that of all but a few of the fisher~e~of the world. Bgrne and Hatding (1976,
V 0 50) also suggest that consf derable resource ient urrently , being earned by individual operators in the fishery. This * .results from 'low capture costs relative to the high Pnit value
--c+. _,L--~_- A_------, of the species beins exploite&_ '-? ,' o It follows that estimation of the relationship betwen
C - effort arid resource renk and consideration of how the benefits
greater immediate relevance than usaal. Unlike the case of a /' well establis'hed open fishery, the assessment of the effect. on' overall rents of increases or decreases in aggregdte ezfprt 1 depends on a knowledge of the relationship betwaan>effort and -r resource rent 'for this particular fishery. The size of Zhe 3
pp---p-p- profits currently being earned by operators also suggests that
direct consideration of the justification for land i~plications- ' ' t5 of full rent retention by fishermen and the alternative allocaticn possibilities is necessary. , . - As yet, none of these matters has been directly considered
by the Sauth ~ustralianGovernment, which is responsibles*
, current regulations. This study will attempt t,o shed some light * 3
i c Lthese.aced6_-.. andso-su-ggesf -~~iSprovemen&-t already a relatively advanced management proqram, The prawn s$ecies which is ex~loitedin -the fishery has -l " three which make the study of particular :# * - P a interest. Firstly, be\ ause it is ext 1y fecund it is . L r -7.f 7- t considered to be non-self-r egulatirg in that-lie level of P
regener+tion f roa a given spawning season is large1y indeperdent
, s- ,of the,size of the pargnt stock. Secondly, its shortm adult life
a tire. Thirdly, its very seascnal regeneraticn Fat in a marked seasonal abundance cycle. ------The study begins with basic basic backgron i the South Australian gram fishery. T -r - -- -spe~aes. ------.------The methods applied in previous studies to estimate the - ., economic yield from a fishery are then reviewed and their applic bility to a -prawn fishery, assessed. methods of 41 adjustment to take account of changes in the seasonal effort a % 1 pattern and the heterogeneous nature of the prawn fleet are also b developed. Suitably modified aodels are then used to' draw broad .) cancXusi?ns concerning what appear to be desirable ad jastments inthelevel and manner ofexplaitation for each stock in the 3 rlsneryyB-resti-hcf ~ulativaec?monic rents which exploitation of each stock is' generatimg and possible rent i -- increases i( This is followed by a discussion ok the efficiency and wealth implica'tions of ,various psssiue methods of distributing 1 access rights and ewg,Bmic rents in a liaited entrl fishery and ' 61" tlieir relevace to the Iisbery under.. consideration. hn outline t of what fysi.considered to be a viable scheme for distributing *> -A- .------access ,rights pnd resoorce rents for t'he a South Y Auq!ylian,pram ccncludes the study. the major faatures of 'the South i ~ustralikinprawn fishery and its management, a very brief ~eview of the justificaticn for public management of fisheries is A significant feature of alnost all fisheries is the ccmnon property nature of the resource. A fisherman cannot exclude any benefidts he receives as a result of other operators* activities. . 1 - It follows that an individual cperatcii is unable to fully . captwe the begefits which may result from any bnhancement or - -5 conservation measures which he undertakes. There is thereEpp no --& incentive for him to indulge in sucE activities even thckgh the$r value may -significantly exceed their cost f r6n the - viergoint of the fishery as a whole. By similar reasoning he is > unlikely to take into account any of the undesirable * consequences for other partidpants of his om operations. - - - Y hilst not exha ostive, the f cllowing ill.dstrate. the-types , of negative externalities which the fishing operation9 of a given unit may generate.1 , - 1. Its fishing reduces the size o'f the fish stock. This may reduce the rate of reprbduction of the stock and hence the size .of .the future fish stock and therefore the catch rate from erploitation of this latter stock. > -. 2. Its fishing reduces the size of the fis$ stock and hence the _ ----l--L -- -- <, catch rat& fromkxploitation of this residual stock. 3. Its use of particF r types of gear or* fishing methods'nay - -- ~ed~~ethe-size of &ticular-saga el& of thestockan&------ therefore the catch rates from exploitation of these segments. , -7 I 4. Its presence in-. a particuhr area mag, because of the uneven distribution of the stock, reqnce the catch rate of concurrentlyo \ operating' units. - In an open entry. fishery, each fishing unit will increase ------its level of fishidguntilit 3TTZsming a qormal. rate of return at the margin, But because of negative externaiities such as those above, its marginal upit of .fi~hin.~effort /is generating a 0 negative s retur.n. L. -- - public management of the fishery is able 'to brink about an allocation of resources which takes into acccunt these negative 7 externalities. If can, as a .result-; significantly i~provethe ' social welfare contribution of %thefishery. - 1Some of these are discussed in ~ontecorvo-etal. (-1977) or Smith- (1969). - .' -8 * . - 11. DEVELOP~ITOP THE PISEBBY AID ITS BBGUL~TIOI r There is no one generally accepted definition of what " I constitutes a fishery. The scope of a9, y study is based on an arbitrarily &awn boundary. This thesisi will foc'us on the primacy s~t~xLoL-theSoukLBzlrs-ali an praw fishing enterprises in South Austcqlia are out processing of their catch, 1 hence the abcv~bo;ndary mans / ------<- - - - - that only aspects of the actual fishing operation will be considered. commercial exploitation of prawn st s of the coast of 3- mutli'rd&%%lia conmence$ in late 1967 afterca a numb& of a - -Gs previous unsuccessful attempts.* ~nitiall,y,trawling was confined to Spencer Gulf, but- grounds uek soon discovered in -- Gilf ¢ and on the lest ,(;east. In 1975, new grounds began to be fished in Investigator Strait. A11 these areas. are shown in Figure I, ------In order to achieve controlled deve+opment'6f tho resource, . - in March 1968 the Government of south ~usttaliaclosed edt& and alloved only those operators issued with prawn trawling permits ~ASat 1977, one prawn. fisherman was processing~onboard his -- vessel-bnttthe-om-- ' -txkkGuiu- cffectivz, sz2 SAFIC (AUg. 1977, 30) . L - 2The early history is described in Olsen (1975, 234-35) and King (1978, 41-42) . - - to participate in the fishery. Since the introductiog of "the a Preservation 02 Prawn Resources Regulationsw in April 1969, the Government has issued more ~er~anentprawn trawling . . - -', authorities.1 1n addition, small numbers-of temporary < flinisterial permits have continued to Se~ssuedat vaqious I - times, of en to explore, possible nevareas. F h -LAP------*~~tiie-%gl~b&i~i ',. a~im nmg at overall management of the fishery, it is . , on soie of the features of a prawn trawling authority or permiti . - -- A ------? ------= e , ~n aytbority,is held* in perpetui$j by an operator, jubject to the payhit 'of a mominal2 licence fee and acceptance of any conditio imposed by the mapabement authority. 3 Permits ar6 , B ', .% tentp&ary, being issued for on13 six monthly deriods at a time, an3 having no automatic right of renewal, bur otherwise carry -i saiue - -- - the access righ_tt$as-au&horities.- Blthoughthe-au~~~i~-os permit is assigned to an individual or partnership, the holder I. = . , must also nominate and have auth-orised, the vessel to be used ------c------1 term @autPrity8is equivalent to the more conventional ll~ce&et.The terms dl1 be used interchangeably throughout the study. A I 2In September - - JThese will be elaborated on below. .. A. (do 40uo Y. wrl $8 a*OW d WOO, .A a a 0 - e TO- . % hare this date, -no aulthorltles heen vauntari Y I - , -/ % L-' * surrendered- - withou+ire holder alsc achieving a transfer na the - - -- - 'e sale of- his iuthorised vessel. d 'The procqdure for allocation cf new authorities or IN 1, re-allocation of those authorities that have involuntarily la e has changed cobsid&ably since 1969. Initial iuthorities fl'were granted to all ~cmpetentapplicants who possessed a vessel A - - a - - F-- - - suitable fok prawn 'trawling. Howe-ver, as the prof itability of , tho fishery became established, rationing devices soon became . net a large nu~berof criteria such as length of service as a id fisherman, -either as ctew on an existing prawn dessG1 ;lor skipper . of a vessel in a less profitable fishery, suitability of the nominated vessel for Frawn trawling, location of home port and -, family involvement in the fishing industry.1 - I Government and Prawn Iqdustry ~dvisorycommittee. * \ ' * Since the disbandaent of t&s Committee in late 1976, new allocations have been based on random selections from a large . number of applicants who met, veky general criteria such as nomination of .a suitable vessel and possession of a Class A & - gk a~ge-numb~sy&fi c facto-vkich wool-d-be considered were detailed in 1974 when the Prawn Industry Advisory Committee -~-es#~isbdrp),es6 are- W&n ~y14c 2.8d w-(1976, 67-68) . a \ 1. \ 9 2 ' \ , - 13 \ - - - -- . . - - --a1 f 1-'4 1 The regulations imposed by the South ~ustt~lianGorernnent in conjunction with the limited entry scheme have been of thr& aain types:2 .. Restriction of the types of entities which may hold an or permit. \ k / - iction of the type of fishing unit which may be used. - An ownff-opera-~r policy en strictzy ~sforCedsince - 'the establishment of the prawn fisbeyy. The authority holder uthorised vessel during all trawling a k operat'ons, and may not hold an authority in any other limited entry ffishery. The motive for this policy h 'z'urnably been a ., *L P desire on the Government1 s part to ensure that working fisherman 2- 9 ------. rather than other groups receive the benefits of the limited entry programme. - In the years 1968 -70 + several authority ho9 ers for the - - West Coast and Spencer Gulf continuad to fish fdr tuna during Y. its short season from February to Hay, then undertook prawn ------y-- / $The criteria whichornust be met to hold a Class A general 6 5 elk Ti~hinglicence ate listed in and Harding (1476, 61-65). fn.-summary a person must be a ent full time professional. 1 e f ishernan. --& b 8 ZThe administrative policies for managed fisheries. in South Australia are summarxsed in Byrne and Harding (1976, 66-71) King (197.8, K-3) . ------trawling for the reiznder of the gear.1 After 1970, authority d holders were not permitted to take other species and al-1 became "1 full time prawn fishermen.2 ' To avoid- an excessive concentration of fishing. on the Pest grounds, each operator has normally been confined to only a part of the total fishery. Fishermen were *initially authorised to Spencer ~ulfor the Gulf-St. Vincent. In 1971 the division 0. between the West coast and Spencer Gulf was removed, creat-ing ------+-- \ two sepa=ate pileas. A third fleet has developed recently with the exploitation of the new Investigator Strait grounds. These areas are shown in Figure 1. Table I lists the number of operators in each fl et on a B k - yearly basis and the number of authority' trans'fers which have ,. occurred via sales of authoris€d- v-eEsels, E can4~seenAha------the number of partjcipants has increased steadily in both'main - .? fleets with the Spencer Gulf fleet being roughly three tines as - lax&? asothat of Gulf St. The numbers of trknsfers have ------1 see Australia, ish he^$ ~ivision,Australian Department of Prim areadustr--m7-t~)~ 0 zT*-sh&s of acciwtel-by-eatdrtakendurinq trawling, is however permitted to a limited extent. 4 2 I 4 - 4v L pup pip - TAB^ I d NUMBER OF' AUTHORITIES AND PERMITS ON ISSUE AND NUMBER OF S~ESOF AUTRORISED BY FLEET g VESSEL^ FOR YEARS 1968 TO 1977 ! * West Coast Gulf St. Investigator , I i - Year and Spencer Gulf Vincent Strait Total i: 9. - A d ~o.~gn~,~.oft No. on No. of . No. on m. of &. on No. of a 4 Issue Sdes Issue Sales Iseue Sales Zsme S&S 4 . e 4 i - Source: Files of Department of Agriculture and Fisheries, South ~ustralih Q Gove- t . ' I r' i The luxhum number of concurrently iaaued authoritiee amd permits during' .D. each year was used, to avoid double counting of reiesued authorities ar 3 permit 8,. .-. i f F- -- - a* '$ To protect prawns of a ncn-ccmmercial size fro^ capture, all haters of less than ten metres' dr;pth are closed to trarllng,' whilst certain other- areas also inhabited by small prawns are - subject to either. seasonal or totai closure. For similar reasons, a minimum mesh size for $raw1 nets is also specified. Restrictions on vessel sizsand type and size of rig have also been gradually introduced to restrict the fishing effort of - .=- d indi.viduaIBssels,.Sessel_s_operatingin- GUSt,-Yin.cenLhzme --A been generally confined to sjngle rig1 and a maximum length of * F .. 14 aetres. In July 1974 a 17 metre vessel length restriction was also imposed for replacement vessels in the Rest Coast--Spencer Gulf fleet. -F In addition, a maximum net? headline length, based on boat length, was introduced, for all regions, in order to limit the A effort which could* be exerted ky a specific vessel. The formula r In December of the same year the lengths of replacement, vessels were further constrained by reqnirinq that, in addition to------the above absolute limits, they be no greater than those of ---Uwblc rig wasalhwd for a bhiefpe&U~LL&147e;t- was not adopted by any ve~sels. the vessels they replac&. The hull of the existing ve.ssel, also "\ had to be in a condition such thatsit would he scrapped on the replacement vessl coming into operation. some elaboration is also necessary ccncerning jurisdiction * over the fishery. In August 1976 it was decided that in fact a I small part of the Investigator StL ait fishing region was Commonwealth of Australia rather than State waters.l This area . - - -A------A - L A - -A - - - A - -- - 2! was then declared a managed fishery by -t$e Commonwealth Government, It has authorisede a nuaber of vessels, including all C &hose - prevAmsly aperating- in *=area, fia trawl h-Gese ------1 waters. Discussions aimed at jcint management, in this area are currently under wap.2 The major part of the fishery is still, however, under State Government jurisdictioa. C i ------* 1Decision of the High court of ~ustfaliaAugust 1976. *See SAPIC (lov. 1976, 8, Ang.,1977, 4-5, ZSov. 1977, 47-48 and -rr297R 3,) ------ 0 111.7 BI L06Y OF THE SPECIES a- \ The South Australian* prawn fishery is based on exploitation of adult stocks of a single species o penaeid prawns (Penaeus -. - latisulcatns) commonly known as the We6 tern Ki~gPrawri.1 ' Biological reswh on south-~ustralian\ ocks is by no means that of the same species which is fished in Shark Bay, Uestern Australia. It is likely to follow the typical penaeid shrimp - - L-- -- pattern, which suggests the following life cyae.2- \ Spawning occurs chiefly in earlx- summer, from November to, F January, with each nature female releasing extreme1-- ---y "large - numbers of fertilized eggs directly into areas occupied by the adult prays. They rernain there in a planktonic form for two to three- weeks then mdve into shallows and estuaries as juveniles. ------p -- - -% - After feeding and growing in these nursery areas for up fo twelve months the ycang adqlts gradually re-enter deeper waters in December to ~ebruary.Females may first spa;n soon after leavihg the nurseries, and spawning is repeated on a yearly basis until death. G 2For a detailed outline of the biclogy of penaeid shrimp see . - Ro-sef+a +97+-34f+~b-bhlo~o f the ua1stev_gin-r awn in Uestern Australia and South Australia is described in Ualker --(19-7?5-U~J197B)~resgectively. -: - a ymus- hemem&w~~ble- ,,y13 re fW , - ,\ to as the pcint of recruitment, soon after re-entering deeper I waters. The average lifespan of individuals vill depeiM on the - level of fishing. At moderate effort levels such- as those in South Australia, it is considered that the majority of prawns + are either captured or die from other causes within a year of leavinq-- the nursery areas, although survival for over ttwo years - 7 has been observed in some cases. 1 - C Because of their extremely high fehndity and the +fact that - - pre- recruit@Tit mortality ST-: dGfpeTe;--t-hee~e~L of recruitment for most is genesally considered to be independeL t of the parent stocd~sizeat @rmal levels of exploitation.2 King (1978, 100) argues that this is*also the case for the South Australian prawn stocks. Ihe level of ------recruitment is instead influenced by various environmental factors. 3 There are considerable randoa fluctuations in the . . yearly recruitment .levels caused bg variations in these latter B factors. Since prawns are subject to capture for a period of less +i than one year on average, and recruitment is concentrated in a -r----r------*I--- t 1The levels of natural and fishing morta1it.y are discussed at i length in King (1978, 115-130). i 4 2Saa .for example Anderson (1977b. 23 knd 103). Griffin et al. b --fi97621)7), Heal (1975, +4)# Bounsefell (A974, 261-263) and - I -$ Walker (1 975) . f 3See King (1978, 180). - -- - 8 \ - 20 1 ------i.-,?L- \ t small- part of the gear,, -lwgel~ of rec is exploited at a time. - As a result, there is little relationship between the level \ of fishing in one year and -the stock' levels in subsequent 'years: \ The high rate of mortality fn the period af$er the annual , 1 \ ' entrance of recruits to the fishibg grounds also means that , \+; -, \ \ . %&ere- 5s -a -saarked-s-easona-1 abundance- cgcl&------_ ----+ 'P I In South Australia, adult prawns are abundan-t in cer'tain areas on the West CoaSt, spencer Gulf, Gulf St, Vincent 'and - - - -- Investigator Strait, as shown in.+Figure 1. The ma jor juvenile .. ' areas are the northernbrts of 'both gulfs and Venus Bay on the west coast. ,. < IV. .THE PISH~~~GOPEBATIOE A1ID STRUCTURE OZ XEB FLEET - . * Fishing is undertaken using the otter trarLtechnique as -I . . - perfecte8,in the Gulf of Bexicc shrimp fishery.'- This * - -. net essentially consists, of towing a synthetic (or nets), over 9 . - uiidertaken atisnight-and extends for up to eleven. hours, with each shot7'taking~fromthirty minutes to two hours. After each, ' I,, .? *; *; -prayns are- separdte& from the rest of the catch. -They age then * stdredain lqge buklt-in refrigerated brine fanks or in z >. I I freezere. At the conclnsion of each fishing trip, the catch is , off-loaded at suitable ports adjacent to the grounds and 1. transported by roadL-to, processing factories in ice-chilled ------i - - -- , ------bins.2 Major home ports are Pt. Lincoln and Pt. Adelaide. 14 There is consideiable variation in the type of vessel - . /HR \ . operating in the fish&.. Many of the initial vessels were :\ converted tuna or rock lobiter vessels. ~aterentrants have , \ - largely been designed. especially for prawn. trawling, either \ \ \ being built for the South Australian fishery cr coming from the - - -7-he fishing operation 5s &scribeif in mu ch-y-rea3zerdetad~ -Xing (1978) . 6 , - J) 22 \ either timber 0; steel. Vessels usually have the wheelhouse apd -- ,", accommodatioxi forward leaving a clear working deck for sorting C 'r" 1 of the catch, which is then stored below deck.@ Catch storage facilities are of two basic types, ' refrigerated brine tqs and dry freezers. As discusse% by Ruello (1975, 192-201). prawn5 stored in refrigerated tanks. a - - - - - L-L , - - -- lll_i / suffer serious deterioration in qualitb aftd~,tkoto three days,- due to both physical and qemical changes. Frozen pra'uns, Brire tanks are used by alaost all the smaller and'post cf the k internediate sized vessels and limit fishing trips to one or two i nighis. Freezing facilities are available on the largest and a * number of intermediate sized vessels, which allows their trips -- to extend until a full load is taken, up to fcur or five sights, ------depending onpthe catch rate. vessels operate independently, and all are equipped with . -i echo-sounders to a$Sist in the location of suitable, tsawling 1 . , areas. L There has always been a large iadge in the lengths of - - vessels operat'ing- -.In Spencer ~ulf,with kxtremes of twelve and twenty-nini metres.. A-len'gth frequency diktribution for each of the periods 1969;71r 1972074 and 1975-77 is qiven in Figure 2. ------There has been a gradual standardization over the last few years L- ... - p- - - -+ but this-has been hampered by the restrictions on size of ': -; 1 -replacement vessels outlined in Section B.11. 1n' Gulf St. @ - L ,& a - w RELATIVE' FREQUENCY DISTRIBUTIONS OF VESSEL LENGTH '* ,.I 9 .r.* * - Y. FOR =ST-W~S? SPENCER. G&F ?'LEST . -6 I4 . , - .- -6 I , it- -- > . Veesel Lep0th (mtree) ------i r' - - - Vincent on the other-hand, vessels have always been very uniform in size, almost all being in the twelve to fcurteen metre range. Average lengths of vessels hare remained-relatively stable ,- -r , over. time, with the Uest toast-spe~@.~d.ffleet having a+,.& . /' +:,\ . I. - 1 . of about seventeen metres whilst the ~dliSt. iincent boatxe * a been. T considerably ' smaller with an, average of abput twelve an . half metres. Average vessd lengt-hsL-for ,allifleetiFfor each year --- 4c are given in.*Table 11. ' 1 * -, Bb .L Both single and double rigs are used in the fishery. ~ouble * -. - - - -- _ or t'win rig consists of a pair of matcded nets side by side, P - -, whilst single rig consists of a single larger net. Initially /--, ' double rig was used only by the ladger vessels, but it has by \ e now been adopted &y all but a few of the smallest boaain.the 4 ~pencei~ulf fleet. ~lthougb~the restriction to single rib in Gulf St. vincenk wasliftedbee_tweenl974- anh 1976, dofihle xis--- S has neve,r been adopted by any of the.vessels operating in this I # region. The percentage of vesspls using 'double rig .by year and c regi'on is ,given in Table 11, -. Brake Horse, kwer (BHP)- of engines of .vessels have beep , ., ' closely related to. vessel lengths in any given year. H~weveq, the average horsepowers for qiven vessel lengths have increased substanti'ally over the"last ten years,. This is reflected in the sig i-f-i-cant~ETl~illCrea ses in aver'age engine powers ' for both ip 4 . , lengths. The smaller (under f owteen metre) single rig-vessels J, J, F 25 " ) ". c . . - .. - AVERAGE VESSEL LBNGTH AND BBP AND PERCENTAGE OF MSSfLS USING DOUBLE RIG BY FLEET FOB PEARS 1968 to 1977 - I Wet Coast/Spencer Gulf L(a) ,BHP D-We(%) .(m) BHP D.'Mg(X) c / - -- 1968 Ilf :@-166- + 12.7 91 0 12.6 100 0 .-r Source: Files of Department of rA$ricultsre .od'Fi@heriee. South Australah ' Goverrrmertt . +e . 5 , . ~.eludas uhlch' vak suthorieed J , a : -' $ iressels for on1 part of year. t -. - \ .z skz&. Agerage BB? of vessels by year and &+et are shown in -- - x Table 11. u 2. 1 \ . - ? , . , The numbR cf crew is also cl,osely related.to boat size, - ? and varies from two to six persons. . \ \ ., \ 1 * .. over a given period is the number cf hours spent actually -.i, 1 trawling.'In all years there have been large differences in \ -= - - , ------c. . , , -hour$ trawied ,&on9 vessels, especially within the Spencer Gulf I I . ~ .. . fleet, ,although the relative number of hours trawled by specific : G ,. 9 , - ,vessels has been relatively stable. In othCr words if a vessel -, . . ;. iravlad much less. than &averagein cne years'it usuqk also . %+ /.- I ..3 . -2 - - ttawled' less. - than aiera-ge* in othef years. Frequency -.,- -2 -- -+ , , :.*--p; - A distributions olyearly-haurs &aw_le_d by ~vesselsin~8Achpofftheee: '3 * ? - t; major fleets for 1971L73,. 1974-75, and" 1976-77 are shoyn in t 2 1 - ... - .Figares 3 and 4.1 . - Possible ~~~~~~~~~~~~~'f& fhe observed 3 pencer Gulf spread include differences in &ml and skippe; efficiences, physical - , = I r _ limits- on the periods'of fishing of some vessels .or variations * f. % :in the work-leisure references of owner-ski~persand 'crews. , . . * . - S-ince there' is a rdafked seas~nalabundance cycle, ..v LThe ye9ars 1968 excl'uded because asnumbel: of vesse3s ~t-thtefrasis may* 5i &tids.a:rI. . . FIGURE 3 ' r$ ' *. : i' 1 e REUTIVE FREQUENCY DISTRIBUTIONS OF HOURS TRAWLED qY VESSGLS IN WEST COAST-SPWER GULF FLEET Frequency hre trawled ( '00 houre) RELATIVE FREQUENCY DISlTRIBUTION OF HOURS TRAWLED 7 Frequency A . Emre Trawled . - f l'erencies n veeF~cle-""~. . f'- unit of cost) could result in a different length R-shing season for each vessel if each-ceased operations when the c3t"c rate dropped. below its break-even point. Ideally one would like to c - calcuYate the break even catch ratr for each vessel and then C T check if vessels ceased fishing only when the abundance level. 4 -----A-Unfortunately tbe- necessaky detailed- cost A data is not available so it was necessary .td resort to less / abv'iws checks. vessels operating for only small numbers of hours over a year shoad fish largely during the peak season, ~bilstthose fishing. for longer periods should exhibit a more balanced effort 4 distriboti.on. In other words, a uniform within-year distribution of fishing for all vessels should he unlikely. To test tlis, the number of hours trawled by eachpssel during the high catch ra&+nthsI cf February to lay4s ak, L - - regressed against the hours trawled in the remainder & the r . . for each of the years 1974 to 1977. The equation estimabed was 1 -y..ei. -- L where: 5 3-.- <: PH = hoes trawled by each .vessel during the peak-abundance 1 \ r p- - - P-slrraaq-mJ$a_wetiad. pp TH = hours trawled by each vessel in the remainder the year* . f - - 30 -r: ir 4 S i with the PH coefficient bef ng significant at - the-99% confidence * level in three of the four years. It was thesefore concluded that efficiency differences were not the major cause of the ?- observed participation level differences. An alternative possibility is that smailer vessels fish less because their less sophisticated storage facilities reduie ------a A ------the length of each trip or because they require more favourable 18 I.-% -* weather conditions for safe operation. However a regression of - t this hypothesis. In only cne of the six years from 1971 io 1977 Y was the vessel length coefficien$ positively significant at the -, -4 95% confidence level, and even then the explanatory power of the -" -+= * - total equation was extremely low. A final reason for the observed variances could be differences in the target incomes of individual owper-skippers. and creus.l Although this could not be tested directly, it was ------to some extent supported indirectly by the fact that those vessef s which had previously been traded consistently operated for longer periods than the rest of the fleet. Purchasers obviously desire higher incomes because of the need to meet the 8 cost------of the- official purchase price and the likely unofficial .~NO-tethat the requirement that the authority holder rust be on I the vessel &king all trawling operations prevents him from hiring a relief skipper to increase his income whilst holding his hours spent at s-Tant. 7 side payments. The averages were as follows: Previously traded Others , (hrs-) (hrs.) - The average yearly number of hours trawled by vessels in - . =------both majbr Zlests has steadily increased, as show$n Table 111. Note the lover average'levels in Gulf St. .~i&nt. Given the lack of any observed relaticnship Tetween vessel size and hours trawled withixf)~pencer-Gulf and tho fact 'that &awns are considered more ab-undant in Gulf St. Vincent, the between gulfs - - - - difference is -edi+el y-ie +e en@+bed-&y akthe~-the ohser~ed- +L - --- smaller vessel lengths or a shorter season in Gulf St. Vincent. ------Again it'would appear that operators deliberately refrain , from trawling, even though it could be indosrtaken 9 They claim that they restrict the totaveffort so as to avoid overexploitation of the stock. Whilst the analysis has implied that operators in both gulfs do not always maxicizgprafi&sin_---__- B given - - period, it is useful to take?soaeuhat broader view of their behavioar. By .deliberately holding down their protit levels, , they are p4obably-- reducinkthe- -- likelihood of further neY -, TABLE 1x1 AWIUGE HOURS TRAWLED PER VESSEL WHFLEET IN YBARS 1971 to 1977 - West Coaet- Gulf St. Tnvestlgator Spencer Gulf Vincent - Stralt (hours) , - (hours) (hours) * . . ------ Files of Department of &piculture und FIB&~~S, South Australian &ernrent. s- I hcludea veasels suthorird for only part of a pat: licences being issued, 1 an event which could adversely affect their long run profits. Hence they may in fact be attempting. to - maximize long run pfofits after all; via adoption of entry- forestalling behavior akin to .the widely observed monopoly It is cowluded thaf there are considerable differences -I- I _- - I ------A A -- fa bet~& the characteristicgb of individual vessels opergting in 16 ady one ski significant. . changed in the vessel mix hare P . . _ exiraqs -ihe fishin$ le.ve$sr of individual vessels in standard 'F .. units before mehingful aggregations and bomparisonsb of fishing * _1 , ef fprt*'levels can be sade.' --: . -J *. b --ri-r---~---,----- '& ---- I- &Tho factorseffecti the num~r~t--m~resiss~ttdari developed more folly in a Later section. but it is clear that --~ti~llgett he, L~~~~~~ likelihood they will be issued* and this pressure largely .-depends an. the erof it levels of current operators. V, S SOIALITY OF TEE PISBEBY/ Ed' /- One of the interesting aspects of prawn fisheries is the , rL interaction of the pa'tterns of abundance and fishing effort throughout the year, f I For. an unexploited fish stock, the'number of mature - A - --A - _ - _ _ -- - - a -- xexploitable prawns in a given area is greatest soon after the* -7 Q e se'asonal influx of 'new members from the nursery area's. .The average siz9 of prawns will ove in the o~gsi$-edir~tidn; -- - being lpueqt, at this time and 'incFeasing over the remainder of the adult - cycle. ~ecausoof high natural mortality, in mdst cases density is greatest scon after the seasonal increment and declinas thereafter.1 It has als6 keen noted that young adults typically migrate slowly over a number -of months away from the 4 a 'later date in areas more distant from them.2 For a given level of fishing, the averaqe size of prawns caught, tie $ggree oi variati& in abundance over the year and the timing of the peak abindance point rill all be affected by the seasonal effort pattern and the'areas being fished. If e . fishing is undertaken in the areas adjacent to the nurseries and ------~ %King (1978, 132-33) imates that the yield per' recruit is gr+eaies~~~r*-~t-itsCz-~~~-~--- which they leave the nursery areas. . , _ 2See King (1978, 68). . a ------is concentrated in the months immediately fjallowf ng the sbasunal exit rate peak, the seasonal abundance fluctuations will be reduced, put the average size qf prawns caught zuill' be small. an tPe other hand,. if &hing concentrates cn' the areas more'P distant from the nursery areas inhabited by the-largfi r more mature prawns and is mure uniform throughout the year, the size affected, the average of pawns .caught increased, and .the 4 s time of maximum abundance will occur later in the year. The " - - abundance levels in the latter =re&, houerer; will be lower. on -- average, because of the greater loss Lrcm natural mortality and ' -, I - the greater -dispeWrsionCS the surviving .individuals before they i) reach such areas from could be constructed by dividing the avekge monthly effort or abundance level within a year into the effort or abundance levels for individual, -month$. That is,t.T Xi '= Hi / B (B: v. 1) I where: * Ii = Index for nonth i I 1 Mi = Effort or abundance level for month i pa~talalag . . B-. The average level over the calkpder year containing month i is \ ------A --p--p . ..& , - ------preferable to the average level over the twelve months centered on month i @cause of the lhrge random fldctuations in the ,strength of the yearly regeneratio t and the correspondence 1 between the natural abundance cycle and the calendar par. -The difficulty i>' to find 'realistic neasur;s of iaonthly effort and '. . , . abundaice levels. given region can be calculated from its hours of operation in individual nonths. However; given the heterogenous nature of the va=ious vessels,fieiag in each regibn, qne should ideally take D. 7.s? into account the differences.between vessels before \ . . to pyvide estimates of the total effort level. per' month in each region. ~dfortunately,only simple aggregates of the hours t J-I-+- trawled by all vessels operating in' each,region were available . Within-year comparisons of these 1atte;- totals ;ill, I ' . x howqver, give simclar r~sult~to the correctly weighted sums . i .* 8 provided that the vesse? mix is stable for all months of phe IS r B. Q year,'In other words it'is necessary for the effort patterns of a\ all pessels- in each regioncto be rea&nably similar. This has . already been shorn to be the case for all vessels in &the~penc& Gulf-Uest Coast fleet, It wculd appear that this is true on' a b -- - -- p- pp % regional basis also. King (1978, T6 and ~e6onstratesthat, catch effort patterns of the small numbers of vessels in other a pppp regions revealed that this was generally fhe caseb .elserheb asD - < ,' well. As a result, the simpless~mof the hours trayled By all ve&sels osor each -month WAS dsqd to.meas&= thiI. uith'in pear . - relative monthly effort leveis in each 'region. 0 > Assuming prawns are egually vulnerable td, 'trawling,. , r in all * I. months of the year1 variations in monthly catcb tates'of a @ vessel or uniform iir of vessels will beo proportional. to 'changeg > ------A -- - in the abundance level3 of the exploited stacks.. . Aggregate monthly catch rates, that is. total catches divide$ ,by the total .' , e. the within-year relative &onthly akundance levels in each ', + \ -. region. s 1 \ .6 . The monthly effort and abundance= - indices for all regions on ; 2 a yearly basis were derived. by substituting the above meaSures of monthly effort and abundance into equation (BV 1) . The. , , ~otethat since calculation of the monthly abundance , indices makes use of actual mentblf catch 'rates, they 'cottl-ld not be calculatedr) for years ipp7 which fishing uas not undertaken in one or more months. This precluded their calculation in the I \ following instances: I 1-- B a- H! nest Coast: 1968, 1969, 1971, 1972, and 1973, JC --- 3 TABLE IV ------4 mrABUNDANCE INDICES BY REGION FlOB YEARS 1968 TO 1977 (AVERAGE MONTHLY ABUNDANCE IN EACH YEAR - 100) IT West Coast Jan. Feb. Mar. April May June July Aug. Sept. Oct. #ov. Dec. 1970 96 73 76 92 152 91 ' 119 73 105 119 103 99 - w- ---- u-AAAL "-a 1971 c ' 54 94- 19 4 0 75 255 153 1 101 1972 152 46 0 3 110 147 106 201 191 114 29 101 1973 0 20 27 12 173 163 220 136 83 120 109 137 - 19f4 109 63 64 18 4 -3f-34~23.L- 1 5_8- _!-at, 1975 114 22 30 38 112 248 189 156 65 70 94 '63 19 76 102 - 70 81 158 182 184 104 79 34 86 45 74 1977 121 96 99 72 13 133 240 131 82 72 121 55 k Spencer Gulf / a Jan. Feb. Mar. April Hay June 3uly Aug. Sept. Oct. Nov. Dsc. - ma - -22 - 33 - - 45 -16- 65Z56 -424 -9% 139!~-&7~-44~------1969 73 50 49 116 110 126 141 83 78 133 143 96 .1970 87 121 134 i49 143 107- in 45 52 06 110 44 1971 62 67 107 210 254 15 59 39 SO SO 69 79 1972 107 127 107 168 167 109 33 31 31 64 172 83 1973 - 92 127 132 122 139 71 49 77 69 124 132 - 66 1974 81 113 l.21 118 157 112 38 48 62 112' 151 87 1975 93 148 129 161 124 74 53 58 .74 85 138 63 1976 101 143 176 136 118 79 b8 61 63 80 95 79 1977 107 127 188 172 129 82 45 25 58 89 106 71 C% , ------, - * . A , . B -- --. . -- pp -- TABZE rv continwd a . . - , 7 " - ~ulfSt. inc cent - Jan. .ltb: Mar. Aptil. May. June July Aug; apt. ~ft:Nw. Dee. .. 1968 0 0 0- -0 23 149 194 74 - 181 - 317 ' 262 0 '. .-. ' a 1969 48' 48 50 36 35 72 124 149 203 183 71- 180 1977 - 56 61 140 210 69 - 94 57 21 53 154 165 124 = x 3 Inveetigator Strait Jan. Ireb. Mar. April May June' July Aug, Sept. Oct. Nov. Dec. -- -- - f975 ' - - Q -- - Q - - --Q o-0 -Q - 253 2QBQBM,.2P6-p - - - 1 I .- . I R i ,e l. - I _ 1 . kst Coaet '~rn.~Fab. Mar. 1l~r1lMa; June-July bup Sbpt. Mt. Nor. Dee. . - F *- - Spencer- Gulf t. Feb. 4&1 my J- July *' Nov- me- - - Jm. Illr. AugaCS.pt- 0ct %------1968 67 61 I30 178 1728 96 73 74 99 69 108 73 ' 1969 97 86 92 137- 130 81 128 84 104 86 93. 83 TABLE V continued Gulf St. Vincent E-Feb. Mar. April May June July Aug. apt. Oct. Nov. Dec. Inveetigator Strait . Jan. r i10 r- UI ~~ a I : u u 'a, E 0, 0 GI Y UI W rl5u-I Id U (d Id 5 a a .rl u 0 a -4 qa'a, :5 3 la, "I z % a, 0 ~l u 3 pY(d a'j: 4 J Y g -H. la f4 8WId 41 'A', I 0 (dl0 U1 (dl 4 4 lI4 0, 4 01 Y'H 10iZ 01 +' P $ -4 a U) id 4' 0 d 0. *i~ a 0, $1 ;($ 91 rn d w a 4 P d Id 10 a, 0 I4 0, an Ql -4 * 41 0 aJ I V1 ad k +' I4 a 4 u (II 0 Y &-4 0 2~ -4 0, Y Id a e u .rl 4 H m HI 3: n 4 3 0 .rl aa u U F * 0. 0, U1 a +'- !a 0 (d R YO 4 tn 0 V +' .,-i 4 U .t, +J 0, 10 ml .rla t a dl C. Id -41 H u a a H 0, cl dl a. TI +' I4 V d iJ c 0, ,9 9, I4 0 Uc a v) v-4 a d P a FIGURE 5 AVERAGE mMTHLY EFPORT INDEX LEVELS BY REGION OVER YEAR 971 'f0 1977 ---Ave 20(1 \ ------r---- - m 3 i i ., st coast. and In Inoeetlgator Strait, however, ghest scvera.l months -after the exit of prawns from 4 the nuqserp areas. The very dominant Uest Coast peak is due to the ability of Spencer Gulf vessels- to switch to it during the calaer winter inonths after the cat'ch rate has declined in the major Spencer Gulf fisheri. noted that during the winter months from June to September water - TUs, i3ther than a decline in the prawn bioaass, is considexed - - to be the causeI of '*the catch rate decline over this period, Prop Table V ,,it can be .seen that the within- year abundance cycles in all region$ have shown little-trend, despite changes - *- in effwt patterns. 2he abunhnce levels for particular months 4 . do,ikMcwe-hn, wmy-tz- , 'iierably between regions, as shown by the s- Y" average monthly lef&s over the 1971-77 period in ~igure6. - The greatest average within-y ear variation occurs in Spencer Gulf, where the peak March catch rate is over two and a half tines the- n@imam rate. Ih the other regions the peak catch rate occurs later in,the year and the cycle is considerably less ------. pronounced. . ------ --.b------*---- %Thefactors affectinq the catchabilm aprnaeid sup -- analyssd in detail in White (1975). See also ~ling(19781. . West -st s - - - -- Spaacdr Gulf -..--.-.---. Gulf St. vipcmlt - ,., ., ., Investigator St. e explaiqed in terms of the the stock segments being exploited in $ the different regions. Tbe Spencer Gulf- and Yest Coast operators concentrate on areas *adjacent..to the nursery areas, resulting in a major catchvr&e p~akat thy time oY entry of new recruits to 4 ------the fishery. Operators in Gulf St. Vincent, 'on the other hand, fish in areas occupied by the qore, mature, larger-Lpr,awns. This , - - - - leads to a' peak catch rate later in the gear. Both Olsea (1975, P 237) and King (1978, 53-54) suggest that different age .groups ale expl&t& inthe tm~hf~~f~~&~;-s~~r~-u~f-and-~~~f - St: Vincent. $he. explanatidn for the ob-rved Investigator Strait abundaxo eycle id slightly more ccmplex. The stocks exploited % .in this region come largely from nursery areas in Gulf St. 1 inc cent. These do not reach the mouth of the gulf until scme / ------months after *hkr exit from the hrseries. !the fish5ng grounds in the strait are largely adjacent toi the gulf, hence +leading to 1 - a catch aTuiEzy .time of arrival of the B seasonal inflow. The greater within-year variitions in abundabce id ~pencel n ~ulfand the Vest Coast, despite effort being concentrated in the pariod of maxi~un-abundance, may be due 2-0 heavier - the exploitation of stocks, in th&e_reqions. Heavier fiahing leads to a smaller residual- stock' at the time of entrance of new recruits, and hence a larger catch rate jump when this inflow --. * occurs. .I % <. . , The weight and size compositicn of*the catch .taken .in a 0, begionover ?a a with a given level of fishing rill theref0.i L7 -. , depend on the seasonal di-stribution of fishi~geffozf andsthe a segments of the stock which are being exp10ite"b. J ------ -, L I VI. THE IUPORTA~CE or TEE PI~SEERY - a In 1976-77 the Frawn fishery became the most valuable in South Australia in terms of value cf aggregate production, due mainly to dramatic increases in prawn prices, Catch has be& Peasonably stable in recent years. Yearly catch and revenue A ------A ---A - le.vels 'are given in Table VI. . . ~t is somewhat nisleadiHg to consider th'e 'fisherg as e ' - skng3,e entityr •÷hen-*at -v esse3s ar e-not =per ~iWx?+tearavefmm- -- - -. ,- . one qegion to another, and that the ffshing operation has . different characteristics fn ea&h region. Yearly catch -levels - for each'fleet' are given in ~dbleVII. It can be seep that by 3 > . * 4 far the larges& catch is t'aken by the West Coast-Spencer Gulf ' fleet, followed by the Gulf St. Vincent fleet and lastly by the ------p ------p--pp-p----pp d --* Investigator Strait fleet. ~atch'eshave declined somewhat in recent years in ~p'encer'Gulf but have increased steadily in Gulf 6 Unfortunately there*is little informaticn available on the -, prawc prices received by operators in each regioo. Bs a result, . exact calculation of the value of the production of e'ach region od a yearly, basis was not possible. The overall yearly prices P-' P-' -pp . and regional- catches can, however, be co~binedwith estimates ------bf : the normal 'price differentials between regions to give rough - - approximations of the above prices. Based on limited evidence it TABLE VI\ \ CAWH, AND PRICES FOR Rig SOUM AUSTRAI,IAN : REVENUE ., i.- PRAWN FISHERY FOR YEARS 1969-70 TO 1976-77 , .. 3, A L Cstch Revenue Price/&. 4- - s (tomes) ($? 000) . ($1 t 11392-3U ,__--.l..2&-L- __----_- '- -- - 1213 1551 1,28 , 1524 2285 1.50 1789 2997 . 1.68 - k ------ Source: Australian Bureau of Statistics (1977). . . -- TABLE VII ESTIMATED TOTAL VALUE OF CATCH AM) VALUE OF AVERAGE CATCH PER OPERATOR BY FLEET FDR YEARS 1969-70 T6 1976-77. / West Coast - Spencer Gulf St. Viacent Gulf - ', .Year Catch Price/Kg. Value NO. of bperators ~eveaue/Op'crator (tomes) ($1 ($ OOo) ($ 000) b Investigator Strait Year Catch Price/@. Value No. of Operators (tomes) (9) (5 '000) 146.5 - 3.31 484.9 5 143.0 8.86 552.0 5 iio. 4 185.2 3.44 637.1 Source : Australian Bureau of Statistics"(l977) and lnforaation supplied by the Department of Agriculture and Fishcrier, South Austkalian - -- -- A-p------ - -*- -- is considered that prices in Gulf St. Vincent have on average been approximately 40% higher than. those in Spencer 6ulf and the 1 0 Yest Coast.1 prices in Investigator Strait appeaar to be approximately mid-way between the two, hence a 20Z markup* above Spencer ~ulfwas assumed for this region, The yearly prices for each region were th'en estimated as follows : - - A------+ - Ps = (P Y) / (Ys + 1.2 Yi + 1.4 Yw) (B. VI. I) pi. = 1.2 PS \ - (B.VI. 2) \ - Pv = 1.4 Ps - fE.VI , , s----- where: P = Average overall price per kilogram for, year Y = total overall catch; in ki1og;ams for gear \\ Pv, Pi, Pv = average price per kilcgram for year in Spencer .Gulf and the Uevt Coast, Investigator Strait 2nd Gulf St. Vincent \ SData collected by the Department of Agriculture and ish her ids from a few processors indicated that- the price differential of Gulf St. inc cent operators had been 4746, 34% and 44% In 1973-74, 1976-77 and 1977-78 respective1g. 2Giveil that the bulk cf the p'rauns cau ht in Investigator Strait have already passed through Gulf St. V 1ncent, it would appear that prices in the former shou e at least as high as in the latte~andso the 20% markup i c low, There are, however, . three main reasons whq this is not the case: 1. A significant component of the Investigator Strait catch originates in nursery areas off the north-east coast of Kangaroo = island. ' prawns from these areas are caught socn after .recruitmen2 and die hence fairly small, - -- 1 2d~or-+'f-~t. inc cents brconcentrated more towards the-- - I end of the year when prawns are especially large. -L3u,ll st. Vjncen+'-o-~~~bssto-he major local market. in Adelaide and therefore face a slightly higher p-rice scale. 6 ------ Ys, Pi, Yv = total catch, in kilograms for year in Spencer Gulf and the Rest Coast, Investigator Strait and ~nlfSt. Vincent. The estimated regional prices and resultant regional revenues are given in Table BII. . ByPdividing the value of the catch for each fleet by the -+ -number - A - A-of vessels-i&it,averagere!iwu= -@_r j_i_cs~~~e_c_a_g~-b~~- - - -- obtained. These averages are also given in Table VII. e As estimates of costs of operators are not directly levels without further analysis. Hcwever, it is clear that II profitability has increaqed markedly in the last three years .S because of the escalation of world prawn pri~q$. C. THEORETICAL ASPECTS OF THE ESTIIATIOY 02' ECOIOUIC SURPLUS.OP A FISHERY I -wa I. THE COBCBPT OF BCOIOHIC SUBPLUS ? - - The economic surplus derived from a fishery ,in a peri.. equals the value of production less the opportunity cost of the resources used up in producing it. It is a function of the size ---- -u--LALp-pA- - -" -- of the catch, the effective demand for each unit of catch, the leve3 of-ffort required to take it and the opportunity cost of - - -ch b-Bg+ ef+ggs%.-~~sr~=s~~~~S- - - pp ------. ad- Vt ,. Xc ~t = Z it' - L ~jt (c.1. 1) C-1 j- 1 where: Rt = economic surplus from the fishery in 'period t Dit = the. price buyers are wiJling to pay for the ith unit of catch in t - - ppp--p - ---- 7--- Ojt = the opportunity cost of the resources used to produce the jth *unit of fishing effort in t, Yt, = total catch level in t, *.~t= total effort level in t. The surplus can be brokenadown into three components to < reflecf how it is distributed, namely 'f e consumer surplus = t (Dit - Pit), i*I Y t gt resource rent = Pit - .f Ojt, -, Xr . and' producer surplus = .TI- (C jt - ,Ojt) where: Pit = the price actually paid for the ith unit of catch in t, h, cjt = the actual outlays required or receipts •’begone to \, produce the jth unit of effort in t.1 1 i In practice, because Dit and Cjt are.not directly observable and must therefore be estimated using proxy prices it is often assumed that consumer and producer surpluses are equal tD-zer o, Thhat--. tlhat----I- - -' Dit = Pit and cj% = ojt. J This means that (C.I. 1) reduces to? xt - - E Cjt i-' jz l 2 Pt = 1-Pit I Ct = j=,it cjt The present value of the psrpetual stream of economic r' r' surpluses equals the the sum of their values aftebthey have been discounted by the social rate of time preference. That is (C. 1.4) 2 lr - ---c------me------lThe components are those identified in Copes (1972). - Zc*' signifies 'to the power of'. C * - - R= it - .F.ojt) (1. ;r) *(-t) (t.1.Q) J*' where: .. r = the social rat'e of tiae preference between- priods, f From an econonic viewpcipt, the resource is being explo&t@d - 1 5- - . + most efficiently when the present value of this perpetual stream - 3 .- o& surpluses is maximised. - *- - - 3 effort. It fdlows that the economic surplus from a single period will be*maxisised when the value of the catch obtained ------Pa - -p--. ------•’~oma furteeffort increase,'houeveq produced, is less than 1 %V A - -*.** .-, the cost of @he inputs used to produce it, that is when aRt / axt = (ayt / axt) Dit - ojt' = o where: i = the marginal unit of catch. in ~eriodt I 4 --* i >A The present value of the perpetual stream of economic . i' V surpluses is maximised- when the discounted value- of the rent-- 1- -L 4 increment any per3t.d irom a further e ort increase in that 4- 4 - Ibl 4 4 * T- * * period *a1 to the present value of the cast of producing -- -= >+ :a ? - a a A mnsiderable literature has been bni2t up in recent years ------exphring the f mplications for .the optimising distribution of 3 effort over -time of various rates cf time preference and degrees ------ot- - b'et wee P ~erioa+i-ef fs~+imtarde-. '--~-i?&~t+-- - , higher the rate of time preference and the greater the degree of between period inter-dependence the hig-har . the ogtiaur effort * levels in*acre immediate periods and th&o$r- the optima^ k f effort levels in periods forther into tb'e $u-\ure. I + x .". <.a' - aaximisation of the economic surplas in'each period will 'I I indifferent ' streaa of eaonomic surpl,oses vly if society is as , to-the period in which the surplus is received, that iS - - - r = -0, or if the catch in each period is completely independent a of the effort levels. in all previous periods, that is dTt / dXk = 0 for all t > k, ! ------*---* 1The redsons for these catch redactions are related to the natare of the pradaction f~cactionsfor renewable reaoarces such I as fish stocks. This aspect will be developed farther later in I 2b%sh?#y. this latte; requirewent is considered to be largely As -a result, proviaed the ecoacmic surplus from the exploitation of each stock in eqch period is malirised so is the present value ~f the perpetual stream of such sprplnses. d 9 - uL-LAuA------A- - --.-- ?I 9 .g'+ The above disnssion highiights the gmporkance of the' yield-ef fort relationship in deter~ining~'the size of the sm m economic curplus f rum a f ishegy. Because. the analysis is concerned with exploitation of lf wing organisss, this ------A-u- A LL ------A------\ relationship is essentially biologically based, As a result, yield functions for each fish stock, defined as those aesbers of - s a given species which inAabit the sala ars-a-and intexact- - - - biologically, are 'normally. considered separately. Formlation of the yield fun~tionfor a given fish stock is a task of considerable co~ple~xity, and pop4ation djynamf -cists _ - have been exploring the field for a considerable period of time, - In order W'simplify the analysis, attention is norfally f~cusktd ------ons ustaf na b3x-y%eZ-m,tEat I stbo=-yT-el--6ffdcc-~.fr~~a~%~~s-- -- -* - -- > : which are in steady-state equilibrium, --\ -- -_ The usabf e stock of a renewable resonrce such -as a. fkshery - ?is in a continuous state of adjustmen,t. It is i8wi:eaeed dl growth and recruitment and depleted by nathral mort.ality and - A- ---, - fishing, This can be r,epreseated graphically as shown in Figure 7 or algebraically by the equation -*. where: ------St = the average size of the stock at the beginning of pkrPod t - --- - = the level of -recruitc#ent tc the stwk during period t \ ~t = the lev'el of growth of existing members of the stad da~lng period t Mt = the level of natural mortality of existing members of the- e* stock during period t. - %\ I , In a steady state gitnatidn, an'd therefore Yt = Rt + Gt - Mt, for t = 0, ?, ..I.. The sum (Rt + Gt -fit). is noraally referred td as the sustainable . - - . . But yield in each peiicd &i. itself, a -function. of the effort * \ That 9s where: .*r 8 . , = f (X) = the proportion of S captared'dith. x_&ni$s of eff art. - - 6 s Ndte that effort is normally measured in units of flshing' I mortality,, that' is iacb unit of &tort" ramvds .an equal . - - ' . / proportion ~f the totak fish stock.& . 0 2 * r , In .addition the levels of zecrui~ment,growth and natnral ~ortalityart also affected bp the size cfatb& osabla :stock. , . .9 - I cf i H'O 0 4 the equilibrium stock and hence catch levels kor each effort level. , -0 A key datermidant 0f.th.e yield-effort function appears to 4 be the relationship between -stock size andnrecruitment.l In . general, recruitment may be: 1. Positively related ti stock density, A -A-2- - - -.------2. Unaffected by stock density, 3. Negatively related to stock density.2 increasing wkthout limit respectively, as illustrated in Figure 8.3 The eventual yield curve shape will of course also be' affected by the relationships hetwen density and giowth amd , I I) , -c \ natural portality. The dynamic po61 model incosporatks separately each of' many estimation of yield-effost positions of 'the fish stock. Horever, , .- - it reguires ex&eaelf debailed information concerningthe . \ , \ biological characteristics of the stock4and this prevented its 1 use-ia the present study. *, . 3 I t20bviously relationships 2. and 3. cannot hold at all stock - J' -- levels, 'However, they may apply over those levels which are ------&kStk 2~- the f imbefn e gsurficiently prof itable to be contfnoed. .* c -. 3Ricker (1975, 280-296) gives a very ddailed' exp'osition of the mathematical forms of the various qlternatives. REUTIQNSHIP-BETWEEN STWK LEVEL, RECRUITl4EiW AND SUSTAINABLB YIFU k Sustainable yield per period ~h4'.surplus.. yield pmodel makes the strong simplifying '- assumption that the relatioqship betwen, (R + G - I) and S can be represented by a simpxe function. That is: But in equilibrium - 0 B(S) = Y = s f(x). (C.ZI. a) ------Since S is not erectly observable, it is normally replaced by the catch rate, to which it is by definition groportional. / - -Equation -- -- -(C.IIa& ------tbarefore-becams- - -, ------a Y = (YD) f (X)' . - - - (C.II.9) E'quation (CII10 is then estimated fro& observed values of Y and X using suitable stati~ticaltechniques. 1 4 , requireaent, it has two ma jcs weaknesses: i I., The observed yield-eYfort levels may not represent 1 7 4 sustainable posi)ions. .I 2. The correct fora of f (X) is unknown. 11 the level'of fishing effort varies-rom period to pepiod, unless the-%natural surplus in one period is independent of the yields of previous-- pri-~ds,observed y3eld-effort ------combinations------will not bea,.sastainable,, In such cases, it is XThe nbrmal nethod is to appiy 0-dinary ldast squares regression to adjusted yield-effort data. &p Pox (19.75). * 7 Y necessary to deduce the sustainable catch Jevels- indirectly, a somewhat hazardqus task.1 Fortunately, as discudsed in Se-ction * - . ?.% B. 111, there is litt& between-year yield-ef f 01% interdbpendance in the fishery under consideration, hence this is not llikely to + . bCG be a source of difficulty -in this study. The for& of f (a should ideally bezsigle but provide a good appro&atkon to the t=oe yield foncti6n. ha problem isL - * - -L - - -A - - -- . ------that there are no objective criteria for deciding ;hat -the best' form is, apart from statistical explanatory power. - 3. - L - - Host research t~ date bas been undertaken on_Stzocks where-- - -- + ------catch initiall~increased,then declined as effort increased, - . A : suggesting a bell or)ome shaped yield curve. The two most . +,. L i common forms of yi-eld equation have therefore been a. parabola2 i C 1 >.r and an exponentialj, that is - where: - 1A large .number of lagging, averaging and subjective adjustment *a b aethods have been advocated, none cf which are entirely satisfactory. See for ewmple -Copes (19'18, 36-38), Gulland . ' f (1969, 120-121 and 1974, 73-74), Ricker (1975, 280-296) and i Schaefer (1954, 32-33) . ! 2This form was initially developed by Graham (l939) but is il usually associated with Schaefer (1954) uho applied it to the ~acifichalihutfwmry. * JSee Pox (1971 68 1 t* ------PA------r, -- a d * u, B - (10-a 6 The uncertainty as to the correct form of the yield -< . * function can,' however, be' exaggerates. Tven where insufficient* *. data areYavailable to apply the coaplete dynamic goal ~odel, . - some 'knowledge of the biology of the stock may be'atailable, ,and .this will ofteh give a general idea 'of -the type of yield curve I to be egected. This is the case prawa stocks under A ------. consideration. 7. It ,was concluded in- Section B.111 that for Westerne ~ing- - ' - Prau~,-~e--~I-ufsecral~nt nas~~a~-?r~sfze~of~ - the parent stock. It is therefore considered that the yield curve for stocks of this -species is of,the general shape . , by the broken line curve in Figure 8. This curve had'three- , general properties: I. 1. It had a but continuousle 8eclining slope, ------.- - P- -- -< ' 2. It approached a positive aSyaptct'e, 7 - - i 3. It passsd through the origin. ------: A 'si?$le producrion functioa -with all of tlese , -, -, is: . 8. i. -. : Y = a (1 '- b*X) \ 4 uheres- . , . . a, b = constants .I -. . . -- - --O - 3 -- * ' The-- larger b the morel rapidly the yield a~proachesthe -- is I I * I :, asymptote a. his 'formpf yield equation has already' been- . ., 0 Another possible form which meets only t~oof the-suggested requirements is where: a, b. = constants - Only (C.If.14) can be expressed in linear form, namely log Y = a + b log X (C. 11.15) (C.U.13) can be estimated by itineration by estimating b for differ'ent values of a and b and chcosing those values which . maximise the explanatory power of the equation. It is convenient to express (C.II.13) in log form namely log (1 - Y/a) = B X (C.11.16) where: B = log (b). before estimating the parameter values. Estimation of both forms will thezefore be attemptea. for - 1 each of the South Australian prawn stocks. i % 4 lSee Griftin et al. (1476). / I \ As butlined in Section C. 11, when calculating the yield function, effort is normally measured in units of fishing + *-z mgrtalkty that is, &h unit of fishing effort E~~QC~Sthe stogk . ' level by an equal percentage. The effort. data available from a fishery, however, is typically available in of perieds &d I terms -- necessary to express the latter data in ~CE~Soi units of . fishing mortaS4g before estimafion of the jieid'curve and hence economic surpluses can be underY aken. As outlined by Anderson c1977b, 22 and 155), the share of 1. The relafive density of those -subsectio~sof the stock which ------the snit exploits,- i .- 2. The shares of these subsections which are captured. capture rates o f ts when etploitin stocks of equal ly referred to as their sexati' re fishis$ .z are a fnactt6n of the characteristics of t&a fishin& parttcalar standara fishing nnit per @nitof the, when - ------o+Atins- _se a- @~e_n_st&k -segnmrt.~ ------? --:- To simplify the analysis, assume that identicaf subsections - - of the stock are exploited by all units. In &is case the effort leiel of a gived unit over a year equal; the producti of its -fishing power relative tb the standard un'it and the amount of - - time it spends fishing. aggreqhte effort equills the sua ok the+ s Xt = the effort in period t in standard fishing6nnit time units I PPi = the" fishing power of nnit i relative to the stydard qnit f Ti+-= --period af cpexation of unit i in period t - .! + ---*------*----- =See -for exampfe King f1978) and Uhi Z-- Z------S~eefare ma m+ 1957,- 29-70 14-9- 591 f L -1 73 + 4 & -,- wr - r - I--Si--YIL-~-".+---&~--rn- *.l---+CF+ - .. , Y Cr* - Pro~idedcoiparative catch rates for the Smdsrd unit and a11 other units are available, tbe fishing pcwers of the fcraex in term of the latter can be calculated as folbws: where: (T/T) s = the catch rate of the standard anit per unit- of ti me. - It is frequently simpler, houerer, to use the relative ------* - - lS catch rat- of a sa.ple of the f 1sX1ng an= to k- f--'-=- a relationship betueen catch raie and rarious fishing unit characteristics and then use the values of these characteristics for all units to estiaate their. relative fishing powers. In algebraic terms [Y/T)i = f (Cli, C2i, ,- 1 --- -- and therefore PPi = f(Cli, C2i, ...) where - .t Cli, C2f, ... = the characteristics ~1,~2, .. . for k ... = the values characteristics Cl,C2, .. . for the standard an&. The la+ter indirect procednre eliminates the need for the standard unit to in fact be one of the actual units. It also B allows estibation of the fishing pcvers of potential new ___ A __ -I---- -. - _ ------9 -___------A- , -, . - entrants, which may be very useful for saBagement purposes. It - ------,- wge therefore the p~ucedureadopted in the present stitCy. ------ Equation (D. I. 3) can be generalised to coves the case uf bj. tho -- A aultiple abundance levels - idcXw&8~~$the xdq+alpaance -- - --<_ - -+A- ---_.\ ._-. _ ----_ level as an additional variable. It therefore becones .- . 1 -\ a ------, where: .Ai = the abundaace of the stock being fished by unit i, . - cli, C2i. .. .) . The most cdmmon form* -has been a Iogarithmic - L function, - - L * Bf, B2, ... = constants. ___ - - - - c -- This for. implies a proportional relaticrurh3.p between I . fishing paver and the values of unit characteristics since and therefore This property seem intdtfvely sensible* since Bne Ir ------I-- the catch rate increase from a given absolute change in the level of a si,ngle characteristic tc depend on the existing level of all characteristics, including the adjusted one. A linear relationship, vC (Y/T) i = Ai + .z B j C ji (D. I. 7) ,): t has also been used in several studies.' Here and is therefore independent of the current unit characteristics and the abundance level. Since both equations (D.I.6) and (D.I. 7) are linear they can be estimated using muItiple regression techniques, a dummy variable being introduced for each abundance level, ------'See for example Beverton and Holt (1957, 172-76), Griffin et al, (1977) and Sluczanowski (1 978) . , . ir The ca'tch ate.per unit of tiaet nagmally used 'in~analyeis r. * -. . .a of the South ~ustralianpram fishery i's L'ilo&a~takeh . der > - a_? hour spent actually trauliig. his is an &eellent. Gashre of I .. -. .. catch per unit of'.. productive-tine and was thefsfore adopted f~r < 0 - ,', -f -- use --in the regsession. ------u- . . Hhes choosing the fishing *unit characteristics for- ., a inclusion in the' model, tbere 'are cbvious pract$%al. , * L - - " extreaely dif f ialt to cpanti$y whilst raan%others, although 3 quantifiable, .are not \read&ly available. It fol~bvsthat thd s. C t I. varikbles nsid are cften far f ram"-ideal. \ , The major previous study of fishing power in shriap fisheries, undertaken- in the Gulf of ffexico. f isheryi fopnd that the siqnificant characteristics uere $HP of units and the length I of.the foctrope, a measure of -net .size. Chhsaoteristica nbicb * .. + ------ were found to be insignificant uere 'gross tonnage, ' length. and .. f ago of unzt. .Because of data limit?tions, the aboye study was - - -. forced to make the strong asaumptidd that individual uni"t9 *ere , not yodif ied in aqy way over the. &rey period of -10 year's. 4 lnT'the present'study, values of only a limited number ;f * - L . t- - . . - '*. , - . . %~ .- - .' * = - . type 'of ,ria)'-~-8,- , - 8 CV , , b .I. * a y&arlf basis, %=nee :alloua&, could ,be made for ' modifications . ,- . . 4 -. 0 carried +out:to specific units over the 1968-76 period be& 5 - *. - * - considered. , - -- '1 - ' ------4. a 1 in 1 ~dea_l.l-_ose +ott~&-~~~eto segment observations sqch h - - - b -L t *- , s ". ua$ tbat a~l'units operat iqg in each group a& -exploiting &ocks r I -, r -t B - ' bf exactly---L. &nal apundaaqe indup so standardisev.s-----7-coppfe~eI~r for .' -- bundance dif fera&t?s;. his ii obviously *impossible-. in practice. , . i -$: ._ The results wi-ll,, houbver, be unbiased 'prodded there! ig nb I . As discussed 'abovafpprawn -abundance varies with .tiie, area . . . . -Q and depth of trauling. For $he South A-usttlian fishery., however, r . -* - + [/I , cafch rate data for 6qqh fisbing unit were readily available- I R -. \ -. , . - ' Fnly by calendar year and A region (West Coast, Spencek Gulf, Gulf . = 4 h ' ------st. rincsnt and mv'estigator strait). In vie. of *he uniformity - i = f o a q of the. seasonal'e5fort-p'att~rns idr unit$ sithin,each year and - -..<- i storti'on ,would be introduced i' . by the use of annual catch ratek.. despite the marked withantyear i .? '# 3 t ablndgn~ecycles. -The IIW~of anpua1:rates oalbo taciiikates the;. ji : T, - < h. +. elihination of random elaqnts. ih .monthly catch ,zates. ' . .- 3 3 -, 'p It was ksd.consid&ed tbat b~causeof the well 'established ,. nature of the West Cozist, Spencer ~ulf- Id @ulF St. VW f -L-- . - * \ . 7 grounds virtually: all of t4e op&ators1had' a good knoyledge of- : UP * 9 - the ateas' of maxi&tm abundance. It.follows that differences * - h. * 1 . between the abundances of thg +tack segments exploited by - I 'indirid~alo~orat-4" in a region at a "certain point in time were A------~rabablylargely due to *chance factors. I I C It was therefore concluded that there was unlikely to be a + s s 2d. ficant ,raationdhip between any unit: ~Yaracberisticsand. L _LA ---- -_l_II_II------ -.% ,.- - abunaance of exploited stock segments .for units within ea&- . /' /' region-pe& strata for the th=& established iegion$. ; - d a ' \ 3. das - - - .'-- - owh her, the I'nye6tigatak ~_trait--q.raumkare-~til~in-Lh-~-~= ------1 \ development stage, having only been openeddup in 1975. I* is -4~ , ',- .. ' therkf rG .pas &ble tha,i .some opratorrj in this region may . . - - -. pbksess &up 3 - - - ,-The data set .therefore consisted of catch pet 6oar on a -.' - - , '- . I . . region-yea- baas for almoat all f e .1s bbatatidg "in*ea-ch .if I G < - ' - 79 -4 - +% e c L 1. -a 6 - . , . length, .and h4' trawled of each vessel. There were - 504 observations altogether,. with the--numberof observations - wiihin each r9gion-year st ata virging fro4 undsr ten 'to over a - 0 - - 4 - - rorty: - * .- - - L - \ P I - "t - --p- 1 tt. 'k- . 1 ,'-l L.. 1 ,' . * . l 5' 4 r .i J. ------< + ------L------1 0 k .-. 2 ? . ' J' Y s .r 4 ..' 9 * . P 4 significant at the 95% level for equation (D.I.6). but for-Lt e * equation (Da,.7) the BBP coefficient Wqs insigni icant. This " - 2 r 'coefficient xalues and t statistics for each o A ------.Ahe - - characteristics and the correlation coefficients for ,the total equations are shown in Table VIII. a - -- - -In- iaw ~ftbei;rrtrri-~@~ad~of-t'helo liGrlaode=,it~L was used to'estimate relative fishing powers, these being little dif feren~ebet ween the equations in terms of e~planatorypower. r " . + It implies that 1% increase=s in ves$el length and BBP*lead to s m .54XWand .l8% increases in. fishing pow er'respectively, that , switching from single to double rig will increase fishing power 0 by 30% and that units trawling 4oi'less than 100 hours i + Y ' -I icular region-time qtpta have a 30% lower. fishing power 11 i, , -- - an other unitsz The results for vessel length and BHP are-not particularly 3 lesgth/ .is length surprising, since vessel closely linked to the A of footrope and hence the width ocacean gloor the net or nets 9 sueep whilst BHP affects the speed with which it c'n be towed. , The qubstantial improvement caused by the adoption of . t double rig is somewhat larger than expected. The supposed ,+ 4 advantages1 of this type of gear. tire that it increases the '1 % feasible f ootrope. length, improves trawling stability and eaFe - of handling of the catch and adds t;o the versatilit-y of the .. * i gear. It may, h6rerer, lead to instability, especially for s.ali :To test the stability of %he estim *a Z log lfnear equation was rerun on a regi a yearly + ------.------t ------ba3sis, The 95% confidence intervals for each qf the coefficients 3 - .- in these segmenXed groupings were then coiparea witb those I . . 'estim'af,ed using all the data sinultaneously. The results 'are i1lustrat~;d in ~~~ure-s9, . 10, li, and 12. + - : Ideally, tbe intervals for the subgroups should encoatpass true for the double rig coefficient it was not,_the case for the 2, coefficients of the 1encjk-b. BBP'OX learn variables. The - - 1. L instability ib the>.learn coefficient was probably due to the - small.numbers of observations within each strata. For lepgth and , I1 BHP it was considered to be due to the high degree of B , correlaticn brtreen tdg-twh variabfe-s resulting in substantial multicollinearity, The variaticns were' theref ore largely -, 7.- 1 ------=-HI---- I - 1See Sluczanowski (1978, 18-20) ; his test was suggested ia Griffin et al. (1977, 20-28) & ," . ~ - . .,. . .. FIGURE 9 f' USING OVERAIL, REGIONAL AND YEARLY MTA I' C 95% CONFIDBNCE INTERVALS FOR MX;(BW) COEFFXCIg#TS - USING OVERALL, RBGIONAL AbYEARLY DATA Total 1968-76 \ -- bet Coa 1968-76 Spencer 1968-76" Coafidence atem4 ' d "- Weat baa 1968-76 Spencer 1368-76 Spegcer -f968+ x, power estimates, The vessel characteristics adopted for the tsstandardn vessel ara soaewhat arbitrary, but for realism and to assist in lat& cost estimaticn, some korrespondence with the actual vessels' used in a region was 'cadsidered sansible. The f dllodng -farel dcuedi ' - -A -- gest Coa t and Spenker Gulf fleet - 1F50BHP and double ' t -- - -- Gulf St. Vincent and ~nvesti~ator/"Strait fleets - 13 metre, 160 BHP and single rig. The fishing power of the Uest coast and' Spencer ~ulfstandard vessel was 58% greater than that of the Gulf St Vincent and Investigator strait standard vessel. of the above varied from -61 tc 1.46 in the Uest Coast and h Spencer Gulf, from -86 to 1.10 in Gulf St. Vincent and from 1.08 . . to 1.61 in Investigator Strait. ~hfs' indicates the relative % * homogeneity of, the-Gulf St. Vincent fleet and the great / heterogeneit coast-spencer Gulf fleet. I Using e n (D.I. 1) , aggregate yearly effort levels for each region essel h*dursC were calculated. They are * shun, tageth erw Ufus-hrs trawled, in Tzble IX. Note- the gradual i~creaksin the adfstctive ,effort,-- Tsper hour -trawled for both main fleets. Prom 1968 to 1977 t&e irrcreases totalled 19.9% and 30.5% respectivbly for the Spencer Gulf and Gulf St. Vincent fleets, and occurred despite the - attempts to curtail vessel capacity outlined in Section B.11. b It is likely, however, that the above adjustments still (A overestimate relative effort in eariy years because of the \, \, \ inability .to take*account of improse6skippar and craw skill ad t ------LL ~p techno~logicaldevelopments in gear and equipuent .l King CHABGES ". - So far it has been assumed thatllden ical patterns of L-J \ exploitation occurred in all years bith respect to'-, seasonal r variation in abundance, This id in practice- --unlikely -- to be-Lh_e_e_------case. There 'have in fact been obvicus changes in the within-year distributicns of sffort within each region. Uhat are needed are - -- .the standard effort patrern equivalents of the observed geafiy effo9 t levels, that is those yearly effort levels required to take &e observed annual catches yith a standard within- year effort distributioc. The most realistic standard effort pattern ro assume for a > region is one based on actual practices. The a erage 'seasonal ------i, - effort patterns for each region have already been derived in Section B .V. The problem is how to deduce the yields which would .I have been teen with these standard effort patterns from the - yields taken with the effort patterns actually adopted. Prawn stocks exhibit very strong natural mortality cycles, hence suggesting that the major part of the uithin-year -*; abundance cycle is due to natural factors. rbis is suppdrted@--@\ b< the estimates- made by Kinq (1978, 126) of_thebnatura1 and fishing mortality rates for the Spencer Gulf stock and the - observed &stabilx~of %h~-&cnal abundapce cycle in Spencer Gulf despite significant changes in the seascnal effort J' pattern. 1 It was therefore considered realistic tol assume that observed monthly catch rates would be unaffected by redistribution of effort to meet the stan-d.@d patterns. It follows that standard effort pattern equivalents of the i. ' = - - ac-1 ~i&& krels-fer--eat-h ifgioa and pericd-ceuU -be ------,:----- calculated from; (D. IV. I) that is 12 where: Yt = the actual catch level in year t ? ' Xt = the effoh level required to take Yt assuqing a . . it.. - .*.. standar-- dised - effort- -pattern -- -- 9 - - - Hj = the standard effort share in month j of any year t (Y/X) jt = the actual catch rate in nonth j of year t. Because the procedure made use of actual monthly catch ratds it could only be applied in years when observations were available . for all months. This precluded its use for the West Coast in 1968, 1969, 197+, 1972, and 1973, Gulf St. Vincent in 1968 and Investigator Strait in 1975. Table IX. The major impact was in Spencer Gulf where effort has , . gradually bwome more concentrated in the period- of maxi mum Q prawn abundance. + I. r .,, The other- factor-s determining thea abundance of the 4 1 exploitedstocks rithin a given kgion and year are the areaq and depth :uhe're 'trawling is undertaken. Since on-ly bottom 1) ,-a ,A _ ------trarling has beer? undertaken ,ipthe fishery, no adjustment for 9 9' e changes in this factor is necessary. ow ever it is EkeX'y that \. * I - there hav€ baen changes between pears in the with-in-region' - - locations of trawling. Unfor,tunately little inforaation on such . / cha~gesis available. It has been suggested that operators in .* 4 Gulf St. Vincent have increased their effort in lccktidns clcser s to the nursqrg areas where are smaller but more abundant. 1 This Is consistent with the observed decline in the prtce-dif fer~ntia1- for~avlrs frola this-reqion s*-ffnfortunatef y--- howeier, no quantitative adjustment for teis factor was possible. - he-affect of this trend would be to increase the rate of fishing mortality, and= hence effective effort, for a given number of hours fishing. It is therefore likely that relative effort levels in Gulf St. Vincent in early years were $ornewhat less than estimated. ------1This opinion was expressed by one of the operators during -& discussion with the author. - * 3 2See section B.VI. FISHING EFPORT STANDARDISED POR CHANGES: I# VESSEL PISH~GPOWER AHD smsom, DISTRIBUTIO# OF FISHING BY REGION FOR YEARS 1968 TO 1977 West Coast '. 1 Year Actual hours '. Standard veasel Standard vessel .. e rawled ,hours trawled standard distribution hours trawled ------A -A - - - A -- bi 1974 5 306 4834 5021 19 75 6081 6299 '6408 1976 3562 - 2539 2511 1977 1393 887 1050 P r - - - - - pp------Pi - - L '- -- -- Spencer Gulf oc < Year Actual hours Standard veeeel Standard veesel t ravled hours trawled standard distribution a hours trawled Gulf Sf. Vincent * ' , Year Actual hours . Standard vessel Standard vessel v - trawled * hours trawled Btandard distribution hours trawled 1976 11758 12 388 12398 1977 10137 9966 10031 - . t Investigator Strait Year Actual hours Staddard Geeeel Standardveeeel - -- trawled - - - houra trawled-- atandar8- die€r-ibtteon- - - --<- - houre trawled 1976 , 4333 5143 , 5215 1. IBTBODUCZOBY COSE$'IITS ' . I I 6 As concluded in Section C.1, the South Australian prawn stocks are being exploited in a most efficient mnner when the econarnic surplus -from each steckisslaxioaise&-i.ne;lcb _ period, this surplus copsisting of consumer and pqducer surpluses and resource rents. - -- To calculate t'hese optimum positions, it -is necessary tc estimate, for each period, f 1. The demand function •’or the yield derived from the <' exploitation of each stock, 2. he cost function for fishing effort applied to each Jtock, 3. The yield function for each stock. However, as the future is unknown, these estimates must be based on observations of present and past conditions only, and so ?re at best soneuhat approximate. It follows that conclusions based on such estiuatqs must also be considered tentative. Management e should therefore always be ready to alter policies to take account of imprcved knowledge as to the nature ofFe - functions and also of changes in the functions t$ens@lves. - . AS d-ffcwxa%in-io~&+nes&eexmw&c&~~f I f isheri~expldt a t ion have highl&ghfeddrem~~erent s only, by 1 I asinmirig perfectly elastic dsgand and cost functions. This approach will be initally followed in this study also. Hoveaer, qualitative estimates of the directicn of bias introduced by ignoring the other com$onents of the 'total economic surplus *ill Q also be made. Rath,et t'han try to predict the future, the analysif will =- ,* concentrate on estimates of curren? fevenue and cost * ------for the fishery. comments will then be made of adjustment necessary to take account of changes in the relative- rates of increase of revenue and cost levels. a those in -more recent years kecause of the effect on Gulf '- ,levels of the dramatic expansion of catch-- in the Strait. I-f sdchq moveraent did occur, one would expect a marked decline in Gulf St. Vincent cdtch rates in 1976 and 1977. The absence of such, a ' + / decline provide? strong evidence that St. Vincent st~cklevels are independent of effort Xevels in Investigator Strait. It ------follows that Gulf St. Tliacent catch-effort combinations for the B period b&fore the development cf the Investigator Strait grounds 1 I The estimated yearly yield-effort combinations for each of Uest -Coast, spencer Gulf, Gulf St. Vincent and Xnvestigator 1. Strait are listed fn'Table X. Because of the exploratory nature i of the 1968 operations cn the West Coast and in Gulf St. a e Vincent, the observat2 ns for this year in these regions were .rr: >addition, because the extremely high 1974 catch rate in Spencer Gulf was considered 'to be due to atnormally farourable ' environmental factors, and -was therefore &sustainable, it was. , -* i also omitted from farther analysis. The remaining obserratitk for each of he established regions are plotted in ,~i~ukes13, f * 14 and 15.1 i The yield equations derived theoretically in sectid; C.11, ----.------.-namely equations (C ,If. IS) and (C. 11.16) , were applied ko 'the A lDisregard the right hand axis at this stage, its signi?i&ance will be explained at a later stage. L - QtTCH, EP~~BTANDCATCHPER&TOF~~~O~~T~ BEGIlM POR 'lrBbRS 1968 TY) 1977 Uest Coaet 8prPcerLGulf Pear Catch Effort C/E Catch Effort 'C/E (158.) .(brs.) (kg-) (ha.) .P .P 1968 130 55.6 384,000 4,920 78.0 I,' 8,OoQ $- -f -~ulf st. ~incmt ~nveetigatorst. FIGURE 13 b 0 YIELD, REVEWE AD COST CURVES FOR* WEST COAST REGION Total Revenue Effort ' YIELD, REVENUE AND COST CURVES PUR SPENCER mFREGION ------ Catch FIGURE 15 YIELD, REVENUE AND COST CURVES FOR GULF Revenue plotted yield-effort- combinations. The 7 -aseegiveni- Table XI. Because of the very limited number of observa*ions for Investigator Strait and *t&-dependence with ~ulfSt. Vincent, estimation of its yield curve was not attempted. The hypothesised equations both providad an 'extremely good fit for Spencer Gulf. In addition, all of the coefficients were in th-e required ranges. In fact the two equations led to almost - --- - identical yield curves over the okserved effcrt range. or Gulf St. Vincent, the double log equation again explained almost all sf the observed yield-effort variat-ion whilst the fit provided by the asyaptote equation was also adequate. The estimated coefficients also had acceptable values. The curves implied by both equations had more gradual rates of decline in their slopes than did those for Spencer Ghlf, and were not significantly different from straigh,t lines through the origin. Although the double log model had slightly greater explanatory power for both gulfs, the asyrn~tctebased equations were adopted for further study because of their greater theoreticgl correctness. The estimated yield equations, in their original form were: I 1, For Spencer Gulf (E. 11. 1) -- 2. For Gulf St. Vincent P -- -- Y = 85000000000 (1 - .99999999996*Xv) (E~11.2) , - - TABLE XI ESTIMATED REGI~YI~D CURVES Equation (c.11.16): log (i - ~/a) Region a B t stat. - W. Coast n,a. n.a. Spencer - .-974 - - 3,80O,.OOQ -,0000170' 32.10 - St. Vincent 85,000,000,000 -.000000000441 21.36 ,919 Equation (C.II.15): log Y = a + b log x RegionM a t stat. b t stat. W. Coast 0.62 0.5 Spencer 6.04 11.9 St. Vincent 3.98 6.5 . % - - -- - where: - Xs = Effort level in Spencer Gulf in Uest Gulf and Spencer Golf standard vessel units Xv = Effort level in Gulf St. Vincent in Gulf St Vincent. and Investigator Strait standard vessel units. The correspcnding yield curves are shown in Figures 14 and 15 Note that r~lativeeffort levels in early years were probably less than estimated, because cf imperfect - -- - standardisation for changes in fishing power and relative abundance of the exploit.ed subsections of th~a.vailable stocks.1 * The error is likely to be greatest in Gulf St. Vincent because f -_of the recent move tcwardo greater exploitation in areas of . maximum stock decsity. Uhen ccmbined with the general increases in effort over-time; this over-est3mate bas 5a&-th= e-ffe~f~f-~~ reducing the apparent catch rate decline at higher effort levels. The possible position of the true yield curve for Gulf ' St. Vincent is indicated by the broken line in ~i~ure-13. \- Because of this under-ad'jus tment, it was considered that only the Spencer Gulf equation gave a reasonable estimate of the true yield curve. For the Vest Coast the fit of the double log equation was ------inferior to that given for the gulfs, but more importantly, the I . value of b was' greater than one, implying an increasing rather P than decreasing. sio~e, a result which 9s biologipdly impossible. The optirntlm asymptote equation was , undefined, with th6 explanatory power of the equation increasing continuously with increases in a. The-unusual shapie of the esti_saa_t&d ~estCoast yiebLcuie -- suggests that the observed annual catch-effort combinations on which it was based do not represent sustainable positions. This -- appears to cocflict with the fact that prawns are considered an annual crop. However, the annual crop concept is to some extent 1 an over-simplication. Depending on the level of fishing, adult prawns Bay live for up toathree years. The greater the level of * exploitation the lower the average age of prawns in the stock. two separate short-run yield curves.1 The first covers the period up until 1973, during which effort was expanding. Here catch rates were above sustainable levels due to the presence of large numbers of oJder and larger prawns not capturd durfig -- -L i I earlier years, whenT'.the region was fished less intensively. After 1973, because of the prior high levels of exploitation, not much more than one year class of prawns was present and this had eff-ecL'c&-siqxxificantlpke t U- duci*heca*hzte--L - though effort had also declined considerably. alternative ---go------*--- 4 i =The relationship between short-run and long-run yield curves is t? outlined in Copes (1978, 25-27) * 1 07 T' the early 19701s to reduce the parent stock below that required to maintain the previous recruitment levels, despite the very high fertility of the species. Both explanations suggest that 1 the sustainable yield curve is somewhere between the 1969-74 and ', 1975-77 yield-sffor t paths. A possible sustainable yield curve - is shqwg in Pigure 13. - - - - A - -- - - ,, --- - The above reduction in average age of -~~awn>caught has, of course, also occurred in other regions to some ertent./~overor, it has' been largely taken into Paccmnt,-&s&ci&- at-Eigh -- effort leveis, by the maintenance! of 'effcrt t these +levels for a number of years. Se%J i Note that the estimated yield curles are at best approximate. In addition, they represent average positions only. 4 *. As discussed in Section B.111, the annual rate of rege Z\ ration, ------and hence the yield -at a given effcrt level for each stock is subject to significant random variation. It is, therefore, perhaps more realistic to think in terms of a yield band rather than a single curve for each stock. Such bands are indicated by rhe dotted lines on eitherfide of the I estimated yield curves in Figures 13 to 15. For illustrative purFoses a 5% variation on either side of the esji3 ted yield levels bas heenused,- 111. COST Am BEVEHUE CURVE ESTIEATES virtually all of the prawn catch is purchased by local procgssing companies, with a smali group taKing the bulk of the i / catch. '~heseprocessors in turn sell largely to the world market, to which South Australia is but a very small supplier. A ------A A -- - - &------A ~onpktitionbetween the processors is such that they operate on essentially a kup basis. As a result of t-kese factors, fisher me^ norm&&y face-an - extqemely elastic demand curve for their catch, with the price being dependent on world demand and supply conditions. The annual revenue function for each region is therefore accurately reflected by a function of the f'orm TRt = ,Pt Yt (E*111 1 ) - -- where: TRt = the totad revenue in year t Pt =-&he average price per unit of catch. "P- ~btethat ~t-is affectea by the average size of prawns caught, % with larger ns commanding significant price premiums. As biscossed in Section B.V. average.> prawn size in tarn depends on I the areas and times of fishing. Given that the estimated yield - curves have already been based on the normal fishing practices -- - - * s in each region, for consistency, price osfiarates were based on ------normal size compositions of catch also. -&-2 d - - - -- I 1, T Estimates of average yearly prices in each region &reshown in Table Y. Note the variability of prices in all regions caused by random fluctuations in world demand and supply. In order to balance out scae 65 the random fluctuations in . prices, they were averaged over the three most recent financial years, 1975-76 tc 1977-78, leading to the following average price estimates over this periLcd: - West Coast - $2.95 per kg. Spencer ~ulf- $2.95 per kg. Gulf St. Vincent - $4.07 per kg. Investigator Strait - $3.54 per kg. v r The total revenue equations based on these prices are: where: TRw, TRs, TRv and TRi = total revenue in the West Coast, Spencer Gulf, Gulf St. Vincent an3 Investigator Strait respectively. , b Since total revenue is prop~rtionalto yield, the yield bands in Figures 13, 14 and 15 can also be used to represent the possible total revenue positions in each zegicn. The iaonetary -- scale isindicated on the right hand vettical. axis in each figure. ------major, seg~ents: 1. Operating costs, which are a function of the time spent fishing, for example expenditure on fuel, repairs and maintenaqce and pryvisions. il 2. Labour costs, which are normally expressed as a percentage of a 3. Fixed cq&s such as licence and other fees, depreciation and '1 +T cost of capital. - It is traditronal in fishing operations foY hired sk$ppecs - and crews to be paid on a share-of-revenue basis,' and this$2- ' practice is norm1 in the South Australian prawn fishery. -+ Possible advantages are that it improves sfficiency, and that it enables risk to be shared between cvner and crew.2.a e (;riffin'a et al. (1976) have, therefore, argued that labour costs s~oaldbe ------4- -p--p regarded as a function of gross revenue rather than time spe'nt a& fishing. ' This line of reasoning, however, ignores the factors determining the share percentages. Whilst in the short run these shares are fixed, their vhues will be such that expected crew payments the long term are dependant on their wages in alternative eaployment. It follows in that labour. costs =ar6 ----me------lsee Zoeteweij (1957) The above submissions claim that cos%s per unit of effort for the standard Spencer ~ulf'vessel increased from $85 in 1974-75 to $137 in 1937-78.1 Assuming uniforra r;ates of cost increases over thls period. the correspordinq average cost per standard vess&lLhour over the 1975-76 to 1977-78 period is $118. t ~i;en tdthe fishing power of the Hest Coast-Spencer Gulf sta-a&-rd-sesselLs-5&4C-~eiste r-t-h an- *hat- -of-t-he-Gu-LTSM-neentt * - and Investigator strait standard vessel, this figure Is equivalent to $75 hour trawled for the latter standard The resultan3 total cost equations'are: TCs = 118 Xs where: e TCw, TCs, TCv and TCi = total costs in the Rest Coast, Spencer Gulf, Gulf St. Vincent and Investigator Strait .respectively C Xw, Xs = Effort in the West Coast and Spencer Gulf in Pest Coast . - and sp Xv, Xi = Effort in 6ulf St Vincent and Investigator Strait in lThe cost esti.at& were standardised by assuming unifori +Lpfeei;at-5orrmtes slid ~ettrmsou~apktol of 7.5%. and 17.5%-if . replacement cost of vessels. respectively. *The compnrability of cost levels in.the various regions will be discussed below. . Gulf St. Vincent and Investigator- Strait standard vessel units. Since total cost is directly groporrional to effort, the above equations will be represented by straight Xines through the ozigin as shown in Pignfeo 13,14 and 15. IV. ESTIEATIOB OF RESOURCE BBBT By combining the yield, revenue and cost equations for a region, one can estimate the resource rent generated per period at each possible effort level, as outlined in Section C.I. TI& techn5cpe can be ilkustrated using the e-stirnated-yi-e3+---d- and revenue functions and hypothetical cost function for Spencer ~uif.He have Y = 3,800,000 (1 - .999983*Xs) 9 TR = 2.95 Y and therefore and where: R = the annual economic surplus in dollars. The surplus will be maximised when dR / dXs = 0 that is when .* -- -- - 7 90 ( ,9-3-9-9 8-3fxE)-=-Tl-8- -- h This reittrrses*~ -- - -- Substituting into the yield and revenue equwions this gives and R '= C $94 0,000. It is interesting to compare the above results with the current rents hw&ls-iqA&ed by - &he same set ctf-e quations,-Gi-wen------ the current effort level of approximately 45,000 standard hours, current catch would be 2,030,000 kg., and resource rents - $680,000, an average of over $17,000 per vessel authorised, tc * trawl in spencer Golf. The yield curve band resource rent ranges corresponding to the above optimum and current positions are shswn in Table XII. i~ Note the extreme sen'sitivitg of the rent estimates to changes in sensitive to changes in price or unit cost levels. A variation* in yield of only 5% at current effort levels alters the resource I rent per kilogram of catch by 8-14, half the estimated current 1 level of $.28. Based on these estimates, it would appear that effort levels in Spencer Gulf are currently past the level which would maximise resource rents. The optimum effort level, however, is \ to 1977 have been past the resource rent optimum al'so depends very much on the position of the yield curve in each particular TABLE XI1 HYPOTHETICAL RANGES FOR CURRENT AND OPTIHAL RESOURCE RENT LEVELS FOR SPENCER GULF -- At lower bound- At upper bound Estimated yield at hypothetical optimum effort of 32,000 hours 1,520,000 1,680,000 (kt!) a - - -- Corresponding total revenue ($) 4,480,000 4,960,000 Corresponding total cost ($) 3,780,000 3,780,000 d Implied resource rent ($) 700,000 1,180,000~ Estimated yield at current effort of 45,000 hours (kg) Corresponding total revenue ($) Corresponding total cost ($) Implied resource rent ($) ------year. The alternative rent levels are shown by the vertical distances between the total revenue and total cost curves in Fegure 14. Because of the subjective nature of the estimated Vest Coast and Gulf St. Vincent revenue curves and the additional uncertainty of cost levels in the latter region, estimates of the rent levels and hence optimum effort levels for these stocks are very rough. Some very tentative conclusions can however be drawn from the subjective revenue and hypothetical cost curves shown in Figures 13 and 15. It would appear that the Gulf St. Vincent stock is currently being much less heavily fished than the Spencer Gulf stock and that resource rents are likely to increase with increased effort. Using the hypothetical cost levels described above and the suggested yield curve band, current resource rent levels are between $680,000 and $830,000. This represents an average of $49,000 to $59,000 for the fourteen authorised vessels, or $1.80 to $2.20 per kg. of catch. Note that these vessels are smaller and hence represent much lower capital investments than those in Spencer Gulf, yet achieve much higher average resource rent levels on a Fer unit basis. A further interesting result can be deduced from a comparison of the resource rent range for vessels operating in tNe two major regions. In Spencer Gulf, where the resource rent represents a much smaller part of the total revenue, it is much k more sensitive to changes in the underlying variab1e.s than in w Gulf St. Vincent and hence operators in the former region face mnsiderablp higher profit variations. It would 'appear that the Best Coast stock is relatively small and cannot withstand continuous erploitation at the high effort levels of the early 1970's. Even at a much lower effort - - A -- - level of say 2,000 to 3,000 hours, it is unlikely to genarate significant resource &rents. Resource rents in Investigator Strait, given the current catch of 145,OO kg. io*5,000 standard hours trawling and the hypothetical cost levels outlined above would appear to be between $70,000 and $120,000, distributed between five permit holders. This represents 5.48 to 1.83 per kg. of catch. No suggestions as to how effort should be adjusted can be made for -- this region. - - - - 1 The kjo1 conclusions from the aborg analysis are:% 1. Resource rents in Spencer Giilf could pcksibly be %ncreased by scme effort reducticn. 2. Resource rents in Gulf St. Vincent could almost cerfiinly be increased by an increase in. fishing effort. 3. A large raducti~hin fishing effort from the levels achieved in the early 1970's is warranted on the West Coas*. 4. The relative rent levels psr unit of catch at current effcrt ------L ------1Note that these conclusions are tentative, and are considerably modified in Section E. V. ? levels are in Gulf St, Vincent, considerably lower in 5 ~nsesti~atorStrait and sdmerhat lower itil.1 in Spencer GUM. 5. The relative- rent levels on a per vessel basis at current +I- effort' levels, are again highest in Gulf St. Vincent but are higher in Spencer Gulf than Investigator Strait. In addition the sffereaces between regionsis- coa~i4,erably lessthan in-the-- rent per unit of catch comparison. 6. The level of resource rent per unit of catch from a region is -- - .extremely sensitive to ch-anges in the position of the yield I curve and prices and unit effort costs, 7. The optimum effort position for a region is also very sensitive to changes in the pcsition of the yield curve or in price or unit effort cost levels. B The above results that 'vessels op*egj%gng in all regions had identical cojts par unit of fishing effort. It is C considered that in fact vessels had higher costs per unit of P effort in Gulf St. Vincent than in Spencer Gulf forothe ------following reasons: ' 1. vessels in Gulf St. Vincent are confin'ed to- use of single rig, despite the accepted superiority of double rig. 2. Vessels in.Gulf St. Vincent fish for shorter periods per year and hence must spread fixed costs over a smal4er number of hours. JL The high costs in Gulf St. Vincent were accompanied by high ,revesue derived from each unit of effort. Of course, the high costs ao reduce tEe potentiar re%€ -for apgiven fisJiing efmrt byppp- keeping cosrs higher than necessary in relaticn to revenue. However, it is considered that the best strategy for this region is not to base policy on existing inefficient methods of operations but rather to encourage adoption of superior fishing techniques. There is little doubt that resource rents fron the region would be int reas& by efficiency imprgvements in each of the above areas, even if they were accompanied by some increase - - -- in effort, since current effort in this region is far from excessive. - s -- \ 4 % The Usst Coast fishery is primarily based on exploitation by Spencer Gulf operators during periods of low catch rates in the -gulf. They are primarily concerned with covering their varsable costs, fixed costs having been met during the main season in the latter region. sin& variable costs represent o~lyabout two thirds of total costs, the relevent cost cKrve for me RSst Coast when fi~Eed-in~€KiS---~---~ , , ahnner is considerably lower than that derived above, which a assunTed full-time operation. ,< + If fished on a pari-time basis, effort levels of about . 4,000 to 6,000 hours may be justifiable*for the region,. Some kents map also be generated in such a .situation, althcujh theyx d are li*kely to be fairly small. . , The analysis so far has also no? ,taken into account the size of th:e consumer- and pr'oducer_surplusesp generateaat- each level of exploietion. f Consumer surplus equ& the difference between what buyers are willing to pay and the harket price. It accrues to the final consumers of a good. since about 90% of the South Australiac prawn catch is exported, most of the consumer surplus associated with it acicrues-to individuals outside the state of origin, Assuaing that the aim of resource management is to maximise the" br benefits derivedfrors, the fisherT3n south Australia alone, thG The price in the domestic parket depends almost solely on f' f' export prices, and hence i6 unPidke,I,y._t~be affected by changes &x.* " in effort and hence catch le'*@s. Any local copsumer surplus is therefore also independent cf the chtch level. It is therefore concluded that' taking account of consumer surplus has po impact at all on the analysis. * A I A It has already been argued that the estimates of outlays made and receipts, foregone provided voluntarily by fisherman probably contain biased information. If they are based on the - operations of the least efficient participants they will also over-estimate the market costs of all more eificient operators. In view of the heterogeneous nature of the vessels within the e b Spencer Gulf fleet and the variation in number of hours worked, the distortion introduced by this effect could be quite -?-% 6 ------>------cons2derable. -- - - In addition, ,as discussed in Anderson (1978), because of the rather unique nature of the fishing activity itself, it is considered that'participants derive some psychic income from it abcve their market remuneration, hence use of wagesdforegone as -& a measure of labour costs overstates true cost levels. To the extent that the hypothetical cost levels used in the analysis overstated the'actual costs per unit of effort, the 0, U TI ' In f-l +' a .r( W 0, 0 h l-i A a (d 4' r-i -4 -4 0, rn U 0 P d 0 4' Q) 0) in l-l I-, Q, U a, P a, a d .rl 4 .A n +' 4' Id Id 0 I-, $4 W vl 0) 0) 0 'd CI a .d a V) 0) mJ a rn 0 Id V U a, a k 0, rn U I .rl 0) rl a W 0) W k +, (d H a0) 0 0, +' W U W 0 4J Q, m Id rl W tn +' 0 +' 3, I .d a a I a0) rl a,I-, .+' a w UI .ri Y crt U) +' 0 U t' td w H +Ju 0 W W 0, Vf . BBGULATIOI OP PB1II CAPTURE SIZE Q The discussicn so far has taken the mahner of exploitation / /- of the stocks qnd.hence the average size of prawns caught in r' each region as given, although the differences between regions result from each po;sible pattern of exploita&ion.%In theory an /- ideal regulation strategy for each -region based on the ------ppppp-p - - - characteristics of each particular stock could be developed. It - ' i vould need to take into account the numerous factors affecting + -,= the yie d, revenue and cost functicgs. . $- We .-\ --. The benefits of any particular regulation will depend on: 1. The costs of enfcrcement and its effectiveness. 2, -me-ratesaf-gcowth-anhaas ?ortality-~Lpravnsover the Cr .Q season. \ %r 3.'The relative prices of prawns of various size classes. 4. The rates at' which* prawns disperse after leaving the nursery areas and hence the rates af change in capture costs as average size increases., -&W A 5. The extent to which fishing costs are fixed and hence"t0 \ % which average costs per unit of fishing effort increase as the - -- - period of vessel usage in the year declines, the weight of prawns is maximised if they are taken at a size - \ slightly smaller than that at which they leave the nursery . areas. However, because of the significant price differential I which exists for larger prawns and their rapid rats of growth .* duri e sunmer months, it would appear like)ycthat the value * of the catch wili be greater if capture occo~sperhaks two or 5 three months lateral This lends support to scme type of seasonal --- r_fnntlr*-x-* in.*)Lg---8fl ------ On the other hand a shorter fishing season will decrease - - the period over which vessels will be utilised, assuming the - Y ------ A- current requirement that operators not participate in other - fisheries continues to apply. This will increase average fixed I costs per unit of tine spent fishing over the remainder cf the 0 year, In addition, the general disp&sion of prawns after they ~xitfrcm the nursery areas shculd /,- - decrease catch-- rates, further------increasing the cost of-taking each unit of catch. The combining of the above factors into a total-econpeic - iodel, even if all the necessary data were available. is a complex problem and will not be attempted here.2. Some very general cements about the simplest form of seasonal regulation, the setting of opening dates for the fishing seasons in ZBased on very rough unpublished estinates by ~ing. ------ particular regions, can however be made. % Rhatever type of seasondl closure is attempted, individual w fishermen nay benefit by cheating. Such cheating reduces the -. possible benefits from regulation and also encourages other operators, who initially abided by the closure, to also cheat, which further reduces the potential overall benefits. The LA -A ------pra~ti~a~i~~of~h~clo~ureis therefore a very relevant consideration. For this reason the current closure of only a part of Spencer Gulf fro@mid-January to mid-Urch is far from ------ideal because the difficulty cf monitoring where vessels are actually fishing leads to frequent violations. 1 A much simpler policy is -total closure cf all areas. ~Liscculd be policed much .<- more easily, by ensuring that no prawn vessels are in operation - during the closure period. w possible benefit of a seasbnal closure nay be provided by comparisons of: 1,;The profitability of exploitation of a given stock in different years when the patterns of expoitation have .been * differeng, 2. The profitabiliky of exploitaticn of two different stocks . . where the patterns of exploitation differ, 3. The p~ofitabilityof exploitation of aqgiven stock under ------ ' varying forms of regulation. + , . The most useful suggestion for South Australia is probably, 2. Gulf St. Vincent operators earn much higher rates of return than do operators in Spencer Gulf. Although this is due partly to the less intensive exploitation and ,bence higher catch rate in Gulf St. Vincect, it is also contributed to by the large -- - - - Up- price differential fox catch taken in-this region. A s discuseed in Section B. V, this is largely because of the larger average 6 C size of prams caught in this region, which i-s in turn dqe to a - L more balanced within-year effort distribution and the fact that ., = operatorspfish in areas well away from the nurseries. * The above dkaly&ssuggests that manageaent shooI d attempt , to achieve this manner of exploitation in Spencer Gulf also. This would entail limiting effort early in the season and - prevention of-trawl-ing--in-*reasawamnt tothemseries~------Unfortunately, the latter type of restriction has already proved 4 to be largely unworkable. Complete closure of the whole region -,: .- JZ - for the two or three months during and immediately after the period*of peak recruitment would be easier to implement and would avoid the taking of large numbers of small pravns,4"but it would significantly shorten the f ishh;:'season and hence lead to - - a marked decline he efficiency $f usage of the available ------vessels. A system9 intermittent total closures is perhaps the best compromise solution. A short total closure early in the season, -- -- - Z -. from say 15 January to 15 ~eI&ar~could be fcllowed by a system of closed and open days or groups of days for perhaps the next six weeks. The ratio of open to closed days could be gradually increased to achieve stepped increases in effort as the season progresses. Towards the end of the season controls could be removed- - altogether, so as to maximise the catch of the large, higher priced prawns. This system, because it is based on total closures, *auld be easy to p61ice and woul-d avofdexcessive emrf early in the season whilst allowing some fishing during almost all months of the year. The rate of transition through the three stages could l of course be modified on a yearly basis in the light of I/ . , biological information deriveda? f~omeither sample trawling in or fear the nursery areas or exam2nation of the composition of the ------catches taken during initial weeks of fishing. For example if the time of recruitmen.; was later than usual or 'if the level of recruitment appeared to be Xairly low, the rate at which the closures are relaxed could be slowed down. The benefit of the scheme, in terms of total rent from Spencer Gulf, is very difficult tc estimate. Slightly lower effort and catch levels are likely, however, since effort is if Catch rates later in the year should increase, although the ---.- overall catch rate for the year will almost certainly be r c3d ed because of reduced effort dusing the, ieak abundance 'months. This average price received for each unit of catch. It is the author's guess that the overall res.ult would be a small, but not insignificant, total rent increase. F. ULOCITIOI OF ACCESS BIGHTS AID DIS'ICBIBUTIOI OF RESOURCE I. THE CHOICE OF THE ACCESS BIGHT UIIP The level of exploitation of a fish stock can be defined in terms of either catch or effort, since they are directly related ,J through the yield &unction. In terms of trying to achieve a entry scheme, however, the results, may be siqnificantly effected by whether the access rights of iqdividual participants are ------ - specified in catch or effort terms. In atteapting to achieve the desired +level of exploitation of a fish stock, management can follow either of two basic -st:&atzq&es. It can limit the catch of each participant directly, by means of catch quotas, or indirectlpia the use of effort , fishing effort of a participant depends on the number of fishing units he uses, their fishing powers, how much they are used and & oh which stock segments they are used, hence all schemes based - on limiting the fishing effort of each participant entail restriction of one or morebof these parameters. In a limited entry fishery, assuming that some resource rents are being generated, at the margin the fishery is still x ------yielding a positive private surplus. It follows that pa~t%apntx-have an incentive to try to increase their fishing - --- - efforts and h&ce catches. Assuming that total effort is at or C* - past the optimum, such increases would reduce the rents being generated by the fishery. In addition, since they allow indivicual operators to capture additional resource rents, \ although it is at t)le expense of other operators, they may be undertaken even if they increase their costs per unit of effort. ------a ------Such unit cost increases ,would also reduce the rent generated by , the fishery. Increases in fishing effort tend to occur because - - -- of the difficulty of achievinq perfect contrcl &the effcrt or catch levels of individual operators. Consider the case where each operator is given an effort quota in terms of a vessel-gear, that is, he is permitted to use a single vessel, but can otherwise fish as he wishes. He is likely to attempt to ing rease his effective effort per unit of inputs such as vessel size, number of crew,-type_' of gear, time -- -__-_ _ _-! spent fishing and areas fished. To the extent that such changes alter his input mix for the fishing operation from the most I efficient one, they will increase hi: costs of achieving a given effort level. 1 The usual strategy adopted by management to prevent effective effort increases is to specify the effort quota in 2 This widely effect is known and is discussed in numerous h --of If d*ed antrschelses.~eefor~exara~gle,Anderson Christie' 34-51, 976) , (1973,. Copes (1978, 10-11 and 80-81) and 1i nclair (1418, 1024). 2 'i L - - -- terns of more than one parameter. For example the fishing power of vessels may be restricted by regulating its size or the type of gear it can use. In theory this could be done in Such a way that all participants would be permitted to adopt most efficient -- fishing techniques but be unable tc increase their effective effort leqels. In practice, many adjustments undertaken by -- - A -- -- u operators both increase ef Eective fishing effort and decrease cost per unit of effort, so that it is frequently difficult to determine the overall impact on economic rents for the fishery ------as a whole. For ease of administrative control, management often finds it convenient to apply blanket restrictions on ceftain types of modifications to fishing units. Sue a policy is likely - to achieve reasonable control of the effort' cf each operatcr, and hence prevent; or at least minimise, the extent of - - - -- over-exploita3i;on. -Howere~,becatl se -it is &3;sc-%ik&rto -preve* ------/-' the introduction of more efficient fishing techniques, it may increase costs per unit of effort,l The overall impact on , resource rents from the fishery o~suchrest%ictions is therefore unclear. If the access right is specified'\in terms of a catch quota, \ operators may be tempted to cheat' on their allocated catches. Such over-quota catches would have to be\, disposed of in a nblack ------p-- - - - costs in disposing of catches in this way - these costs may in fact take the form of lower unit prices - the cost of taking' a given catch will also be increased. One efficiency advantage of a catch-quota scheme is that it is not necessary to restrict in any way t.$e fishing methods used 3 by participants, since their effort levels are regulated already ri *Y i; II terms of-tMra3-3uwabl-e- ~=a-t@ites-~'Ph-e i nef fieie*-i-n-put--- distortions which occur under ef f ort-quota systems because of attempts by operators to increase their effective effort levels \ ------and because of management, attempts to prevent such increases are - = therefore avoided. The cost of taking the quota may still be Bbove the minimuia, however, because of the restriction which is ' ' placad on each operator's scale of operation. Only if quotas - were saleable could unit costs be completely minimisea. Insummary, under anp limited ent~yschemethere is a ' - -- -- P tendency for a gradual erosion of resource rents to occur via increases in the level of effort and concomitant increases in -U - costs per unit of effort. If the number of participants could be L readily adjusted, the first trend could be neutralised by i i gradually reducing the number of participants. However , for i reasons which will be developed below, such reductions are 6 usually difficult to achieve. must-&* t'-ibleLesSe=ee+-- f level of exploitation and adoption of inefficPent fishing -> 137 / ' techniques. One particular aspect which may be especially * relevent is the ability of the scheme to pr~videthe flexibility necessary to adjust quickly to changes in the desired level of exploitation. In the South Australian prawn fishery, access rights are currectly lspecified in the form of vessel-years, however sever31 ------vessel characteristics are also regulated. Alrhough the effective fishing effort level per vessel, in each fleet, has I f increased considerably since .the closing of entry-- to- P the------. . fishery, as shown in TSble EII, it wohld aRpear that the scope for further such effort increases is limited, Most of the I - possible strategies have already been followed. In terms of A their ability to control tbe level of exploitatJon in each region, therefore, the curs ent regulations are probably - - - gene~aL~yadequete, espei%=y-sgnce-sonre-fnrther effort b increase can probably be accommodated in most regions'without an excessive reduction ic economic surplus. There is, one obvious exception to the above .conclusion, however, the Usst Coast. It was concluded in Section E,,VI that -. .'. the stock in &thisregion is relatively small and was subject to excessive exploitation during the early lWOfs. Thpse high I - d 1 fishing levels were possible because of the ability of operators ------to suitch betwee? it and Spencer Gulf. This potential for over-e~pl~itationshould be avoided by terminating this % interchange right and introducing specific control of the number 1 38 TABLE XI11 AVERAGE ANNUAL EFFORT LeveL PER OPEBATOR IR EACH , - FISHING PLEET'FOR YEARS 1968 TO -- - *Ft:-m------L&f~+st,"--- -Irrvm i-gator- - -Year Spencer Gulf Vincent Strait (hrs. (hrs. ) (hrs .) 'Because operator are free to operate in both the West 8 cmd sp&cer Gulf, the ef f t levels of operators in each region were combined to give a ~ingleoveralj figure. - -- 6f vessels permitted to operate in the West Coast region. There are three possible ways to exploit the Hest Coast stocks: 1. Grant a small number of licences specifically for the region, and allow only the holders of these licences to fish there. 2. Allow a limited number of Spencer ~ulfoperators to fish - there on a part-time basis duringpart of the yedronly. '* 3. Have a mixture of some full-time licencees and some part-time operators from Spencer Gulf. L - - The advantage of full-time operations is that it ensures that a substantial part of the available stock is taken thfoughout the year. However, because of the need to cover total costs, it is unlikely to lead to any resource rents. Part-time operation, on the other hand, would mean that opsrators would ' only have -to cover mrg-inal costs and -would-be fishinq---. previously unexploited stocks and hence achieving improved catch --h. s. rates, both of which should significantly improve returns fron I ... Vest Coast operations. In addition this strategy would decrease the pressure on the Spencer Gulf stock during the period of ? :lowest catch rates, thus iaprcving the catch rates of those c, operators still fishing in this region. 1 Whilst the available data are inadequate to allow a qiniteconclu~ion as to the bast stratagg to be reached, a - com6Tnation of perhaps two3ull-time licencees and a small' 'G number of about three to six part-time operators from"spe + r w - -- Gulf may be a reasonable comprcmise stratagy. It soold allow some of the benefits cf both full-time and part-time exploitation to be achieved. It is difficult to assess =the inefficiencies yhich have ., been intrgduced by the current regulations with respect to . + vessel length and net size since the relative efficiencies of - St - -A ------" various input combinations are largely tfnknown. " It is likely that one advantage'of a larger vessel would be I , - greater carrying capacity and hens less fre~u"entneed tx-return - 7 I > to port for unloading. This advaqtage would he greater when the : - +'7 grounds are'more distant from the Forts or unloading ports. E . 1 Given that the Spencer Gulf more distant from such f i ports-than are those in Gulf St. Vin ent, the current .smaller 3 k allowable vessel size in the latter ion has. some efficiency qi2 -1-p----p-ppp-p - - p-pp , j"g+ifioatkn.p- -- one restriction which is cledrly hhmperdeffkcienc in Gulf St. Vincent is 'the confineme* of all vessels to single - 1. rig. It has been estimated that double rig increases vessel . { catch rates %J! approxfmately 30%, yet it' entails a much smaller I l. k increase in vessel operating costs, hence it 3s clearly a more i efficient type of gear than single rig. In view of the fact that CYI ! effort is probablyo under the rent-maximising level in this $8 * region anyway, the adoption cf double rig is an ideal way to - $ * Z -- both increase fishing effort and decrease costs per unit of a _ effort. - 141 1 permitted and encouraged, if rent i~40 be aa&ised. The *.' 'ne&5sary incentive ccuv be provided by the threat to increase effort by issuing -additional licences if current participants - ris ' fail to idcreare tLeir effort levels by moving to double rig. At present there is no regulation cf the hours trawled by individual vessels, This means that uperatorE have the ------A ------? flexibility to adjust their effort levels on a short term basis. \., ahilst operators, acting independently, cbvicusly will not 1 period, provided they pttempt to maxinise private profits, a the directioPhf adjustment vill at least be correct. A* possible alternative to the current system would be the .. allocation of cakch quotas to individual fishermen. Because cf the small number of grocessors, their independence- from the . fishermen and the yentual sale of the bulk of the catch on overseas, .- markets, it is considered thst the government, by - monitoring processor company purchases, would be able to accurately check operator catches, There would be little scope for over-quota catches because of the absence of a suitable market. It is therefore concluded that from a control aspect the use of catch quutas is feasible. % ,I -- - Ona-shanl-d-,bore ve r , alao ey th~~easi~~c~n~~ic 1 This aspect will be, discnsseaTiiSher in a later section. <, rents achieved under such a quota system. Prawn stocks are subject to considerable fluctuations in abundance overthe years and also exhibit a marked within- year abundance cycle.. The total desirable catch will.4 heref ore vary significqntly among years. add the size of each qhota should be adjusted accordingly. In addition, as discussed in Section E.VI, there may also be gains ' example it may be desirable to hold down the catch early in the year uhen prawns are small and fetch a low price.- There- is, ------however, little t~ be gained by regulating the catch at the end of the season when prawns are large and natural mortality is wry high. The id tal catchduota scheme should therefore encompass variable catch quotas for part of the year bat allow unlimited - -- of the residual stock to be taken. For this type of scheme' to be successfnlly iaplemented it is necessary to predict at the very , beginning of the season the strength of the recruitaent and hence the ideal total catch and catch distribution for the pear. 4 Z Unfortunately the biological data necessary for this type of fine tuning is got currently available, and hence precludes use of a catch-quota scheme at this time. Even if the required data were available, it uould be difficult to prevent operators with freezing capacity from using it to disgase when catches were actually taken, so as to cheat on their allocated quota for the ------early- part of the season. ,Hence the scheme would still be difficult to isplement. It is concluded that the current system of allocating access rights in terms of vessel-gears should be retained. subject to three provisions: 1. The practice of allowing vessels to interchange freely . A *A-a- A ------between Spencer Gulf and the West Coast should be discontinued. 3 7 Instead, access should be restricted to a very small number of I f ull-tiae operators and a f €M Sspsncer Gulf opera4csson-+-- part-the basis. 2. The ban on use of double rig in Gulf St. Vincent should be discontinued. 3. Effort in spencer Gulf should be delayed by the use of 5- intermittent total closures. 11. CLAIEAITS TO TEE RESOURCE BEBTS There are two obvious claimants to the resource rents generated by a limited entry program, the actual participantdin the fishery and the general public, who are noraaaly considered - ta xe-TE- e prlaary owners 6~L~~-m3~rT~.uuu6~SfA~equestion ot rent distribution is largely ccncerned with equitp and is therefore more political than economic, it is worthwhile to ------. clarify at least some of the issues invclved. The rent distribution may also have some economic implications. J The major econ-omic argument-advanced in support of rent retention by fisherman is that it ~rovidesan incentive for greater efficiency and innovation. 1 It is true that if all operatorspina fisAeryredu ce -i~c-csfs 31unFf afAfort ,by-. adoption of a uore'efficient method of fishing this will increase resource rents at a given level of effort and if some rents are retained by fishermen it will as a result increase operator profits. For this to act as an incentive to operators - to make such changes, however, it is also necessary tlat operators attempt to ~ximisetheir financial surplus. In many fisheries, operators trade off fishing income againstleisure time. Asincome per unit of fishing the -- Incredses, they may pafarinmmmed leisure time to additionalp --.----.----.--.-- . &See Copes (1976, 80) and Evans (1977, 10) .-. - * - --~ni081e,-amTsoiserhetime they spend fishing. assuming each operator has his own fishing unit, a reduction in fishing time per operator reduces the rate of capital usage and hence -- - --C * -increases the cost of achieding a giwen effort level. Here rent setention may reduce rather than increase efficiency.1 The net effect of rent retention on operator efficiency can only be On equity grounds, allowing rents to be retained by ------fishermen is frequently supported because of concern fir what are considered a poor and disadvantaged group. f here is no doubt 4 that the major argument advanced for the .introduction cf limited entry schemes in traditionalFoFen entry fisheries is their' % ability to improve the welfare of the fishing ccn~unities .I involved. . . If assistance to fishermen is considered necessary on U equity grounds, allowing them to retain resource rents has * 'several advantages over the alternatives. Since the rent is generate4 hy the isherman himself, it does not h@ve the stigma associated with untied government handout and therefore leads to a superior feeling of well being or additional psychic income above the actual monetary value of the assistance, Xt also has lThe issues involvqd are very similar to those consiaered in attemptinq to assess the effect of varying tax rates on work incentives a familiar public finance question. e u the advantage over direct subsidisation of particular aspects of the fishing cperation of not providing an incentiveTta -distort resource allocations in order to maximise private +returns. For .&% example a special tax allowance for capital erpimditure on fishing equip~entis likely to lead to excessive expenditure on such equipment in terms of social as opposed -to private costs --A - - - A- --- - and benefits. One should, however, also con sidei critically the equity of such assistance.- 7 Fishermen's- - -earnings -- - are a function- - of- their ------alternative employ~entopportunitites, not the economic state of the fishery. If fishermen are poor it is not because the fishery is unprofJtable but because there is little work availablle elsewhere for them, If -it is unwise in terms of enkouraging resource reallocations to attempt to compensate all groups whose consideration? In addition, fishermen may not in fact, all be as badly. off as they appeax at first glance. .In most fisheries,. ~ a broad spectrum of earnings prevails, 1 due to differences in operator efficiencies, The benefits cf rent retention accrue to all M particigants regardless of their actual earnings. Fishermen ' s . . incomes also frequently include a large psychic component in addition to their ~onetaryremuneration, hence use of the latter . ------CIIIIIIIIII lSee Copes (1 972). - - - will deflate their true overall income levels. Evans (1977, 10) argues that 'vResource rents are earned in othe;: industries and seldcm are pukl-ic attempts made to effect its dispositiontt. He cites the example of an agriculturalist with rich land close to an urban market. The exceptions, however, for example royalty payments made for the right to - - -A ------.----A -- exploit miceral and forestry resources on public lands, appear to be in situations which closely parallel the position in a limited entry fishery. Whilst the- - issue of whether- a partichlar . ' ------, property should be considered as part of the public or ~=irate domain cannot be unambiguously resolved+fisheries would almost certainly appear to be towards the public\ nd of the spectrum. Note that the equity arguments advanded in support of rent retention by fishermen lose much of their rorce when the size of rather than owner-operators since the benefit* then largely accrue. to individuals unassociated with the actual fishing operations. In addition, the higher the resource rents generated B by each operator the more difficult it is to justify full retention of these rents by them in terms of their need for welfare assistance. Evaluation of all the above efficiency and equity argumenas involves complex value judgements and will not be &tempted ere. kt would appear however that for the South ~ustralian prawn -fishery a strong case on both efficiency and equity grounds for removal of at least part of the res,ource rents froa the actual qperators can be made. As discussed in Section C.IV, there is evidence of short periods of operation and hence inefficient ca~italusage by many vessels in spencer Gulf and especially Gulf St. Vincent. This is probably primarily an attempt by operators to lower + ----A- - A ------A -- profitability and so reduce the pressure for and hence likelihood of further licences being issued or of some rents very high incoaes which can be achjeved at relatively low effort levels. Lack of profit motive may also hamper the willingness of all operators to make correct use of the effort flexibility by ! provided the non-restriction of vessel operating' hours. ~Qhovalof part of the available resource tent from operators ------pp - should reinforce the profit motive and hence lead to resource rent increases via impr-oved efficiency and exploitaticn flexibility. Given the apparent very high average incomes of operators in all fleets, the case on equity grounds for complete rent retention by them would alsc appear to be very weak. t 111. BEBT CAPITUIZATIOU ABD ACCESS RIGHT TBAISPEBABILITY The value to a particular entity af the right of access to a limited entry fishery will equal the discounted value of the flow of abovi-normal returns or econonic rents which the entity could obtain by participating in that fishery. It follows that -A -A - if su'Zh-rl'ghX are transferable on the openmarketthe - C' free-market price will equal the highest value placed on such rights by a non-holder. ------The initial * of such rlghts is therefore able to capture all the abcve-normal returns which tPhe above non-holder ciates with them by a market sale, the rents being capitalised in the4transfer price. Assuming the purchaser is realistic in his estimates of the future rents, he will, net level of profits.~ullock (1976) refers to this ability of initial' o capture all oono~olyprofits associated with the entr.y restriction as the transitional gains trap, since subsequent rights hol'ders earn only normal profit$. . - 4 On the other hand, if the access right is non-trapsferable, the holder rill only be able to capture rents by, actually participating in the fishorg himself, and hence the rents ha ------_ will gain are limited to those over the length of time he is an $c3ieEsher man. Several arguments are advanced in support making access rights or licences non-transferable. Firstly, it prevents initial holders of such rights frcm capturing all of the future rents available to participants. This allows rents to be spread among successive generaticns of operators via' the regular reissuing of expired licences. 1 This is considered more A --- e~uit&&e-+-hatt.- c*p&e+eapt*+of a12 -ren&--by~in&t&e~csnce- F -7.- holders. In additioc it avoids the social problems which nay be *. I associated with all subsequent generations of fi'shermen earning Secondly, if licences are non-transferable, all + p,articipants are earning above-normal profits, hence reaoval of some economic surplus can be 'achieved2 without operators suffering overall capital losses. For this reason, it is . suggested by Evans (1977, 13-4) as a useful imterim measure -----p------~ -~ until management decides its bng.term rent allocation strategy. Thirdly, if licences are non--tran sferabla, management is able to adjust the level of exploitation of the fish hock to meet changing circuastakes merely by altering the number of expired licences which are reissuedma If licences are transferable, no licences will be surrendered, since they have a ---r------i-- I * - 1See .copes (1 976, 10) . JSee Copes (1 978, 129-30) . .. ------p-pp-- - , positive market value. If a reduction in the numb'er of licences is desirable because of excessive effort, it will therefore require re-purchase of existing licences from current holders. This procedure, usually refered to as a buyback, has 'yet to be ( successfully implemented because of the numerous administrati've and socio-political difficulties which it gives rise to. A ------, --A ------A- non-transfera ble system, by al*/ng effort to he reduced, therefore is likely to result in a superior level of . - - exploitation if the stock- is--- initially A- -o~e&~loi_ted. ------Fourthly, if the capital market is imperfect, inability to \ obtain the funds necessary to purchase a licence in a fishery where large rents are retained by individual operators may preclude some owner-operators from participation if licences are freely transferable. For. both equity and eff iciencp reasons, L a -? '. Fifthly, unrealistic optimism by potential participants' may . 'i.\ rbsult in excessive prices being paid for transferred access ,\ rights, leading to subsequent social problems in the fishery. '% This is probably more likely where ihe individual fishing unit I\ 'z is small and unsophisticated, as here potential purchasers may be less well informed as to the actual size of the available rents and'klso because the existence of psychic income in such situatiocs increases their willingness to absorb low financiat re turns. F Note that the above- advantages rely on fishing being undertaken by owner-opera tors. Company owned and managed fishing , aa= 4C LG enterprises hgve an indefinite life hence $lo not nded to transfer their access right tc obtain the full value of future 3 rents, and will never be forced to invcluntarily surrender their ------A - .--- -*IA + - -A- licences. There are few equity arguments favouring' redistribution of wealth to such entities. 'Ithey are also likely , of a fishing licence because of a more professional approach to evaluation apd concentration on financial rather than psychic k returns. It is likely, however, that costs per unit of effort will - be adversely affected by the application of a non-tramsferable lifetime licence policy. Initial recipients of such licences will probably not be the most efficient operators available. However, as long as. they earn some rents from their fishing operations, they will not voluntarily relinquish their fishing rights. Sinclair (1978, 1026) argues that this leads to high cost "grandfather" fishing operatcrs who retard the adoption of new technology and the entry of new low-cost production units. This map-signif icantly reduce the level of resource rents , generated at effort? f +ransf er 2 4 is past the 153 ------, --ppp T ------ppp-p -- 4. optimum level and the possible variation in operator efficiencies. Obviously if effort is well past the desirable level then a no-transfer policy, by achieving reductions ia I effort, will probably increase the rent level even if it .a increases unit fishing co str. Existing participants usually favour transferable licences $ ------stronqiy because they are then able to capture future resource \ / ---- /- . 1. rents. This is especially t,heI ,/- ye-% a tradition of licence a '-., decisions have already been made based on the a4ility to capitalize future rents, even if actual capitalization has not yet been achieved. When considering- thedesi-rabikity of employing a n6n-transferability rule for prawn trawling authorities in south 1,Authorities have been effectively transferable at market - prices since the ince~tionof the limited entry scheme. - 2, Forty three percent of the current authority holders purchased their licences on the open market. As a result, it is certain that at .least some rent 'capitalization has already occurred for a large number of licences, The exter&-g~'_this--_ _ capitalization, however, is -.-- difficult to estimate. --_--- - -- -- l Given that profit expectations and hence transfer prices of ,licences are largely based on Frofit levels at the time of sale, it is likely that only sales since the drqmatic price escalation I . /' of 1974-75 would have achieved aniything like full capitalization / / of 1976 to 1978 rent levels. In addition, give the extremely high prices which it is * runouredl have been paid for vessels with authorities attache&, 1 I $200,000 to $350,000, there may be relatively few potential , - 2--IILLLILILIII------L- 111 ---- I owner-operators in the ma$ket, leading to the 'possibility of a i 1 .purchasers being able to ..*netain - scEe economic surplus for s -a- iL ------'? - a*:+L~~~-~-~~~- r- - - -- tw&ves ------& T- The Government has indicated for some time that it plans to take action to remove a substantial proportion of the rents currently retained by prawn operatcrs. Recent purchasers have no -a.- 2 doubt reduced expected gains accordingly in estimating the value of authorities and hence the prices they paid for them. . It is considered that because of the substantial amount p,f aoney involved, and therefore the realism of -the associated ------financial analysis, that no purchaser would have paid -,#o~&&&an / .- A 1 a realistic anticipated value cf the licence purchased, 0 r? In summary- it is considered that up to the present time v .% some rent capitalization has occurred fo~sonewhat less than 50% of current authorities, but that only for approriaately hq3f of AAesa.-+# has anything approaching full capitalization been - achieved. Even for recent sales, ca~pletecapitalihtin of all -- ---.------.--- 1Exact figures are unknown because of the uncertainty of the value of the under-the-table payment for the licence itself. probably unlikely, The situation is in fact similar to that drscussed by Evans (1977) in his analysis of the shark ~a~~prawnfishery in iiestern , . .? t iustralia, the mjor policy i.sbaing & 1. ilhether or not to continue to allow market trading of - 2. Bhether or not .to remove some (cr all) of the rents from - * participants. (original licence recipients) and high cost operators (later entrants) in any rent removal ~rocadure. --1 . , Each of +he above issues, since they involve the evaluation -.. of both equity -and ef ficicncy considerations, must eventually be resolved by the proces ,of political response. The following factors are, however, clearly relevant; I 1. The State Government has permitted lice-nce transfers to occur .. . - knowing that thef were being accomgaaied by rentcapitalization.- Although, according to the regulations, prices paid on transfer of aothorised vessels vere meagt to ex%Iude any coaponent for * licence value, this has been ignored by routinely re-issuing discontinued licences to-the purchhsers of such vessels - regardless of the transfer price, 1 2. Up to this time, fall rent ~Ptpitalizationhas cccprred for very ' few licences. /- 3. The feasibility of a licencing scheme is considerably. enhanced if it is acceptable to those most closely involved, ' name1 y current licence holders. They are likdy to favour fall 4- -re& ret-eenee-+-s&-eza~~- ---- 4, only, the rent Bent capitalization can occur * to extent that are left in the hands of licence holders. T~Elower the de&se # ------% of retention the lower the potential for*. capitalization. ,, 8 < 5. The size of resource rents in the fishkg is very higg, hence the value of a licence if full capitalization occurs is very large. 1 6. .There is little need at present to reduce the number of I participants in any region of the fishery. ------7. Host fishing units, although they are not company controlled, are reasonably sophisticated entities. They consist of a - skipper, tuo or more crew and a vessel vorth betueen '0100,000 I 1 and $300,000. They are certainly not single Baa operations. ; , . As writers such as ~arlett(1973) and Buckanan and Tullock + (1972) have demarrst rated, government decisions rsre sabstantially influenced by the relative Fressures applied by the affected $7.. - &See Section B. 11. CtsSdi strategy is to allow licences tc be openly t~adedbut at the- - same to time take immediate measures to reaove a substantial part of economic sorplnses from all operators. Special consideration of recent purchasers is not warranted at the present tine. This would ensure that licences are held by tbe most efficient operators, avoid full capitalization of-rws, - --- ZllFw----.------.--. €hepubTcCt~h~tbirruitsof theregalatory policy rml,*~-t-~,rrr,r,-,,,^.~~s ',~eatJ~r&scEmzr- such collective act ion. and gi~esome befrefits to cvrrent participants. Since current effort levels are not excessive, there is no significant welfare loss f rcm the increased difficultp in achieving effort reductions. The acderate fknancial sophistication- of the participants should make \. -- - -L-capitalization of reas unlikely. _- ---.\----_ II__L_LLLLI__III1lIIIIIIIIIIIII - 1. . IV. BEEOVAL OZ RESOUBCB BBETS It is desirable that the method used to remove resource rents from participants be equitable in that larger made .br those earning larger rents. This suggests that the 9 - - - - paxment be either in the fo~~-aar_atf~zLha&.Ake.-m-a-k- royalty on catch, and that separate scales of charges be calculated for each fish stock, where the sto eld different ------Cents per of effort. ------r------Given that operators already/' pay a nominal fee per vessel year, a rough measure of fjshing effort, it mould be administratively simple to increase such fees to the levels at which the desired amount of rent is captured by the Government. It would pr bly be worthwhile to scale the charges by taking ------into account7 vessel length and BHP so as to. provide an even better measure of potenkial rent levels for individual licences. - The fishing power calculaticn results in Section D.IV could be used for this purpose.. It has also been argaedl that measurement of the catch P f each operator could be achieved ~4tha minimal amount of 'G difficulty, A tax cr royalty based on actual pearly catches is As discussed by Copes (1975, 149-56). ideally the rent 5collection system should: 1. Be flexible. with the level of rent collected from a region adjusting with the overall rent level. / 2. Be known in advance so that operators can incorporate it in their decision-making proce ss. ------A A -- As outlined earlier. prawn yields andshence total revenues from each stock are extremely variable. .and resourcb rents, being a residual after subtract_ion of capture castsF\ exhibit ------even greater variability. For ~xam~lea 10% increase in total revenue at a given effort level map increase rents from q region by perhaps 50%. In general, the prcfitabilitg oi a region also \ v V seflects the profitability of operators uithin that region. 2 hence the latter also experience 1arg.e variations. in incope. licence fees set before each fishing season is its inflexibility. Because such a fee represents a largely fixed cost to the operator. it will result ic even greater variability ' in his re"sidual income. c A royalty on catch, however, adjusts withhthe catch level 3 and hence operator profitability. This sensitivi*ty of payaents - 4 to actual operating results could le further increased by: 1. Making the royalty rate progressive, that is increasing it as fr: the regional catch .increases, !I 2. Relating the payment to revenue rather than catch levels, - ' 8 / 161 hence also taking account of yearly price variations. 3. Indexing the rate structure to take account of changes in yearly cost levels per unit of effort. Under such a system, the royalty payments raade by operators would be related to the size of the rents captured and hence their ability to pay. Fluctuations in their incomes would be ------decreased rather than increased. Whilst Government receipts would be subject to large fluctuations, this is,not a problem - shsce it dees --&- 3sac-hi* ve-crh~ee~+m-~&r*-/- basis. For these reascns it is considered that this latter type of system is the one which should be implemented in South Australia. Based on the very rough. relative rent estimates made in Section E.IV, a hypothetical royalty rate scale for each region, based cn total yearly ,regional revenue, is shown in P Table XIV. rfb The royalty rate applied to the total receipts of each operator in a given region depends on the total value of the catch in that region. For example if the total revenue of all operators in Spencer Gulf is between $5.5 h. and $6.5 m., the royalty rate would be 2-55, so an operator taking a catch worth $200,000 would make a royalty payment cf $5,000. ------To give some idea of the size of operator payments which - - - would be made if the above scale were irpaeaented, the average payments per operator in each fleet in the years 1975-76 to \ y.i 162 / * WPOTHETICAL ROYALTY RATE SCALES FOR EWB RBGI~AT 197678 06%' &~@RICB UVltLS. West ~oast Spencer ~ulf : ~ulf~i. ~@ceat ~nv~stigator st. 8 . P - -TR1 -- --loyalt). TR Rayalty TR Royalty8il----- TRt Royalty * t- Rate ~ete----- (XI (XI (XI "7x7-7.i -all 0 0-5.5 0 0-1.2 0 Q-. 4 - 0" -- - - Z*99 - ~evele --5;5=6~F----f;3~+2=3~& -I 6.5-7- 1.4-1.6 5 6 s b 7.5-8.5 7.5 1-6-1.8 7.5' .6-.7 ' 7.5 oGr8.5 10.0 over 1.8 10.0 aver .7 610.0 'TB 14 the total revenue for the rragio~for the year. F - A- -- ppP------ - r 7- - 1 " + 1977-78 wouid have been as shown in Table XV. < _ In ,the absence of accurate data on cost ,levels in the , - --- industry, .this scale could> be indexed by a generalzy accepted . \ cost index. The gross doaestic product deflatcr uould seem to be suitable for this purpose. In a very sophisticated royalty scheme, the rates could ------a- - - --a - - also be varied during the year to match the rents associated with catches taken during different parts of the season. Fox \ -- -- - exaPrpZe- t-fre ra-mrkb -be red-for eatehetajc+fbt ek-tb year when catch rates and rents,are lowest to encourage operators to mop up the residual stock. This may induce operators to disguise the time of taking of their catch, however. It would also require detailed knowledge' df the + within-year changes in rent per unit of catch, and this is not sophistication is not feasible at this time. A final comment is prcbably warranted concerning the constitutionality of a State Government levying a charge based on operator revenue. In general, State Governments in Australia are not permitted to levy sales or income taxes. There is therefore sane doubt as to whether the above scheme is legal. --- - -p-----pThis issue has already been raised by Copes (1975, 151) when he suggested a similar scheme for the Gulf of Carpentaria prawn - p-- fishery. iihilst this issue would have to be clarified before the scheae was implemented, it is considered that it should not 1 TABU rn , * AVERAGE ROYALTY PA&S WM& UlULD EAVR ,"i Year TR Royalty rate Total +yalty Rovalty ' ,. Gulf St. Vincent 1975-76 19.76-77 1977-78 Investigator Strait or coavanicnce, in calculating the royalty rate it was assued a11 of , the catch was taken in Spencer Gulf. 'Phis leads to a slight over-estfsmte of royalty payrents for operators fishing in both regions. present a major problem. One form of arrangeaent which could be used is to relate the current licence. fee to the previous year's b a revehue, a system which has already been shown to be a constitltionaUy valid. A Y. ALLOCATIOIOF ACCESS UGBTS p At the present ti=, it would appear that no adjustsent in ., - B the number of operators in1 any fleet is required. Although + 4 current effort in Gulf steavincentis alaost certainly below the I.-7 "? optimum level at present, this will probably no longe-e the - case after all vessels adopt double rig and the. two most recent ir 1 The question of how the*number of operators in each region can be adjusted therefore bas considerably less relevance than 3 usual, It is an issue which should not, however, be completely . ignored. i+ - :9 At present, as discussed in Section B.11, new licence 5 applicants, Whilst having the advantage of not discriminating . among such applicants, this system Bas the disadvantage of not - t - i i necessarily resulting in €be most efficient applicants receiving 7 . < i i licences. In addition, if licences are transferable, it leads to .i the 'initial recipients being able to capture all future rents i i associated with them, e 1 - If all licences are transferable anyway, it map be t p-p--- preferable for tKe governsent 40 offer new licences for sale in i - - Th5s all being the open market. would lead to rents captured tor f 1 the general' public and guarantee that the licencp would be - -- * -- -- - -- by the most efficient non-holders; hence ataxirising the rent generated in fhe fishery. I In a similar manner, if it were considered that effort should be reduced, the government could purchase and retire one or more of the licences already on issue. Such re-purchases , could be financed out of fees previously collected from , i ------partipants. The pther important aspect of current licence aliocaticns ' is that processing companies- are precluded- from holding prawn' - -- - L ------travling authorities. I? here licences are non- transferable and there is a desire too distrLbnte rents to successive of fishermen, the Leasons for this rule are clear. Is its retention justified in a transferable licence scheme? On efficiency grounds, it is considered that thare are no - signi;fi-eaat--eeo~fes-oT~l&c~ou&~e~~&by-- processing companies by operating fleets of pram trawlers. Ine - - fact it is likely that- individual cwner-operators will* be aos* efficient because they have a maxi~umincentive to achieve the 4 best operating results from the vessels o-f vhich they have < direct charge. Processors argue that if they were granted access rights then they would 'be able tc achieve greater security of supply . and so be less vulnerable to afly acnopolistic practices of other processors. This is undoubtedly true, but it would require I processors to control the bulk of the catching capacity*of the prawn fishery 4Z !$oath 1 Australian is that sSoclcs 'are capable of levels of resoukce n&ts without large adjustme~tof carrent levels of ezplufiation 9s most cases, The ~jczcmsiderathtc is &--- fa*. il equitable and -acceptable aist~ibhtjonof tho resultant benefits among curreo+-ald future fishermen and the rest of society.- -, regulation of each stack, is able -to tak1 into account the f b different -chracteristfcq uf the fishing operation and stock in . each region, an extremely impoztant property of rational - resource use. 0 - '\ .- djer co%clusioms withpp respect to the manner of i exploitation of individual stocks are: I 1. Access to the ocks should continue to be controlled by ------t ------ ,f means of vessel 1 ences. The number of such licences sh06lld be - held at cqrent levels. B 2. The restri~tionscurreatly in force concerning the .allowaUe characteristics of such yessels should be maintained, with the + exception of' the single rig re&remnt in 6&f St. Vincent, between Spencer Gulf .and the Vest Coast should be discontinued.+ Instead, access shaald he restricted to it very slall number of full-ti me opera.tors and a" feu Spencer 6ulf operatozs on s ' pait-tiae basis, 4. A system of inter~ittenttotal closures should be implemented J" in spencer Gulf in order to reduce fishing pressute early Fa the season, incsease the average size cf prawns caaght and hence A- -. increase the price receired for thCYa%bakenin7533region. conclosions ray reached: 1. A strong case can be made fcr ~eio;al of a substantial of the available resdnrce rents generated in the fishery for the general community. Given ,the variability oi the rent level between years, o+rator payments in a pear should be in the for. rate should b,e detired from the application of a9progressive t 3 rhkh the licence applies. 2. In +order to ensure that licences are held by the most * . efficient op@rators, the practice of allowing transfers of aathorised rsssels at market prices should be officially -\ sanctioned. ~hhsgovernment shoald also adjust the number of C *licences'for each region by open market pufchase or sale ,as it 3. ~he'~racticeqf exclading processing coapaniesL from the holdings of autdrities should be continued in arder ta ensure fair coapetetion between procetsurs and independent owner-operators. mderson, t. 6. 1976. "The BAyonshaetreen Firm and mdustry in Common Property Pi eries. fl l&& .Bfono.ics. lol. 52 (I), PPO 179-SMc- - ------A - - - -.------a- (&*)a 19779. &&p~&s,&&p3icw. Bichi-n Arbor Scrence. i is -AilliC iIIIIIIIIIII -.--.------p 1977b. Baltimore and London: J ----*--I-----1978. tt mOPti.Ol&~f& - --- of Delaware. ------P~~~1- -=a, Fisheries Division, Dapartaent of prima& Industry. 3974- EmSprgev s& us SoPte &!mauka P.rare EUsTa* Pisberies -port lo. 12. Canberra: Australian ~overnmeht Publishing Service, . \ . . pnllar'. Bartlett, 8. 1973. pf - " '. London : Collier 4 acaillan . ------p- -- # Beverton, B. J. H. and S. J. Bolt, 1957. Qg meics \ po~um.Fisheries Investigations Series 11, ExDloiteaVol. XIX. London: Eer4a1esty's stationery OffSce. \ ------\ Bradley, P,G. 1969. nSo8e Seasonal dodels of the Fishing Industrymmin A.*D. Scott. (ed.), & & Jectore~& Fisher- J#c~,norhcgnf -w 4 UJWQS$A. + Vancouver: C Institute of Animal Besource Ecology, U. Be C., pp. 333.46. - - ." Buchanan, J. EI. and G. '1962. Tfia Pf -ar3h-pf ioga &nocrag& Ann Arbor, University of Bichigan . - paim- lQ3gkQ Fisheries Background Paper 1, laelaide: Sonth Australian -Department of ~gricnltureand Fisheries. .. 2. -Christie, I. T. 1973. upative -seaen- k&@ 2 Pisha. &g -view. Paper 1, Program of International Studies of Pishery Arrangements. Washington D.C. : Resources For The Future. ------. 1977. fttinited Access Systems Under the Fishery Conservation and fia'nagement Act ~f 1976." in L. G. Anderson >. bd.1, Econ- Im~act sxtended asdictm. tlichigan: Ann- bor Science, pp. 141-56. Clark, C. W. and 6. R. Munro, 1975. "The Economics of ~ishing and ffodern(~apita1r Theory: B Simplified Approach. JoPrgal a -E~-.*--~*-WA* 2, 92-SBd. Copes, P. 1972, rnPactor Rents, Sole Ownership and the Optimum Level of Fisheries E~ploitation.~* laofhesw -, Vol. 40 (2), pp. 145-63. ---.-.-.. 1976. fequ pf Sou# u ushew. Fisheries * Green Paper 1. Adelaide: South Austral an Department of Agriculture and ~isheries. --_-----. 1977. "~he'~awof the Sea and Management of Anadromous Fish stock^.'^ Oceag Detrslapa a * Val. 4(3) , pp. 233-59. -..-----1978. BBSsLEB Jlsa4eiient fpy f& m lobstsr @ Fisheries a South LPstza$&. 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Effort ~*~~--~ietp---pj,ect-C llege Station, Texas: Texas Agricultural ExperiDent Station, Taxas ACB University. ------_------, 8. a. Lacewell, a Nichcls. 1776. NOptimum - - #xo-*st ni ~blxkicmint -ofL&xica 2hcLm p ------Fishery." e aournal Of &A,Vol. 58 (4) , pp. 644-52, 1 Gulland, J. A. 1956. Qg g& Pjsb- Effort a Enslisk Deme~sal Fisheries. Pishing Investigations, Series II , Vol. XX. London: Her Bagestyls Stationery Office. -b=@'" ' ------.--. 1969. 8 u &= a& stgck -merit; &g& &%&$fawm-. Rome: Food and Agriculture Organization of the United Hations. pp - pp-p ------_---. 1974. Banasment sfsf- EiSB erie~.' Seattle: Universfity of Washington Press. -, H ndrCJ. S. 1975, "The flanagement of flarine Fisheries from the - A - V f ewpoint of a Fisheries Bi~Xog~s+,~in Australian Fisheries- Council, Northern Fisheries Research Committee, -w Seminar. Canberra: Australian Government Publishing Service, pp. 246-51. King, fl. C. 1977. "Bethods of Conserving Small Prawns." 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