sh_vol12_08_1960.pdf (483.1Kb)

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F I S K E R I D I K E M T O R A T E T S S K W I F T ' E R

S e r i e H a v u n d e r s a k e l s e r

( R e p o r t ott Norzoeginn l?is/zery afzci Maritre Investigatio?rs) 1701 X I I . N o . 8

Investigations on Pelagic Fry

of Cod and Haddock in Coastal and Offshore Areas of Northern Norway in

July-August 1957

1 9 6 0

A.S JOHN GRIEGS BOKTRYKKERI, BERGED;

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CONTENTS

Page

Introduction . . . 5

Horizontal distribution of the cod and haddock . . . 7

Length frequencies of the cod and haddock . . . 8

Cod . . . 8

Haddock . . . 9

Stomach contents . . . 9

Cod . . . 10

Haddock . . . 12

Summary . . . 14

References . . . 15

Table 5

. . .

16

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I N T R O D U C T I O N

I n the period 9. July-31. August 1957 investigations of small and fat herring were carried out from the R / V "G. 0. Sars" in coastal and offshore areas of northern Norway. During the cruise a number of horizontal hauls were taken with a Petersen pelagic youngfish trawl.

As a rule, the trawl was towed for 15 minutes in steps with 150, 125 a n d 100 m wire respectively a t a speed of two knots, the corresponding depths being estimated to 45 m, 23 m and 12.5 m respectively. Hydro- graphical observations and vertical Nansen ("8/72") net hauls 100-0 m were taken on 234 stations.

A preliminary report of the cruise has been published by DRAGESUND and L J ~ E N (1957), and I take this opportunity to express my gratitude to Mr. DRAGESUND for entrusting me with the material of fish fry and zooplankton.

Kr. Fr.

Wiborg.

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H O R I Z O N T A L D I S T R I B U T I O N O F T H E C O D A N D H A D D O C K

T h e cocl ancl lladdock fry was chiefly taken in the area froin the Vestfjord ancl northwarcls (Fig. I). F a r t l ~ e r soutll the hauls were mainly negative. The sts. 505 -599 were worked from 17. to 3 1. July, sts. 606- 707, 4.. to 18. August, ancl sts. 720-734., 21. to 31. August. 'The hadclocl< was most abundant, especially from S o r ~ y ancl northwards, maximum 69 lry

S 1"AS3CCi< 0 COJ

o e : - i O PE? r . A b L

3 @ :. - 2 5 ,, ,.

'2, @ 26. 5 0 '' ,

s g

>,o ,, , DdiS; SElh:

X l i Z G 4 T I \ ' E STAT.O'.lS

Fig. 1. The cluantitati\re clistributioll of cocl and hadclock of the 0-group taken in 20 minutes hauls with the Petersen youngfish trawl (200-50 m wire) July 17-August

3 1. 1957. Obliclue figures, station numbers.

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per horizontal haul, a t a number of stations 15-40 fry per haul. T h e cod fry was mainly distributed along the coast from Andenes to S ~ r 0 y as a rule less than 10 individuals per haul, sometimes as much as 35.

At the end of August, 30 fry were taken per l ~ a u l in the inner part of the Vestfjord.

LENGTH FREQUENCIES O F T H E C O D AKD HADDOCK T h e fish fry was measured in millimetres, and the figures combined in groups of 5 mm.

Cod

During the first part of the cruise (sts. 505-699) the cod sampled on the wllole had the same length distribution, and all the figures have been combined into one

%r---

^-^-^---^-^ST.⁷^505-699^{( l j ~}

^/NO)'

^curve(Fig' 2)' The lengths

( 591

,

^, vary from 30 to 80 mm, with

SO ! I, 701-707 ( 4 6

11

the peak a t 55 m m (mean 54

- - - "

I I

I ; .. . .

.

. . . .

.

708 -734 (67 'I ) , mm)

.

I n the coastal and fjord

' I

I ' I

a area east of Vard0 the cod

.

1 , I I

. .

i . . . .

1

fry was on an average a little

I I . .

i

ÎÎ ÎÎ ^.^.^{. .}^.^. smaller (mean 53 mm), with

45 mm. The cocl n the Vestfjord a t the end of August hacl ge length of 68 mm.

igures agree very

! well with those given by (1909) and COR-

LETT (1958) for the pelagic cod in the same 21. July, a number y was taken in a purse seine a t st.

to be expected, were larger than ken in the Petersen

. trawl, measuring 50-85

-

Fig. 2. Percentage length distributions of cod taken m m ~ ^Inean length 69 mm.

in the Petersen pelagic trawl, and in purse seine (Fig. 2).

(st. 591), in mm.

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- ST. 505-683 (571 1ND.j

1

Fig. 3. Percentage length distributions of haddock taken in the Petersen pelagic trawl, and in purse seine (st. 591 j, in mm.

Haddock

The haddock fry was on an average somewhat larger than thc cod.

(Fig. 3). From st. 505 to st. 683, 90 n. miles north of Vardo, the length distributions were mostly uniform, with a mean length of 62 mm. Off Vardo, in the Varangerfjord, and on the banks east of Vard0, the haddock fry was much larger, with a mean length of 73 mm. At the end of August the haddock taken in the fjords to the west of Vardo measured 80-110 mm, averagely 92 mm,

The haddock caught in a purse seine at station 591 also measured 80-110 mm, with an average of 97 mm. I n July the pelagic 0-group of haddock off northern Norway, according to the data given by DAMAS (1909), has a length of 50-90 mm, in August 60- 110 mm.

STOMACH CONTENTS

Previously, there are very few observations on the stomach contents of pelagic cod and haddock of the length group 30- 100 mm. The author has studied the stomach contents of deinersal and littoral cod of the 0-group in the waters of northern Norway (WIBORG 1948, 1949).

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'Table I . T/ze Percentage Occurrence of the Various Food Oqanisms in the Stomachs of Pelagic Cod Fry Taken in Petersen Pelagic Trawl in the Coastal

and Oflshore MTaters of ~I~ortlzern jVorzoa3, in J u b -August 1957.

All the fry of cod and haddock during tlie cruise were investigated with respect to the stomaclz contents. The degree of filling was estimated on a subjective scale in 5 degrees: empty ( I ) , riearly empty (11), medium

(111) , full (IV) , distendccl (V)

.

Area

Cod

A total of 371 stornaclzs of cod fry from 63 stations has been investigated. Except for 72 cocl taken in the purse seine, all of which had tlze stoniachs distenclecl (V), the filling indexes of the other stomacils T\.erc clistributecl as follows :

1 I Lar-

Coin- other1

I

Deca- vae of

Stations L J cope- Krill / pod-

1 botto111 I f pods

I ^I

^larvae I n \ .

Degree of filling I I1 111 I V V

Per cent of tlzc stolnaclis 8 10 32 37 14 Most of tlie stomachs liad a filling inclex of 111-IV.

T h e stornach contents were dissected out and investigated under a low powered stereoscopic microscope. T h e organisms found in the stomachs were grouped as sllowll in Table 1, ancl the percentage occurrence of the clifferent groups calculated for four separate areas.

The copelsods range first as foocl organisms, mainly Calanus, finnzarchiczu, next come Oitlzona si~nilis and neritic copepods. The second important group is the krill or euphausiids, the third one the copelates, Fritillarin borealis and Oikopleura spp. Local occurrences of Balanus-nauplii and larvae of pagurids at the sts. 598, 599, 690, 704 ancl 707, which are all locatecl near the coast, explain tlze comparatively high percentage of bottom invertebrate larvae and decapod larvae in the areas I and 111. Limacina retrouersa is of a certain importance as food in the area north of S 0 r ~ y .

As mentioned previously, tlie cod taken in a purse seine north of Anclerles were larger than those from the trawl catches, and the stomach contents were also different.

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Table 2. A, Arunzber oJ',Stations with Cod Feeding on a Particular Organism, B,

~vurnber

oJ'

Cod Feeding on this Organism at A, C , Total Afurnber o f Cod in- vestigated at A, D , Frequency o f the Organisnzs in the Stomachs of the Cod at

1 0 0 . B A i~z ger Cent

C

Medusae . . . Oih-o~lezi~ a . . . Fritillarin sp. . . . Lit7zacinn . . . C'lione . . . Calanus fitznz. . . . Other copepods. . . . Cladocer ans . . . Ostracods . . . Krill . . . Decapod larvae . . . Amphipods . . . . . .

Larvae of bottom in\?.

Herring fry . . . Fishes, indet. . . .

Chaetognaths . . . Insects . . .

In the 72 stoinachs illvestigated, the pcrcelitage freque~icy of the various food organisms Tvas as follows:

I

Krill Herring Redfish fry

I

:b of all stomach. .

1

¹² ⁴ ⁴⁹ ¹ ⁴⁹

^,

⁷¹ ³

The larger food organisms, sucli as krill, and fry of herring and rccl- fisli arc of greatest importance. The maximum size of the herring was 35 inm, of the reclfish 13 mm.

If we only consider those stations -cvliere a particular foocl orgaliisrn is found in the stomachs of one or more cod, the frequency may inclicatc if tlie cod prefers a certain kind of foocl, supposiiig that the organism has been present in the plankton in sufficient numbers. (Table 2).

As in Table 1, the orgallisms dominating are Calanus fin/narchicus ancl other copcpods, krill, bottoni invertebrate larvae and appelidicularians, but other groups may be of local importance, such as Limncina, clado- cerans, amphipods and fish fry.

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Table 3. The Percentage Occurrence of the Ziarious Food Organisms in the ,Stomaclzs of Pelagic Haddock F~_L. Taken in Petersen Pelagic Trawl in the Coastal

and Offshore Waters of Northern ~ V o r w q in July-August 1957.

Stations Me- OzXo- Fiztil- durae plsiiia

1

^laiia

i

^ClioneÎ ^Cal. ÎOther' Krill Î¹

J i n a .

I

^cop.

1

I

1

^Larvae

Deca- of bot- podl. tom

inv.

The number of organisms per stomach vary considerably according to the relative size of the food organism and the fish, a maximum number of 15 krill or 40 ^--50 adult Calanus being found.

Haddock

I n all, 829 stomachs of haddock from 89 stations have been investigated. T h e filling index has becn determined in the same way as in the cod, with the following result:

Degree of filling I I1 111 I V V Per cent of tllc stomachs 4 6 26 50 14

T h e haddocl~ had on the whole a little more stomach content than the cod.

The occurrence of the food organisms in the stomachs of the haddock has been tabulated in the same way as for the cod (Table 3).

T h e diet of the hadclock is somewhat different from that of the cod, although both fishes have been caught in the same water mass. Calanus fitz?na~chicus is still the most important food animal, but the medusae have been added as a new, important group, which in August completely dominates in the stomach contents of haddock taken in the fjords, while the krill is then entirely lacking. Appendicularians, Limacina and Clione are all of much greater importance than in the cod, whereas the krill has an average percentage frequency of 17, as compared with 35 in thc cocl. The difference in diet may to a certain extent be explained, as the haddock is mainly found in the northernmost areas and far out in the sea, the cocl more close to the coast. But if we compare the diet of the two fishes a t the same stations, the same difference is again found.

I n Table 4 the occurrence of the food animals in the stomach contents of haddock has been tabulated in the same way as for the cod (Table 2).

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Table 4. A, .Number of Stations witlz Haddock Feeding on a Particular Organistn, 8, Arumber of Haddock Feeding on this Organism at 11, C, Total Number

03'

Haddock Investigated at A, D , Frequeng of the Organisms in tlze Sto~naclzs of the 100 ⁺B

Haddock at ^ilin Fer Cent : ^- C

Xfedusae . . . . . . Oikopletira sp.

Fritillaria sp. . . . Li~~zacina . . . Cl ione . . . Calanus finm. . . .

Other copepods . . .

Cladocerans . . .

Ostracods . . .

Krill . . . . . .

Decapod larvae.

Amph ipods . . .

Larvae of bottom inv. . . . . . .

I-Ierring fry

. . .

Redfish fry

Fish indet. . . . Too,no/teris sp. . . .

Chaetognaths . . .

Insects . . .

I t is again stated that medusae, appendicularians, Limacina and C'lione are more important as food for the haddock than for the cocl,

\vhereas krill ancl larvae of bottom invertebrates are of less importance.

T h e other food animals have approximately the same frequency in t h e hadclock stomachs as in those of the cod.

A total of 41 small haddock was caught with a purse seine a t st.

591. They were larger than the cod taken at the same time (sec Fig. 3 ) . All the haddock had food in their stomachs, as shown below:

Frequency, % . . .

.I

80

1

20

1

⁷ ^I ⁷

i

49 2 Limacina

T h e same food animals were found in the cod stomachs, but in the hadclock the frequency is different. Limacina is of greatest importance,

I

i

I

I ! I

I

^Crusta-

Krill

/

^cean

/

^larvae ^Herring^fry

1

^{~ l s h}

y h

1

^i;zt.

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whereas krill ancl especially herring fry, are of little importance. Rcdfish fry is relatively numerous, but not so important as in the cocl (71 ^{O b ) .}

As aclults, the cod and hadcloclc differ in their food habits, the hadclock in some periods feeding more intensely on bottom animals. B L I ~ there is evidently a difference even in the pelagic stage, at an age of 3-4 month. or perhaps less.

I n Table 5 is shown the occurrence of various food organisms in the stomachs of cocl and haddoclt at the different stations. The plankton organisms taken in Nailsen net hauls at the samc stations arc also incli- cated. As the different species are very often founcl in separate lumps in the stonlach, the cod ancl haddock evidently select the most suitable food organisms. But the food animals have a l s ~ been sho~vn to occur in definite swarms in the planl<ton. For the samc reason the animals may be present in the stomachs, but lacking in the plankton sample from the samc station. It is, ho\\-ever, to be talten into consideration, that the fish fry has been caught in horizontal hauls, ancl may also have migrated while in search for foocl, whrrcas the plankton has been salnplccl in vertical hauls.

I n July-August 1957 the distribution of pelagic cod ancl hacldock of the 0-group was investigated in the coastal and offshore raters of northerll nor^ ay. The cod was most abuildant near the coast, the hadclock also numerous farther offshore, and usually outnumberccl the cod.

The cod measured 30-90 mm, the average lengths incrcasing from 53-55 n1n1 in July to 65 nlm in August. Cocl, talcen in a purse seine off Ande~les in July, measurccl 50- 85 mm.

'The hadclock measurecl 30- 110 n ~ m , the average lengths increasing during the cruise from 62 mm to 92 mm. Purse seined haddoclt mcasurecl 80-110 mm.

Copepods were most important as foocl both for cocl ancl liaclclock, Cnlalzzls fzn7nn~clz~cz~s ranging first. The other foocl components were of varying significance in the t ~ v o fishes. The cocl had eaten krill ancl appendicularians to a great extent, locally also Lzmncznn, cladocerans, amphipods ancl fish fry. The larger cod talien in the purse seine, hacl mainl) taken fry of redfish and herring, ancl krill.

I n the hacldock, appenclicularians, L~mnczlzn and Clzolze were gencrall) of greater importance than ill the cod, whereas krill hacl been eaten to a much smaller extent. Locally, meclusae played a great part in the clict.

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Li?~zncina was found in 80 per cent of the stoi-~iachs of the haddock taken in purse seine, whilc krill and herring fry were met with in only 20 and 7 per cent respectively.

A comparison of the food organisms with those taken in simultaneous plankton hauls indicates that the fish to a certain extent select their food, partly that the food organisms may occur in swarms in the plankton.

REFERENCES

CORLETT, J. 1958. Distribution of larval cod in the western Barents Sea. Intern. Comm.

.Northw. Atl. Fish. Sj~ec. Pzcbl. No. 1, pp 281 -288.

DAMAS, D. 1909. Contribution B ^labiologie des gadides. Raj~fi. Proc. Verb. 10 ( 3 ) . DRAGESUND, 0. and L J O E N , R. 1957. Smisild- og feitsildtokt med (tG. 0 . Sarsn i

Norskehavet og Barentshavet fra 9. juli ti1 31. august 1957. Fiskets Gang, pp 560-565.

WIRORG, K. F. 1948. Some observations on the food of cod (Gadzls callarias L . ) from deep water and the littoral zone in northern Norway and from deep water a t Spitzbergen. Fiskeridir. Skr. Ser. Havundersok. 9 ( 4 ) . pp 1 - 19.

- 1949. T h e food of cod (Garlzts callarias L.) of the 0-11 group from deep water in some fjords of northern Norway. Ibid. 9 (8). pp 1-25.

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T a b l e 5. Plankton Organisnzs Found in Stomaclzs

of'

Cod X ,

oJ

Haddock 0 , and in Vertical Afansen Net Hauls

a,

oJf Nortlzern Normay in July-August 1957.

I 3 S I C A P A

LiXopl.uia iabr.

<1..IC"

0 8aLx x x x u 0

'I sP. X 0 X X 0 0 0 0 " o ~ ~ ~ ~ ,

h<liofiir lvmlda

~ v , t , , , ~ ~ , ~ h s c a , % n x B 3 x G 0 O

LIOLLUSC*

X X

,.7,ac,"* re,ro\.e,sa

C . l a n c Ilmar,nr

o g E 8:

O ⁰ ⁸ Lx

ir,,.ropa*a ;arvilr O 0 0

8 0 0

⁰

7 . . . i , ; a e l a i v a ~

T i i i l N O D E R l < A l h i a r r r I I 0 \ I

F". Y C , , A F T A ~ -. . 7 " m o p i c i i a r p .

w , e h a s t a , k r v a ~ n n n n o

COPEPOD*

0 0

cn.anus ilnmarchirul E3 0 0 0 0 0 E d X B X 0 5 O K l O X D 0 0 8 0 B C 2 E 3

< r!anr. h,pc'bo'""s P s r ida'iirnua rp.

I l l c r * r r i i n u # p,,r.i,rs

C : l m C E L A AVOMULA

t.tialaa r p , iaivae 1 q 0 g% 0 B 0 0 B D O 0 0 0

Ponlaphii", s e x g t r t c r arctic".

-,as sp.

0 0 n$; X x q 0 0 8

D e i a o o d r ,"dc,.

*).,Ph-,POD*

Themisto a b y s m a r u m 0 0 x x x

>:yP"Orhe m e d u s a - o a n

*ms*ll.ia so.

'IRPIPEOI.4

Bd,anvr "a"p,,a X 0 x 0 0

Bnianul iyiir,.

I I s U u P B C r z , irrra*

srbs.t.. m . r i n u ~ @

c i s p e a haiengu. 0 0 X X 0 0 @

,*l!i0,", ",,lo.".

*mmraytcli rp. 0

Cadtdle 0 X

i l % e t L .

R l c e l i . e n .

8 8

0 o O a

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Table 5 (cont.).

. <,,>,.,,

- 4 6 9 6 39a 899 600 602 604 606 610 611 61s 617 61e 625 626 62S6%636 637 6 9 a1 642 &U 6 M 650 652?&6M 656 657 661 665 665-

,, d:oi'i

" 'P. @ 8 0 @ 0 0

o o o n O 0 x

0 0 0 0 0

A r i - o i i i i tumlda

i ; l c i ~ i a i i a barcrlis @ b o o B 0 @ 0 0 @ U @ O C , @

:D."Oyleiis sp.

-- -

"lrl>i>r

^...

^,hyp"1boir"a ^!^.^:^:^.^.^o o ~ f i n o e o a o . a ~ = a o a @ a a a m g E ^-^. ^-- ^-

Prri*orairnua IF. 0 0 0 X O n o O o O 3 0 0

*"iroiriZ"us wr>,,ur i i r i " " c ! l r r t r n a i w e g l c r

o n o x 0 0 0 0 0

'. mnorr i o n j i c e i n i s

*'art'" 'P.

> , ' t " d i n i o n g r

x

8

:.!rri2dir lui~ns q q x 0 o

8

0 o o d R ~

p,. .;amamma r b d a m l a i i ; l

oI? ^Om&6 j n l j j , s 0 0 0 X 0 X g

8

0 X o @ 0 0 ~ 0 8 $ $ 0 K x

a::,~e"a 3p,",ro*,r&s

0.j"F" - - O o r c l i l . q @ O X 0

U ; r r a s o f c i ! r r o i u . r g i i r X 0

. I I , I , . L , C I I I I . L*OI,

e u C E

i i , O i l . l i l" IliVi*

< I S I I W L O O *

,O IIIIDCCII I.. o o n o n w n n -.

. ..

-.rPliAUSIACE*

il.ga,,iliphana. n o r u e s i c *

x q

i . , i i ? o E r r a lnermlr

:-i.., ^., a ^u," ,,,, o

o y ~ , g o

~ 8 / 3 " O

g o

^,o a x

p

^q n , a 8 f j # a E --

:,ICAPODA i r r v a e

P a . ~ d a t ~ # s p , X

Po-ilaphlius 0

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Table 5 (cont.).

-ILL-- x

C A O O i i i A @ x x X 0 x B X X O ~ X X

.A\OL.*UP<',

\,>,.,,.~ ;,, ! < - \ " e

P a . % . J s s > o n 0 o x 8 n s o 0 o x

ilS T R l C O D i

? < . ' a i r s n,.