."

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'rhis~ not -Co Da citec1 withou:c·---'D"rior rafc-r8--:"1:Ce t6 the author

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IHTElliTATIOlTAL COUlTCIL Il'On~XPLORATIOn OF TH3 S~A

rnT T'7 ...!-J. ..J

CRI. 72 - F. 42

ßvnd0sforschtJ!,':,~(m3h1'T 1für Fischor",j Hornburg I

ßibliolhe~..,JCOnrrJents onthe Bio-Econo~ics of Cod

Pi shill:ß.._=b1.1 the Horth Atlanti c

By Pm.L1 'Adrul1

Head of the Fichorieo Divisioil$ O~E.C.D.

(The-author is Dololy responsiblefor the ideas'expressecl Cl.i.1D. presented in this paper)

A eooprehensive study, Dade by Cl. joint ICHAF/I.C.E.S.workinG eroup~ haG surveyed the fishery for North Atlantic codover the past decade aud built v~ a siDluation model enabliuGthe assessment of the, offeets of hypothetical changes in thepattern of fiohing. Econo~ics were to SODe degree taken intoo.c count , at least as reGards the mobility of thevessels.

Unfortunatel:i' the intricacy, of the caso is onormous:several different coel stocl:::s behaving differently, are fishedby a dozencountries undcr ~idoly different cconomic$ geographicaland technical conditiollS~ Furthermore, 0. ntüuber of fleets arenot fishing solely for cod all the year round and 0. totallycomprehonsive modol fron the economic otandpoint should includeother spocies, to l~l::mtion alternative grounds.

, It, is thorofoI'G lil;:ely that the roport of the Joint\"lorking Party Vlill bo vlelco!:led but that :~ractical conclusionswill be postponad u:'1til the specialists could go into moredetails still further oxpo,nding the scope of thoir study.Cortaitily, the continuation and developDc~t of such undertcl:ingsare highly desirablo. The following c02ffiants hava been notedas 0. contribution to futur~ discuGsions and lead to sorne 'preliillinary bio-oconomic conclusions which~ althoush partial,arG important onough to justify SOlle eillDhusis.

I. TIm DESCRIPTION OF TIm !'TORTE ATLAlTTIC COD STOCKS SITUATIon.

The first l:13,in idea which io conveyed by the paper underrevievl, as rend by a 110n-C11aciali8·~, is an en1pho.sis on th.:; com­plexity of the bioloGical problo~s. ~~en trying tolist all thedifferent parameters usad by the bioloGiots the rosult ~ißht beas follows:

Parameters of tho stock

gro'uth rates Ylhich cau bo widoly different fordifferent stocl::s 0::: the SO,1113 specics (sec Graph I) ~

E. 55 456

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natural mortality rateD, which nre not nocGssarilysil:1ilar for all stoclw or are 'i1.ot accurntely l::no\"rn;

fishing offort r.lOr-cali ty on oach stocl:: as obsorvedovery yoo.r or o.s. forocast frOl:l the oxisting fleetson the basis of the foroc~steQ fish availability onall stocks;

it boing weIl lUlucrstood tho.t each year claos of eachotocl~ haG to bo consic1ered oeparntely, so as to tCl2~e

into account the differont behaviour of the fishos atdifferent aGe 0 allel the impact of the various t~TpGO

of fishing effort accordiug to the year clasoos, tImooo.sons, etc~

Variablos which can only be rocordea whon they haveoccurrod

rocruitli.lOnt nhich is uevor regular but tho irregu.- .larity of rJhich mißht woll diffor significalltly fro~l

one stock to t11.e othor ·(cf. Gr:lph 2);

ocological factors which nic;ht completoly chango thepattern of thJ otocl:: if not ::mdaui5er i ts very exiotonce(cf •. West Groonland cou stock, Gro.phs 2 emd 3).

The abovo list, in spito of its brevity, is comploxenough to give a rou~h idea of the vory spocialioec1 nature oftho biologioto' worl::. A first conclusion cnn bo dorivod: forthe tine being it is not poosible to build up a bio-oconomicmodel which would be cowploto onough to givo evon an approximateaccount of the o.ct1.1.0.1 fiohillg activity far 1000 ostablish abaois of 1:leasuromont of sucll fishing 8.ctivity that coulcl boappliod over a reasonably 1011G torn. Obviously in thoir loading­up work, the biologiot anel the oconomist vlorl:: sopar:J.tely butthore come timos whe~ they are interdapondant and Olle of thooatimos in vihen arrivinC at conclusions on otock managoment.Co-operation in the more nocossary for economists bocause theyco.nnot cyan ote.rt vIi t110ut bioloSic:tl aSOOOGLlonto ~ c..ud it Elightbo usoful to bioloeisto n11.osc aSGeS8lJ.1O:1ts could bo io.provod ifSOBO ocono~ic factors ~ere t~:on into couoideration.

The 8ocond IJ.lain idoo. which io convoyod 1Jy the roportundor roviow io that tho cOBplcxity of the diveroc factorsinvolved does not lead to any killd cf annrchical rosult but onthe contrar~T to vory 10Gic2.1 rcsults.

Thc diversity of tho different North Atla~tic cod stocksis roconcilod vlhen -I;hoy aro proGonted 0.0 on Gro.p}1. 4, v/hich chonstho.t tho calculatod optinUl:1 fishing. offort f.lOrtali ty alwayscorrcsponc1s to circ:!. 90 por cont of· tho calculatod Iilaximul:lyield, Qud that tho avoraGo fishing effort Dortality is fro~

38 to 75 pOl" cent abovG this optili.1UD.~ In other wordo, in opitc

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of their diverso char~ctoricticD tne dyn~~ics of ~ll thosocodstocbJ 0.1"0 vory sir.1il::'-l~. Furthormorc, tho fisho~:'lcn 0.1"0 inpractice oxcollont bioloC;ißtc as Yloll aß OC01l0Dicts; they ho.voDuccoodod in using thc rocont Sib~lifico.nt improvemonts in thomobility of thoir floots for getting tho bost they could outof all the NorthAtlo.ntic stocks. ' '

Two oxcoptionc only, tlic stocl::s of, tho Gulf ~ncl Eo.st, .Grconlo.nd, are not overfished. I.Io.ybe tho formol" is o.,rolo.tivclypoor stoclc conpo.roQ to tho othors anel tho lo.ttor presonts morodifficult conditions (0. rolutivcly no.rrow Continental sholfwhich is not o.coossiblo nllon winds bloV'Tin,s froLl the lo.nd 0.1"0

pushinc off drifting ice)~

The.third main iuoo. arisinß from tho roport is Dorerecont andtherofora ovan Doro interasting. The biologistsoeom to givo up the 'l~iJ.::iwuEl susto.iunblo yiold COl1copt or ro.thorto sot tho total maxirJ.lm custo.innblo yiolG. at 0. point slightlybolow und bolero tho ca.lculo.tod Elm::iLluin~ Tho rOo.S011 for suchn chango io obvious from Graph 4, tho arcto-NorW05io.n stoclc: ,it sufficoo to select tVlO differont, but accoptable, growth ,curvoo -Co arrivo at \7i<lel~T difforent l)ooitions for the Li. S. Y. ,i t bei'i1g dono in lcoopinß' the yield curve unchcmgod o.-c least fori ts oection which Ü3 ll::cactically relevo.nt c.nd lcnO\'m~ with bothgrowth Clrrvoo tho o~timurJ. fishiug effort ic oimilar. The rcasonfor these ctifforent croYlth CUr".r8S is Que to 0. C11:111::;e in th8pattorn of fishine; rocelltly thoro 'VlUO rol:::,.tivoly Boro activityOll the spawl1,iug po.rt of tho otock tho.11 in tho Baronts Sea~

It mißht bo o.ddodth:1t t110 definition ßiVOll for t110optiowu F is rosorv?d fortho happy fow vn10 mo.otor oxponontio.lalld othor functio:l0. "Fopt, calculo.tocl followil1C; '1;110 uso.ßo oft110 1972 ICNAF l:.1id-torn o.OOOOSl:1ont roport, a.n thc levol o.t Vlhichthc l:1o.rßino.l yiold (tho not addition to t110 total co.tch proQucodby 0.11 adtUtiono.l unit cf offort ) is' ono-to~th of tho cntch pOl" .unit in 0. vory lightly, o:qüoitod sti 0cl;: 11 ~ But if i t is intorprotod0.8 boing ~ roalistio li.3.Y. sli~1tly bolow the thooretic31l.1~ S. Y. i t :o.ight bc sufficient emd 110t c1istort too L.lUch thoprocioc dofinition uood by tho biologisto~

In o.ny case covoral rOiJ.oons c::m bo ::;ivea to oxplo.inthi s llOVI yardnt i oIe :

- ono roo.coa wo.s o..lreacly giVOll b;;,T reforol1ce to tho gro.phon o.rcto-lTorwegian coel, sliGht tUfforolloos in the ooloctedparal';1otoro can vlidoly cho:i1~o tho thoorotico..l I.1. S ~ Y. but wouldpractically 11ave no efiect on tho OptÜ1Ul:1 F ~

- i t l:light well bo th~t tho thoorotico.l I.I~ S. Y. cloes notmeint in pro.ctice;. vlholl t110 I:lO.Xü:rur:l F is l)ushod vory far on thoright h::m<l' aide in Gro..1Jh 4, i t might corrospo11dto vory abundantyoo.r cl:l.sseo and to ouch o.n averago levol of thc stock thc.t therücruitIJ.cnt conc1i tio:1.:J woul<1 n.lroncly hnvo bean G.ltorod; inothor vlOrdo the o.ctu:1.l yiolel curve Vloulcl be .:w shown in Gro.]!h 5

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but thio chango oftllO rocru.itnont boinG rolatod in an ulllcnovffifashion to tho l)c1.r~T-1o-(;ors of tho stock, thoro Vlould bo no Y1C1.Yof introducing such 0. factor into tno bioloCical nouols f

- if it is npplioc1 to spocios othor than coel or domorsal,e.ß. polo.gic specioo lil:o horring, tho grorrbh curve y:ould ShOVl

ito Dnxim~u before tho fioh is maturo; ~ss~rr.1ine that thoauthoriooel mooh.oiz.e catches only fioh that h2.vO o.tloo.stspavnLed onco~ tho corroopol1ding groTIth curvo could push to aninfinite F tho theoretico.l E~S.Y. Hoedloss to Gay thio Vlouldbo toto.lly unroalistic.

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VIithout ontoriaß illto COI:lplic~tocl l:lo.th0 no.tics, i t l:lightbo worthrlhilo to note s folloV':inS tho.t lc.st l~Oi:1D.rl~, that thopoint of inflex:ion.on tho grcwth curvoo in Gr8.ph I(a) (whichfor thoso coel otoc1m alvlays corrosponc1o to c. l:lo.turo fish) i::::clifficult to locato. In fact i t 1001:::::: !1S· if this poil1trloulc1.havo boen transformod illton strnight lino covoriuG sovoralyoar:::: of tho fishts lifo~ This is tho no.thonatical roo.son for •tho variations in thalocntions of tho point of thoorotico.lU. S. Y.;, i t o.lso tonds "GO Elo.1~c tho top of the yicld curvo soflo.t tho.t tho recruitnont factors not intoGra.tod into the modolcould woll in reality push it dornl oarlier und nore sharplythan. shornLby the nvoraee co.lculatou yiolc curvos.

To conclude thnt review of tho nain descriptive pointsof tho roport on lTorth Atlc.ntic cod stocko, 0110 vory simplefnct emerges as prodc)l:linant ~ \Vi th tho oxcoption of two of thonwhich only havo 0. l:orcinal importanco o.ll.thooo stocl:o nraexploited si~lificantly abovo tho optinvn. Thio is cbviously0. b['"d situntion, dotrinollt2.l in tho long rUi.L to tho fishingindustries, in opito or tllO short term bonofits thay cnn hc.vodoriveu. froü1 such ovorfiohing~ Honco tho sil:mlc.tion OJwrciso~

11 ~ SHIULATIOn FOR lTOTITH l\..TLAHTIC COD STOCKS DEVELOPIISNT

Tho objoctivo Qinod at by such biologicnl studios isobviouoly to COf.l0 bc.cl:: to or oto.y nt, or avoid ovortc..l::ing~ tho •point of optimur~ fiohiuC offort (fishinc; offort/nort~lity)~

Thi [3 is thoC?roticnlly truo both frOl:l biologic:J.l nnü 0 cOllonicstcmclpoints. But tho ~ctu~l ocononic i;:]lJ1ic~tio:1S shoulcl·bot0.1::011 illtO o.CCOU:Lt vlhon ov['.lu~tinG t110 C':.iiforont Do.n:J.Go~:lOnt

possibilitics and thoir political fOßsibility. This TIill loc.dto t11.o olininc.tioll of Dost of tho solutions sinulntod inthoroport ul1c1cr roviow, n81dnc; tho bost L1..';.i.l~ßor.l0l.1t Golutioi.L onsiorto ic1ontify.

The top graph oi' Fi[,"uro 4 L1 the rOlJort ShOrT8 tllo fish­iUG offort and tho botton Graph of tho so.~o lit~ro shows thocntch pOl" uni t of offorti. 11..0 could bo o:;::poctocl bcth run inopposito diroctions so that an incroasa in fishiug offortrosulto in a aocronoo in co.tch pOl" unit of offort. Thoroforo,if D8.xinisntion of tho profits liloro tho main objoctivo it v/oulabo bost to Galoct -eho rUlW 6 01" 7 "to decro.:lso fishillg offort

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in Yeur 3 to u levol th::.:ti coulc1 gel1or::::tto F O])t Oll p-ll otocko sbut with 110 rootriction eil I:l0bility (i. e. 50 lJer cont reeluctionin overc.ll fishine o:efort)" anel "to c1~crQo.so fishing offort by10 par cont per yeo.r froD Yop-r 4 to Yco.r ß ~nd hold nt tho.tlevol thero~.:fter".

But with indicated landil1.Ss of ~roul1.el 2 nillion tOllS,v/hen l10arly 4 million tons could be absorbed o.fow years o.go,it is obviouo that tho most urgent proble~ io not thoro o.nd thatit V'loulcl be vory difficult to ronder acceptablo the overalldecrcaso both in catchos o.11d fishiu[; nctivity 't;:hich is shown bythooo t\"vo runs.

Tho run 8 "to allmv fiohiuß to increaso in Yco.r 3 to50 per cont nbovc i-es pro~JOnt (1970) level" s shows tho mostpronouncod docroo.so of c.p.u.e.~ it canbe elininated withoutcliscuooion. The run 4 "to o.llow fishinG effort to incrcaso by~

5 per cont por yenr ovor 0.11 Jro~.rsu should also bo olinino.tedbocauso if i t bril1ßo o..bout sooowl;.o.t increo.oocl co.tcho s, i t doosso with a decronse of -ehe c.p.u.o. quito cloooto the oiniDur~

of the run 8 auel thoro~cro is 0.100 lilcely to ondnngor -ehe pattornof rocruitnont to tho stoc~~"

It being so tho only romo.ining solution is the run 3"to sto.biliso fishing offort o.t its 1970 lovel" which seeLlSalso to be the objectivo selocted by the ROgluo.tory bodies whenthey can t~:o SODe eliroct action~ A cOillfortine rosult whon ithnppens tho.t, beforo any discussion, thore is full ngreooontbotwoen oconooists and policynakoro !

Figura 5 i-:'l tho rO:;.Jort shows 0. further ex:m.1ino.tion of theruns 6 emd 7, c.bru.pt o.llel lJho.sod ree:'ucti -no cf the fishing offort ,to which o..ro utto.choel 0. rodoylo~~ont of -eho Qiscc.rdod fishin[;offort towards othor o.vo.ilo.blo fish otocl::s. If this roclOlJloymontcould be naQe with ~ c.p~u.o. of two-thirel~ thc.t o~ cod, itwoulu bring equivalent ~nd progrossivoly higher c~tches, 2tleast in wüißht •

Tho OCO:l0r.1ist D.Uct unfortuno.tely o~:::;?resß uoubts nboutthe optimisnl of this hYl10thoois for tr;0 roo..ooJ.1s:

(c.) vlith tho l1rooont l1ir.1inishi':.l~ catch ro..te8 froI:l NorthAtlnntic cod 8tocks~ such l'oucploY:J.cnt is o.lre::lcly u11.c.~erv'laY,

e. g. on o0..i tho. It c01J~d quiclcly load to ~ ilOW ovorfishingproblcI:1 vlhich woulcl i:lo..!::e tho vlhole I:ntter Doro difficult ~nel

intrico.te. In f~ct it clooo not 80e1;.1 ['.0 y.::d; to h~vo leel toovorfiohillg of tho s:::'..itho stocl::o hut f0r obvi0US occno;:licronsons •

. (b) Tho FrOi.1Ch lI crc.ndo pQche ll vos801s h8-vO durine; tholc.st fow months cC'.uCl1t ü.1port:::.nt qunntities cf s:l.ithe roplo.cinCthe clil:1inishing coc.~. Dut vlhile ccel coul0.. be sold eo.sily o.t E1oroth:111 F. 4.00 pOl' !dlo of frozen blockG of fillots, tho. rJarl::otcoulc.1 only Ill.:1.intnin tho l)rico for n. sill1ilo..r s:J.i tho product o..tF 0 2.50 lJcr kilo ;'l11.c1 [~CC'l,1I.11ÜCLtiIlg stoclm arc Lloro aUG Doro

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diffieult to soll. Tho introduetion 01'" dovolop~:lont of 0.. nOVI

produet ofton 10.3's bohincl tho f08.sibility of ovorfishingtho rolcV:1.nt rosourcoo, so f-mch so that, in c..nothor eountry,Süli.lC unoold s::üt110 co.tchos 11[1.<.1 cxeoptiono.lly to bo oont forfishQo::::.l, whicll could bo :1.ceoptablo fcr tho fishcr~on who worogotting ;;>rieo cOl:1ponoC'.tiono throuGh r.ünin1X:l pricc SyotO:"lS.

Tho conclusion on thio ~o.ttor seono to botho..t thofishernon themsolvos fincl tho nost profito.blo short torm W::1.ysof rodeploying their o.ctivitiosj it would not b:::: 110coss::::.ry tooncouro.ße thon in th::::.t diroction ::::.n~ it mißhtwell bu unrenlisticto t['.l::e into o.ccount rocloploymonts th::::.t t1'1e fishormen ho.(1 still110 po ssibility of u::lClorte.l:illß.

Consoquontly 'eho Dolution 3 rorJo..ins 0.10110 o..nd i t doos notsoen that any furt11er otudy mo.do o.loPß those linos could bringa.bout 1:101"'0 rofi:l0C-:' r08ults unlos8 tho 8C01)0 01' tho study wo.oonlargocl by tho 0.c.l..c.ition of 1:.101"'0 stoclw. -Dut anothor enlnrCOl:lOntcoulcl bo wade by 0. LlOl"':) clota.ilod trOo.ti:.1011"G of tho fishing offort • •Thoro io in fact 0.. ot::-onG clistortioll butwooll tho rolovo.nt CLo.to.,on tho one side, the fish which 0.1"'0 trc~ted with Duch detailaecorcling to thoir o.Go, their rolative growths, otc. allel on theother tho voosols whieh 0.1"'0 roußhly clo.soifiod into foul'" brco.dgroups.

In fo.cttho avo.ilo.blo otatistical do..t::::. for fishing floetsdo not. allow noro rofinor2Cllt o.ne.:' t11is dro.wb::'.cl:: ho.s Iod to thobiologioto 'usinG tho concopt offi8hing effort/norto.lity, 0. .

Ll00.suro of tho fishing activity relo.toc1 to t110 fish o.bundo.neo.This method o.lloVl8 tho coc.pleto study of 0. fioh stock with ol1lyincomploto illforD~tion on tho ~etuo.l fishiuG activity oxortodon tho.t stock. TIspocic.lly far ::3inulo.tion pur~)osos i t woulci. bebottel'" , for the bioloGic:'..l oic.o of such C'.. vlorl::, to refil1c thorel~tionGhip botwoon tho fiohinß offort Dort~lity and the o.ctuo.l01'" foreco..st fishine activity. Furthornore, Oll such ~ conditiononly tho ocononist coulcl e~tor into tho ß~~e ~nQ porh~po holpi t in Q r.J.oro rofinocl \7':'.Y thC'.n tho ['.b~vo ol::otchy ror,l~rks whichhc.vo boon givon fron :.:'..11 oconorJ.ic stancbc.i:lt but vlould ho.vo boon •oxactly tho snno if clorivoC.. frOli.1 ohoor: ciuplo, bO~cl souso~

Conclusiol1

The roport by tlw Joint I.C.E~S~/ICnAF Grou}) is highlypror..lisiug hut vlaulli '00 iJ.uch nore fQ.r-ronching if i t could ~pply

to i to vory .cloto.ilocl 1::i.l0vlloc1c;o of tho fioll ot::-cl:o, sor.1Othingnoro t1'1C'.l1 th~ vo.ry il1C'..doc~"l1.,-':'.to infor...:l::'.tion Oll t110 fiohorL1011' S

o.ctivity ~ ,

The dr::1.vib:-.el:: c:':: auch c. conclußioll iß tho.t, according t ':the prOSOllt pro.ctico in nogulatory bodio8, all inforDC'.tion"concerning the fish atocl::o o..ro o..1.l.toL1o.ticC'.lly consicloroc.1 ashaving [1.11 intern~tiono..l no..turc whilo infol~lo.tion on veooolsc..ncl on t110 ocono~ico of procluction 0.1"'0 lcol::ocl upon c..c boine; of

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a nationnl nature~ As long as this prejudice predominates, theunfortunnte oconoDist TIill cnvy the refinements open to biologicalresearch und thebioloßists will be forccd to insert into theirmodels SODe restiictod bits of economics hidden behind a wordingwhich avoids showing that they havG to enter into an unscientificdonain.

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GR0\7TH CURVES (IN WEIGET AND FERCENTAGE OF WEIGET AT 14 YEAR5 0LI1)

COUR13,;:; H" CROISSANpE (EN FelDS ET FeURCENTAGE DU FelDS A 14 Alf3)

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RECRUITMENT RECRUTEMENT

GRAPH 2

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CURVE OF AVERAGE YIELDS

COURBE DES PRISES r40YENNES GRAPH 4

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ACTUAIJ lüm 'l'l!EORE'rICAL AV.8RAGE YIELD CU;~VE

COURBE, REELLE ET THEORIQUE, DES PRISES l.'IOYENIillS

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