CM_1982_G_33.pdf (2.556Mb)

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This report not to be cited without prior reference to the Council*.

INTERNATIONAL COUNCIL FOR THE EXPLORATION OF THE SEA

C.M. ll)~Q/G: 33 Demcrsal Fish Committec Ref.: Pclagic Fish Committec

REPORT OF THE MEETING OF THE COORDINATORS OF THE NORTH SEA STOMACH SAMPLING PROJECT 1981.

ICFS

)>;d;~q.'.;llk 2 -l.

DK-12!.1 < < >Pl.NII.".< ,LN K.

Denmat!-.

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This paper not to be cited without prior reference to the Council INTERNATIONAL COUNCIL FOR THE

EXPLORATION OF THE SEA.

C.M. 1982/G:33

Demersal Fish Committee

REPORT OF THE MEETING OF THE COORDINATORS OF THE NORTH SEA STOMACH SAMPLING PROJECT 1981.

IJmuiden, 12 - 16 July 1982

1. Terms of reference

During the 69th Stat~tory Meeting in Woodshole, ICES adopted the fol- lowing resolution (C. Res. 1981/2 : 21):

(i ) member countries should collect stomach content data on saithe and mackerel in 1982 as a continuation of the programme agreed for 1981.

(ii) Coordinators for all species considered in the stomach sampling scheme should meet in IJmuiden for 5 days to prepare an interim report on the results of the sampling scheme for the 1982

Statutory Meeting.

2. Participation

The meeting was held ln IJmuiden from 12 - 16 July 1982. It was attended by:

N. Daan (Chairman) H. Gislason

J.R.G. Hislop J.G. Pope

~. Westgard o

Netherlands Denmark

UK (Scotland) UK (England) Norway

Mrs. J. Beaudouin, the coordinator for haddock~ was not able to attend the meeting. However, during the meeting a letter was received from Mr. B. Letaconnoux explaining the situation in respect of the stage of

analysis for this species as well as providing a description of

preliminary results. This letter was appreciated by the members of the Group.

3. Introduction

A good deal of progress has been made in the analysis of the stomachs collected in 1981 and the computer processing of the data. However, since the sampling intensity for the different species has been rather

variable and also because the amount of work involved in the primary analysis of the stomach contents varies with the specific feeding habits of each species, the progress that has been made varies considerably with the species. It was appreciated that in particular the large

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quantities of fragmented pieces of hardly recognizable benthic animals in haddock has held back the analysis of these samples. A fuller account of the situation is given in section 4 and in the sections presenting the results for individual species.

It should in general be made clear that at this stage only very preliminary results can be presented. Firstly, in the~process of exchanging samples between countries jars have been misplaced in the batches prepared for mailing and as a consequence samples are still turning up at odd places.

In fact, it has as yet not been possible to'trace the present location of the sets of samples taken by the G.A. Reay during the 4th quarter of 1981. Secondly, up to this stage the emphasis has been placed on the primary analysis and the primary processing by computer. In the latter process an important feature should be to check against input errors.

During the meeting it became evident that there are still input errors present in·the files and that the checking routines in the software have to be extended. Lastly the analysis programs available so far do not allow for a completely homogeneous analysis for all species and more effort is required in the near future to adapt the programs·. in this respect.

4. General information on sampling intensity

The numbers of samples and the total numbers of stomachs collected in 1981 are presented by species, quarter and country in table IV-1.

Only in those cases where the samples have been analysed are the number of samples and the corresponding number of stomachs accurately known.

In other instances the figures are approximate and have been placed in brackets.

Taking into account that the haddock figures for the last two quarters are largely underestimates, it is concluded that the target of 1500 stomachs per quarter has been exceded for cod, haddock and whiting in all instances. For mackerel and saithe the numbers sampled have remained well below the target in all quarters.

The number of stomaches sampled by size group, species and quarter are given in table IV-2. Sampling has been unsatisfactory for cod over

100 cm and whiting over 50 cm. Apart from the fact that the numbers of stomachs are generally low for saithe and mackerel, there is an almost complete lack of information for saithe below 4o cm and mackerel below 25 cm. All of these sampling deficiences result from the difficulty of catching sufficient numbers of these species and sizes in general purpose trawl surveys and there is therefore a need for programmes dedicated to this fish.

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TABLE IV-1 - Number of samples (n) and number of stomachs (N) by species, country and quarter.

Figures in brackets represent preliminary estimates.

Quarter Country C od Haddock Whiting Saithe Mackerel

n/N n/N n/N n/N n/N

1

Eng

195/ 861

⁽

84/ 250) 252/ 2066 19/ 187 3/ 19

Ger

108/ 431

⁽ ?

/1398) 99/ 688 16/ 51

Net

288/ 1861

⁽

212/1378) 336/ 2234 10/ 20

6/ 6

Nor

124/ 532

⁽

188/1228) 155/ 967 15/ 76 3/ 3

Se o

74/ 483

⁽

96/ 608) 115/ 2108

^l

2/ 2 ---

uss 38/ 192 --- --- ^--- ---

--- 1-:--- 1--- r---

^,_

___________

---

Total

827/ 4360

⁽

580/4862) 960/ 8063 62/ 336 12/ 28

2

Den

---

⁽

^{12/ 69)} --- ^{17/ 141} ---

Eng

112/ 431

⁽ ?

l

^? ⁾

^{40/ 268} 5/ 5 10/ 53

Net

253/ 1650

⁽

76/ 388) 221/ 1649 2/ 7 35/'208

Sco

84/ 355

⁽

192/1540) 153/ 2401 7/ 17

Nor

--- --- --- ^--- ^{42/ 310}

--- --- ---

^,_

___________

Total

449/ 2436

⁽

280/1997) 414/ 4318 31/ 170 87/ 576 3

Eng

73/ 536

⁽ ^?

l

^? ⁾

21/ 159 22/ 86 11 l 70

Ger

10/ 91

⁽ ?

l

^? ⁾ ⁽ ^6/

⁴⁹⁾

Net

176/ 1167

⁽

55/ 338) 165/ 1243 69/ 434

Nor

16/ 77

125/ 539

⁽

51/

^? ⁾ ⁽

44/ 862) 3/ 201 12/ 115

36/ 178

⁽

234/

⁾ ⁽

131/ 478) 1/ 1

Quarter Spe eies Size group

7-10 10-15 15-20 20-25 25-30 30-40 40-50 50-70 70-100 1 C od 1 113 253 532 610 854 460 557 683

.Haddock not available

³⁷ ¹⁸⁰ ³³⁰ ³⁷⁰ ⁵³⁸ ³⁹¹ ³⁹² ¹⁸⁰

Haddock not available

Whiting

*

^- ⁴²⁸ ⁷⁶⁵ ⁹⁴¹ ¹¹⁹⁶ ⁹³¹ ⁵⁷

- -

Saithe

-

^- ^-

- -

¹⁴ ⁶ ⁴² ¹⁰⁵

Mackerel

- -

³ ²³ ⁴⁹ ²⁵² ²¹⁷

-

^-

3 C od 90 355 232 87 186 372 347 367 260

Whiting

* -

¹⁸⁰ ²⁰³ ³⁷⁶ ⁴²⁰ ³⁶³ ²⁸ ² ^-

Saithe -

- - -

^- ³⁹ ⁴⁸ ⁶⁰ ⁵³

Mackerel

- - -

³³ ²⁷⁵ ⁵⁵⁰ ²⁰⁹ ^- ^-

4 C od 1 177 199 198 223 384 334 358 300

Whiting

*

not available

Saithe

- ^- -

^- ^-

^-

⁴⁶ ⁸² ⁷⁸

Mackerel -

- - -

³³ ²¹³ ⁵⁸

-

^-

*

In the case of whiting the values represent the numbers of stomachs examined to date.

100-150 117

- 16

- 19

-

3 - 49

-

4 - 53

166 -

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5.1. Cod

The stomach samples of cod (table IV-1 and fig. 5.1.1.) have all been analysed and stored on computer files. However, output is only

available for the first two quarters of 1981, because, in the process of weighting samples taken in individual squares according to the abundance of the different size classes in those squares, output lS

required from another program dealing with survey data and the

analysis of the survey data from the 3rd and 4th quarter has not yet been completed.

Tables V-1 and V-2 present summaries of the information for the 1st (Q1) and 2nd quarter (Q2) respectively. Although these data cannot be readily compared with similar information for 1980 (DAAN, 1981) because the earlier set applied only to cod feeding in Roundfish Area 6

averaged over the year whereas these tables refer to the total North Sea, they both indicate similar trends in "preferred" size classes of prey and in the amount of fish prey with size of cod.

The percentage consisting of commercial fish species amounted to over 50% in large cod in Q1, but this component was considerably reduced in Q2 ( fig. 5. 1 . 2. ) .

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TABLE V-1

STOMACH CONTENT DATA FOR COD BY SIZE CLASS - 1st QUARTER 1981 Size class

n Sauares samPled N Stomachs

/. En1Pt'::l Mean N/ho1Jr Mean Lensth

Mean W Stomach Contents Mean N of Pre'::! Orsanisms Averase W Per Pre'::! Item

7-10 10-15 26 113 10,0 4 '5 13,3 0.60 2.83 0.21 Food ComPosition

PHAEOF'HYTA CNIDARIA RHYNCHOCOELA ANNELLIDA GASTROPODA BIVALVIA SCAPHOPODA CEPHALOPODA PYCNOGONIIIA CRUSTACEA SIF'UNCULA ECHIURA PRIAPULIDA ECHINODERMATA CHAETOGNATHA UROCHORDATA CEF'HALOCHORDATA AGNATHA

GNATHOSTOMATA

in Weisht X b\:1 MaJor Taxal

Wei9ht /. Commercial sPeciesl COD

HADDOCK WHITING NORWAY F'OUT HERR ING SF'RAT SANDEEL PLAICE SOLE LEMON SOLE DAB

NORWAY LOBSTER BROWN SHRIMF' PANDALUS

1 '02 13.27 6.15 7' 16

32.57

39.83

1 '49

9.20 0.83

25.33 1 '21 Size Class

Esss

Distribution Pre\:! in Number z:

<=7 111114

7-10 ^flllfl 10-15 fiiiTl

15-20 mnl 20-25 ^fllfll 25-30 fllfll

30-4 o ^{fli Ill}

40-50 fllfll

50-70 11111\

7-10 c~

10-15 cm 15-20 cm 20-25 cm 25-30 cm 30-40 Cfl1

Not known

18.37 0.91 44.08 0.31 0.45 0.61 9.45 5.65 4.80 0.94

14 '41

15-20 48 253 10.7 12.7 18,3 0.92 2.18 0.42

8.09 7.75 4.59

55.02

0.02

24.54

8.09 0.29

46.48

o.oe

6.99 2.87 25.40 1.94 3.17 1.58 15.82 16.55 8.25 1.52

15.92

20-25 69 532 11. 9 20.1 22.6 1. 51 2.56 0.59

0.07 5.05 2.60 20.08 0.88 0.32 36.09 0,04 0.02 0.09

o.oo

~4.76

0.27 o.oo 3.05

~2.83

1.50

0.19 0.25 22.54 0.26

0.56 5.81 6.50 13.20 3.53 6.36 3.20 6. te 12.18 11 .13 3.89 0.49

27.16

25-30 76 610 13.7 16.1 27.3 t.89 4.31 0.44

o.o5 o.o1 9.t8 2.40 7.35 5.84 o.58 37.78 0.50 0.30

o .16 0.04 35.82

'2.58

o.o::;

6.09 0.61 3.56 o. 40

0.03 0.29 3.81 3.11

0.53 4.86 7.13 32.87 6.89 13.72 4.01 5.86 2.98 5.54

,1.

⁷¹

1.04 0.28

12.57

30-40 96 854 11.2 14.6 34.2 5.45 5.11 1.07

0.28 12.30 3.66 8.71 o.oo 3.03

~1. 71 0.42

o' 12 0.24

o.o8

o.o8 0.03 39.32

0.49 2.22 8' 15 3.24 0.05 13.80

~.22

o. 1 o

0.55

o.o8

1. 64 1.84

L 91 4.93

25.~3

6.81

3.7~

8,08 10.18 5.48 3.83

4.~8

3.09 0.09 0.02

22.15

40-50 69 460 12.3 10.9 44.3 16.84 4.82 3.49

0.09 7.85 0.51 2. 1 ~

0.33 49.77 0.75 0.04 1.06

0.06 37.41

0,35 1. 45 3.70

1. o 1

3.01 1.53 9.83 0,07 6.56 0.41 1 '01 o' 13

0.25 1. 24 4.81 4.09 3.93 10.79

~6.76

7.70 8.71 6,40 7.66 1.40 0.44 0,05 15.77

- 6 -

50-70 70-100 >=100 90

557 19.5 5.9 59.2 33.58 5.04 6.66

o.o1 o.o8 4.78 0.37 0.34 o.oo 0.67 13.44 0.56

o.oo 78.51

2.60 7,80 16.39 6.83 4.58 1.38 26.80

o. 14 o.oo 6.12 1. 73 0.41 0.97

6,95 0.30 0,39

7.78

2.34 5.56 4.00 6.91 5.71 6.32 8.01 16.01 9.37 7.85 0.42 0.23 l l . 85

93 682 14.5 5.6 82.8

40 117 1 '8 107.7 66.47 138.16 4.88 5.95 13.61 23.22

o.oo 0.07 2.66 0.25 0.23 0.42 9.54 o.oo 0.01 0.05 o.oo

82.63

5.19 21. 19 28.03

6.~1

2.87 3.13 0.43 0.71 0.81 0.46 7.39 4.14 0.24

o.o7

6.87 0.27 0.32 0.96 3.03 5.63 8.86 4.55 7.00 12.97 16.51 10.05 6.17 2.38 0.35 10.53

0.84 0.32

o' 15 0.29 7.39

0.08

90.92

13.49 1. 76 28.46 1 , Bl 3.21 1. 33

o.o3

4. 15 8. 15 15.04 1. 94 0.01 o.oo

o.o6 o .11 3.26 3.60 7.24 2.51 5.67 10.28 15.75 19.05 12.33 4.02 2.39 13.74

=============================================================================================================

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TABLE V-2

STOMACH CONTENT DATA FOR COD BY SIZE CLASS - 2nd QUARTER 1981 Size class

n Sauares samPled N Stomachs

X En1Pt\:!

Mean N/hour Mean Lensth

Mean W Stomach Contents Mean N of Prew Orsanisms Averase W Per Prew Item

7-1() 10-15 7 37 35,8 1. 3 13.5 .26 2.02 .13 Food CoiiiPosition in Weisht ~ bw MaJor Taxa:

CNIDARIA

ANNELLIDA 9.67

GASTROPODA BIVALVIA SCAPHOPODA CEPHALOPODA CRUSTACEA SIPUNCULA ECHIURA F'R I AP ULI DA ECHINODERMATA CHAETOGNATHA UROCHDRDATA CEPHALOCHORDATA GNATHDSTOMATA

Weisht X Commercial sPecies:

COD HADDOCK WHITING SA !THE NORWAY POUT HERR ING·

SPRAT SANDEEL F'LAICE SOLE DAB

NORWAY LOBSTER BROWN SHRIHP PANDALUS

58.72 3.19

28.43

4.70

Size Class Distribution Prew in Number x:

Esss

<==7 ffilll

7-1 o 1!111'1 10-15 111111

15-20 mm 20-25 111111

25-30 111111

30-40 ffilll

40-50 111111

50-70 111111

7-10 cm 10-15 CIJI

15-20 CITI

20-25 cm 25-30 cm 30-40 CITI

40-50 ^CIT1 Not known

18.32 4.27 26.11 0.92

6.56 9.01 2.60

27.94

26 180 1813 14. 1 1817 178 3106 .25

4 ^l1 o

2131 3162

55188 0102

0122 0101 33184

1127

1. 69 0101 15129

0156

38.58 0130

13.66 0.76 12129 7196 7146 11 l o 1 6101 13124 11127

16133

20-'25 44 330 1917 46.4 2219 1. 19 2.85

l 42

22166 2125 7.29 0102 45.43 0.06

().15 21185

0120

0127 (),06 1.34 1:3.90 0101 0156

8.44

3.98 1. 91 3.34 37.66 2.85 4.20 4.72 4.96 3.11 8.85 0.71 1.13

22.58

25-JO 50 370 12.7 51.3 27.4 2.69 6.65

• 41

10.60 1. 52 1.47

o .10 35.30

o~o1

0.04

o.o5

3.04

47.88

0120 0.33

o. 15 0.35 4:3.()5

0.27

4198 0.34

0.05 1.54 2.51 14.26 3.30 2.73 32.77 1.76 10.90 14.46 2.65 1. 42 0.04 (),00

11.61

30-40 74 538 11 • 1 25.4 34.5 7.96 12.70 163

o. 13 4.27 2.84 0.93

o~oo

0101 9.99 0.09 47.24

0.63 1. 29 0112 0.88 0.26 6.02 34.92

o.oo

0.47 0.08 0.67 0.88

30.67 3.26 0163 4.19 2.55 6.21 22.61 2.99 1.46 13.54 6.70 1. 78 0.20

o.oo

0.01

40-50 58 391 10.4 19.5 44.2 14.99 7.82 1. 92

0.09 8.44 3.75 0.22 0.02 36,31

0104 16.81

o.oo

34.32

0.34 0.72 1.08 0.21 0.44 1. 25 3.23 l.9.39

o.oo o ^l1 o

1.25 0.21 0.59 0.34

2.36 0.54 2. 16 3.38 16.84 11.05 21.47 3.01 4.40 18. 12 6.31 2.89 2.22 o .10

5 l 16

- 7

50-70 70-100 65

392 9.0 8.6 57.8 34.70 11.05 3.14

0.04 3.39 0.03

o. 17

o.oo o.o2

29.48

0.02 4 .12

62.75

4.22 3.30 3.62 2.87 1.64 2.64 l.0.94

o. 16 0.07 21175 3.48

o.oo

0.29

0.74 0.03 0.82 4.78 10.79 45.24 5. 40 1.28 8. 13 4.54 6.36 5.89 1.08

4.92

44 180 1. 8 3.9 81.2 112.53 137.95 0.82

0.13 4.20 0.06

0.13 41 .13

0.01

54.33

6.75 2.65 8.30 2.82 4.08 0.93 5 .t'l2

12.14 8.32 0.01

0.03 0.03 6.32 86.68 0.93

o.o7

2.34 1.67 0.94 0.49 0.31 0.07 0.01

o. 13

>==100 13

o.o 19 1. 3 105.5 158,18 11.85 13.35

12.45

o. 13 26. 12

61.31

0.26 11 • 73 0.35 2.83 3.39 1.42 2.50 13.20 14.79 0.02

o. 19

0.32 2.92 13.31 1. 46 5.03 15.62 16.59 32,98 5.52 0.97 1. 4 6 0.49 2.84

=========================~=============================~=====================================================

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j j j j j j j j j j j j j j j j j j j

j j j j j j j j j

j j j j j j j j

j j j

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Fig. 5. 1 . 2.

Cod: Percentage weight of various prey groups by predator size class

A - 1st Quarter B - 2nd Quarter

A

_1oo%

L~f~Ja,:

uTfiER TAX/1 OTHER C!<USTflCER

~

COinmERC/1/L CRLJST

~::~:r~~H F!SH

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o% fl~·.·.·.·.·;··~·

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l

^l

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CD l

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5.2. Haddock

An estimate of the numbers of samples of stomachs collected during each quarter of 1981 is given in table IV.1. The French workers have

experienced some difficulties in the analysis and processing of the large amount of material sent to Nantes and the current situation is that approximately 2000 stomachs collected during the first quarter have been analysed and the data from 1200 of these have been filed ln the computer. In addition, a further 4oo stomachs collected during the second quarter have been analysed, but the data have not yet been computerized.

The preliminary impression from the material that has been analysed to date is that the food of haddock consists mainly of polychaetes,

echinoderms and crustaceans and rather small numbers of fish (mainly sandeels, Norway pout, sprats and Maurolicus).

5.3. Whiting

The numbers of whiting stomachs collected by each country in each quarter of 1981 are given in table IV.1. The total number of stomachs collected was approximately 17650 and of these nearly 14000 (representing all the material collected during Q1 and Q2, and most of the material collected during Q3) have been processed and the data filed in the Aberdeen computer. The geographical distributions of the samples that have so far been analysed are shown in fig. 5.3.1 ., for Q1 and Q3 respectively, and the numbers of stomachs of each size group that have been analysed in each quarter are given in table IV.2. Unfortunately, as difficulties have been experienced in developing programs for the retrieval and tabulation of the data, no outputs were available for

consideration by the Working Group. It is hoped that the remaining stomachs will be analysed and the output programs perfected, befare the end of

1982.

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CM_1982_G_33.pdf (2.556Mb)

1

195/ 861

84/ 250) 252/ 2066 19/ 187 3/ 19

108/ 431

/1398) 99/ 688 16/ 51

288/ 1861

212/1378) 336/ 2234 10/ 20

124/ 532

188/1228) 155/ 967 15/ 76 3/ 3

74/ 483

96/ 608) 115/ 2108

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827/ 4360

580/4862) 960/ 8063 62/ 336 12/ 28

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12/ 69) --- 17/ 141 ---

112/ 431

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40/ 268 5/ 5 10/ 53

253/ 1650

76/ 388) 221/ 1649 2/ 7 35/'208

84/ 355

192/1540) 153/ 2401 7/ 17

--- --- --- --- 42/ 310

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449/ 2436

280/1997) 414/ 4318 31/ 170 87/ 576 3

73/ 536

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10/ 91

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49)

176/ 1167

55/ 338) 165/ 1243 69/ 434

16/ 77

l 364) 29/ 170 14/ 117 73/ 543

97/ 499

312/

134/ 556) 1/ 1

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368/ 2370

367/ 702)

355/ 2177) 37/ 204 153/1047

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128/ 707

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