Report (2.001Mb)

International Cou:acil for 'the Explora'tion of the Sea

The Liaison Commi ttee of ICES, ac; general (:,oncern expressed abcnxb the North Sea h,srring fisheries at the ~'ifE,AF;J :tn }lay 19689 invited the Pelagic Fish

(1iforthern) Cornmtttee ^{)f ICES ^tCl set ^{1J.1' Bc} \1'Y:'JrkJrrg Group to describe the present state the North Sea herrinR' stocks 8.nd to d18(:U::;8 tn.easures fOI' the improvement the fisheries ⁰ At; its meeting In Oetobe:r 1968 .tn G')pero.!lagen,. the Pelagic Fish (Nort;he:cll) COmID.i ttee:Jf ICES appointed such a ' t T i t h Hr.c J, ,J ⁰ Zijlstra (Ne::'therlands) as Chaixman., Member States

Jl.iro :EL JiIro jiJ.. ^Cl

Dru g,-, M.ro ^{c :..,...1 I~}

PrOl~(}

T1:r. P-^{. 0} lVIr. Aa i''lro K, Dro ~J 0

r~Cr G 17 1'_0

lVlrv Aa Dro Ko The

Ackef0rs C ^u :Surd

Dr ^J G, RemI'e 1 S ⁰ fJIalko\r r1au.c ()Jq' 8

Popp Vladsen Popiel

Ho Post1Jilla

Charlottenlu:nd Slot ~ CharlottenlllilcL unable to ati;end the meehng,.

Post;='lN'ar changes up to in tile

l\forth Sea herringwer.''8 re;c'i.e~"ed 'by fo:r;:rrel~'

scierftists ~-=

'~-; 'J S (J;3 ^c' R,:;

-Pr9.~~JC'~6

F;ES Hea,dqllarters.

XY2gre t tha t Dr 0 Porte 1 ",ra.s and in the fisheries of

':'£ ICES!)

Trle \.vorkJ~ng Groups c,.f the Liais.:);t) C(:mm., , '["'0' reports oovering the meetings in May

1964

and lYIay years up to

1963,

which ^W8X\j

1965

~ respeeti vely ⁰ lvIoreover ^{9 &..}

for 8~n e.x:peri.mental closure of the .Area. the Report of ,\Thieh \AlaS :::: )l::Imi tted

its

consider plans :Big.11.t and the :B10flen

in IVtay 19670

The present loJorking Group consid.ered maiD] y i'rle d^c2velopment in the stocks arid fisheries in the North Sea sinCe aT<t'J.:c·.>ck note ( ) f i;he findings of the former 'Horking Groups on North Sea he

Tl'1.e present Report cb, verges f'r',Jill t<tce

Working of

1964

and 1:=)6')0 At tba,t centred mainly on the fisheries and stock",

of the English Chsnnel ,U::i

this decline mU.ch attsntion had. to bcs g5.~;r'en

of Nort!(J, Sea,

muoh more general ~ lrl.cluding thel,rh:ll El N

G-:rtil.rp ,'bherefore ~ decided, ~ :in

consider the North Sea fu'1d Skage:rrs.k f(,~:

In

the Liaison Committee con::em expressed in 11EAJ:!"C

ti~l~ Sou them :Bight and east&r.n par,JG

·C"";.e C t,e) inves the causes of

" the complicated stock structure a,:[ui Its :fisheries is

8,:;,,9 H~,a_ Sk.age:rrak 8 .. reao T:(}€ Work.ing

9'!i ,::;,1' the l:irr.i ted time availal:::.le -

' 3 as:38ssmen'L as a\i.."lole~ paying

i8\ offered by the results tagging Justification

experiment8~ T~ich

central and north~

Repo~ SeroB~

Annex

o.:;,onnec'tions between the herring sJGc~cks ~ fished in all Sea, area.:s~ includ:Lug the Skagerrak (see also Coop.Ress

? Fig1.1lxe ~,) ⁰

In -Et fiJ::::'m.i:;~' Repor'I;, presented to NE~FC i_u 1965, attention

'WaS <\:l:ca:\lm to the sb~".pe Ollr"',re .in herringt which differs in some respecits

from the yield C'l.L~""e demeJC'SaI Bpec::"es", such as plaice and codo Heavy fishing on de:m,ersa1 :8tock.f:~ gene.>J,,11;y ][:es1l~J_t:s in a. decrease of the to'tal oaten, wereas in herri.ng hea.:vy e:.r..--ploJ 11 l,aaCl. to a decline in the torts! cat oh ⁰ It must b,,· tha' the ^Jc ^{~d.' cri tb.e herring fJ.8heries with mexeasing effort wIll remain steady if :reC:::C'lli tment is not affected by hea:1T,)f exploi. tation of the stockc

As p,~inted

yield curve is: ma.iruy weigb.t by 20~ 30 timez

3

times.

Factors o the:':":

the fisheries~ e0go catch per effort, range of the fish C@l

1J1',"" the fot"Tller Report ~ the difference in tlh.e shape of the 0attaed by the fact that those demersal species increase in

the ek~loited adult 8tate1 the herring

only

by 2 to t;hai:ll, total yield also play an important role in the economy

of the individual fis~~ng vessel in terms of o:{{;l:ie lanc"L ngs from year to year and optimum size

b(~ .'E!£.:fected heavy exploi tationo

110 rfaterial

of

The

materia.l ,o .. cvaila:bl,e for c,:msul tation to the \1Torking Group, covering mainly i.;he period 1960~196? "TJa.ried considerably in quantity and quality between areas and fisheries ⁰

In the course of the discussions it appeared that the material from the sO",!:tthe:rn. and cen·t;ral SeE 1~re,8. suffici·ent to follow the dsyslopments in the

~(t()cks of fisherieso For the northern North Sea and Skagerra.k~ the areas of' :major importance since th,s m.irJ:~fifb.es (Table 1), the material available was generally conSidered to be less sa"ci.sfao Tb.eI's was for insta."1ce doubt concerning the allocation of the 1anitings: as tr) d.ifferent areas foOr SoOme countrieso Wi th some exoeptions the oateh/ ",ere foOund to be poor in the northern areas

aXld~ when available" r:1..1.l\l to the main fisheri2s o Simi.lar r:bj ec "ions

Sa.mplmg was most t;.imes the catch ruld sampling

~the areaso

The deyelopment descri"bed.

in

a p"eVi01),S Sil"lce then tlbexe hatre been bee--n a t~lJxtJler (decljJj~,s :tIl central and

scaleo

er, g; _ to 8aml:.1in~~" agaj .. n I'd t1'1 some exceptions ⁰

actual cat(;J;leS₉ referring some=

minor importa;nce ()1:' reseaxch=vessel catches$

ne: 1:e1a."cion t.o the llagr.1i tude the landings f'rom

the he:r.ring fisheries in the I'lorth Sea up to

1963

has been -tre! the Liaison Committee (CoopoResoRepo ~ SeroB,

1965)

⁰

fur:1:;hr~r roa,] or changes in the fisheries ⁰ There has thus fisheries in all areas par-~icularly in the

d:r'ift~net f:Lsning is now on a very small 'Th.e tra1<71 chel"2g,ed. iJ., tl"H:;ir natureo The large German. trawlers

which in the

1950

^G8 a large part of the trawling eff'ort have almost completely . wi thdra""l!1 from the Se·a herring '~isheries ~ but the number of trawlers from

other countries mos~ likely inc~ea8edo No direct information on the size of the tra;wl fleets operat:.ui..g'l;'laS a.YailaJ)le to the Working Group. In the trawling fleet there has been a general change f:;:"om. bottom trawling to pelagic or semi=pelagic pair= and single=boat trawling'~ the introduction of sonar leading to greater fishing ef'fioienoy al1.il ne,,¥" tactics 0

stri.k"l1(J.g change in f~he fisheries~ ho'!tlever~ has been the The most

.ini;ro8.uction of

No~vegian fleet in The Norweg1an fleet

area in the summer of

1965

seine vessels of other

Sea herringo This ,iaS started by the

1963

in the north=eastem North Sea and Skage:r:rakG

the ran.ge of the purse=seine fishery to the Shetland arAQ have since been joined in these areas by purse=

o

=

3

"the North Sea and ~:f,~ by atatistieaJ.

a:reas :in the yeWJ::'El ⁰ :'reoc,rden la1l:'l~

or

juvlt!nile herring f~ the- central North Sea ) b90ve "been sep~tely aocounted f©ro It should be noted,

h©wever₉ that the 'P~o6i:!111'bij he:r:cing~ especia.lly for the ncrth=ea8te:rn

North Sea. a;nd Skage:v.."'l:'tik~ oa~"~e a proportion of juvenile he:r:ring ~ an.d i t was

reported t.'i:lat tl'18 aw.m~:i!;; 'DJ! jU'lrexlLiJ e her:rlng" lan.ded Ut the !iad:ru"t^mJ herring fiaiheries mcreased

m

recent Jie~So

Tables 2 to 6 2ibi']"4,;' "db:,,:> lanf~""13 L.~ countries from different statistical axeas from the Nortk":i Sea and Skager"!:'iElk in the years 1960=1968 (see Figure 1) ⁰

10 The total ca,t!m he~..i1J!.g .from the North Sea~ Skage~ and English (J~el i""luctl'JEfted a.round 7759000 tons in the post,=wa;t' period

~p 1963< ~:~b.tm fi:lllcfwed a sha..rp increase to a peak of l~4009000 tons in 1965~ fQllm,-;ea~by ,911 eql~ally sharp decrease to about ~OOO tons in

1968

(' "- 1

\pr©v1.sl.,O,:sna, '

The declll'le :ill JGne EngLi.sh Chaunel (aL>eas

(CoopoResoRe:p"" SeroE, In the centra,l

20CsOOO tons In the norlhe:-m 200₉10100 1:;0118

19620 After

lsm.dings from the southern Nmt."i;J,::!, Sea and the IVe + TIld, e) mentioned in "tha previo'l!lJ.S Report 1965) oontinued after

19630

(area

no)

^JQ'1e lan~ fluotuated aJJ:'o'lmd 101),"1; '~ended to decline after that Jrearo Sea (sn1?ea l&'1.dinga fluotu.ated around

t©ll~ in 196

5

~'jt;l'le!:l

and around 35091000 tons in the peri@d 1955 to 181ndLtogs L.l1ore&ssd sha.-cply to a peak of 930~OOO

fell to ~OOO ton~ in 1968 (provisi<tm.al figttre}o I^v; ~

t1.,,,,

l..lv <;;''''". ~~.,II.t;:'.,.f.%, lrr",~","j \. ... <;;.!,t";.",....iblt:. '" 0;l\\ ;:, t= tJ -"" l1"'''''''''''''''''''''~'''h ,.il"",,-a<.J.,.l'6Q '1,.".9~ tt,,'4J~ 1(;"",,,,,,,_ \\ ''01 Yi '9'db 'llI!:::O COO &;. -.;; 9

tons) was made ::Lu ·!;hre years: 1965 a,nd

1966,

due entirely to the entry of the 1:Ionleglan pi21?sG=seine fiesto In recent years (19675J 1968) the landings fr())f, o~he are;a, deor'€asad agai.no

In the north=sastel,71 Sea 3) the landing~5 rose from a

level of 9000 1,;;)7(1;8 in the yea,r;B 1960=1963 to aro'lm.d 600~OOO tons in

1964=1965.

a,,&.:d~ dtleto JQ:16' effort of t;ne !;ron"egi@Il purse=seine i'leeto

Since 196:;1 land.mgs declined again 8JQ,d possi'bly retumed in

1968

to the fOJC:mey' 1e,7e1 ^{( i f} ~ 000 tern:; ⁰

5" D.l the Skager~dk (area, IlIa) trend.::. in -the total lrand.i.ns'2 were les!li:

sharply defi.n(~a thau

m

the other ares-IS ~ &1 though since 1963 the 1an~,

have "been at; an, aver"2ge level of abOitd:; 250~OOO tons, about twice the average level ~;he precec'i'1"Dg ;)rears.

Some doubt has been, eJ:pressed sbout t.11.e 1966~1967 1andinb-"S1 'ifil:rlch were thought to be par~ly derived from othBr areaso

60

The reoordecl 1andillglS <l1Jf juvenile herring (Tables 1 and

5)

from the central rlorth Se8., (Bl~den area) have been rather stable since 1955 at an. ayerage level of about lOO!, 000 tons ⁰

Cat~h=Der~nnit=effort

r r ...

Estimates of the catch=per=1Imit=effort might be used to indi~e stock al:randance ⁰

D.l Table 7 t1a6 catohes per ^l1;oo,i

t

of effor"!l; of those fisheries axe given for 'lW-nich data ""vere ~:;;~ilable 1.1[& the period obserlred and in which no radical charclges L"1 gear and fi8:hL"1lg techJ."!:li que ocourred during this periodo The series covers the years 1960=1967 (1968) and, possible9 the average catch per w.i

t

of effcrt in period. 19.55'=1959 ha~ 'been includedo

Tb.e choice of' :f:L~heries, from 'JIlllich tlie data could be derived, is rather limi ted9 includir.,g th08~ :fishl3xies ⁹ "fr.:.1.ch in rec;ent yearsl have yielded only a small :pirOpor"l;ion tcrtal catooo

Th. the southern.

e1~~ Sh01rled, in ge~e::L'2hl a e'st~te for 1955~1955Jo

drift~net = ~~d trawl = catCh per compared with the

In the central. N©Jrtb Sea the 1955=1959 average estimate for the cstcb=peZ'=1mi

t=

of'=efforl was higher ~ ~ eetil,m:te in the ~.

1960=1961

^j7 'for b~ d:rlft=net and t:rawl, ^with the ~ti@n @f the Grl.f't.=net estimate for 19.630 Since 1960, no defini te trend is ap~t 1n the two estiaa.teso

In the ll@rth...~.st~ .I'@rth Sea~ Were the two sets of data. are by: no means derived trmn at present impc.rim:tt fisheries in the area, the traw'l estimate shows a.

defin.ite deel.ine in the oo,teb=pm!'=lmiii.=of=e.fi'ono The drU''t...net estima;te varies

e~:i~ be~ ~" ~ tends

to

decljl!l!jl! s.ince

1965 ..

:m

'the nort.h=W!Bte.:m, !forth Sea tbe drl..ft=:aet l!!I:.D.d trawl estimates also show different fea;wreso ~ drift:=Det eat.bl!a.t-ea show llC obrious ^~, but the trawl cswh=per=tmit=o.f=ef.f@;rt ~as ~ decline at least since 1%4<> C~ with the

ave~ :tor

1955=1959

the ~l eilt.imates. v.ere. cm.. a. l.mIe:r 1.eve19 the d:rlf't=net esti:r.llatea ^@u a.bmi:t ~ ~ level. as in. th:e years.

1960=1961

^<>

Wj:t'h the axceptian of th.e SO'\llth~ lforlh Sea'} were ab~ce is indicated to have decl.m.ed ~e

1960, it

is di.fUcW:t to decide from the eatch=per=lmit=of- effort in:fozmation, h~ ad i f the abm:l~ l.eve1 of the !iorth Sea her.ti:ng ehanged smce

1960

^@r 1955, the

trawl

data indicatiDg a generally declu,iDg level, the drif't=net data. a

:mlloo.

more stable situation ..

. e)

Effort

Direct est:imates of effort, e .. g" n:lmber and type of vessels in operation, time of fishing etco

were

lacldng for most countrieso The inf'ol!mi!i.tion available -':irWficated an increase m the purse=seine operations in the yea..,,""'S 1963=1966, but a

decrease in the trawling activities of some countries in the yea.rs 196&.19680

Indirect estimates have been obtained by di-vidi.:Dg the total ~ from an area by the catchesc=p,sr='i!mi t=of'=efforl of some ef the fisheries in that area" This tech:aique can be expected to produce fairly reliable results in cases where the catches=per=uni t=of=ef'fo:ll."t have been derived to the major fisheries in the areao Estimates of effo:rt~obtamed by this method, are sham in Table 8 and indicate that 8=

10 in the aout:r!em North Sea and English Channel the effort tended to decline since 19609 Which means a continuation of a decline which st~ed around 19550 (CoopoResoRepo, SeroB, 1965)0

20 in the catltra1 North Sea. the eff'orl fluctuated up

t©

1965~ but thereafter tended to decline to approximately half its fo~er

leveL

30 in the n©rth=weBtem North Sea both ef'fort indices

mov

^{a sb.az:p}

increase by about

3=4

times in the years 1965=1966iJj decreasing again iD. 19670

40

in the II.OO!'tb~~<errn-lfo:rth Sea and Skage:t"l.'Sk: the estimates of the catch per llIdt effort availa.ble were not derived from the major fisheries (paiL' tra.wl~ purse=seine), so that the effort estimates are not ver,y reliableo

Tald.ng~ however, the more 3table catch=per=tmi't=of=effor't of the d...~ft=net fiiBherieslI a stro:ag increase, in the orier of 3=4

times~ in the effort is indicated sinee the ea.rly 60^Us., After 1962 the ef'f'art seems to have fluctuated without a def'ini te trendo

50

taking the North Sea as a whole, it seems reasonably' cerlai:n that between 1963 an.d 1965 tbe_ effort ros~, sharply in the northern areaso After 1965~t

is

impossible to define exactly how the effort developed, but """'some decrease might have taken place ⁰

d) Total catches in number

!. first attempt was made to cIOn vert the total catches of North Sea herring into numbers of fish by age grOups~ by using, where available, estimates of the mean weight cf -tlie~ fish caught and the age distribution ef the f'isho This methed was applied to the di.fferent areas, mentiened in Tables 2 tlO

60

In the time availa.b1e and TrI-J. th the material at band only a.m:mal estillates of mean weisht and

age

composition could be obtained, Whereas a proper analysis should be done en a monthly basiso

- 5 -

In the case of the s«mthem, central and north-western Worth Sea fairlY' ertansi-ye series of data by years and sometimes Bonthil were available.. The series for the

jmrmrile fishery in the central North Sea (:al.den) of the meau veightil and age C©l1Iq)ositions o:f the her.ring in the catches wall moaat exteruiiveo tIid~:rtunately, the ilrl'omation from the norlh-eastem North Sea and Skagerrak vu not very satis:factory 9

as :mentioned in Section Ilo Hatsrialo It seelU likely that in these areas the

n1lJll!lhers o:f fish ~t ~ tOil!) low and the ca tellea from y01lllger age grou.ps are 1m.der- estimated, especially in the later yearso

Table

9

gives the numbers of imm.a.ture her.ri.ng ~t each yeta in each ~ and also the catch o:f a.dul. t herring., It is seen that in the ~ a:ree t~

. . .

^~

a sharp increase after 1964 in the ml1il!bers o:f iJIIIrmture herring-~; the "total ~

of au ages rose by ©ver 3 times, while the catch of ilEattzreii1 has r.lJ3en by up to

5

times ~ There is sme d@ubt, however, as to the size of the catch from the S~

in 19679 lIIhich was probably lower tha;n shmm by the st&tistics~ In the nortb.-. .

te:t'D

area too, the ca.t~es ~f i1mIm.tm:e herring have risen by

3-4

times, and the adult catch

by

about 2~3 tiBeso The y~-cl&Sses entering the

1965, 1966 and 1961

fisheries are indicated from other da.ta available to be not above average compared vi th earlier

year-classes (see Section IV ^<> e) ⁰ Th.e increased catch of these fish l!ImSt be a reflection

of

increased effort~

In the north=wElste:rn area there has been an overall mu.ll increase in total catch in numbers ^Q In contrast, i:a. the central and southern areas, there have been decl.ines in the numbers caus;ht of the order of up to :2 tiJmes iD the fom.er and 10 times in the lattero

IV" The Herring Stocks a) !ge c(mlposi tioo

From the preliminary analysis described in Section IIIed, converting the catches in weight into catches in numbers by age groups, age compositio:as by areas were

obtained" Table 9 shows the herring caught in different regions, divided into three groups g iRmia.ture he::t'Ting (1=2 years old), yo'lJllg a,dul t rutrring (~4 years old), and older adult herring (Qver

4-

years old) ^e Due to uncertainties about the age composition aIld weight of the fish in the

two

important areas = north=eastern North Sea and

Skagerrak - the figures in Table

9

for these areas are not ver,r reliableQ The main features in Table

9

areg=

1) an increase in the catch in numbers in the total North Sea since

1963;

2)

a decline in the numbers of herring caught in the southern North Sea since

1960,

but

a

recent increase in the proportion

of

older herring;

3)

a decrease in the numbers of herring caught in the central North Sea, and a decline in the proportion of older fish;

4)

a sharp rise in the numbers of herring caught in the north-western.

North Sea in the years

1965-1966,

followed by a decline in

1961,

which

affected the older adults more than the younger age groups;

5) after an initial rise in the number of adult herring ca.ugb.t in the north~easte:r.n North Sea and Skagerrak in the years up to

1965,

a decline set in, which redu.ced the catches of older

herring more than the younger age groups;

6)

an increase in the catches of ilmu.ture herring in both the north- eastern.

North

Sea

and

the Skagerrak~

The prelimina.:ry natu:re of this information DnlSt be stressed and a further analYSis

of

the material is thought necessar,ro

b) Mortality rate.!

Table

10

gives the mean avera.ge mortality

rate!!

over fGUr~year periods for the north=westem, centnJ. and southflm North Seae The values for the north-wester.n

]j~rth Sea are calculated from the abundance indices of the Scottish drift-net fishery in AngtlSt=September; :for the central North Sea from the abundJm.oe indices of the :Bti tish dtift=net fishery 00. thespaw.ning grounds along the Eoglish l'lOrth=ea.st coast

~d of the Dutch tm.wl fisbery on spa1mi.Dg he~ in the Doger

area.o

Those from the southem North Sea are derived from the EDglish drift-net f'ishel;)T in the southern Bight ⁰

FOZ' me north=westenl North Sea the lOOlly m©rlality data ava:aab1e show a.

shsJ;p increase after 1955? but a constant, lower lev~l th'9"reafter up to 19670 In the central Norlh Sea the mortality level would

seal

to hAve increased in each f©Ur=Yea.r peri(l)d considered" hilt vi th a iSha:!:'p increase af'ter 19600 Lu tb.e southern North Sea.

mortality he~ beel1 high throughout the period c©DBidered, but increased considerably from 1955 to 1959, gnd decrea.sed to a level of the period 1951=1955 in the

last

f~

ye~ o@nsideredo

Tl1~ catches by age grv~ in num.ber (Table 9~ lIflotal North Sea) have been used tOl calculate :mOlrtali ty est:.Lwates per year~clas8 for the total North Seao The- values of Z are given in Table 11, iltlhere it Ca:ll be seen that there has been a_~

incZ'esse .in total llmJrtali ty on successive year=classes ⁰ The valu.es of Z ae:ri:'veci ~.

this teclm:ique, as they are in total ll'Whber ~d not i:a catch per effort, t;~~ be lowe:r in vru,~J,e than thQS~2l obtailled by the other merthAJdo The increase in total, mor-",s,1i:ty 'Wt7ould suggest tha.t there has been ~ .in~a,Be in effort :in the North Sea

by ©ver

twc

times

~ince

19600

c) !,bmdan66 a~stima.ted f'rom t.a§~

Since

1964

several NQrwegian tagging experiments have been made in the

Ska.ge~ :and the northern North Seao These experiments ~ carried out; with inte:ma1 steel tags ~ have g.:I:ven a high. numbeZ' of retums to be deal. t wi tho Though the

e:r:peri.me;nts only- partly fulfilled the requirement:e: for :making a quantitative

asse~8ment, they allow to mak~ rough estimate~ of the abundance cf the herring stock in this pari of the North Sea in the winters ©f 1966 and 19670

In the winter of 1966 the herrin.g stock in the Skager:rak and the north=

eastern. NQrth Sea was estimated to be about 2~

55

million 'tons 'Which correspcnd to 1508 x 10:1' millions Qf herring (Dragesund and Ha.ra1dsvik~ 1968}0 One year later~

in l1'inter 1967 ^fJ the herring stock in the nor't1:1ern. North Sea was calculated to be

1905 million tons Cl.' 603 x 109 ~llions of herxing (Haraldsvik₉ perscnal commnnication)o These figures give a decline iD, stock abundan~e fr@m ~~ter

1966

tQ winter

1967

of

about

60%$

!inich correspQnd to a tota,l instant~e()'i1.s morial!

ty

rate Qf' Z ::: 0090 The stock size figures above are, however~ estimated from different tagging experiments and are not directly comparable due to probable reC'!rull tment differences during the

wo

^{~ periloaso}

It Slb.o'llld therefore be stressed that </;he fOigw:'es of stock abundance and mortality rate based on tagging e:x:periments are r~ esti:mates and are included in this xeport @Uly tQ indicate that a drastic reml!y~ion L'Yl stock abundance has taken pla©e in the nor+l1ern North Sea between winter ~966 ~d winter 19670

d)

Larval 2,bulldafice

Ab'Wldaiacs of yo1.I!lg la.:rvaEl of less tha'fi 10 mm. has been considered as a

mea~e of the size of the spawning stocko

Table 12 compiles data from the litera:t"U,..~ and 'UJnpubliBhed res:W.ts of the Inter.natiQnal Larval Surveyso ~ne figures fQr the Downs stock refer to ave~

larval abunda;nce in December and January in the eastern English Channel and the Southern Ei~to Da."Ga for the central North Sea caine from th6 western slope cl the

!logger :Bank only ~ they do not include some of the maj or spa'WIling grounds of' the area ⁰ The figures an the northern

NOrill

Sea cover most of the north=western North Sea up to the Shetlar'..ld a.rea (Savil1e, 1968)0 Attempts to looste larvae in other areas (n@l::'th=easte:rn North Sea), which were made in re©ent years, failedt except in the eastem Kattegato

The following might be concluded from the figureso

Larval abundance of the Downs stock went down to vexy low figureso

The figures given for the central North Sea indicate very low production during the past three seaso:cs ⁰ These figru:-esl' however, do not include spawning off Whitby and on the No~.st Banko

Taking the B,?rthe:m North. Sea as a w"h©le~ larval production had been more or less tJie same from 1951=19650 During the last three seasans~ however, ltanal production ~afaS" poor in the northern Nort.b. Sea too ~ the decrease being more

prono~ced in the l3uchan area ·tha.n. in the Shetl~d=Orkney a:rea, where du:ri.ng the last decade spawning 'Was always more intense than on the Imchan g.roundso

= "'{ =

The 1~1 abundance in the North Sea, ha:e: ebvioualy decreased d:I:tring recent

ye~ p~intiDg to a decr'ease in spawning potellltiaL It has been pointed (!)ut in earlier. re-poris tb.at a reductiOI'. of spa-WIring potential to a, certain level will lead.

to a. moti(~eabIe- decline ,of recruitmento It i8, howeirer, ml open question whether at present the spa,wning potential has already reached such a low levele

e) Recr!rlmen.t

Estimates of rec:rui tm.ent to t.h.e lforth Sea ha..-r:i.ng stocks 'Were a;vailable from. three different s.ources~-~

10 fJ:Xll! the adult fisheries in the north~

oentral

and

sQuthem Nsrth Sea, calculated as &b~ at

3-

^~

of' ages

20 fxOE. the B10den fiBhe-r;v '00 immB:t-ClXe herring at an.

age;)£' two yea,rs. old"

3" from the Internatio:nal Young Herri.l1llg S'l!U:Veys, in :M'a.:!.':ch

aJ.t

an age of l i years cldo

In Figure 2 recruitment to the adult stoc~s is show.oo In the northern and central North Sea a .fair degree of similarity exists in the recruitment

estimates by ye~=c;la;sses, showing no obvil"rotS t~n.d in the period

1951=1964 (1965)0

Three relative strong year=classes recruited in the recent ten years, eogo

1956,

. 1960'

ruld 19630 In o~he scut..1-].ern North Sea. rec.rui.tmen..t declined i.n the period

1948-1964,

with only ysar=class

1958

as outstandiz:!go

In Figure 3 a comparison is made between the adult recruitment estimates averaged for the northern a.n.d central North Sea (:B)~ with the estimates from the immatu:Jre herring in the Interne,tional Young H/e~.J.D.g Su:rveys

CA)

and the Bl"den fishery (C) ⁰ Tb.tO' thr69 indA~pendeni estims tea 'of recrui tm~t agree :reasonably well~

with

the exception of the most recent yea.r=claSlses

(1962=1964)

ⁱⁿ the :BliIJden fisheZ"j'"0 None of the three estimates :--'hows an obvious trendo The slight

tendency for recruitment to decline in the later years could easily be explained in tel:'.m.S of the high :naiural 1f@xiabili ty of l.'eCrlll tment in the North· Sea he:r:t'ingo

Vo Discussion

The inad.Gq~Jacies of the material~ maj.nly ID the a:~ present major fis'b.ing areas in the North Sea, make an evaluation of the siti!J.ation in the her.ri.Ilg

fiSheries rather difficult 0 . The fact that the ~s in fisheries and stocks a.:re of recent calate, leaving only few years to :rol1~w the situation, accentuates the ciifficru tieso

The increase in the landings of North Sea herring in the years

1963=1965

~as almost certainly beeu -the result of a sharp i:D.crease h, the effort in the

norlhe~n Nori:;h Se].o This follows not only from. the indirect e::-fort calc'llaticm.s (Secti~n 1II9c) but also from the fact that the laniings rose in a perioi of rather steaq rec:mitmento Whether the decline in the laniings since

1965

is

partly

or completely the resultof a decrease in the effort is not at all certaiD,

al theugh some decrease in the effort see:ms likely ⁰

There a.:re some indications of a reduction of the adult stock and a high rate of a"Cploitation following the rise in efforto

Thus the ICvP01","UOn of adult herring in the landings declined. in th9 most recent years and the fishery tended to ~ to immature and probably pre~

recruit herring.

The mortality rates estimated in central North Sea fiSheries iBcreased considerably since 1960~ and also in the total North Sea, as appeared from catch curveso The relatively low mortality rate in. the Scottish data for the north=vestern No~~ Sea, however ⁹ does not indi~ate a higher rate of exploitationo

On the ©tlb.er hand~ tagging ex:perima.Tlt in the northern Borth Sea in

196~1967 indi©ated a strong reduction of the abundance of the adult herring

&ai

a high :m~rtali ty :l1:'a te

(60%

per year) ^{0 • .}

I

Laxval ab'lmd.a.nces in the North. Sea t.endei to d.ecli.n.eg especia.l.ly since

1965 .

(nor+"hem and cen.tral North Sea)~ sUggeSting a red~tion in the a.dul.t. stockso

A reduced abundance il2lf the heuing is not clearly indicated by the data ~n

catclles p$T tml-'~ t:»f effort ~ which gi1ffJ ra;ther contradictory ev-ideneeo It seems questiltllnable₉ hil1irever₉ wether catch=effort data in a he1.".t"'l....:ng fishery give much

in£@~tion on ab1lJlfiQance under the present fisl:dng techniques and tactics ~ inel~

shi£ts to other f'iiShing 8.;"':efIlMS and ^1;:,0 Q.ther 6pec:te8~ wen catches fall bellOW a . ci&.r:tain mirrhm:xmo 'rhe fact -tb:s:t ~ome fishing fleets have been reported to bave left the Nort'h Sea in r.eeent years fer reasons of rentab.ili ty of the fishing operatums would certa:!:ruy indicate a lower abundance of the her.rlng

Tne relatively high numbers of older he~ caught since 1964, according 1;:0 'the m:lal.yses of the catch in nmnbers of North Sea herriI:l8, do not agree very well with a concept of a high rate of exploi tati©:uo It Ill.USt be kept in mind,

however~

tha.t

^these high numbers were found by ti!,Siing poor infomation on age -Ctim,pi{l)Y;,,"ftion in the north=easte:r.n North Sea~ where oost of the older fish were

c~t according to t~e analysis.

Recrw.:tm.ent was indicated to be fairly steady up to 1964~ but it should. be realised

that

a yossible ~ffect of stock redncti~ on recruitment can only appear in 'tb.e year=classes crig-.l.nating Skfter 19640 I'll; is thus

too

early to say thB,t

recra:d.tm.ent

was not affected by a

reduction

of' the stocksc

Under these condi tiollS and

'TIn

th the materl~l a1railable9 the Working Group

has

drawn

the following Conclusionso

VIe Conclusions

In

the

fcxmer report of the

North Sea

'W1(ll:t'ki:!'.:!g

G::t'O'l'.l!p

it

was

show. that iD

the

period 1950=1962

the total North Sea catch

~JaS

remarkably stable for a long

period s.t a level fluctuating around 9000000 tons\, including i.mmature fisheries,

m

spite~ prooablY1 of a gradual increase in overall efforto

After 1962 a steep rise in the effort took :place and resulted for the first years in an increase in the total landings of 'liilp. to a level of 10

5

million tons of

No:r1ib.

Sea

he:rringo

Th.l.ring

the last three

year's (1966=1968) the tota.;l. eateh has

been falling off dei-m

to

the previot1!.r.J l~v~l of ~teady yie1do This was probably accompanied by :f.ll(jI.UE~ d.ecrease in effort for reM:G'lD.rEl @If rentabil.i.ty of the fishing

operations

⁰

The recent high effort rawl ted in a reduc'ti©n of the. matut:e stooko With the inc~e

of

fishing intensity

the

prop®rti~n of immature ~ in

the

oatcihes increasedo

~ne. catohes are oomposed

@f

fish of lower age~ length and

weight

than

beforeo

From. those events the Working Group c®lncluded that under the present

envi-~~ental oonditions

the steady yield

of

the

population of North Sea herring will be about 8509000 tons of aCiul t a:nd juvenile herring 0 A maintenance of

effort at the high. level experi~nced in recer.rt years will not lead to a sustained higher yield~ but will have some tmfavou:r:a.ble conseque:noe8~=

a) low

catch per unit effort~

b) a young population, in which the fisb.er,r is based on very f~f year~classes, giving wide ~ual fluctuations in

the

total catch~

c)

a relatively low number of large=sized herring for human

consumptioDo

Ix:!, add.i tioD ~ the low abundance of matUlre herring under heavy exploitation will result in low egg production and possibly in lower

recruitmento

that

~t.p. be

tu_ to @!tabl1i!;e the effort

8lf,t ill.

Imrer

level ~ uert.d durJ"ng rGClmt ye~, in order to inc~

ave~

•

in

the

iIlltlOcko

!'h..'ts ~t be ~eved by the 1ntro~m IOr an @"l~z&11

quota

:r~r :lorth

Se&

h~ .fillherieso In rt~ of the camplex1 ty ©f the herring population a i the

M~ filiherie. in thIfil 1'1O:r;-'th

S.il

~ct reactim ~f

u.tort

~ reductia of the fleets ~ ~~ closed ~ i!J!;D:d elo~!le&Uionii 'Wow.d net be

r ...

ible"

TIO allow a recovery of the BtlOok, the quota b.as tc be 'Well belw

8500000

tou 'but m18ht

be adjuted ⁱⁿ later years acCI!')rd.ing to the. dGVelo~t of

the l:eilllCimrCe ⁰

HI!')'W .fax, in addl:tioo_w tepecific r~atl!')ry ~u:reS-.m!, the i1IIB&tu:re her.r~

f'ilih.erie!l are Advisable M!I to aWl! t reliable .fi~1lli I!')ll the effect of neh fi~_

0I'i th.e yi~d mli &iiult .tocko The intfil."lwdiomal ~C echae .ffJr jumile herri~,

to

~e cur.iei out wdiljl!' the aupiee. of ICES in 1969=1910~ fill a:.lmed at pdOOrti:i!lg

the

nec.silllL~

inflOmation on thie quelltilOII.o ID the lIIeantiM the 0017 advice would

be

t@

:int~duoe an ©verall qucta~

refiltrlcting

both juvmrlle ed adult

fium.efio

Year IlIA

Table 10 Total Catch of Herring from the Ncrth Sea, Eastern Channel and

S~~~errak by

Statistioal Areas

(~~ding, ~n

Tone). Ca.toh of "a.dul

tYV

Herring

by

Areas IVA Iv:B IVC

+

VIrC+D Total "adultil Total recorded Catoh,of ( Skagerrak) (Northern North Sea)

~Central

NS) (Southern NS + North Sea Young Herring from Area Iv:B

(C~tral

North

Sea)

English Channel) 1947 5 2

7

671

220,906 212,402 191,521 683,500 0 1948 81,364 221,841 196,362 244,105 743,672 300 1949 78,529 195,471 200

9

863 172,176 647,645 200 1950 91,244 154,510 191,188 197,374 634,316 5,400 1951 103,974 174,416 296,230

2~j5j'

820,173 44,595 1952 138,794 220

9

434 239?140 221,365

819~733

50,185 1953 137,358 226,724

275~471

271,861 911,42t1 78,407 1954 99,293 205,336 257,368 225,51"5 781p5'!O 95,294 1955 113,466 352,750 182

9

2 47

168,412 816,875 112,450 1956 123,262 303?307 165,814 13399'64 126,40'7 103,695 1951 158,191 341,856 165p530 125,402 790,985

103~190

1958 215,807 279,913 183,436 93,416 112,512

158~880

1959 205,448

370~800 193~845

71,)24 847,417

156~357

1960

~19v641 386~729 171~009

78,117 755,496 1151574 1961

1~,,259 348~280

178,897 101,431 761,867 96,768 1962 168,583 344,892 152,953 60,219 726,647 105,901 1963 2301)741 4179

676

232,575 5 1

9

162 932,154 711564 1964- 367,11;

592~507

183,032 54,797 1,197,449 121,586 1965 324,254

931~O26 132~120 25~679 1~4139079

152,153 1966 212,943 756,121 125,797 12,166

1,107~O27

92,782 ,1961 3079

1

41 564,109 84,904 9,570 965,724 102

9

016 11968* 250,696 401,236 39?450

= 706938~ 1~~2

,000

--~---~-~---------" --_ ... -.~ !fJJ

ProvisionaL **

Includl11g

extra 15,000 from Ge:rm.anyo

~l~ 20

Total Catch in Tons

by

Countries from the 1M North Sea (Area IVa west of

2~E)o

Total Catoh 683,500 743,972 647,845 639,776 8649768

869~918

995,827 8829864

~iSl,325

830

9

102 8949 1 75 931,452 1,00;9774 87 1

9

0 70 858?635 832,548

l!lOO)p718 193199

0

35

1~565~232

1,1999 80 9 1,067,740 828,382

Il"""-~~--"'F"""--~--. ~-~~_.~~~mc~_~~_>L---' !F=~~~~_H,llilland. :Belg~::r! I=~g~and

Scotlamlf Norway Sweden USSR _ Denmark

~an?eI

Faroes _ Iceland,

~

47,765.6 23,82706 100.3 112.1 23,191.2 1,654.5 222.0

109~79101

19,183.0 14,66906 17953800 1,13700 60

9

48006 7,007.2 6,57702 18,958.8 66.1 36,23501 11,279.2 17,14902

29~56504

2,586.2 3,636.0 74,829.8 6

9

06300 15,48102 17,04405 2,590.9 3,80900 56,52400 4,48808 15,12100 19,990.8 194,07400 20,095.0 286,39108 7,064.0 5,31907

6

17,18603 205,11104 52400 259983906 7,074.0

4,496~O

21,41200 41,15103 21300 1,27702 83922108 4,268.0 6,24700

=,

27,71706 100,289.0 136,52106

B fJ=9 () o

f

~

l

I~

Table

'0

Tetal C.,tches

1n !ras

-.t'o

Countries from

the NE Werlh Sea (A..L.4. ITa

east

of 2°E). Ge~ H~11a.nd

Belgium Jrnng1md

SOl'lOtlanci l!To~a.y

Sweden USSR

D~xk FrQ1llce Farosllil

33,36600 11

9

417,,0 22.0

."

1959800 18,00000 9 2 991200 163,10500 46

9

964,,0 17151-:0

=

13,49800 43,,0 12000 900

3~877

00 19900000 9',42900 61,72200 70

9

36300

9,3B100 =

9,91500

59()72~O

12500 1400

4~89900 0

17900000 90,61200 00

9

26500

52~18000

8,4610lO

= 10~92100

79400 34300 1700

=

!

12~43500

112,011.0 75,96500 639 8 56cO

~Ow165Q() o~

15940500 59 2 52,,0 15500 8 00 62700 124931900 103.,34500 39,63100 S8

p

869.,O

9~289o«)

913.0 25p47100 39,06,,0 22700 41.0 6

9

78900

334~98400

107,00800 279 2 2100

55~282oij 6~09~oO 3~11100

14944500

090,,0

11800

= r"3916boO 237~63300

129,41200 16

9

44200

57~43BoO

3992400 1,49100 :')959500 631

0

0 200,,0 1500

=

2°'9

2 3100

140,53800 27

~22100 55vOOOo(V

8,37400 35999300 255 0 ° ____

710.,~~L_ = =

1605 9 1

9

1 7800 70,55400 60

9

00000 40pOOO.O

= = ~~ Total He:l"Ting C~tch in Tons in the Area" IlIA (Sk~:tTiitk and Kattegat)o

Year

Poland

1960 1961 1962 594 1963 329 1964 4,324 1965 5,330 1966 511 1967 127

196~ ? «r hovisieM1o ilK\> Iceland Catooo

~ Ge~ NO~j~

44 4,204 9

7~712 3 7~917

1,235 8,249 3,726 87,088 4,248 879745 1,301 30,943 1,259 96

t

120

=

98,296

- Various Sweden

DerJJ!lark

Denmark

+

Sweden 27,658 62

9

6 54

25~O81

28,314 65,806 11,358 38,862 lO8?257 12 9950 49,56,

150~175 21,190

45,494 178

9

465 48,016 45,860 1439 600 37,471 55,687 119,620 4,881 60,300 144,441 2,151"

?

152,400

~

Iceland

Vu Q St~eden .,., = ..,

14,892,,0

= 2696901))0 =

61 972400 1p75700

53~8(14"O

1,04100 3951'300

5~684QO = .., "" -----

Total IlIA 119,641

13~,259

168,583 230,741

367~113 324~254

212,943 304,998

250~696

:£ 276,51200 281978000 308

p65800

318,36600 536

9

97900 6449 6 3500 4939 11 400 I 484,324.0 262,71400

8 I-' I-' i

I

'Y@c.-:-\,T?

1961 196:)

~j

61&540

10

9

336

4·7 ~ 81;0 69

T79

Clj,tch by Ccun:b:i@s in tha CentreJ. No:!:,vth (Al'@H;t IVi)"

5

Hol1n:o/1. ~?O 9 ~!B ~} '1",101 144

Table

~ Catch~per~unit=of=eff0rt

in Drift-net and Trawl Fisheries in the Southern, Centra19 North=Westernand North=eaatern North Sea.

Years--~ N(l)ri;h~vll"lst.F,:rn

North Sea Drift 1 ) Traw1

2 )

Avo1955=59 409* 45.6 1960

30~

3300 1961 402 27.3 1962 307 21.7 1963

3~9

24.3 1964 '04 3307 1965

';l:

4 )0 2409 1966 403 1802 1967 407 909 1968 1606

-

~

North-Western

1Ti};T,"bh Sea """"""'" -==-"="".b=.=~~ 1) prift=~n.!!~J

2)

Trawl ~ North=E~s~x~~~~tLSe~

3)

Drift=nei, ""====----==='!:;>

4)

Trawl ~

Central North

Sea ='i"~---"'~-=-~=. _ == 5)· l?~~~!

6)

lJ}rawl =....,..~ Southern

Ni:'lrtJ:.t

Sea,

7)

Drift"~~

8)

TI'i't'wl ~

North-Eastern North Sea Central North Sea Southern North Sea Drift

3)

Traw1 4Y Drift 5 ) Txa,,,1 6 ) Drift 7 )

T">01~"ll"'8J .t . .,~~ ...

19.9 302 5900 3.3 100.2 3036 11.2 2.4 3100 301 11300 3026 1003 201 42.0 300 16900

1084

1209 200 2500 205 5600 1020 11.6 506 45.0 2.0 50.0 2048 603 206 4508 304 5705 3003 408 2.7 3607 1.7 380 '7 2076 6.2 208 4500 1.3

=

1.81 007 209 2506 1.3

=

008

=

2001

= -~ ~=~~~~~_,b_~~<~~~· ~~ ~ Sco'~tililh, ca;toh per shot

(to:n.13)

0

*)

mean oe/tah per e,rrivalo Netherland.i8? catch (tons) per 100 hou:.es of a 'h'19,'l,'iler of

500

BHPo (.ruly=Septembe~::,)o Polish drift=net $ catch per shot (t()n~j) 0 NErtherltitnds s catch ("t;O~lS) per 100 hoU!::'r~ ;9, i;ra'i'der of 500 HHP (July=Decemhf~:t') ~ , .) N e'bllerlt"L1'J.cl.S r ca toll \ '!;0118 per shot 0 N1'lt,herland.e:, ca/teh ('l;cms) per 100 hOUJ~'B fishlng trawler 500 BHP (Auercust=Ocrtobe:.cp G :I11nglish

catch

(tons) per

shot

in EEtst A:ng1.i8Jl fisheryo Nei;horla;ncls 9 cfl,te,h

('cons)

per 100 hOllt:'S f'isldng of a traMler 500 :BIiP 0

I-' \.N

Table 80 Effort elCltiJ1)r!Jj;el3~ (1)talneti by dividi:r.lg the tot;e,l ca"bch in al1 a,reo, by the catches per unit of c(lf the d.rifot~t l1J.ld ire,l'll fi!3h&ri~ in i~h@4t ar,eao c, It sho!;tld be n,ote(l t1V3/u no' eomparil'Hj~Y bE~tiiolEl8n 8..reIM~ le possibleo Nort;}}

5403

~p 1180

:i 7103

5~)o2 :)

14011,

2202 12902 8502

4206

908

~, 04

n.-___ -! .. 6102 2401 I !'Oo) .,6 41o~:i

5107 2506

IJ

;--~

4

0

1601

'-' /:. (';

4809 3600

1501 u

4409

2ELU :0 1\ 1

2905 3302

0000 f(1l:M:r1;t~o 9 '3li t~o th,a 'l'mEl Uf.hSi(L

~b!.~,".2!..

Amlua1 Catch in

NUDi~jjrli!l

(x 10=6) 9 by Areas and Age Groups (provisiona1)* r'

- - -

Irnma:bl.u.'s Young Adult; Old Adult Immature Young Adu.lt Old A duI

t

1 + 2 ;rse,r!l

3

+

4

years over

4

yeara 1 + 2 years

3

+

4'

years over

4

years Year old oldo old Total Yea,:!:' old old old Total -~ ~E:Wt £.!.ntral North~!,~

% % % % % % 1960 687 64 293 27 91 9 1071 1960 1720 56 1213 39 163 5 3096 1961 352 32 659 59 103 9 1114 1961 1113 42 1166 44 397 -1.5 2676 1962 966 60 564 35 81 5 1611 1962 13B5 66 451

22

251 12 2087 1963 73 4 1446 83 217 13 1736

196~

1016 43 1251 53 76 3 2'43 1964 316 14 1476 67 421 19 2213 1964 1B39 65 922 33 76 3 2837 1965 1788

61

707 24 416 14 2911 1965 1780 65 33 43 2 2731 1966 1380 60 603 26 323 14 2306 1966 717 4, 875 53 53:> 1645 1967 3233 89

338

9 79

2

3650 1967 1249 63 699 35 44

2 199i~ Neprth ::E!;>.1<lte:!"n No:rth Sea Stluthern North Si1:l1i.l> ~-========~==== <t.>.=':>-~~=

1960

152:W

693 48 611 42 1456 1960 16:5 520 92

28

5 564 1961 5 - 294

22

1036 78 1335 1961 1

=

735 94 . 48 6 784 1962 193 11 '103 41 632 48 1728 1962

12

3 306 84 46 13 ,64 1963 39 2 1396 65 702 33 2137 1963

2

1 270 91 24 8 296 1964 293 10 2191 74 492 17 2976 1964 19 6 268 91 6 2 29' 1965 428 13 903 2034 60 3365 1965

= =

85 69 38 31

l~'

1966 232 B 1665 54 1160 38 3051 1966 3 4 59 79 13 17 75 1967 651 23 1211 44 911 33 2773 1967 3 6 41 84 5 10 49

N~~vle~~1T,ffi;!4! S,2,t1 ~!o~

1960 7 1 512 77 146 22 665 1960 2528;8 3231 47 1039 1;) 6852

i 1961 = <~

69

22

240 78 309 1961 1471 24' 2923 47 1824 29 6218 1962

2 1 28

16 141.

f32

171

19~2

2558 43 2052 34 1351 23 5961 1963 165 38 180 41 94 21 439 1963 1295 19 4543 65 1113 16 69,51 1964 1

=

254 84 48 16 303 1964 2468 29 5111 59 1043 12 8622 1965 237 15 654 41 719' 45 1610 1965 4233,9 325'7 ,0 3250 31 10140 1966 6

=

186 50 784 50 1576 1966 2338 21

3988

46 2333 27 8659 1967 25 :5 260 57 172 38 457 1967 5161 58 2549 29 1211 14 8921

""-~---=== ---== =~""" "'""" "" = ..,...

* Only part of the

Bl~den

oatoh added, due to

uncerta.in:ti~l1i!i

about an

admixture of

apra t

in the la.n.wgtt! ~

~~.J ~\'l

,;;S

oT~~_l(I~ I<1Io:r'tg;l,li ty e~tim~:tes from ~ome northe:11:1, oentral and 801.:rthern NortJtJ, Sea fjsherisfj ~ "l9~~r:;/E" d'. . ')j ::'H)=

195

6

/59 c)

00 00 ) 10=9)

'~) -(10 2() ~I ,L ('0 ;'22~!O

(J04:r

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LOS

10

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9)

Cin weatem DO,Q:ttl;ex.' in 1) Prel1mtnaI'Y

T~.bll1'! 110 T~;rl;al:--r~:;;:tal:t

t;.r

Estj ma:t€il§j dtlri v'ed from C~rtch CUY'V8S ~ \: .sing the 1:lwnbtlllI' by A;t:e Graul)!; ill the tl'Jtal 1~1J~~tl:1 Sea~ 00 00 00 Oa Oe

45

25 24 23 22 21 20

19 18

16

15 14 13

12 11

10

96 95

94

93

10l'lW T

I~

IBICID,E,fIGI

oe

I

with the boundaries of the areas used in the

I ^Report.

I I

HL 19.0 20 .. 21 .. 22 .. 23 .. 24 .. 25 .. 26 .. 27 .. 28 .. 29 .. 30 .. 3'1.. 32 .. 33 .. 34 .. 35 .. 36 .. 37 .. 38 .. 39 ..

24 23

22 21

20

19 18 11

16

15

08 07 06

05 04

03

02

150

10

^.~

1

~ ~

~ looj

north western North Sea

(Sav/lle)

i 1

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~ W x ^{~ ~ W W ~ M}

central Sea

(2!J/stra)

,

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1948 50 '52

~

9J 60

Downs

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64

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herring surveys

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-I

If

North Sea

fishery

group ^fi6h

as I

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