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MVFORSDINGSINSTI~TS EGG- OG WIVEPROGM (HELP)

SPAWNING AREAS AND SPAWNING PERIOD OF THE NORTH-EAST ARCTIC HADDOCK (MELANOGRAMMUS AEGLEFINUS L.).

Per Solemdal, Tor Knutsen og Herman Bjorke

F i s k e r i d i r e k t o r a t e t s H a v f o r s k n i n g s i n s t i t u t t Postboks 1870, 5024 BERGEN

ABSTRACT

Spawning of North-East A r t i c haddock occurs on t h e Norwegian c o n t i n e n t a l s l o p e . The l o c a t i o n of t h e spawning grounds i s , however, d i f f u s e . This i s mainly due t o d i f f i c u l t i e s i n i d e n t i f y i n g haddock eggs. I n t h i s work t h i s problem i s s o l v e d by u s i n g t h e biochemical g e n e t i c a l approach of e l e c t r o p h o r e s i s . The r e s u l t s from haddock egg and t r a w l surveys i n A p r i l -May

1987

and

1988

a r e analysed i n r e l a t i o n t o previous knowledge of haddock egg d i s t r i b u t i o n and mature f i s h . Gonad m a t u r i t y i s compared t o t h e d i s t r i b u t i o n of egg developmental s t a g e s i n d i f f e r e n t r e g i o n s . Both h o r i z o n t a l and v e r t i c a l g r a d i e n t s i n gonad m a t u r i t y of haddock a r e r e v e a l e d , Most of t h e Tromsgflaket a r e a from Nordkapp t o n e a r t h e s h e l f edge b o r d e r i n g t h e Norwegian Sea (Norskehavet) a r e i n h a b i t e d by immature haddock. An i n c r e a s e i n abundance of mature f i s h t a k e s p l a c e i n t h e western p a r t of t h e s h e l f . The main spawning a r e a s of North-East A r c t i c haddock seems t o be t h e s o u t h e a s t e r n p a r t of t h e c o n t i n e n t a l s l o p e of Tromsgflaket a t depths from 303 t o 600 m and temperatures between

4

and

6'

C . Other spawning a r e a s a r e found i n V e s t f j o r d e n and over t h e c o n t i n e n t a l s l o p e from Tromsoflaket s o u t h t o Rosttunga. The spawning i n V e s t f j o r d e n seems t o

t a k e p l a c e a t depths shallower than 200 m, b u t w i t h i n t h e same temperature l i m i t s . Spawning seems t o s t a r t a t t h e beginning of A p r i l , reaches i t s maximum a t t h e end of t h e month and ends d u r i n g t h e f i r s t h a l f of May. Very l i t t l e spawning i s recorded on t h e s h e l f and t h e

0 0

c o n t i n e n t a l s l o p e from Rosttunga t o

64

N. Spawning i n t h e a r e a

62-64

N (More) i s supposed t o o r i g i n from a l o c a l s t o c k . The o n s e t of t h i s spawning seems t o t a k e p l a c e a week o r two e a r l i e r than what was observed f u r t h e r n o r t h . A d i s t i n c t bimodal d i s t r i b u t i o n of l a r v a e sampled i n J u l y

1987

i n d i c a t e a p o s s i b l e i n f l u x of haddock l a r v a e t o t h e Norwegian c o a s t which might o r i g i n a t e from a p o p u l a t i o n d i f f e r e n t from t h e North-East A r c t i c haddock.

INTRODUCTION.

The Norwegian s h e l f c o n s t i t u t e important spawning grounds f o r f i s h of c o n s i d e r a b l e economical i n t e r e s t , such a s North-East A r t i c cod, s a i t h e , c a p e l i n and Norwegian s p r i n g spawning h e r r i n g (Anon.,

1979).

The c o n t i n e n t a l s h e l f is a l s o d e s c r i b e d a s a spawning a r e a f o r North- East A r t i c haddock although t h e l o c a t i o n of t h e spawning grounds a r e r a t h e r d i f f u s (Anon., 1979, Bergstad, Jorgensen and Dragesund,

1987).

F i s h eggs and l a r v a e of t h e s e s p e c i e s a r e t r a n s p o r t e d northwards and eastwards by t h e r e s i d u a l c u r r e n t s ( S ~ t r e and Ljoen,

1971).

Sonina (1969) d e s c r i b e s t h e d i s t r i b u t i o n of t h e North-East A r c t i c haddock i n t h e Barents Sea ( B a r e n t s h a v e t ) . I n warm y e a r s t h e haddock i s d i s t r i b u t e d more e a s t e r l y , i n c o l d y e a r s more t o t h e west.

Information on changes i n t h e spawning a r e a due t o t h e geographical d i s t r i b u t i o n of t h e mature s t o c k i s a p p a r e n t l y l a c k i n g i n t h e l i t e r a t u r e .

I t i s d i f f i c u l t t o a s s e s s t h e maturing p o p u l a t i o n i n t h e Barents Sea, s i n c e t h e maturation t a k e s p l a c e d u r i n g t h e west and s o u t h e r n spawning m i g r a t i o n (Sonina,

1981) .

S o v i e t and Norwegian s c i e n t i s t s have d i f f e r e n t o p i n i o n s concerning t h e spawning a r e a of t h e haddock. Based on t h e i r i n v e s t i g a t i o n s on t h e sampling of p l a n k t o n i c eggs, Baranenkova and Khoklina

(1967)

demonstrated spawning from

Rest

t o t h e western c o n t i n e n t a l s l o p e of

T r o m s ~ f l a k e t , up t o

74'

N . Maximum egg c o n c e n t r a t i o n s were found d u r i n g A p r i l . These r e s u l t s were l a t e r confirmed by Mukhina

(1983)

and e s p e c i a l l y by Mukhina and Dvinina (1986). u s i n g t h e same g r i d system a s Baranenkova and Khoklina (1967).

S a t e r s d a l (1952) and Wiborg (1956) suggested t h a t t h e spawning a r e a covered t h e c o n t i n e n t a l s l o p e from R0st t o about

65

0 N, and even s o u t h of t h i s a r e a . They based t h e i r assumptions on t h e r e s u l t s from tagging experiments and m a t u r i t y s t a t i s t i c s ( S ~ t e r s d a l ,

1954)'

and t h e p l a n k t o n i c egg d i s t r i b u t i o n (Wiborg, 1 9 5 0 ) . Comparing S o v i e t and Norwegian r e s e a r c h on t h e spawning a r e a of haddock, Bergstad e t a l .

(1987)

conclude t h a t t h e main spawning of haddock occurs s o u t h of Rgs t

.

The main weakness i n a l l t h e i n v e s t i g a t i o n s based upon p l a n k t o n i c egg- sampling i s t h e d i f f i c u l t y i n s e p a r a t i n g haddock and cod eggs (Solemdal,

1987) .

T h i s problem was solved by u s i n g t h e biochemical, g e n e t i c a l approach of e l e c t r o p h o r e s i s by Mork e t a l .

(1983).

MATERIALS AND METHODS

The m a t e r i a l s i n t h i s r e p o r t were sampled d u r i n g t h e following c r u i s e s : R / V "Odin Finder" A p r i l

1-17

1987, R/V "Johan Ruud" March

31

-

A p r i l

8

1987, R/V " G . O . S a r s " A p r i l 21

-

May

15

1987, R / V "G.O.

S a r s " A p r i l 27- May 1 2 , May 1-23

1988

and R / V " E l d j a m " May 1-23

1988.

Plankton was sampled by v e r t i c a l h a u l s with modified MP 2 n e t s ( 0 . 1 , 0 . 5 o r 2 . 0 m 2 ) ,

375

pm mesh s i z e (Anon., 1 9 6 7 ) . from 200 t o 0 m. The n e t s were equipped with a TSK flowmeter and a Scanmar depth r e c o r d e r . Eggs ranging from approximately 1.25 t o 1 - 7 0 mm i n diameter were removed immediately upon sampling. T h i s i n c l u d e s p r a c t i c a l l y a l l cod and haddock eggs according t o Solemdal and Sundby

(1981)

and Moksness and S e l v i k

(1987).

A f t e r measuring t h e egg diameter and t h e egg developmental s t a g e according t o Solemdal ( u n p u b l . ) , a sample of e g g s , u s u a l l y between 20 and 50, were s t o r e d a t -90' C O The e l e c t r o p h o r e s i s was c a r r i e d o u t on board. The eggs sampled with R/V "G. 0 . S a r s " and R / V "Eldjarn" i n

1988

were removed from t h e p l a n k t o n , measured and f r o z e n t o -20 0 C. Within one week they were i d e n t i f i e d .

The m a t u r i t y s t a g e of haddock females was recorded according t o a s c a l e developed f o r cod a t t h e I n s t i t u t e of Marine Research, Bergen (Table I ) . Haddock i s a b a t c h spawner, spawning up t o 24 batches w i t h i n

5

weeks ( H i s l o p , Robb and Gauld,

1978).

Kjesbu ( p e r s . comm.) found t h a t spawning of cod occurred from m a t u r i t y s t a g e 1 t o s t a g e

3

a s w e l l a s i n s t a g e

4 ,

which i s d e f i n e d a s t h e spawning s t a g e (Table I ) . He a l s o found t h a t 50

%

spawning corresponds t o m a t u r i t y s t a g e about

3.5.

Since cod and haddock a r e two c l o s e l y r e l a t e d s p e c i e s and t h e haddock spawning m i g r a t i o n (Sonina,

1969)

i s p a r t l y s i m i l a r t o t h a t of cod (Bergstad e t a l . , 1 9 8 7 ) , t h i s f i g u r e i s a l s o used f o r haddock. The term Mi, l a t e r r e f e r r e d t o a s t h e m a t u r i t y index, i s simply t h e mean v a l u e of t h e d i f f e r e n t m a t u r i t y s t a g e s .

Trawling was performed w i t h t h e s t a n d a r d "Norwegian bottom r e s e a r c h trawl f o r sampling bottom f i s h and shrimp, Campelen 1800", u s u a l l y f o r 30 minutes. T o t a l weight of a l l specimens was recorded. Length, o t o l i t h s and m a t u r i t y s t a g e were recorded f o r samples of cod and haddock. A l l haddock specimens were i n v e s t i g a t e d f o r s i z e and m a t u r i t y s t a g e .

The a c o u s t i c d a t a were processed and e v a l u a t e d according t o Blindheim, Eide, Knutsen and Vestnes ( 1 9 8 2 ) . A more d e t a i l e d d e s c r i p t i o n of t h e a c o u s t i c and c a t c h sampling and p r o c e s s i n g procedures i s given by Dalen and Nakken

(1983).

The procedure used i n t h e p r e s e n t work d i d n o t e s t i m a t e t h e abundance of f i s h deeper than 580 m .

The spawning i n t e n s i t y curve a t T r o m s ~ f l a k e t (F i g . g ) , were based on v e r t i c a l n e t h a u l s along t h e c o n t i n e n t a l s l o p e from 70 0 20' N t o

71'

20' N ( F i g . 1 and 2 ) on f o u r d i f f e r e n t d a t e s :

5

A p r i l ,

13-14

A p r i l , 28-29 A p r i l and

5

May, The spawning i n t e n s i t y curve a t H ~ l l a ( F i g . 1 0 ) i n V e s t f j o r d e n , covers t h e following d a t e s :

7

A p r i l ,

9

A p r i l ,

21

A p r i l and

9

May.

RESULTS

F i g u r e 1 shows t h e l o c a t i o n of t h e t r a w l s t a t i o n s , t h e d i f f e r e n t s u b a r e a s and a r e a s f o r spawning i n t e n s i t y i n v e s t i g a t i o n s . The

s u b a r e a s a r e : Rosttunga ( I ) , t h e c o n t i n e n t a l s l o p e from R ~ s t t o TromsBflaket ( I T ) , t h e c o n t i n e n t a l s h e l f from Rost t o Langoy ( I I I J , t h e V e s t f j o r d e n a r e a ( I V ) , t h e western c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t (V ) and Nygrunnen ( V I ) . Area V i s subdivided i n t o

3

r e g i o n s , A

-

C , while a r e a D i s i d e n t i c a l t o a r e a I b u t i s used i n connection with f i s h d a t a while a r e a I i s used f o r egg d a t a . Names r e f e r r e d t o i n t e x t a r e shown i n Fig. 2.

I n Fig.

3

t h e d i s t r i b u t i o n and c o n c e n t r a t i o n of haddock eggs i n t h e p e r i o d

21

A p r i l

- 14

May

1987

a r e shown a s numbers p e r s q u a r e metre s u r f a c e . The numbers i n c l u d e a l l egg developmental s t a g e s . The d i s t r i b u t i o n of haddock eggs sampled i n

1988

i s shown i n F i g .

4 - 6.

Fig.

7

shows t h e percentage d i s t r i b u t i o n of t h e d i f f e r e n t egg developmental s t a g e s from t h e d i f f e r e n t subareas I-VI, while t h e p e r c e n t a g e d i s t r i b u t i o n of egg developmental s t a g e s i n t h e main a r e a s A

-

C i s p r e s e n t e d i n F i g .

8.

The c o n c e n t r a t i o n and percentage of cod and haddock eggs i n t h e a r e a s I

-

V 1 a r e shown i n Table 11. The h i g h e s t c o n c e n t r a t i o n of haddock eggs was found a t t h e c o n t i n e n t a l s l o p e of Tromsoflaket and i n V e s t f j o r d e n . Cod eggs were most abundant i n Vestfjorden and on t h e c o n t i n e n t a l s h e l f o u t s i d e t h e Lofoten a r e a .

The percentage of immature males and females and t h e sex r a t i o a r e shown i n Table 111. The t r a w l s t a t i o n s a r e arranged from e a s t ( t o p of t h e t a b l e ) t o w e s t (bottom of? t h e t a b l e ) , a s can be seen from F i g .

l.

T o t a l number of haddock from t h e a c o u s t i c s u r v e y , number of mature haddock, number of haddock caught p e r t r a w l hour, and t h e percentage of mature females from a r e a s A - D a r e shown i n Table I V .

I n Table V t h e d i s t r i b u t i o n of t h e m a t u r i t y s t a g e s , i n p e r c e n t , from t h e a r e a s A

-

D i n

1987

and A

-

C i n

1988

i s shown. There i s a s i g n i f i c a n t i n c r e a s e i n t h e p r o p o r t i o n of running haddock females, m a t u r i t y s t a g e

4 ,

from a r e a A t o a r e a s C and D i n

1987.

I n

1988

t h e samples i n a r e a s A - C where taken n e a r l y one month l a t e r and t h e m a t u r i t y index show t h a t peak spawning i s o v e r .

I n Table V1 t h e abundance of haddock i n each m a t u r i t y s t a g e i s arranged i n an east

-

west d i r e c t i o n f o r each s u b a r e a , which corresponds t o a depth g r a d i e n t from shallow t o deep water. The abundance of running haddock females i n c r e a s e d towards deeper water i n a r e a s B and

C,

while a t depths l a r g e r than

550

m t h e numbers a r e reduced.

The spawning i n t e n s i t y curve a t Troms0flaket shown i n F i g .

9

a r e based on egg s t a g e

1

and pooled s t a g e 2

- 6

eggs. The curve from Holla i n Fig.

10

i s based on a l l egg s t a g e s . Maximum egg c o n c e n t r a t i o n s i n both a r e a s a r e observed a t t h e end of A p r i l .

A temperature s e c t i o n from t h e western bank a r e a and t h e c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t i n a r e a B i s shown i n Fig.

11.

The l e n g t h d i s t r i b u t i o n and t h e p r o p o r t i o n of maturelimmature female haddock from t r a w l s t a t i o n

190

( s e e Fig.

l),

a r e a l s o included i n t h e f i g u r e .

A s i m i l a r temperature t r a n s e c t from a r e a

C

_{i s} found i n Fig.

12.

This f i g u r e i n c l u d e s t h e l e n g t h d i s t r i b u t i o n and t h e p r o p o r t i o n of maturelimmature female haddock from t r a w l s t a t i o n s

184, 185, 191, 192,

and

193

( s e e F i g .

1).

Note t h e g r e a t i n c r e a s e i n mature haddock from t h e bank a r e a towards t h e deeper p a r t of t h e c o n t i n e n t a l s l o p e .

The temperature s e c t i o n from a r e a C ' , F i g .

13,

i n c l u d e s t h e t r a w l s t a t i o n s

199, 200,

and

201

( s e e Fig.

l),

which were sampled one week l a t e r . The h i g h e s t d e n s i t y of f i s h i s below

350

m d e p t h , and a l l females a r e mature ( F i g .

13).

The temperature p r o f i l e i n subarea D , t h e l e n g t h d i s t r i b u t i o n and p r o p o r t i o n of mature/immature female haddock from t r a w l s t a t i o n s

196,

197,

and

198

a r e shown i n F i g .

14.

A s i n a r e a C ' a l l females a r e mature while t h e peak i n haddock abundance i s c l o s e t o

400

m d e p t h ,

DISCUSSION

Spawning n o r t h of R @ s t

The spawning haddock, d i s t r i b u t i o n and number

The p r o p o r t i o n of immature female haddock decreased from

98%

i n t h e e a s t e r n p a r t of t h e i n v e s t i g a t e d a r e a ( t r a w l s t a t i o n 181, s e e F i g . l ) t o

81%

i n t h e western p a r t of t h e bank a r e a i n r e g i o n A ( t r a w l s t a t i o n 187) and

17%

i n r e g i o n C ( t r a w l s t a t i o n 191) ( s e e Table 111).

According t o Sonina (1981) t h e immature haddock a r e mainly found i n s o u t h e r n Barents Sea and i n t h e Bear i s l a n d (Bj@rn@ya)

-

S p i t s b e r g e n a r e a . During maturation t h e haddock migrate t o t h e spawning a r e a s i n t h e Norwegian S e a , along t h e c o n t i n e n t a l s l o p e from Tromsgflaket ( t h e Kopytov bank) t o Rgst.

Both temperature and y e a r c l a s s s t r e n g t h i n f l u e n c e t h e d i s t r i b u t i o n i n t h e Barents Sea (Shevelev, Tereshchenko and Yaragina, 1987). b u t changes i n spawning a r e a s s i m i l a r t o North-East A r c t i c cod (God@,

1984)

have n o t been d e s c r i b e d . Such changes could be t h e reason f o r t h e e a r l i e r mentioned d i s c r e p a n c i e s between S o v i e t and Norwegian s c i e n t i s t s concerning t h e spawning a r e a of North-East A r c t i c haddock.

During a c o l d p e r i o d i n t h e Barents Sea mature haddock were tagged o f f Varanger ( S a t e r s d a l , 1952; 1954) and r e c a p t u r e d from t h e Malangsgrunnen bank t o t h e R ~ s t b a n k e n a r e a d u r i n g t h e p e r i o d of l a t e March

-

A p r i l . Assuming t h a t t h e spawning s t a r t s a t a l a t e r m a t u r i t y s t a g e and t h a t t h e haddock have a c e r t a i n c r u i s i n g speed, t h e authour suggested t h e main spawning a r e a t o be l o c a t e d a t l e a s t a s f a r s o u t h a s

65'

N. However, t h e a u t h o r concludes: "There i s , however, s t i l l some doubt a s t o t h e e x a c t Location of t h e spawning ground"

( S a t e r s d a l ,

1954).

Bergstad e t a l . ( 1 9 8 7 ) , b e l i e v e t h a t t h e main spawning o c c u r s s o u t h of Rest, obviously based on S ~ t e r d a l ' s s u g g e s t i o n s from t h e 1 9 5 0 ' s . The p r e s e n t knowledge of t h e batch- spawning of haddock (Hislop e t a l . ,

1978)

and t h e r e l a t i o n between t h e m a t u r i t y s t a g e s and a c t u a l s t a g e of spawning i n t h e c l o s e l y r e l a t e d s p e c i e s of North-east A r c t i c cod (Kjesbu, u n p u b l i s h e d ) , i n d i c a t e t h a t t h e r e c a p t u r e d haddock were a l r e a d y spawning.

The v e r t i c a l d i s t r i b u t i o n of spawning haddock along t h e c o n t i n e n t a l s l o p e showed a maximum a t about 400 m depth c l o s e t o t h e bottom and a t temperatures of

4 - 6'

C. This' i s w i t h i n t h e depth range of 350

-

600 m on t h e c o n t i n e n t a l s l o p e a s r e p o r t e d by Sonina

(1981).

Compared t o t h e North-East A r c t i c cod, t h e temperature range f o r spawning i s s i m i l a r , b u t t h e cod p r e f e r more shallow water and o f t e n spawn p e l a g i c a l l y ( E l l e r t s e n e t a l . ,

1981).

Contrasted t o t h i s o b s e r v a t i o n i s t h e spawning of haddock i n Vestfjorden which seems t o t a k e p l a c e a t a much shallower depth. T h i s was confirmed A p r i l 30

1988

when

26

female haddock with running r o e were caugth by l o n g l i n e a t 90 m depth n e a r H g l l a i n V e s t f j o r d e n (Hylen, p e r s . comm.)

The t o t a l number o f mature haddock i n

1987

was c a l c u l a t e d t o be 269 m i l l i o n s (Anon.,

1988).

I n t h e a r e a of Malangsgrunnen t o V e s t f j o r d e n ,

8.5

m i l l i o n mature haddock were r e p o r t e d i n March

1987

(Godg e t a l . ,

1987).

I n t h e p r e s e n t s t u d y t h e population of mature haddock a t t h e end of A p r i l and beginning of May

1987

along t h e c o n t i n e n t a l s l o p e from 70' 10' N t o 72' 50' N was e s t i m a t e d t o be

14

m i l l i o n specimens (Table I V ) . Summing t h e s e f i g u r e s only amounts t o one t e n t h of t h e spawning s t o c k , according t o Anon.

(1988).

P a r t s of t h e gap between e s t i m a t e d number (Anon., 1 9 8 8 ) , a c o u s t i c abundance e s t i m a t e (God0 e t a l . ,

1987)

and p r e s e n t r e s u l t s might be i n f l u e n c e d by :

1) Spawning s o u t h of Rest

2) P e l a g i c spawning i n t h e Norwegian Sea (Wiborg,

1957) 3)

Spawning deeper than 580 meters.

4 )

Overestimation of t h e o l d e r y e a r c l a s s e s i n t h e VPA-analyses.

5 )

B i a s i n t h e age/maturation keys (Sunnanh, p e r s . comm.).

Norwegian t r a w l e r s r e p o r t e d c o n c e n t r a t i o n s of spawning haddock down t o 600

-

⁷⁰⁰ m a t about

3'

C ( F i g . 1 2 ) , along t h e c o n t i n e n t a l s l o p e of Tromsgflaket. S i n c e t h e a c o u s t i c equipement o n l y worked down t o 580 meters t h e e s t i m a t e of t h e spawning p o p u l a t i o n given above i s an underestimate.

The spawning p e r i o d of t h e North-East A r c t i c haddock.

Based on t h e c o n c e n t r a t i o n s of p l a n k t o n i c haddock eggs i n t h e p e r i o d from t h e beginning of A p r i l t o t h e beginning of May

1987

i t appears t h a t t h e maximum of s t a g e 1 eggs occurs a t t h e end of A p r i l , b o t h on t h e c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t and i n Vestfjorden ( F i g .

9

and F i g . 1 0 ) . Table V 1 1 p r e s e n t i n g d a t a from t h e Vestfjorden a r e a i n 1988, shows t h a t t h e m a j o r i t y of haddock eggs must have been spawned during t h e l a s t week of A p r i l . This i s supported by t h e c a t c h of spawning female haddock (N=130) by l o n g l i n e and Danish s e i n e , n e a r H g l l a i n V e s t f j o r d e n between A p r i l 25

-30 1988

(Hylen, p e r s . comm.). These haddock showed a gonad m a t u r i t y index of 4 . 0 , i n d i c a t i n g t h a t t h e p o p u l a t i o n of female haddock had j u s t passed maximum spawning. Data from Baranenkova and Khoklina (1967) i n d i c a t e maximum egg c o n c e n t r a t i o n i n t h e same p e r i o d , though minor y e a r l y f l u c t u a t i o n s occur.

The index of gonad m a t u r i t y of female haddock caught a t t h e end of A p r i l along t h e c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t and a t Rosttunga showed t h e same f i g u r e of

3.8

(Table V ) . According t o Kjesbu ( u n p u b l . ) t h i s v a l u e corresponds t o h a l f - s p e n t cod females. The marked i n c r e a s e i n t h e m a t u r i t y index from

3.8

t o

4.3

i n t h e p e r i o d from A p r i l 29 t o May

6

i n r e g i o n C (Table V ) , t o g e t h e r with a d r a s t i c r e d u c t i o n i n number of haddock (Table I V ) , c l e a r l y demonstrate t h a t t h e maximum spawning i s over and t h a t s p e n t f i s h l e a v e t h e spawning a r e a .

T h i s i s confirmed by t h e i n v e s t i g a t i o n i n 1988 by a mean gonad m a t u r i t y index of

4 . 6 (N=94)

i n t h e l a s t week of May (Table V ) . A low abundance of haddock eggs found i n subareas A -C d u r i n g an i n v e s t i g a t i o n i n mid May

1988

(Fossum p e r s . comm.) v e r i f i e s t h i s . The spawning m i g r a t i o n s of t h e s e r e l a t e d s p e c i e s a r e very s i m i l a r . The North-East A r c t i c cod migrate from t h e Barents Sea t o t h e Norwegian c o a s t s e e k i n g a temperature g r a d i e n t f o r spawning (Sund, 1 9 2 7 ) , while haddock m i g r a t e t o t h e Norwegian c o a s t a l a r e a and t h e s l o p e of t h e Tromsqjflaket a r e a where they c o n s e n t r a t e on a temperature g r a d i e n t from

4 -6'

C . We t h e r e f o r e conclude, on t h e b a s i s of t h e maturation index and t h e development of p e l a g i c eggs, t h a t peak spawning of

North-East Arctic haddock at Rgsttunga, the Vestfjorden area and the continental slope of Tromsgflaket occurs at the end of April.

Combining the information obtained from planktonic eggs, maturation stages and changes in abundance of haddock at the spawning sites, we conclude that the spawning of North-East Arctic haddock in the region

65' ^N - ^{Vestf jorden} - ^R~sttunga - continental slope of Tromsoflaket starts at the beginning of April, reach its maximum at the end of April and ends during the first half of May. This is in contrast to the North-East Arctic cod, which starts spawning at the beginning of March, with the maximum at the beginning of April and end at the beginning of May (Solemdal , ¹⁹⁸²

;

Pedersen, 1984) .

Distribution of eggs

The distribution of haddock eggs found in 1987 is shown in Fig. 3 and fits well with the distribution maps given by Shmit (1936, 1937), Baranenkova and Khoklina (1967), Mukhina (1983), and especially with those of Mukhina and Dvinina (1986). Along the continental slope from R@st to about 74

0

N, the Soviet scientists have demonstrated spawning of haddock every year since the investigations started in 1959. The egg distributions given by these authors are not given in strictly quantitative terms, the actual sampling period is unknown, and there is also some uncertainty about the identification of haddock eggs, This

is

also the case for the egg distribution given by Wiborg (1950, 1952, 1956, 1960). Early egg stages of cod and haddock cannot be separated by visual means. However, the distribution map given by Mukhina and Dvinina (1986) is based on the last pigmented egg stage which can be identified. They found that egg concentrations along the continental slope from R@st to about

70'

N was low, with increasing concentrations further north. The concentration of haddock eggs over the shelf from R@st northwards was also higher than along the slope.

The distribution of egg developmental stages in Vestfjorden (Fig. 7)

is dominated by eggs in stage 5, indicating retention of eggs during

the developement. This is also observed for cod eggs in the

same area (Ellertsen et al., 1987).

The d i s t r i b u t i o n ( F i g ,

3)

and age composition o f t h e haddock eggs on t h e s h e l f o f f Lofoten and i n Vestfjorden ( F i g . 7 ) , a l s o i n d i c a t e a d r i f t from Vestfjorden s i m i l a r t o t h e d r i f t of cod eggs and l a r v a e ( E l l e r t s e n e t a l . ,

1981).

Haddock egg c o n c e n t r a t i o n i n Vestfjorden i s a t t h e same l e v e l a s along t h e c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t

(Table 11). b u t d a t a from e a r l i e r y e a r s a r e l a c k i n g . The d i s t r i b u t i o n p a t t e r n of haddock eggs i n Vestfjorden ( F i g .

3)

i s a l s o s i m i l a r t o t h a t of cod eggs ( E l l e r t s e n e t a l . ,

1981).

Data from t h e s h e l f a r e a R ~ s t t o L a n g ~ y from t h e beginning of May d u r i n g t h e y e a r s

1981 - ¹⁹⁸⁵

show a percentage of haddock eggs varying from 2 t o 21, with no i n c r e a s e i n t h e abundance of eggs towards t h e s l o p e (Solemdal, 1987).

This i s supported by t h e d e c r e a s e i n egg abundance towards t h e s l o p e i n t h e p r e s e n t i n v e s t i g a t i o n (Table 1 1 ) , a l s o i n d i c a t i n g a d r i f t from t h e V e s t f j o r d . The s i g n i f i c a n t haddock spawning i n V e s t f j o r d e n , t h e r e f o r e seems t o be a r e g u l a r phenomenon. Findings of haddock eggs i n s t a g e

3

and o l d e r i n

1988

support t h i s (Table V I I ) .

Concerning t h e western l i m i t of haddock-spawning, Wiborg

(1957)

r e p o r t s both p l a n k t o n i c haddock and running haddock females from t h e weather s t a t i o n M (66' N, 2' E ) i n t h e Norwegian Sea. North of Rgst Baranenkova and Khoklina (1967) r e p o r t haddock eggs a s f a r west a s

5'

E a t a l a t i t u d e of about 68' N .

The maturation p r o c e s s , spawning and d i s t r i b u t i o n of eggs a t t h e c e n t r a l spawning a r e a .

The main haddock spawning a r e a n o r t h of Rgst i s shown i n F i g .

3.

The d i s t a n c e from t h e c e n t e r i n a r e a A t o t h e c e n t e r of a r e a C i s about 100 n.m. ( s e e F i g . 1 ) . There i s a c l e a r tendency towards more advanced maturation s t a g e s of t h e haddock from region A t o r e g i o n C (Table V ) , probably i n d i c a t i n g a southward migration along t h e c o n t i n e n t a l s l o p e . The number of mature haddock i n c r e a s e s from about 0 - 7 m i l l i o n i n region A , through

5.4

m i l l i o n i n region B and 7 . 0 m i l l i o n i n r e g i o n C

.

The p r o p o r t i o n of mature haddock i n c r e a s e s from 27% i n r e g i o n A t o

69 %

i n r e g i o n B and 96

%

i n r e g i o n C (Table I V ) . The gonad maturation index shows t h a t t h e p o p u l a t i o n of female haddock i s i n maximum spawning i n r e g i o n C (Table V ) .

The number of haddock found i n t h e western bank a r e a is low and less mature compared t o t h e haddock from t h e deeper p a r t of t h e c o n t i n e n t a l s l o p e ( F i g . 11

-

Fig.

1 4 ) .

T h i s i n d i c a t e s t h a t t h e m i g r a t i o n from t h e e a s t i s completed o r i s of minor importance.

The d i s t r i b u t i o n of p l a n k t o n i c eggs i n t h e a r e a r e f l e c t s t h e d i s t r i b u t i o n of spawning haddock. Above t h e easternmost t r a w l s t a t i o n i n r e g i o n B, only

4

s t a g e 1 eggs p e r m2 was found, while 24 s t a g e 1 eggs p e r m 2 were found above t h e deep westernmost t r a w l s t a t i o n . Above t h e easternmost t r a w l s t a t i o n i n region C no p l a n k t o n i c eggs were found, while 24 s t a g e 1 eggs were found above t h e t r a w l s t a t i o n s a t 300

-

500 m depth.

The eggs d r i f t both t o t h e n o r t h and t o t h e e a s t . S t a g e 1 cod eggs i s from 0-2 days o l d a t t h e p r e v a i l i n g temperatures (Solemdal u n p u b l . ) . The mean ascending v e l o c i t y of cod eggs i s about 1 m m / s (Solemdal and Sundby, 1981; Sundby,

1983).

Using t h e same f i g u r e f o r haddock e g g s , and a spawning depth of 350 m, they w i l l u s e about

4

days t o reach t h e s u r f a c e c u r r e n t . To t r a n s p o r t t h e s t a g e 1 eggs from a r e a C t o r e f l e c t t h e peak of s t a g e

3

^{eggs (}

5-6

days o l d ) i n r e g i o n A ( F i g .

8)

i n d i c a t e s a h o r i s o n t a l t r a n s p o r t v e l o c i t y of

35

cm/s. T h i s seems t o be r e a s o n a b l e compared t o t h e measured c u r r e n t speed of around 50 cm/s along t h e s h e l f edge (Sundby, p e r s . comm.), The d r i f t of haddock eggs eastward from r e g i o n C i s i n accordance with Baranenkova and Khoklina

(1967) .

Haddock spawning from 62' N t o Rost

F i g s .

4

and

5

show t h e d i s t r i b u t i o n of haddock eggs younger than

4

days recorded d u r i n g two subsequent c r u i s e s i n

1988.

South of R @ s t eggs younger than

4

days were recorded between 62 and 64 0

N

( F i g .

4 )

and between 65 and 66' 10' _N ( F i g .

5 ) .

I n t h e same a r e a s haddock eggs were found d u r i n g t h e f i r s t h a l f of A p r i l i n

1987

( B j o r k e , Bakkeplass and Hansen, 1988a and Table V I I I ) . Also d u r i n g i n v e s t i g a t i o n s i n A p r i l i n t h e p e r i o d 1976-1982 were i d e n t i f i a b l e haddock eggs i n l a t e s t a g e s of development recorded h e r e ( B jo r k e ,

1984) .

The d i s t r i b u t i o n of haddock eggs i n d i c a t e t h a t t h e spawning a r e a between 62 and

64' N

( o f f

More) i s i s o l a t e d from t h a t between 65' and 66' 1 0 ' N and west of 10' E, s i n c e no eggs were recorded between t h e s e a r e a s . Bergstad e t ^{a l .}

(1987)

s u g g e s t s t h a t i t i s p o s s i b l e t h a t l o c a l s t o c k s of haddock can be found along t h e c o a s t . I t i s t h u s conceivable t h a t r e c o r d i n g s of eggs younger than

4

days between 62 and 64' N ( F i g .

4 )

o r i g i n a t e from a l o c a l s t o c k of haddock. Some of t h e eggs sampled i n t h i s a r e a April 1-3, 1987 were 10-18 days o l d (Table V I I I ) . No haddock eggs were found d u r i n g a coverage i n March 18-20,

1987

(Bjorke e t a l . , 1988a).

Eggs younger than 2 days were recorded May 5 1988 (Table V I I I ) . This shows t h a t spawning has been recorded o f f More from t h e l a s t t h i r d of March t o t h e f i r s t week of May. It i s , however, n o t p o s s i b l e t o make any conclusion about t h e spawning p e r i o d of haddock from t h e p r e s e n t i n v e s t i g a t i o n , although i t i n d i c a t e s t h a t spawning may s t a r t a week o r two e a r l i e r than spawning f u r t h e r n o r t h . A l l t h e eggs younger than 2 days recorded i n t h i s a r e a ( F i g . 4 ) , were sampled over depths shallower than 200 m . Most probably t h e eggs have been spawned over t h e s e d e p t h s , a l l t h o u g h i t can n o t be overlooked t h a t t h e eggs could have been spawned over a small 450 m deep b a s i n i n t h e a r e a . I n t h e North Sea most of t h e haddock eggs a r e spawned over depths shallower than 200 m (Anon., 1 9 8 1 ) .

The eggs found between 64 and 65' N n e a r t h e c o a s t i n

1988

( F i g . 6 ) , were o l d e r than 10 days when sampled A p r i l 30. A few eggs were a l s o recorded i n t h i s a r e a A p r i l

5 ,

1987 (Bjorke e t a l . , 1988a and Table V I I I ) . An Argos buoy drouged a t 60 m and r e l e a s e d A p r i l 4 ,

1988

( F i g . 6 ) , shows a r a t h e r s t r o n g n o r t h - e a s t going c u r r e n t i n t h i s a r e a . The eggs recorded between

44

and 6 5 ' ~ n e a r t h e c o a s t i n 1987 were younger than

4

^days. T h i s i n d i c a t e t h a t haddock eggs i n t h i s a r e a might o r i g i n a t e from a l o c a l s t o c k f u r t h e r s o u t h .

Haddock eggs were a l s o found between 65' and 67' N ( F i g . 6 ) over t h e c o n t i n e n t a l s l o p e . One Argos buoy drogued a t 60 m and r e l e a s e d a t 63'

45'

N and 6' 21

'

E March 2 9 , 1988 i n d i c a t e a d r i f t towards t h e c o n t i n e t a l s l o p e from t h i s a r e a ( F i g . 6 ) . T h i s buoy, however, passed 65' N May 3 , i . e . i t used a t l e a s t 36 days t o d r i f t from t h e r e l e a s e d a r e a t o t h e a r e a were t h e eggs were recorded. Thus t h e p o s s i b i l i t y of a d r i f t of eggs from t h e spawning a r e a between 62 and 64' N t o t h e c o n t i n e n t a l s l o p e between 65 and 67' N b e f o r e h a t c h i n g a r e r a t h e r

s m a l l - Lack of eggs i n t h e a r e a between t h e s e two r e g i o n s both i n

1987

(Bjorke e t a l . , 1988a) and

1988

i n d i c a t e t h a t t h e eggs r e p r e s e n t s two d i f f e r e n t spawning a r e a s . The eggs between 65 and 67' N were sampled May

4-7

and May

17, 1988.

Table V 1 1 1 shows t h a t some of t h e s e eggs were near h a t c h i n g i . e . 18-20 days o l d , while o t h e r s were less than

4

days o l d when sampled May

4-7.

The o l d e s t eggs sampled i n t h i s a r e a A p r i l

4-7, 1987

were

4-5

days o l d and t h e youngest less than two days (Bjorke e t a l . , 1988a and Table V I I I ) . Thus spawning of haddock i n t h i s a r e a have been recorded from t h e beginning of A p r i l t o t h e beginning of May. It i s , however, n o t p o s s i b l e t o make any conclusion about t h e spawning p e r i o d of haddock i n t h i s a r e a from t h e p r e s e n t d a t a , although t h e s t a r t of t h e spawning seems t o be reasonable documented. The s t a r t of t h e spawning i n t h i s a r e a seems t h u s t o c o i n c i d e with t h a t found f o r t h e haddock f u r t h e r n o r t h on t h e c o n t i n e n t a l s l o p e .

The eggs younger than

4

days recorded between 65 and 67' N ( F i g .

5 )

were a l l sampled o v e r depths between 370 and 762 m. The r e s i d u a l c u r r e n t i n t h i s r e g i o n runs p a r a l l e l with t h e c o n t i n e n t a l s l o p e ( S a t r e and Ljoen, 1 9 7 1 ) , and a bathymetric map over t h e a r e a and t h e d r i f t of t h e Argos buoys ( F i g . 6 ) show t h a t none of t h e s e eggs could have d r i f t e d from grounds shallower than 300 m . T h i s i n d i c a t e t h a t t h e spawning df haddock i n t h i s a r e a t a k e s p l a c e over depths s i m i l a r t o t h o s e found on t h e c o n t i n e n t a l s l o p e f u r t h e r n o r t h .

Rather few haddock eggs were recorded between 64 and 67' N _{i n}

1988

over t h e c o n t i n e n t a l s l o p e ( F i g ,

6 ) .

Assuming t h a t t h e spawning i n t e n s i t y i n t h i s a r e a i s s i m i l a r t o t h a t of t h e haddock f u r t h e r n o r t h , t h e number of eggs should be much h i g h e r d u r i n g t h e sampling a t t h e beginning of May

1988

i f t h i s was a spawning a r e a of any importance ( c o n f . F i g .

3 ) .

R/V "(3.0. S a r s " made

5

bottom t r a w l h a u l s on t h e s h e l f between

64

and

66'

N i n t h e p e r i o d A p r i l 30

-

May

5 1988

( F i g . 6 ) , and found haddock a t one s t a t i o n a t a depth of

468

m . Of a t o t a l of

19

haddock p r . trawlhour

9

were females with a gonad m a t u r i t y index of 2.3, i n d i c a t i n g an e a r l y s t a g e of spawning, T h i s low abundance of spawning haddock i s i n g r e a t c o n t r a s t t o f i g u r e s given f o r t h e spawning a r e a on t h e s l o p e of Tromsoflaket i n

1987

(Table V I ) . Bearing i n mind t h e low number of eggs recorded i n t h i s a r e a a t t h e

beginning of A p r i l

1987

( B j m k e e t a l . , 1988a and Table V I I I ) t h e r e a r e reasons t o b e l i e v e t h a t only a s m a l l f r a c t i o n of t h e North-East A r c t i c haddock spawn between

6 4 ' ~

and R ~ s t both o v e r t h e s l o p e and over t h e c o n t i n e n t a l s h e l f .

The presented view of t h e spawning and egg and l a r v a l d i s t r i b u t i o n of t h e North-East A r t i c haddock r e c e i v e d a new dimension from a l a r v a l survey i n J u l y

1987

from 62 t o

74'

N ( B j a r k e e t a l .

,

1988b)

.

^Haddock

l a r v a e l a r g e r than 50 mm were mainly found s o u t h of R g s t , and l a r v a e s m a l l e r than 20 mm mainly f a r n o r t h of t h i s a r e a . A w e s t e r l y c o n s e n t r a t i o n between

64

and 65 N of t h e former a r i s e q u e s t i o n about 0

t h e o r i g i n of t h e s e l a r v a e . I f they were hatched between 62 and 64' N i n A p r i l t h e d r i f t of t h e Argos buoy ( F i g .

6 )

i n d i c a t e t h a t t h e s e l a r v a e would have been found much f u r t h e r n o r t h when sampled a t t h e end of J u l y ( S c t r e , p e r s . coma.). During t h e same c r u i s e i n J u l y , whiting l a r v a e were found t o have t h e same w e s t e r l y d i s t r i b u t i o n ( B j ~ r k e e t a l . , 1988b). Information on t h e l o c a t i o n of spawning grounds of whiting i s l i m i t e d , b u t spawning has been recorded i n t h e English Channel, i n t h e s e n t r a l p a r t of t h e North Sea, i n t h e a r e a w e s t and e a s t of Scotland and n e a r t h e Faroe I s l a n d s . The spawning season i s long; beginning i n January i n t h e s o u t h and August/September i n t h e n o r t h (Anon

1981).

Along t h e Norwegian c o a s t spawning has been recorded n o r t h t o

64'

N , from March t o May (Dannevig, 1960)

.

^The

s i m i l a r w e s t e r l y d i s t r i b u t i o n of t h e s e two s p e c i e s and t h e f a c t t h a t both s p e c i e s spawn i n t h e North Sea, n e a r t h e H e b r i d i e s and around t h e Faroe I s l a n d s i n d i c a t e t h a t t h e s e haddock l a r v a e might o r i g i n a t e from o t h e r s t o c k s which spawn i n t h e n o r t h e r n North Sea and west of t h e Orkneys from March t o mid-May and around t h e Faroe I s l a n d s from l a t e February t o mid May (Anon.,

1981).

S i m i l a r l e n g t h d i s t r i b u t i o n s of haddock l a r v a e have a l s o been recorded i n e a r l i e r y e a r s .

Conclusions

-

Most of t h e Tromsoflaket a r e a from Nordkapp t o n e a r t h e s h e l f edge bordering t h e Norwegian Sea a r e i n h a b i t e d by immature haddock i n l a t e A p r i l and e a r l y May

1987.

-

^An i n c r e a s e i n abundance of mature f i s h t a k e s p l a c e i n t h e western

p a r t of t h e s h e l f . Gonad m a t u r i t y i n c r e a s e s with i n c r e a s i n g depth a t t h e c o n t i n e n t a l s l o p e of Tromsoflaket, and from n o r t h t o s o u t h along t h e s h e l f .

-

The main spawning a r e a s of North-East A r c t i c haddock seems t o be t h e s o u t h e a s t e r n p a r t of t h e c o n t i n e n t a l s l o p e of Tromsoflaket a t depths from 300 t o 600 m and temperatures between

4

and

6'

C.

-

Other spawning a r e a s a r e found i n Vestfjorden and over t h e con- t i n e n t a l s l o p e from Tromsoflaket s o u t h t o Rosttunga. The spawning i n V e s t f j o r d e n seems t o t a k e p l a c e a t depths shallower t h a n 200 m b u t w i t h i n t h e same temperature l i m i t s .

-

Spawning seems t o s t a r t a t t h e beginning of A p r i l , r e a c h e s i t s maximum a t t h e end of t h e month and ends d u r i n g t h e f i r s t h a l f of May.

-

^Very l i t t l e spawning i s recorded on t h e s h e l f and t h e c o n t i n e n t a l s l o p e from Rosttunga t o

64'

N .

-

Spawning i n t h e a r e a 62-64 0 N (More) i s supposed t o o r i g i n a t e from a l o c a l s t o c k . The o n s e t of t h i s spawning seems t o t a k e p l a c e a week o r two e a r l i e r than what was observed f u r t h e r n o r t h .

-

A d i s t i n c t bimodal d i s t r i b u t i o n of l a r v a e sampled i n J u l y

1987

i n d i c a t e a p o s s i b l e i n f l u x of haddock l a r v a e t o t h e Norwegian c o a s t which might belong t o a population d i f f e r e n t from t h e North-East A r c t i c haddock.

REFERENCES

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153-159.

I n : T r a n t e r , D . J . , ( E d i t o r ) , Zooplankton sampling. Monographs on oceanographic methodology 2 , The Unesco P r e s s . P a r i s .

174

pp.

Anon.,

1979.

The b i o l o g y , d i s t r i b u t i o n and s t a t e of e x p l o i t a t i o n of f i s h s t o c k s i n t h e I C E S a r e a , p a r t 11. 1nt.coun. Explor.Sea:

Cooperative r e s e a r c h r e p o r t 86:5-6.

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1981.

A t l a s of t h e s e a s around t h e B r i t i s h Isles. M i n i s t r y of A g r i c u l t u r e , F i s h e r i e s and Food. Lowestoft.

Anon.,

1987.

P r e l i m i n a r y r e p o r t of t h e i n t e r n a t i o n a l 0-group f i s h survey i n t h e Barents Sea and a d j a c e n t waters i n August- September

1987.

Counc. Meet. I n t . Counc. Explor. Sea

(G:38):1-31

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1988.

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1987.

Counc. Meet. i n t . Coun. Explor. Sea, C.M.l987/Assess:5, 142 pp.

Baranenkova, A.S. and Khokhlina, N.S., 1967. Abundance and d r i f t of eggs and l a r v a e and comparative d a t a on s u r v i v a l of f i n g e r l i n g s ( o f bottom s t a g e s ) of haddock (Melanogrammus a e g l e f i n u s Linne) i n t h e Barents Sea i n 1959-1963. Proc. of t h e P o l a r Research I n s t i t u t e of Marine F i s h e r i e s and Oceanography (PINRO), Murmansk, XX: 11-64.

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Jgrgensen, T. and Dragesund, 0 .

, 1987,

L i f e and ecology of t h e Gadoid Resources of t h e Barents Sea, F i s h . Res., 5:119-161.

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1984.

D i s t r i b u t i o n of eggs and l a r v a e of gadoid f i s h e s from Stad t o Lofoten d u r i n g A p r i l 1976-1982. I n : E. Dahl, D.S. Danielssen, E. Moksness and P. Solemdal ( E d s ) , The Propagation of Cod Gadus morhua L. Flgdevigen r a p p o r t s e r , l ,

1984

: 365-394.

Bjgrke, H., Bakkeplass, K,, and K . Hansen, 1988a. Forekomsten av f i s k e e g g f r a Stad t i l Gimsoy i f e b r u a r

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a p r i l

1987,

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P o s t l a r v e u n d e r s g k e l s e r

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j u n i / j u l i

1987.

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, 1988

( 1 4 )

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Blindheim, J . , Eide, P.K., Knudsen, H.P., and Vestnes, G,, 1982. A shipborne d a t a logging and p r o c e s s i n g system f o r a c o u s t i c f i s h surveys. F i s h . R e s .

,

l : 141-153.

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Dannevig, G., 1960. T e k s t e r t i l p l a n s j e v e r k e t . I n : G. R o l l e f s e n ( e d . ) . Havet og vAre f i s k e r , Bind 1. Pp. 1-87. J . W. Eides f o r l a g , Bergen

.

E l l e r t s e n , B., Furnes, G.K., Solemdal, P. and Sundby S . , 1981, E f f e c t s of upwelling on t h e d i s t r i b u t i o n of cod eggs and zooplankton i n V e s t f j o r d e n . I n : R . S a t r e and Mork M . ( e d s . ) . Proc. from t h e Norwegian C o a s t a l Current Symposium, G e i l o , Norway, 9-12 September 1980. U n i v e r s i t y of Bergen, 1981:604-628,

E l l e r t s e n B., Fossum, P . , Solemdal, P . , Sundby, S. and T i l s e t h , S . , 1987. The e f f e c t of b i o l o g i c a l and p h y s i c a l f a c t o r s on t h e s u r v i v a l of Arcto-Norwegian cod and t h e i n f l u e n c e on r e c r u i t m e n t v a r i a b i l i t y . I n : H . Loeng ( e d . ) . Proceedings of t h e t h i r d Soviet-Norwegian Symposium, Murmansk 26

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28 May 1986, on "The E f f e c t of Oceanographic Conditions on t h e D i s t r i b u t i o n and P o p u l a t i o n Dynamics of Commercial F i s h Stocks i n t h e Barents Sea". Pp. 101-126.

God@, O.R.,

1984.

Migration, mingling and homing of North-East A r c t i c cod from two s e p a r a t e d spawning grounds. The proceedings of t h e S o v i e t - Norwegian symposium on reproduction and recruitement:289-302.

God@, O.R., Hylen, A., Jacobsen, J . A . , Jakobsen, T . , Mehl, S . , Nedreaas, K . and Sunnanh, K . , 1987. Estimates of s t o c k s i z e of Northeast A r c t i c cod and haddock from survey d a t a

1986/1987. Counc. Meet. I n t . Counc. Explor. Sea

(G:37):1-47 (Mimeogr.).

Hislop, J.R.G., Robb, A.P. and Gauld, J.A., 1978. Observations effects of feeding level on growth and reproduction in haddock, Melanogrammus aeglefinus (L) in captivity. J. Fish.

Biol., 13(1):85-98.

Moksness, E., and Selvik, J.R., 1987. Description of the spawning and the early life history of haddock (Melanogrammus aeglefinus L.) from the Norwegian Skagerrak coast. Flodevigen Rapp.

Ser., 1:l-15

Mork, J., Solemdal, P. and Sundnes, G., 1983. Identification of fish eggs: a biochemical genetics approach. Can. J. Fish.

Aquat. Sci., 40:361-369.

Mukhina, N.V., 1983. Distribution and abundance of early stages of haddock and deepwater redfish in April-June 1980. Ann.

Biol., (37):256-259.

Mukhina, N.V. and Dvinina, E.A., 1986, Results of the ichthyoplankton survey in the Norwegian and Barents seas in 1983, Ann, Biol. , 40: 69-71.

Pedersen, T. 1984. Variation of peak spawning of Arcto-Norwegian cod (Gadus morhua L.) during the time period 1929-1982 based on indices e stimated from fishery statistics. In: E. Dahl, D.S. Danielssen, E.Moksness

og

P. Solemdal

( e d s , } ,

The Propagation of Cod Gadus morhua L. Fl~devigen rapportser.,l:301-316.

Shevelev,

M,S,,

Teseshchenko, V,V,, and Yaragina, N.A., 1987,

Distribution and behaviour of demersal fishes in the Barents and Norwegian Seas, and the factors influencing them. In

:

H. Loeng (ed.). Proceedings of the third Soviet-Norwegian Symposium, Murmansk 26 - 28 May 1986, on "The Effect of Oceanographic Conditions on the Distribution and Population Dynamics of Commercial Fish Stocks in the Barents Sea". PP.

181-190.

Shmit

,

V. F.

, 1936.

Some f e a t u r e s of t h e economic biology of haddock.

F i s h i n g I n d u s t r y i n t h e North, 10,1936.

Shmit, V.F.,

1937.

Biology and reproduction of t h e c h i e f commercial f i s h e s i n t h e Barents Sea. F i s h i n g I n d u s t r y i n t h e North, 2-3, 1937.

Solemdal, P . , 1982. The spawning p e r i o d of Arcto-Norwegian cod d u r i n g t h e y e a r s 1976-1981. Report on t h e working group on l a r v a l f i s h ecology, Lowestoft, England, 3-6 J u l y 1981. ICES C.M./L:3. 21 pp.

Solemdal, P . , 1987. G y t e f e l t og gyteperiode hos n o r s k - a r k t i s k hyse.

H a v f o r s k n i n g s i n s t i t u t t e t s Egg- og Larveprogram (HELP).

Report no. 1 0 , 1987, pp. 1-21.

Solemdal, P. and Sundby, S . , 1981. V e r t i c a l d i s t r i b u t i o n o f p e l a g i c f i s h eggs i n r e a l t i o n t o s p e c i e s , spawning behaviour and wind c o n d i t i o n s . Counc. Meet. I n t . Counc. Explor Sea,

(G:77):1-12 (Mimeogr.).

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Sonina, M . A . ,

1981.

The r a t i o of mature and immature haddock Melanogrammus a e g l e f i n u s ( L ) . i n t h e Barents and Norwegian Sea. Coun.Meet.int.Coun.Exp1or.Sea. G:23:1-13.

Sund, 0.

,

1927. Undersokelser i Vestf jorden i f i s k e t i d e n 1926.

Arsberetn. Norg

.

F i s k . ( 2 ) : 500-504.

Sundby, S.

, 1983.

A one-dimensional model f o r t h e v e r t i c a l d i s t r i b u t i o n of p e l a g i c f i s h eggs i n t h e mixed l a y e r . Deep- Sea R e s .

,

30 ( 6 ) : 645-661.

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En

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Satersdal, G.S., 1952. The haddock in Norwegian waters I. Vertebrae Counts and Brood Strength Variations of young fish. Fisk.

Dir. Skr. Ser. HavUnders ~ ( 4 )

:

1-14.

Satersdal, G.S., 1954. Age, Distribution and Migration. Ann.Biol., (11):97-100.

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from the POAC . ^Conf . ^, Trondheim, 1971, 1

:

514-553.

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Fiskeridirektoratets SmAskrifter, nr.1, 1950:l-20.

Wiborg, K.F., 1952. Forekomst av egg og yngel i nordnorske kyst- og bankfarvann vkren 1950 og 1951. Fiskeridirektoratets smkskrifter, nr.1, 1952:l-22.

Wiborg, K.F., 1956. Forekomst av fiskeegg og fiskeyngel i nordnorske farvann vgren 1954 og 1955. Fiskeridirektoratets SmAskrifter, nr.6, 1956:l-22.

Wiborg, K.F., 1957. Forekomst av fiskeyngel og fiskeegg i nordnorske farvann vgren 1956, samt

p&

stasjon M

i

Norskehavet i 1954-

56. Fiskets Gang, nr, 14, 1957

:

188-191.

Wiborg,

K , E , ,

1960, Investigations on Eggs and Larvae of Commercial Fishes in Norwegian Coastal and Offshore Waters in 1957-58.

Fisk.Dir.Skr.Ser.Havunders.XII(~):l-27.

TABLE I

Maturity s c a l e of gonads used f o r cod and haddock a t t h e I n s t i t u t e of Marine Research, Bergen.

Stage 0 : Immature, s m a l l r e d d i s h t r a n s p a r e n t gonad.

Stage 1 : Maturing, o n l y small ova, no hydrated eggs. A l l s i z e groups.

Stage 2 : Maturing, some hydrated eggs.

S t a g e

3

: Many o r most hydrated eggs.

Stage

4

: Spawning, a l l eggs hydrated.

Stage

5

: Spent. F a i n t b l u e appearance. Large blood v e s s e l s . Stage

6

: S p e n t , maturing.

Stage

7

: Uncertain.

TABLE I1

Percentage and c o n c e n t r a t i o n of haddock and cod eggs from s i x a r e a s c o n t i n e n t a l s h e l f and s l o p e i n n o r t h Norway 21 A p r i l

- 15

May 1987

(see F i g . 1 ) .

Cod

I

^Haddock

I Rosttunga 20.0 0 . 9

I1 C o n t i n e n t a l s l o p e Rost

-

Tromsgflaket 83.9

13.3

I11 C o n t i n e n t a l s h e l f Rost

-

^{Langoy 7 0 . 8}

15.4

I V Lofoten

/

V e s t f j o r d a r e a 79.8 109.9 V C o n t i n e n t a l s l o p e of Tromsgflaket 1 0 . 6 3.2

V 1 Nygrunnen 64.5 1.1

TABLE I11

The percentage of immature haddock i n bottom t r a w l c a t c h e s a t Tromsgflaket ( T and A-C) and Rgsttunga ( D ) 21 A p r i l

- 15

May 1987. The s t a t i o n s a r e on a g r a d i e n t from e a s t t o west. M : Males. F : Females.

See Fig. 1 f o r t h e a r e a code.

-

^: Not p o s s i b l e t o c a l c u l a t e . N : Number of f i s h caugth. C ' : Area C sampled one week l a t e r .

Area S t a t i o n Depth(m) P o s i t i o n S e x r a t i o

%

M

%

F N

TABLE I V

Stock e s t i m a t e s and percentage mature haddock i n f o u r r e g i o n s on t h e s h e l f Tromsoflaket ( A - C ) and Rosttunga ( D ) 2 1 A p r i l

- 15

May

1987.

The edge at Tromsoflaket and Rosttunga. I : No. of f i s h based on a c o u s t i c e s t i m a t e s

I1

: No. of f i s h p e r t r a w l hour and c a t c h .

*

: P e l a g i c t r a w l s t a t i o n s used only f o r a c o u s t i c e s t i m a t e s . N : Number of f i s h caught.

-

^: Not p o s s i b l e t o c a l c u l a t e . See Fig. 1 f o r a r e a code. C ' : Area C sampled one week l a t e r . Areas a r e p r e s e n t e d on a g r a d i e n t from n o r t h t o s o u t h .

T o t a l s t o c k

No. of f i s h Spawning

%

m a t u r i t y I I I s t o c k of s t o c k

;' Area S t a t i o n no. ( m i l l i o n ) ( m i l l i o n ) T o t a l Females

TABLE V

Maturity of female haddock i n a r e a s A ( A p r i l 2 6 ) . B ( A p r i l 26-27), C ( A p r i l 28-29) and D (May 2 ) a t Tromsoflaket and Rosttunga i n

1987

and

1988

(May 20-22). C ' : Area C sampled (May

5-6).

M i : Maturity index. See Fig. 1 f o r a r e a code.

Degree of m a t u r i t y ( % )

Area S t a t i o n 1 2

3 4 5

M i

TABLE

V1

Number of haddock p e r trawlhour and m a t u r i t y s t a g e a c r o s s t h e c o n t i n e n t a l s l o p e of Tromsmflaket i n 1987. Area A

-

C : A p r i l 24 -April 29th. Area D : May 2nd. Area C ' : May 5 t h

-

May 6 t h . S t . n o S t a t i o n number f o r bottom t r a w l . C ' : Area C sampled one week l a t e r . See F i g . 1 f o r a r e a code.

Area S t . n o . Immature 1 2

3 4 5

6

'7'

Depth ( m

TABLE

V11

Developmental stages and number of haddock eggs from Vestfjorden, May

10-12, 1988.

Stage and age after Solemdal (unpubl.).

Stage

1 2 3 4 5 6

Age (days)

0-2 3-4 5-6 6-10 10-18 18-20

Percent

0.0 0.0 30.8 4.1 48.2- 16.9

Total ~ o s / m * 0

0 69 9 108 38

Mean Nos/m 2

0 0 4.3 0.6 6.8 2.4

TABLE V111

S t a g e s of development of haddock eggs sampled between

62

0 N and R @ s t i n 1987 and

1988.

The f i g u r e s show t h e t o t a l number of haddock eggs sampled. Unit: number p e r m 2 s u r f a c e . Stage and a g e , i n b r a c k e t s , a f t e r Solemdal ( u n p u b l . ) .

Fig.

1.

Area of investigation north of R ~ s t in 1987 and 1988, Hatched and cross hatched area of spawning intensity investigation at Tromsa- flaket and H011a respectively.

:

Bottomtrawl stations. A

^:

^Pelagic

trawlstations. Areas I -

V 1

was investigated for egg developmental stages. Subareas A, B, C and D was a.0. investigated for acoustic estimates of stock size and egg developmental stages. -

^:

^Hydro-

graphical sections presented in Figs 11- 14.

T- . 2 . Names used in t h e t e x t .

Fig.

3.

Distribution of haddock eggs in nubers per m 2 surface. All developmental stages included. April 22

-

^{May 14,}

1987.

F i g .

4.

D i s t r i b u t i o n of haddock 2 eggs younger

than 4

days. A p r i l

27 -

May 1 2 ,

1988,

Numbers p e r m s u r f a c e .

F i g .

5.

D i s t r i b u t i o n o f 2 haddock eggs younger t h a n

4

d a y s . May 1

-

May

23. _1988.

Numbers p e r m s u r f a c e .

F i g .

6 .

D i s t r i b u t i o n of haddock eggs i n numbers p e r m 2 s u r f a c e . A p r i l

27-

May

23, 1988.

Data from coverages shown on F i g .

4

and F i g .

5.

A 1 1 developmental s t a g e s included.A:Bottom t r a w l s t a t i o n s . A : B o t t o m t r a w l s t a t i o n s with c a t c h of haddock. Lines with c r o s s e s show d r i f t of Argos buoys. Crosses every f i f t h day. Dates of deployment and recovery i n d i c a t e d .

60

55 N e g g s = 2 3

N s t = 7

50 45 40 35 30 25 20 15 10 5 0

60 -

N e g g s = 18 60

55 55 N e g g s S 7 7 -

N s t = l 8

50 50 N s t = 3 0

v

45 45 -

40 40 -

35 35 -

30 -

25 ^O/o 30

25 -

20 20 -

15 15 -

10 10

-

5 5

0 0 -

N e g g s = 54 N s t = 1 9

' U

s t a g e

Fig. 7. Distribution of egg developmental stages

in

areas I-VI. I) Rgstunga, 11) the continental slope from R ~ s t to Troms~flaket, 111) the continental shelf from Rgst

to

Langay, IV)

the

Vestfjord area, V) the western continental shelf of Tromsgflaket

and

VI) Nygrunnen. U

=

Unidentified. Neggs= Number of

eggs,

Nst= Number of

s t a t i o n s ,

60 1 N e g g s = 38

N s t = 4

N e g g s =l44

50 ^{N s t = 9}

N r g g s = l 9 5 N s t = l 7

Fig.

8.

Distribution

of

egg developmental stages in subareas

A-C. U

=

Unidentified. Neggs= Number of eggs. Nst= Number of stations. (See Fig.

1

for investigated area).

D S t a g e 1 D S t a g e 11-V1

A P R I L M AY 1987

Fig.

9.

Number of haddock eggs per m 2 surface at Troms@flaket.

Developmental stages

I

and 11-V1 are shown separately. (See Fig. 1 for investigated area).

AP R I L M A Y 1987

Fig. 10. Number of haddock eggs per m 2 surface at HDlla. Numbers represent stages I-VI. (See Fig. 1 for investigated area),

0 603 607 601 S93 S T N O

'5.0 100

200-

"W

1n.m.

r '=C

F i g . 1 M a t u r i t y , l e n g t h d i s t r i b u t i o n and number p e r trawl hour o f female haddock. Temperature d i s t r i b u t i o n ( 0 C ) on a s e c t i o n from t h e western bank a r e a and t h e c o n t i n e n t a l s l o p e of Tromsmflaket i n a r e a B .

a ^-

Mature haddock f e m a l e s .

m ^-

Immature haddock f e m a l e s .

Fig. 1 2 . M a t u r i t y , l e n g t h d i s t r i b u t i o n o and number p e r t r a w l hour of femzle haddock. Temperature d i s t r i b u t i o n ( C ) on a s e c t i o n from t h e western bank a r e a and t h e c o n t i n e n t a l s l o p e of T r o m s ~ f l a k e t i n a r e a C .

I -

Mature haddock females.

-

Immature haddock females.