View metadata, citation and similar papers at core.ac.uk brought to you by CORE

provided by Horizon / Pleins textes

FISH STATISTICS IN THE LAKE BASIN DURING THE DROUGHT (1969-1976)

ALFRED STAUCH Hydrobiologiste O.H.S.T.O.M.,

RÉSUME

Attuché à la Commission du Bassin du lac Tchad, l’auteur a eu l’occasion d’installer des postes de contrôle sur les plus importants axes routiers, l’uutorisard ainsi à suivre l’t~volu~ioil du trafic du poisson, originaire du lac Tchàd cf du Bas Ghari. Il met en évidence la corrélation qui ezisie entre la séchertwse et la production et souligne la fragilité de l’équilibre biologique dans le bassin.

SUMMARY

1CThile attachecl fo the Basin Commission, Ihe uuthor had the opportunily to seI up checkpoinfs on the main road axes and Iras thus been in a position to follorn the evolution of fhe fish traffic originatirly from Lake Chad and the Lo(ver Churi River. He shouw fhe correlation that ezists betlveen ihe drought and the fi& production, and stresses the instability of the biological balance in the basin.

1. INTRODUCTION of its tributary, the Chari River, whose hydrology in turn depends on t.he rainfall in its southern The except.ional droughi; experienced in 1972 basin. (Fig. 1). and 1973 bas transformed the hydrology of Lhe Since t.he flood bas been more or less deficitary Lake and iis effecls on the fis11 st,ock from 1962 and 1972-73 having heen catast.rophic lias been catastrophic. The price of dried fish rose years from a hydrological point. of view, the surface considerably and it is likely to remain SO until such of t.he Lake was reduced from ahout 22,000 km- Lime when the fish st,ock is rest*ored, a matter of to 7,000 km2, thus drying up its nort.hern part as several years. t.he t.hrust, of the llow was net strong enough to This constitxtes a serioua prohlem eince fish is an allow the inundation front 1.0 cross the Grand import.ant, source of animal protein for human Rarrier. (Fig. 2). consumption and, furt.hermore, represents a signifi- With t.he good 1974 rainfall in the southern tant source of income for the riverine populations. hasin, the incoming flow was suficient, to prevent, We are trying here t.o give an analysis of these another significant drying up and the northern problems. L part came partially under water again. The flood of t,he Chari River in 1975 lias been 2. HYDROLOGICAL EVOLUTION slightly less than t.he calculated average but the 1976 flood xas onc.e again a poor one which will Lake Chad is a shallow water body wit,hout any lead t,o a further dryness of the northern part of out.let, itz volume depending solely on the inflow Lake Chad. .\. STAUCH

m Dried up Areas

Fig. 2. - Lake Chad in AIay 1973 (irrcztrr lerlel 278.9 m) (O.R.S.T.O.Ai., N’Djamena, 1974). LG lac Tchad en mai 1973 (niveau dc: I’IWII : 278,c) mj (O.R.S.T.Cl.RI., N’Djam~nn, 1971). FISH STATISTICS IN THE LAKE CHAD BASIN (1969-1976) 203

3. FISH STATISTICS the yield, we haue t.0 refer to fi.11~:fluctuation of t,he water levels. 3.1. Considering the orographie nat.ure of t.he TO analyse the c.atc.11of the sout,hern part of basin, fishermen cari settle anywhere they like Lake Chad coming through the N’Djamena Road and fish traders too cari reach the t,emporary checkpoint we are using the readings obtained on fishing places eit-lier by lorries or by the traditional the gauge at. N’Djamena (Chari River) because no camels, donkeys, etc. other data are available. As far as t,he hydrology 3.2. The collection of landing Aatisiics was yuite of the basin is concerned, it would appear t.hat impossible without strong logistical support. because there exist,s a good relationship bet.ween the flow t.he fishermen never stay a long period of time of the Chari and the rise in the water in the part of at a same place. They c.arry their eyuipment from Lake Char1 sout.11of the Grand Barrier (if it is not one place to another by boat, moving around the overflooded). islands, the archipelagos and the shore. Therefore: For the Baga Road checkpoint, hearing in mind it has been very difficult. t.o follow their movements t,he obstacle formed by the Grand Barrier for an and study their catches. On the other hand, it, has easy flow of the waf.er t.o the northern part, and the to be noted that Lake Chad is an int.ernational fac-i. that this part was isolated from the southern body, divided into four parts, and for the fishermen in 1972-74, we bave usetl the reaclings on the gauge t,he polit,ical houndaries do not exist. They move loaated near Malamfatori which are, however, according to t.he seasons, the fluctuation of t.he perturbed during November/December by the contri- water levels and t,he breeding grounds. but.ion from the Komadugu-Yobe River. 3.3. In Nigeria a first statist.ical survey was carried out. in 1960/61 (MANN, 1962) whereas in Chad and the Cemeroons similar studies began in 4.2. Southern Part of the Lake 1962 (COUT~, C~UTY et DURAN, 1968). l!Xd; Fig. 3 which gives the t.ot.al annual catch shows While att.ac.hed to the Lake Chad Basin Commis- an yearly increase from 8,856 t in 1960/70 to 10,235 t sion, we sugqested t.he organization of a fis11 t,raf+fîc. in 1973174 while the Chari contribution decreased c.ensus wl1ic.h would enable us bave a better from 1,056 m3/sec. to 575 mS/sec. Despite the knowledge of flsh catches and fish trade in t,he increase in t.he catch as a c.onsequence of the drought,, aren and to see the economic importance of fishery the difference when compared with the yield of the ac.tivit.ies in t.he aountries concerned. nort.hern part (Fig. 4) is net- so significant. This 3.4. In general, the lorries carry traders, fishermen, is due t.o casier movement, of the fish sinc.e the gear, petrol for outboard engines, et.c. to the shores. mouth of the Chari River is net tut off. There, the traders who liire the lorries go to appoint,ment.s with wholesale traclers who c.ame QUENSIÈRE (1976) shows the influence of the by boat from the fshing camps. Sometimes several drought, on t,he structure of l.hc existing fish popula- traders hire a lnrry together, at other times a lorry t,ion and he explained that t.he most important may belong to a sangle owner. species caught during 1966-Tl were replaced by more From t,he shores, t.he trucks loaded with the unsteacly fish populations having a higher diver&y. processed fis11 have to go through Maiduguri before proceeding to the sout.11.For this reason we set. up in this town, at, t,he entrante of the roads to N’Djamena 4.3. Northern Part of the Lake (formerly Fort Lamy) and Baga, two checkpoints Fig. 4 sh»ws a decrease in t.he wat.er level on the for the purpose of gathering informat,ion from a11t,he gauge at, Malamfat.ori from level 281.4 to level lorries or other means of transport carrying fish, 276.8 constitut.ing a loss of -1.6 m over a period of and collec.ting data on the number of packages, t,he five years. During t.his period of time the catch nature of the fish, t,he yield, etc.. This work started increased from 8,790 t t.o 26,862 t. This strong on 1 July 1969 and has since been cont.inuing on a increase in the ratch is due to the reduction of the daily basis up to the present time (table 1 to VIII, water surface and t.he format.ion of small pools see appendix). where the fish population becnme highly c.oncentrated ;lnd easily t,rapped by the fishermen. 4. RELATIONSHIP BETWEEN CATCHES This natural phenomenon stimulated fishermen AND DECREASE IN THE WATER LEVEL to move north and aut.omatically brought about a great,er fishing effort. TII Tables S and XII which 4.1. General indicat,e t.he linding points of t.his part, of the Lake, TO st*udy the figures in the attached tables and we cari fnllow this progress from 1969170 up to to explain the fluctuation of the yearly change in 1974175.

Cah. O.R.S.T.O.M., sér. Hytlrobiol., vol. -Y-I, no 3, 1977: ?Ol-215. .\. ST413CH

69 7” 70 71 ,102 12 73 71 14 74 15 75 16 Yearr

Fig. 3. - Sozzfhwn part of Lake (:hnd. E-ield in relufion fo fhe hydrurzliciiy of ihc k’hari River of N’Djumena (Al. (+) : hydrazzlicify, mJ/s ; I-, (0) yearly fonnaye, mefrics fans drird fish 1. R@gion sud du lac Tchad. Rendement de la pêche Fig. 4. - Norfhern przrf of Lake Chad. I‘ield in relation fo fhe en rrlation UYW l’hl-drauliritt: du Chari k N’tljamena. (M, (+i : zvafer levcl of lnke (yarzye czf Malamfufori) (‘H. (+) : ynuge; dPt)if. en m3/s; Y (0) tonnage am~ucl de poisson &clu?. Y, (@) : yearly fonnaye, meirietons dried fish). Rkgion nord du lac Tchad. Rendement. de la pikhe en relat.ion avec le niveau du lac jlimnigraphe dn Malamfatori) (H, (f) : In t.hia counectiou WJFU~W (1973) nientioned niveau du lac; Y, (0) tonnage annuel de poisson si’ché). that. tbe results with experiniental fishing carried ou frorn 1963 t o 19ïl (landings at, Baga Kawa ;II~ Ivlalarufnt.ori J show that catch per unit effort the two gauges during 1970 to 1972 but when t.he had been decreesing rery fast up till 1967 and Grand Barrier tut. off the inflow to the northern becarue c.1uit.est.eady afterwards. AnrI he explains t,his basin, the sout.hern part, WRSsubject to the intluence phermnrnm hy an increase of the tot.al catching of the Chari river while the other part was isolated. effort. rather t.han by the dec.rease in the Lake level In Fig. 6 we bave calculat.ed, for the northern which was not very significant. during this lime. basin, a linear regressinn in order to demonst.rak But later on, the fa11 in the Lake Chad level has the existing correlation betweeu the fa11 in the cert.airdy had an influence on the total production. water level and tbe rise in the catch. From 1969 until 1974 we cari observe a very narrow correlation (r = -0.96) between t-he fa11 of t.he 4.4. Discussion water level and t.he large inrrease in t>he catches. This is due t.o t.he conc.entrat.iou of t.he fis11population In Fig. 5 WC bave indicated t-he curve of t he and the case wit,h which they could be caught. Chari Kivnr, t.he reduction in the water level in t.he During t.he following years the yearly yield fell northern part., and the total yield obtained in the sharply notwithst anding t.he fact t.hat. the northern Lake as a vvhole. \Ve cm see the parallelism bet.ween basin carne under wat& again. The explanation to

(“oh. O.H.,Y.T.O..1I., sér. Hydrobiol.. vol. .YI, no 5, 1977: 201~Ul.5. FISH STATISTICS IN THE ~LI

L

Fig. 6. - Linear reyression befareen I7ield (103 meiric tons 100 dried fîsh) and lake leoel (I-I) af dlalamfafori : I’ = -7,191 H+20.‘34,6 (years 1969-79Yd). Relation entre le r?ndement. de la pèche (en 103 tonnes de 69 70 70 II 7, 71 72’73 7374 74’75 ,5176 Years poisson sPché~ et le niveau du lac (H) j Malamfatori Y = -7,191 H +2034,6 jann&z+ 1969-1074). Fig. 5. - Tofal yield of fhe Lake in relation fa ifs Ieuels (H, (0): Lake leuel af Malamfalori; AI (+) : hydraulicify of the Chari River ut N’Djumena; I’, (0): total yield in mefric fons dried psh). Rendement total de la pêche dans le lac Tchad en relation 5.1. Banda avec ses niveaux successifs. (H, (0) : niveau du lac B Malamfat.ori ; M, (+) : hydraulicitb du Chari à N’Djampna ; Fig. 7 shows us t-hr charart.erist.ic impact. of the T, ( 0) : production totale de poisson séchiij. drought. 011 the cakhes in t.he nort#hern part of t,he Lake. Howerer, when comparing the t,wo graphs we cari see a certain homogeneit,y bet,ween t,he cat-ches this lies in: t.he la& of genit,ors whiçh had been of the southern part, and those of t.he northern part. caught during the drought and/or the bad living For esample, t-he fa11in the cat,çh during t.he fourt,h condit.ions for the Young fish. This confirms that t,rirnest.er of 1971 obserced in the southern part was “Lake Chad is an ecosystem in perpetual change noticed during the first trimester of 1972 in the where t.he environment cari be considered stable northern part. Eut, it k nota possible t,o find out the only for short, periods” (DURAND, 1973). reason for this sharp fa11in t.he catch, as observed at, the two che&point.s. .\lso, at tAe end of 1974 the fa11 is simult,aneous but while the catch in the 5. SEASONAL INFLUENCE ON THE CATCHES sout.hern part increased again following a bet.ter inflow from the C%ari Hiver, the nort.hern part did To explain the annual seasonal variation in the not receive enough water and reproduction was yields, in Figs. 7 and 8, we have used trimestrial data perturbed by the unfavourable hydrobiological which are much more significative than the monthly fonditions ad oat.chrs continued t.0 fa11 more or seniestrial ones. and more.

Cah. 0.R.S.T.O.M.~ st?r. Hydrobiol., ~101.SI, BO 3, 1977: 201-21s. A. STAUCH

1 4 3 i 1 Il ! 3 4 12 3 4 12 14 12 3 4, 2 3 4 1 ËY w II 72 73 7.l 75 76

Fig. 7. - dosrage trimesfrial yield (Banda) (+Baya Road: l N’Djamena Road). l?oductiun trimestrirlle moyenne de Banda (+ : rout.e de Baga ; @ : route de N’Ujamen:l).

\ \ ‘1, I \ 1 \ l \ +t \I \ \

Fig. 8. - Azrerage frimesfrial yield (Salanga) (f Baga Road; l N’Djamenu Road). boductiori trimrstrirllr mo)wme drh Salang (+ : route de Baga ; l route dc N’Djamena. FISH STATISTICS IN THE LAKE CHAD BASIN (1969-1976) 207

Fig. 9. - Map of Norfhern Cameroun. - Carte du nord Cameroun. -- Tarred road + l Principal ozztlefs for Salanga frade - mczinfrcz/îc channels for Rnndtz ----- rout.es hitumbes l principales voies de commercialisation du Salanga principales vairs de commercialisation du Banda 4” 6@ 8’ 1z” 14”

e Trunk A Roads ___--___- __------___---__-___------zzzzz:Lr.._------___------_------~-~~~-zz~~~~-~-zz-~-___------__-_-----____-____-_----- __-____------_------___------_-__----- 100 150km ------_-_------____------==.rzzzzz- -ZZZ-ZZt:ZZZL.Z- 4”

Fig. 10. - Jlap of Sigrrin. See fi{/. 9 for ezcplanofions. Gartr du Nigeria. Voir fig. 9 pour les lt@ndrs.

5.2. Salanga we cari observe a considerable increase in the yield each second and third trimest,er followed hy a Fig. 8 Rives us t.he data for salanga. 1 would sharp decrease during t.he nest two t:rimest,ers until again dring t.o mind herr thnt. zI1esies buremoze 1972. and -4 lesttasdtxtt,J’ unclertake anadromous migrat-ion, After 1975 these species disappeared completely moving from the Lake through t,hr Chari and Logone from the ratches, t.his following the drought of Ri\-ers, to brerd on t,he fringe of t,he “ya&&“. 1972/73 when t.he flow of the was very The ~~11ng fi& are washed away when t.he river poor and insuf‘ficient. to inundate t.he yaérés whic.11 ovcrtlows the embankment. and carried through t-lie consequently hrought, about, an interruption in the natural drain antl t.hth El Beid river t.o Lake Chad. fish stocks. VVhen two years of age and mature, the;y likewisr However, we ttave bren able to observe the sale fnllow t bis aame reproduction migration. This of salanga, raught in the sout.hern basin and in the phenomenun is t.ypical1-j pharac.t.erized hg the data de1t.aof t.he Chari River. in some market;s in Northern crollrrted et. I.he N’lI),jert~na Road checkpoint. where . FISH STATISTICS IN THE LAKE CHAD BASIN (1969-1976) 209

1 think Chat these data could also be useful in the southern Lake shore anrl the Chari de1t.a helping to explain the biology of these species. throughout the year. This lias an etfect on the From the dat,a collected for the northern part of tradit.ional trade routes and some of the yield which Lake Chad we c.an observe a certain cycle but it is previously was transport.ed by way of Maiduguri not as clearly marked as for those fish which make through Garnbaru or Wulgo is now carried directly anadromous migrations. Anyway, we have to to the south using t.he new road. It would, therefore, mention here t.hat salanga fisheries started only be advisable to bave a c.heckpoint~ set up on the very recently in the Lake (the first observation Cameroonian side in order to check the fish trafflc was made in 1969/70). Before t.his date the salanga a1 ong this new asis. sent through Baga to Maiduguri were caught, mainly in the Iiomadugu-Yobe River. Going through Table No.IV we observe an anomaly 7. DISCUSSION in February 1974. In effect,, the 4th and 1st trimesters are those where t,he yield is, in general, the lowest 7.1. Lake Chad ii: a very shallow water body and to find such a high tonnage at this t,ime of the wit.hout any outlet and with only one main tributary. year is beyond explanation. Situated under a lat.itude with arid and subarid climate the evaporalion rate annually is very high. Xnd if, depends on the rainfall in it.s southern basin 6. EVOLUTION OF THE TRADE which cari be very irregular. We bave been observing this phenomenon since 1964. 6.1. From the figures in Table IX it would The general richness of the Basin and particularly appear thal. the Lagos market dealing in the Lake of the Lake may be explained by the large area Chad fis11 t.rade has lest 111uc.hof its importance flooded for part. of the year, t,he shallowness of the while Benin City, Onitsha, Enugu and Okene have water, the vast areas of submerged or floating vegeta- been progressively increasing their demand for these tion, high intensity and long durnt.ion sunshine fish. By contrast., Maiduguri is. and Will always be, permit,ting phot.os~nt.hrsis at. a11 leTels, and the a dist,ribution centre for bulk sale. In the other at.mospheric condlt.ions which c.ause continuous cities mentioned in the table the tonnage carried mixing thus keelring a11 the nutritive elements in to t.hem is more or less stable. suspension. 6.2. On the annexed map (Fig. 10) we bave 7.2. \Ve cari expec.t thal Lake Chad, whatever indicated the different. lowns involved in fish trade its surface, will continue t.n be exploited to the originating from the Lake Chad basin and the main rnaximurn, as the need for protein-rich food is in1et.s for t,his produce. hound t.o remain high. Even SO, despite this very rich nutrit.ional potential of the Lake, it can never 6.3. In Table &XI we have calculated an index be stressed sut%ticiently that there is a correlation which shows us whether or not t.he demand for fis11 bet,ween t-he surface area of the Lake and the fis11 is increasing in the area concerned. This could be si-ock. The fa11 in it.s level and the risk of drying useful in future for other economic analyses. out in the northern part. are indeed factors that 6.4. The Lake and the delta of the Chari River Will affect the fishery which could erentually are regional bodies where fishermen and traders of the disappear completely for a cert-ain period of time. four countries, components of the Lake Chad Basin 7.3. If the Chari River is the main tributary to Commission, carry on their activities. t.he Lake, it has to he mentioned t.hat. the flood As t.he currencies in the c.ountries concerned of the Logone River is essential for the inundation of are different and, bearing in mind the world economic the LLyaérés” in Northern Cameroons and in a part of crisis which has brought about a general inflation, Nigeria. For t.he fish population the drying up of the prices practised at t.he shores and on the islands these plains would be a tlisnster. Also, given the fluctuate according to the supply and demand law; very special tnpographical character of t.he basin, t.he exchange rate t.oo follows this rule and the CFA it. is not. a question of depth of the inundated area francs and Naira are exchanged at an unoflicial but. more SO a question of t.he large extent of the rate. For this reason it is not possible t.o give an flooded area during several months of the year. accurat.e up-to-date estimation of t.he eçonomic irnport,ance of the fis11 trade of the area in question. 8. CONCLUSION 6.5 It has to be mentioned t,hat. for about a year nom t,he road network in the Cameroons (Fig. 9) Notwit.hstanding t.hat. t-his Baain lias an undeniable has been improved with the c.ompletion of the nori& fish potential. neverthele PSit.s equilibrium is fragile. south axis w-hic11 permits lorries a direct link with This is net. only due to climat.ic reasons as demons-

C:ah. O.R.S.ï’.0.M., s(ir. Hydrobiol., vol. SI, no 3, 1877: 201-21s. t.rat.4 rarlier. There is another point which ii; never int.ensified. InduStria rlevelopment. cari also affect suf&~icntly Arassed. ‘IXe four countries bordaring ayuatic. life especially through chemical pollution. the Rasin bave wide development. programmes t.0 Therefore. to develop the fishery indust,ry in develop the area. Survevs are carried out and t;he Basin it is necessary that a11 surveys and proje& Su(‘11 as irrigation scllemes and other act,ivities be c:oncerted and t,hat a c.oordinat,ion agriculture act ivities are already under way. To exist, between the diffrrent. agencies, departments drvelop and estrnd proje& for c.rop farming on an and othrr bodirs working on the tievelopment and industrial scxle, the use of Iierbicides, insnc.ticides improvement. of tlie economy of the Basin. and ot-lier pesticides is inc:reasing from year to year and the ~truggle agitinst parasitées will be dlanuscrif repz le -C ucic~bre 7977 azz Serrlice des pzzblicczlions dc 1’O.R.S.T.O.M.

LXeiv~c.:nIV.~, 1973. - Effets de la séchc~rcssrsur les peuplr- ChUTY (P.1, lt%k. - LV conm~wc du Imisson dans le nord rrrents dr poissons dans le lac Tchad et le delta du C:ameroun. I.R.C.A.M., O.R.S. T.O.M.. Paris. 225 n. (:h:iri. O.R:S.T.O.AZ., N’Djamma, zmfr ferhniyzze nu 9, f;OUTY (P. 1, ~)I’R.ANU (T’.i, 1968. - Le commerce dl1 ~JlJkSOn 15 p. znulfi~yr. :ILI Tchad. O.R.S.T.O.N., C.T.F.T., Paris, 25% p.

HILLON (B.) cf (21.. 1971. -. Lx bassin du fteuvr (‘:hari. DURANE) (.l. Fi.), lYï3. - Note SL~F l’&olution drs prisc’s par o.H.S.T.o.l~I., Paris, 4x.1 p. unit& d’efiort dnns le lac Tchad. Ctzh. O.R.S.T.O.M.,

du lac Tchad. C&. O.R.S.T.O.AI., s&. H!ydrobioj.,‘\.I, MANN (iN. .J.,, l%XL - Fish production and marlteting from 2, ICI:%109. lhe nigeriari shorts of lake C:had., 1960-61. Fed. Fish. Depf., Lagos, 60 p. znrzlfigr. CHCIIIRET (A. I d CI[., 197.4. - LVS effets de In sbcheresse actucllr QUE~-~SI~~RE (J.), 1978. - Tntluencr dr la séchcwssr sur les VII .Afrique sur le niveau du lac Tchatl. L’ah. pêcheries du delta tlu Chari (1971-1973). C:ah. O.R.S.T.O.AI., s4r. Hydrohiol., SI, 1 : .X5-46. O.R.~9.T.O.dl., st?. H{ydrnbiol., X, no 1 : 3-18. (;HOIIRBT (.A.\, LT-M~ALLE t.J.1, 19%. - tivolution hydrolo- ST.\UCH (A.), Oar-OLALA (0. K.), 1971. - Evolution of lhe giqw du lac Tchad (juillet 1974 à uctohre 1975). fishrrirs in thc lalie. Chad basin arra during the last O.H.S.T.O.M., N’Djamcna, mzzlfigr. fivr years. F.d.0. - C. I.F.d. O.P. 4., Banxlko : 8X-104.

Ctzh. 0.R.S.T.O.~~I., sPr. lfyuru/~iol., zof. SI, nu 3, 1977: L?OI-21.i. FISH STATISTICS IN THE LAKE CHAI3 BASIN (1%:bl:)%) 211

169/70 ( 70/71 1 71/72 72/73 1 73/74 1 74/75 1 75/76 1 TCYPAL I ,689.a 2,083.2 21399.0 2,963.l 1 A;;-; 11,832.7 1,918.6 2,053.O 2,222.5 2,783.5 11,307.7 1;500.0 2,433.0 2.912.8 2,987-Y 1,063:Y 12,588.l 650.0 869.1 2,o41.5 2,380.Y 2;&04.7 2,721.2 948.9 12.216.3 700.1 582.2 1,481.6 ;,;g; 2,682.B 2>769.3 1,572.o 12,134.3 1,414.4 3,282.Y 2,342.2 1.163.9 11,653.l 1,004.l 2:209:8 2d45.3 2,130.Y 1,565.O 11,030.7 1,250.o 1,974.5 2,377.Y lr791.5 771 .O 973.8 1,150.l 2,766.P ;,;Xz-; 2,016.l 882.3 1,671.7 2.642.9 29711.5 , . 1,791.2

8,730.2 tl,815.8 20,607.6 34,035.y 26,709.l 14,483.4 144,624*7 I 1

7 6 69/70 70/71 71/72 72/73 73/74 74/75 75/76 TOTAL

JUL 4-7 4-4 19.5 13.6 16.5 39.7 - 98.4 AUG 10.4 10.4 12.1 21.4 19.4 - 119.0 SEP 21.7 13.0 46.1 56.4 25.5 g*; 172.9 OCT 0.9 2.8 1.6 38.6 77.6 13:4 - 1;;'; NOV 3.7 0.6 1.4 8.4 65.7 0.4 - DEC - 12.6 0.7 3:*z 109.2 0.3 - 160:3 JAN 4.3 1.0 3.2 26.1 5.9 - 64.1

WBMm 1.7- 2.91.5 3.1- 29:713.3 25.187.6 21.1- - % APFf 2.5 19.9 10.7 12.5 100.2 13.1 - 15819 NAY 2.6 22.2 6.9 3::: 48.4 3.6 - 90.8 JUN 7.6 31.7 9.4 203.3 - - 282.1

60.1 123.0 114.7 292.2 804.6 153.0 - 1t547.6 l 69/70 70/71 71/72 72/73 73/74 74/75 75/76 TOTtlL

JUL 377.2 442.6 104.7 832.5 346.4 865.1 706.1 4,584.6 AUG 266.8 371.8 924.7 680.1 819.2 4,642.6 SEP 420.7 712.5 936.8 31675.9 OCT 1,079.l 447.4 920.3 41074.4 NOV 521.0 606.1 838.3 3,408.l DEC 221.9 866.6 $2’9 950.8 4.152.8 JAN 604.0 86916 884.5 4t247.9 EZB 151.1 777.7 NAR 301.9 1,028.i m 294.9 244.7 805.9 975.4 MAY 355.3 561.3 919.4 264.4 l,O39.2 Jm 317.1 454.4 520.2 634.7 970.4 583.6 4,210.6 3,361.a 41997.4 6,621.0 8,030.8 9,714.l 7,587.4 9.226.1 49,538.6

Yield in motric tons (dried tkh). -- 69/70 1 70/71 71/72 72/73 TOTAL

JUL 160.0 103.6 138.9 30.3 526.3 AUG 83.4 139.3 38.1 68.2 SEP 65.8 181.8 86.3 72.0 OCT 16.6 41.2 18.7 47.7 NOV 21.5 7.4 24.2 22.0 95.7 DEC 16.9 10.6 3.2 12.4 58.5 JAN 0.2 11.2 14.3 41.7 FJ3B ?:8 11.3 173.2 MAR 29.5 3::: 24.1 8.6 117.0 Am 22.7 30.4 MAY 29:; 316 13.5 10.3 JUN 53.3 42.3 9.7 44.2

495*1 577.1 390.6 371.7 521.1 280.1 0.3 2,636.0

BANDA 1 SALANGA 910/71( 1971/72 1‘I 972/73( 1973/74( 1 V74/7! 972/7:973/74

791.7 2410.8 1627.9 1043.1 11p.1 10357.5 28.6 72.7 46.1 58.1 67.4 7”‘: 8621.0 Y-w.7 6412.' 3119.: 45760.6 3.2 14.3 18.4 47.2 t$; :,79*5 3942:o 6301.6 2620.' 25774.2 7.5 15.8 11.0 54.5 z-8 194:6 334:2 1366.8 zg; . 3531.1 w . 1825.t 5.4 7.; 5314 114.1 43.7 637.0 1934.0 4370.: 2216.1 29.9 152.1 KANO 1491.1 2140.8 2568.6 :;:?y . la03: 1224.C 12101:3:.%-: 10.1- 10.6 2617 37.1 104.5 PcIRTriARCOmr 329.7 1315.9 1430.8 r4Lfo. 1 57w 139.1 79.4 30.4 IBADAN 108.4 55.4 &IV;6 1452.0 1713.: 4;;.; 2; 3.0 23.1 89';. iWJUlJA 146.5 50.1 z7 . 124.4 159.8 151.t 0.7 2.0 NAKURDI 8.4 1g.; 134.0 8.9 21.' a:t OI3 1.3 MUBI 86.9 30.7 163.2 7.2 13.7 4;:; 17::: BANA 15.0 5Ie 0.5 19.9 4:i 3.: 7.0 IliXIN 101.2 43.1 a.5 52.t 7.C 0.4 0.4 BRUCHI 43.3 0.3 aulIA .3.n ii:; 0.1 0.1 PcTIsm 2.2 ns 38:: 225.5 1049.2 255.E 442::; 0,7 0.7 33.4 26.3 716 68:7 KWSINA 15.3 4.5 20.3 - IKEJA 20.5 9.1 29.6 - LaIcaIA Y.0 70.0 7216 95.6 - 0.9 9GKoTO 27.2 27.8 55.2 0.3 0:: l.xJluN 2.4 12.9 15.3 0,2 0.3 0.5 CBLILBAR 0.5 10.2 10.2 OIma 120.5 28b2 1312.: 483% - 6.0 36,O 3T8 45.8 291.1 53.5 0.1 0.5 2.4 4E . '2 15.0 15.0

3730.2 1815.0 20607.6 28242.7 34035.9 26709.1 44624.7 1 60.1 23.0 14.7 92.2 8 04.6 53.0 1547.6 ^I l I I FISH STATISTICS IN THE LAKE CHAD BASIN (l%%lc)%) 213

TABLE NO. VI : I~AC~A ROAD : DISTRIBUTION OF CATCH PER LANUING AREA (in rnetric. 101s dried fish).

SALANGA ORIGIN BANDA ,y69/10 1970/11 1911/12 l912/13 l973/14 lp4h5 'fi5/@ TCfUL ,%y/70 I~I~/I' 1911/12 'TF!/13 '9l3/14 Wl4/15 '915ht TWIXL , I 4 l I I , I I 8 I I l I BACA 5047.8 6308.2 9129.4 10112.5 12013.1 5851.0 10129.3 58591.9 23.4 54.2 33.6 58.9 510.1 13.5 - 699.3 MALBMFILTCRI 484.6 683.9 2162.3 5510.8 14285.4 18862.2 2857.3 44846.5 2.5 0.5 2.5 95.2 135.1 113.3 - 399.1 ABADAN 2011.1 3541.1 6590.4 9149.1 5341.3 1335.3 340.5 20370.5 15.7 28.3 39.4 91.3 69.9 1.0 - 251.6 AUGUNO 53513 1034.0 1956.0 2800.3 2097.3 386.6 391.0 9262.0 13.0 24.6 11.4 22.1 33.9 4.2 - 109.2 NOIK4ONJ 323.2 221.3 550.5 219.1 41.8 40.6 35.3 1492.4 3.5 13.4 25.2 10.0 0.6 0.1 - 52.8 BINDIR 29.8 - 32.2 43.3 19.2 27.3 13.1 1.65.4 0.1 - 0.2 - - - - 0.3 BADERI 80.3 7.7 a2.s 19~6 73.8 41.3 72.2 543.7 - - 3.2 - - - 3.2 ALLINEiwI 43.5 5.6 51.0 13.6 3.0 11.6 - c9.3 0.1 - 1.5 - - - - 1.6 MmmP. - - - 17.2 30.9 51.0 31.3 130.9 ------OEWS 23.1 2.1 32.7 107.2 87.1 93.4 112.9 461.1 1.3 2.0 0.9 5.5 4.4 9.9 - 24.5 MARTE 34.9 11.3 4.3 17.3 36.9 10.3 - 121.0 - - - - - I I I l I I I I I I I I I I 3730.2~11315.3 20607.6 28242.7~34035.9~26709.1 14433.4 144624.1 60.1 123.0 114.1 292.2 304.6 153.0 - 1547.6

BANDA SALANGA DEWINATION 1915/16 TOTAL ~l%Y/lOl m%L I 933.4 953.5 6069.1 151.4 111.4 9.9 2lm 21z 1509.0 2055.8 13313.4 64.1 93.3 0.5 2’3 943:4 1016:2 1467.7 8032.5 6.4 13.6 2.7 3317 EmIN 117.3 405.2 983.4 4363.9 0.4 2.5 64.2 ONIEXA 3.9 139.4 1462.8 4710.4 10.1 29.1 KANO 279.4-1 635.9 807.6 525.4 4263.3 34-4 141.7 PORTAARCOURT 159.0 395.4 165.3 1789.7 0'5. 24.4 IBADAN 1916 37.6 230.1 333.6 1327.0 1-6 20.9 26.7 11.1 lP.4 1.5

22.6 3:; $:a 3% 4-1 $2 . 11.1 16.1 s:*; - 146:l 0.1 ._- 1:3 9:T 9.9 1.0 - - 16.6 - - - 37.6 0.1 - ::: POTISKUN - - - - Jcs 213.8 263.9 193.0 263.1 119::: 5.0- - ~ 19.3'T 21;6 46:9 KATEINA - 100.9 - - 104.4 - - IKZJA - - - - 3.5 - - - - KKOJA 10.9 - - - 22.6 - - - - som?o 11.7 - - - 19.1 - - 1.1 - 1.1 NlJNm - - - - 1.3 1.6 - - - 1.6 CAUBAR - - 0.2 - 255.2 63010 lo73:9 205% : : 0.9 0.9 OKISNE 35.5 3.2 3.9 or3Efls 16.5 48,3 19.8 - 34.3 - 233.7 - 3.7 4-1 1 1::: KAROUA 133.6 255.2 1g:; . 2.5 20.3 32.7 - 1:*: 1::: 299.9 10.0 3,7 367.1 223.1 - 983.5 OAROUA 15.1 ------. 21.7 - - - - 2.7 - 24.4 XOUNDOU ------10.0 ------10.0

3361.8 4997.4 6621.0 8030.3 9714.1 1531.4 9226.1 49533.6 495.1 517.1 39.6 311.1 521.1 230.1 0.3 636.0

TABLE NO. VIII : N'DJAMENA ROAU : DIBTRIHU~ION OF CATCIT PER ~.mn~i-ir; ARE.~ (in mrtric I.ons dried fishi.

BANDA SALANCA 1

69/70 10/7I 71/72 72/73 l3/74 74/75 15/76 TOTAL @/70 70/71 71/72 12173. l3/74 l4/75 75/76 TCTAI

1977.2 2873.1 2896.7 3328.9 3148.2 2009.8 2654.7 18 338.6 126.4 176.9 216.5 153.3 210.8 9.4 0.3 894.1

1010.1 '3'6.4 3494.7 4345.7 6161.0 421L5 5265.0 26 311.4 181.7 90.2 170.3 193.9 303.9 19.1 - 959.1 94.6 20.9 - 6.3 - - - 121.8 47.1 14.1 - - - - - 61.2

255.6 258.9 35.7 122.6 98.1 813.3 1103.5 2 687.7 130.4 284.0 - 17.4 6.4 245.7 - 684.7

24.3 28.1 '93.9 227.3 306.0 545.8 202.9 1 529.1 9.5 11.1 3.3 6.6 - 5.9 - 36.5

4991.4 6621.0 0030.8 9714.1 7587.4 9226.1 49 538.6 495.1 577.1 39.6 371.7 521.1 230.1 0.3 2636.0

Cah. O,R.S.T.O.AI., s&. Hydrobiol., ool. XI, no 5, 1977: 201415. 64. lb 40’61 90’ Lb G9’F 95-t EF’L F9’6 14’6 PO’E2 %‘9L Ll’4 91'Li LV'LI 56’1 OP.6 ti6’81 LO’OZ EO’VI lb-fi L4’9L ez’fl 00'9 F?E 40.1 6L.61 bl’lrt 4o’b1 bv’ol L9’91 29’Lt bE.41 R%I LP’Ol !2’9 56’51 flO’OF LL.42 LB’EC 6g’G LO’Oi VD'bL 89’21 ba’t 64-t tb’ot ?G'Lt 4b.z L Y-F Vl’W 4E’L 8b’tZ t9’61 5ew 1X’i2 3b’O 14-Q OÇ’OE t5f’PI )F’bl 110-82 673% %‘SE LV’fi : ’bL’E1 L6’D :z*g fi-e bL’: 9L’G Z66’6 ZO’b i2’ LE OO’OCIL ez*ft GT’L LS’EI YO’4C i2’51 LE’0 9e’bt L 9’0 EF’EE 26’L 13’Pl L3’LI CIL’92 lp’6t lO’B1 El’1 %-et FL’L 9F.52 EV’9 PF’Z ZL’Z OB’Z bL’al ;a% EeW 9s. 12 bo’ tC ta-02 : b9’0 Eh’22 a;*1 1 22-b el’b 49’2i PZ’Oi E2’1i Pl.11 2F.3 bL’Li LL’LC : 6 2’4 66’01 60’3 16’2 Ev’b 05’Rl ! 69’1.C iQ'Zi LZ’ZI Lt-L eP9t 4e*fi : F9’0 21’0 EP’O LE’9 yo’zb 58’ Ll: 62’21 Ze’b FÇ’L 80-L fO’f1 ZbV 08a.b 4L’L Sf’i QZ’LL66’6 Od’Oi 42.LI g4’SI VL’OI 09-e ------, aL/tl IL/01 oL/69 059 :L/bL j.L/EL l ?L/2L :L/LL I,L/aL oL/Gv pLIFI fL/Zl z L/c oL/69 VL/CL z$-i G ------VUNVE

- OO’WI -I- I- l------i6’eu - - - w-00 - - - - FF’LE 88’0 20’ t ;P*OE oç+L YP’P 4L.O Li.2 eo’94 9:‘62 30’001 - - W’CO - - - - VWdV?l Z6’Çf - LZ'tz ;y:: bgc EL'% ZL'G woz - 1tGL 20’0- OL’E- OZ’O $2” g-2 95’2 92’LL sm - - . - - EG’PS Lo%b ;2’24 lP’2L OF’8 O?'UL 3L’FL - - 2t’Lz Gf’ef FL.42 . . 9f’O - 3tlZClO - - - W’ool - - - W’OOI - - - W’WL - - - - - w.w nvEv?vo - 00'00 1 - 00’09 oo’ob - - - tf’be - 69’4L NminN - - - 4~~6~ - 4l’OL - 00’00l - - 9F’O - VE’05 - 82’6b OLOXOS - - - Ea’eb LL’lI - - W’WI - - - b6'SL 26’02 Pl’f VrnXM - - - - W’WL - - - - bL’oC - - - 92’69 - VmiI - - :3’% - 4F’i ------Lt’22 FB’LL VNIsmx 40’9ti i2’2b - TY’OL LP'L f4.22 12’9l a4.22 46*Ll ob’tt 98’1 90’11 3Z’BF Zv’eb 20’1 20’1 eL’4 L6’4t EL’EZ SOP - - - - Lb.94 6Ç’Eb - - - - NEISIJDd 4~~~6 - 42’9 - 4t%b LF*ot eb’4b - OO’WI - - - 29’13L i’l’ll P2’01 VJXVZ - - - - OO'MI 00’00 - - - w’ool - 92’51 02-F K’tg IA3flVE C-26 - 6g'L 10-F 99’s fL’gF ;;*y Ol’ti - OO’WI - - Lt’2 - EL'G!I LO’LL 96’42 NIwII - - CZ’LO 46’F 5t’bt 41-o %'gF LL’Z çe-s2 as’ 12 i4’Ft 68’4 * La'62 - WLL LE.08 LO’L - VL’CL Et’Of vim ÇL’k32 La.15 CIL.1 21*it 00’2 ;f’lF ;?62 LE’: brft 6t.L 19’09 IV'L - !L’l 80-ï ;p’;’ 32’L ze-9 69.02 8f*02 Ism - 00’001 ZF’Z G:6’ w2 56’FZ L9’tZ Fl’lP - 38’4 Ib’vL 49’Lt - - 4G6’9F PL.0 2b’ob ZF’2 IUhEM - 00’02 CE’4 44’21 25’9 lR’4L LI*EZ 91’tz 2O’Pl 30.4f - - - CO*49 Op’L1 PST1 OP’PZ SP.4 46*4t vlfflm 2.2 42’ LT - VF’VF t6’ez L6W a2’61 4t.41 !3F’LC f@‘2 @‘L 38.58 ZL’tt L6.2 - - OL’!32 aL.Lt La.9 ot.1 bl’2 NvavEI TP.2 LL*eP - - 92’6 FP’G go% 60’22 Ga*g - Lt’1 34’2f lP’4L - - LS’LZ Ef’L2 El’42 62.9 - &k3,OOWEI PdOd 16’9 Pb’f 60’02 LL$ y: 8Z’PZ tF.Zt :z: LO’Ll 00.02 26*at O6’Pl 44-T ZL’L 26 ‘f 44-52 PL’OL rb’L1 LT’6 Sz’et 22’12 69’Ll BF’21 6p’S ONVX 1O’bf LP’fl . - 60’42 0g’LF G6.L 2O’P DO’0 - 3b.40 CL’1 - - - 46’21 La-b 62.0 - . 9;::; LE:SE VSSLKNO tz L6.02 - 2.3’0 ES SS.fZ Le’ff 62’6 Lo’b Pi.0 i L9’22 EL’tr - - 52’12 6f’ot BS.2 Lb’0 WI0 NINSI 2:: LL’LZ 41’1P Ef.41 22’L LZ’at ;5:: 2L’OZ Lt.61 oP’ft bL’l1 zp’l :F*at %i LO’B S9’5 !1’8 92T X.tZ ~1.12 62’41 fb*g 42.2 mnNa 22**2 a6’ot !&‘41 bg’Lt GL’5t 46’bl oy’ot Z6’6 SS’LE sa-62 wtt :0’6 20’2 . g:E “w”:;; . . brer 6L’vt cwft y;: SOOVI E LE’ 01’62 6% OZ’Vl LP’22 tt’ol LE-Lt 98’4 YL’LC LY’L lb’ tb ;F’bt Zb’lt lo’et 6o.L LE L~*EZ 26’ft WL IBliXlUIVH - I , I - EL@L BL/lL lL/oL 0L/69 sL/4L G bL/fL FL/2L 2L/lL tL/oL ol/GT G sL/pL kL/fL ZL/2L ZL/lL rL/oL 1oL/69 bL/FL iL/zL zL/tL tL/oL oL/69 - - r oItwNIss3cl VONV’IVS VUNVE voNv?vs IVE

uvon VNBNVPUN uvon VOVE