CM_1995_H_7.pdf (1.084Mb)

International Council for the Exploration of the Sea

CM 1995/H:7 Pelagic Fish Commitee

Ref.B

INVESTIGATIONS ON BLUE WHITING IN THE AREA WEST OF THE BRITISH ISLES, SPRING 1995

by

Terje Manstad

Institute of Marine Research P.O.Box 1870, Nordnes, N-5024 Bergen

Norway

Sergei V. Belikov and Eugene A. Shamrai

Polar Research Institute of Marine Fisheries and Oceanography (PINRO), 6 Knipovich Street, 183763 Murmansk

ABSTRACT

Rus sia and

Ian R.B. McFadzen Plymouth Marine Laboratory Prospect Place, Plymouth, PL1 3DH

UK

In March/April 1995 the fifth Norwegian-Russian joint acoustic survey on the blue whiting spawning stock was carried out. The shelf edge area to the west of The British Isles was covered by two vessels in a general south-north direction. A ship-to- ship calibration of the acoustic instruments justified a 1:1 relationship between the vessels when combining the acoustic data.

The biomass of the observed blue whiting stock within the area surveyed was estimated to 6.9 mill. tonnes. Of this, the

spawning stock constituted 6.1 mill. tonnes. The 1994 year class was found to be the richest one contributing with 27% in numbers.

As the survey also was part of the SEFOS programme, plankton stations were carried out throughout the whole area for

studies of blue whiting eggs and larvae.

The hydrographic situation in the surveyed area was similar to the one observed in 1993.

2 INTRODUCTION

The fifth succesive joint survey on the blue whiting spawning stock was carried out during the period 22 March-25 April 1995, by research vessels from IMR, Bergen and PINRO,

Murmansk. The main objectives of these surveys are to obtain acoustic estimates of the blue whiting spawning stock size and to record the distribution and migration pattern in relation to the hydrological situation, as well as record the structure and composition of the stock.

For the years 1990-1993 except 1994, both countries carried out these investigations together (Monstad and Belikov, 1990, 1991, 1993; Monstad et al., 1992). In 1994 the survey was worked by Norway alone (Monstad et al., 1994).

The Norwegian survey in 1995 was also included in the EU-

project SEFOS (Shelf Edge Fisheries and Oceanographic Studies) and personnel from Plymouth Marine Laboratory, England,

participated onboard the R.V. "Johan Hjort" for studies of blue whiting eggs and larvae.

MATERIAL AND METHODS

One research vessel from each country paticipated within the following time period and geographical area (latitudes):

Russia: R.V. "Fridtjof Nansen", 22.03-24.04, 48°30'-62°00'N.

Norway: R.V. "Johan Hjort", 27.03-24.04, 50°30'-62°00'N.

Both vessels operated Simrad EK-500 echo sounders of 38 KHz frequency with settings as given in Appendix I. The instru- ments were precalibrated by use of a copper sphere (Foote, 1981) and a ship-to-ship calibration was also conducted. It took place along the shelf edge northeast of the Hebrides during daytime the 15 April, over a distance of 46 nautical miles. After comparison of the recordings from 100-300m and calculation of the values, i t was concluded that the

relatonship between the two vessels' integrator values obtained during spring 1995 should be 1:1.

The shelf edge area west of the British Isles was surveyed from 48°30'N northwards to 62°00'N, including the Porcupine bank (Figs. 1 and 2a-b). In addition to daily radio communi- cation with exchange of cruise inforrnations, the two vessels also met twice for exchange of the data obtained and

preiminary results ready prepared so far.

Pelagic as well as bottom trawls were used for identifying the echo traces and collecting biological samples. The Norwegian vessel used a Rock-hopper bottom trawl of 18 x 4 m opening and a pelagic trawl with 25 m vertical opening, both having inner- net in cod end of 11 mm mesh size. Russia used a pelagic trawl with 45 m vertical opening and innernet of 16 mm mesh size.

For the assessent of abundance and biomass the area surveyed

3

was treated on maps as 5 separate subareas. These again were divided into rectangles of 0.5 deg. latitude x l deg. longitude size. The acoustic method used for the stock size calculation was the same as used for the previous blue whiting surveys, described in eg Monstad (1986) and Belikov et al. (1990).

The target strength value

TS

=

21.8 log L - 72.8 dB

was used, where L is fish length. For a 30 cm fish (cod) this equals the length dependent density coefficient of

Separate estimates of blue whiting abundance and biomass were made by either country and combined on subarea basis.

For investigation of blue whiting eggs and larvae, R.V. "Johan Hjort" carried out plankton sampling at a number of 57

stations by means of double oblique tows with a 60 cm diameter bongo net (180~ mesh size) at 2.5 knots towing speed (Fig.

3). Maximum depth sampled was to 400 m but with most hauls sampling to lesser depths around 150-200m. Preservation was in 3.5% buffered formaldehyde solution with the sample from one cod-end being subsequently analysed for eggs and larvae.

The hydrological situation was observed by use of CTD-sonde at a net of stations, including 8 standard SEFOS-sections. Two of these were worked in Norwegian waters during the last period of the cruise, i.e. outside the blue whiting spawning area.

At the very end of the survey, the 24 April, the two vessels roet for exchange of data and separate results.

RESULTS

Distribution

The distribution pattern of blue witing was found to be alike the ones obtained in earler years during same periods.

Concentrations were recorded along the continental slope from south of Ireland at latitude 48°30'N, to the Faroe-Shetland area at latitude 60°00'N. Fig. 4 shows both the Russian and the Norwegian observed distributions of the blue whiting stock.

The Russian vessel operated in the southern Porcupine bank area 3-4 days before the Norwegian vessel, but in rest of the surveyed area the opposite situation was the case.

The densest concentrations were recorded the 5-6 April near the slope of the northern part of the Porcupine bank, between the latitudes 54°00'-54°30'N and the longitudes l2°00'-l3°00'W.

Approximately a week later these heavy recordings had moved northwards along the slope to between the latitudes 55°00' and 56°3 O' N.

To a great part the blue whiting appeared in a 25-50m thick

4

layer of varying density. Off the slope this layer was mainly recorded between 450-550m depth, but sometimes also as deep as 750m. Near the slope i t fellow the bottom up to 300-200m depth where the recordings ended.

Stock size

The countries separate estimates of the total biomass and abundance, as well as the mean length and weight at age, are given in Tables 1 and 2. The combined results of the acoustic assessment for each subarea and total, are given in Table 3.

The total biomass estimated was 6.9 mill. tonnes with the abundance of 67.4 x 10⁹ individuals. Of this 6.1 mill. tonnes representing 45.5 x 10⁹ individuals belonged to the spawning stock. The biomass estimates on a rectangular basis are shown in Fig. 5 for Russia and in Fig. 6 for Norway.

Compared to the latest years, the weather conditions were very favorable, and a rather "good" coverage of the spawning stock was obtained. Due to the fact that the period of pre- and postspawning migration is longer than the survey period, acoustic measurements of the stock in the spawning area must be considered as underestimates. The 1995 result of 6.1 mill.

tonnes, however, can be regarded as a lesser underestimate than obtaind for many years.

In the text-table below the acoustic estimates of the spawning stock since 1991, are shown. Except for 1994, when Norway

surveyed the stock alone, these are the combined Russian- Norwegian results.

Abundance Biomass N X 10⁹ 1000 t

1991 35.2 4.4

1992 36.9 4.3

1993 39.3 4.9

1994 26.8 4.1

1995 45.5 6.1

The difference of 2 mill. tonnes from 1994, is partly due to the significant underestimate that year when the weather conditions were extremely bad (Manstad et al., 1994) and partly due to increased recruitment to the stock.

Stock composition

The total age and length composition of the blue whiting

stock, as observed respectively by Norway and Russia and their combined result, are shown on Fig. 7. By numbers one year old blue whiting dominated, especially in the Faroe-Shetland

area, but was absent off the Hebrides. Totally, the yearclass (1994) made up almost 30% of the stock, which is the highest contribution recorded for one year olds during similar surveys in the area. Among the adults, the 1992 yearclass was most

5

numerous, but the 1989 yearclass, which has predominated the spawning stock since 1991, still contributed significantly.

Hydrography

A meteorological situation in the studied period was caused by anticyclonic atmosphere processes and winds of SW- and W

directions with predominating speeds of 6-8 m/s. Atmosphere pressure changed within 1014-1038 mb range. Synoptic situation during the survey was generally favorable for works.

Horizontal distributions of temperature at sea surface, 200, 400 and 600m depths are presented in Figs. 8-11. This year, maximum temperatures (11.1° C) were noted in the southern part of the surveyed area where they were higher in the 0-200m

layer than in 1994. At horizons of 400 and 600m in the south- eastern part of the area, the temperature was higher than last year. Temperature distribution in the sea surface of the whole area was analogous to that of 1993.

On the section of 53°N in the 0-200m-layer (Fig. 12), the temperature was lower than mean temperature in March-April of 1983-1991. Characters of distribution and temperature values were analogous to that of 1993. Salinity values within the

section ranged from 35.1-35.3 °/oo at 1000m depth to 35.3- 35.4 °/oo at sea surface (Fig. 13).

The Faroe-Shetland section (Fig. 14) was made the same way and revealed a very expressed temperature stratification:

temperature changed from 8° to 0° C from surface to 500m.

Deeper, the temperature had negative values that are typical for deep waters of the Norwegian Sea. In the 0-200m layer of coastal part, where a channel line of the North-Atlantic

Current is located, water temperature increased from 5-6° to 8°

C. Water temperature in 0-500m and 200-500m layers turned out to be 1.4° and 1.8° C, corringspondingly lower than for 1987- 1993. The salinity in the section varied from 34.9 °/oo at bottom to 35.1-35.2 °/oo at sea surface (Fig. 15).

Eggs and larvae

Of the eggs, those of blue whiting comprised 40% of all eggs taken, with eggs of mackerel being present at similar levels overall (37%). However, the abundance of mackerel eggs was biased by being particularly numerous on a few stations over Porcupine Bank. Excluding these stations the percentages

occurence of eggs was 63% for blue whiting and 12% for mackerel.

Of the larvae, those of blue whiting were overwhelmingly the most abundant (89% of all larvae taken) with larvae of other species being present at levels between 1% and 2%.

Blue whiting eggs were numerous throughout the sampled area except to the north of Scotland where spawning may not have

commenced (Fig. 16). Since the sampled depth did not include the full depth range of eggs (Coombs et al., 1981) i t is probable that the concentrations as plotted are under-estimates.

Larvae of blue whiting were taken mostly at the same stations as

6

the eggs, but with relative higher concentrations around Porcu- pine, indicating that spawning had taken place for a longer period of time in that area than to the west of Scotland (Fig.

17). Under-sampling of larvae was probably of less significance than for the eggs.

The blue whiting larvae ranged from 2.0-7.5mm in length (Fig.18) with a mean of 3.75mm. Larvae larger than 4.5mm predominated over and to the south of Porcupine Bank, indicating that

spawning had been in progress for at least a few weeks in those areas. West of Scotland the blue whiting larvae were predomi- nantly smaller than 4.0mm in length.

REFERENCES

Belikov, S.V., Mahon, D.M. and Molloy, J. 1990. Results of blue whiting investigations in the northeast Atlantic in

spring 1990.ICES, Doc. C.M. 1990/H:38.

Coombs, S.H.,Pipe,R.K. and Mitchell C.E. 1981. The vertical distribution of eggs and larvae of blue whiting (Microme- sistius poutassou) and mackerel (Scomber scombrus) in the eastern North Atantic and North Sea. Rapp.P.-v.Reun. Cons.

int. Explor. Mer., 178, 188-195.

Foote, K.G., 1981. Echo sounder measurements of back-

scattering cross sections of elastic spheres. Fisken oo Havet, Ser. B, 1981 {6). Institute of Marine Research, Bergen.

Monstad, T., 1986. Report of the Norwegian surveys on blue whiting during spring 1986. ICES, Doc. C.M. 1986/H:53.

Monstad, T. and Belikov, S.V. 1990. Preliminary report of joint Norwegian/USSR acoustic survey of the blue whiting spawning stock west of the British Isles, spring 1990.

Working paper for the Blue Whiting Assessment Working Group meeting, September 1990.

Monstad, T. and Belikov, S.V. 1991. Report of the joint

Norwegian-Soviet acoustic survey on blue whiting, spring 1991. ICES, Doc. C.M. 1991/H:4.

Monstad, T., Borkin, I. and Ermolchev, V., 1992. Report of the joint Norwegian-Russian acoustic survey on blue whiting, spring 1992. ICES, Doc. C.M. 1992/H:6.

Monstad, T. and Belikov, S.V. 1993. Report of the joint Norwegian-Russian acoustic survey on blue whiting, spring 1993. ICES, Doc. C.M. 1993/H:10.

Monstad, T., Belikov, S.V. and Commbs, S.H. 1994.

Investigations on blue whiting in the area west of the British Isles, spring 1994. ICES, Doc. C.M. 1994/H:12.

7

APPENDIX I

Acoustic equipment and settings of the instruments:

Echo sounder:

Frequency:

Transducer:

Absorption:

Pulse length:

Band width:

Max power:

Angle sensivity:

2-way beam angle:

Sv Transducer gain:

TS Transducer gain:

3 dB Beam width:

Range:

Johan Hjort Simrad EK-500 38 kHz

ES-38B-SK 10 dB/km Medium (l ms) Wide (3. 8 kHz)

2000

w

21.9 dB -21.0 dB 28. O dB 27.7 dB 7.2 dg lO O Om

Fridtjof Nansen Simrad EK-500 38 kHz

ES-38 10 dB/km Medium (l ms) Wide (3. 8 kHz) 2400

w

21.9 dB -21.1 dB 23.4 dB 23.4 dB 7. 3 dg 500m

Table l . Abundance estimate of blue whiting in the n·orthen stock, i.e. 48°30'-62°00'N, west of the British Isles, March/April 1995. R.V. "Fridtjof Nansen", Russia

Length Age

cm l 2 3 4 5 6 7 8 9 lO 11+

15 180.2

16 2189.5 17 5363.7

18 4684.5 344.5 19 3720.3 117.5 20 2853.9 229.0 21 1010.1 332.6 22 513.8 516.9 23 244.0 476.4

24 69.8 831.4 220.6 103.5

25 2117.1 540.2 107.2

26 2234.1 1780.6 209.5

27 1764.4 2440.4 978.8

28 460.1 2975.9 1183.9 428.0

29 47.7 2621.4 1332.4 859.5

30 20.4 1191.2 2424.1 1067.7 52.0

31 454.8 1390.0 1403.4 282.5 98.9 6.7

32 346.9 1209.3 2338.9 572.7 41.1 8.3

33 76.1 775.0 1189 .. 5 649.9 149.3 35.9

34 8.8 262.2 727.5 356.7 137.2 46.9

35 52.2 643 .. 7 247.3 193.0 75.3

36 117.5 288.6 101.6 88.6

37 127.4 127.4 131.4 37.5 4 6 .. 8 14.3

38 39.0 45.5 97.6 43.1 42.6

39 28.0 73.1 13.4 15.8

40 64.8 38.5 17.3

41 4.5 123.7

42

43 8.6 8.6

44 5.4

45

Total 20829 .. 8 9492.0 12656.8 10028.0 8942.1 2650.6 1092.5 408.2 131.1 14.3 123 .. 7 Length 18.3 24.8 28.0 29.9 31.8

...

. 33.5 35.3 36.2 38.4 37.0 41.0 Biomass 742 .. 5 815.7 1466.6 1388.0 1463.5 502.7 247.2 99.6 38.2 3.8 41.7 Weight 35.6 85.9 115.9 138.4 163.7 189.7 226.3 244.1 291.2 264.0 337.2

e.F. 5.8 5.6 5.3 5.2 5.1 5.0 5.1 5.1 5.2 5.2 4.9

number biomass weight C.F ..

10"6 10"3 g

180 .. 2 3.6 20.0 5.9 2189.5 53.1 24.3 5.9 5363.7 155.0 28.9 5.9 5029.0 163.3 32.5 5.6 3837.8 145.2 37.8 5.5 3082.9 146.0 47.4 5.9 1342.7 69.8 52.0 5.6 1030.7 56.9 55.2 5.2 720.4 48.2 67.0 5.5 1225.2 97.5 79.6 5.8 2764.5 238.1 86.1 5.5 4224.2 405.2 95.9 5.5 5183.6 550.9 106.3 5.4 5047.9 574.9 113.9 5.2 4861.0 607.5 125.0 5.1 ^CD 4755.3 659.8 138.8 5.1 3636.3 545.0 149.9 5.0 4517.3 743.2 164.5 5.0 2875.6 515.5 179.3 5.0 1539.2 301.5 195.9 5.0 1211.5 259.2 213.9 5.0 596.2 133.9 224.~ 4.8 484.8 128.0 264.0 5.2 267.8 72.2 269.6 4.9 130.3 41.7 320.0 5.4 120.7 40.8 338.3 5.3 128.3 43.3 337.2 4.9 17.3 6.9 398.0 5.0 5.4 3.4 620.1 7.3 66368.9

25.7

6809 .. 6

102.6 6.0

Table 2. Abundance estimate of the blue whiting stock west of the the British Isles, March/April 1995. R.V. "Johan Hjort .. , Norway.

-Jurnbers : N x 10 Exp-6 Mean length : Cm Biomass: Tonnes x 10 Exp-3

1ean weight : Gram Condisjon : 1000 x weight/length Exp+3 ^{--. ~·.}

Age years · Mean

Length l 2 3 4 5 6 7 8 9 lO 11 12 13 14' 15+ N Biornass weight

cm

.0-13.9 3 3 . l 28.0

.0-14.9 \

o . o .o

.0-15.9 27 27 .5 18.7

. 0-16·. 9 1156 1156 25.7 22.2

.0-17.9 4426 ^... 4426 115.0 26.0

.0-18.9 3324 3324 103.3 31.1

.0-19.9 2938 2938 108.8 37.0

.0-20.9 1716 54 1770 78.2 44.2

. 0-21.9 1248 643 ^1-• 1891 96.6 51.1

.0-22.9 832 444 , 1276 74.5 58.4

.0-23.9 115 894 1009 69.3 68.7 ^lO

.0-24.9 1752 184 1936. 144.4 74.6"

.0-25.9 2664 797 64 3525 298.4 84.6

.0-26.9 1423 1369 126 52 6 2976 282.5 94.9

.0-27.9 610 2322 444 235 81 3692 387.8 105.0

.0-28.9 20 2412 809 654 184 4079 470.7 115.4

.0-29.9 34 1641 1(371 1016 987 186 5735 742.9 129.5

.0-30.9 747 2113 1418 1831 113 6222 869.8 139.8

.0-31.9 336 1462 1677 1247 286 16 5024 763.2 151~9

.0-32.9 66 683 1097 2620 386 295 25 2 5174 864.5 167.1

.0-33.9 249 279 1260 123 132 51 38 2132 385.1 180.6

.0-34.9 85 250 687 262 166 39 32 1521 298.8 196.5

.0-35.9 125 336 197 197 82 72 14 1023 233.9 228.6

.0-36.9 16 138 127 149 117 59 606 141.8 233.9

.0-37.9 42 83 67 87 18 18 315 80.1 254.3

.0-38.9 7 31 10 76 124 35.1 283.3

.0-39.9 17 31 17 65 20.4 313.3

.0-40.9

o . o . o

.0-41.9

o .o . o

.. 0-42.9 57 57 22.6 396.0

.mber : 15785 8538 9874 7906 6861 9467 1795 1083 . 482 149 48 38

o o o

62026 length: 18.96 24.93 28.12 30.28 31.01 32.04 33.23 34.67"•36.81 36.14 34.71 33.50 .00 .00 .00 26.90 .ornass : 551.5 677.51099.01081.11018.31553.1 327.3 230.4 125.0 33.5 9.7 7.8

. o .o .o

^6714.0

weight: 34.9 79.3 111.3 136.7 148.4 164.1 182.4 212.7 259.3 224.8 201.5 204.0

.o .o .o

108.2 Cond.: 5.0 5.1 5.0 4.9 4.9 4.9 4.9 5.1 5.1 4.7 4.8 5.4

.o . o . o

5.0

Table 3. Assessment factors of blue whiting to the west of the Britsh Isles. Combined results of R.V ... Johan Hjort ..

(Norway) and R.V."Fridtjof Nansen" (Russia).

Sub Latitude Square Abundance N x 1

o·

^{6 Biomass t X} 1 0"³

area north nautic

miles lmmature Mature Sum lmmature Mature Sum

l 48°30'- 51 °30' 5846 7344 2515 9859 229 314 543

11 51 °30'- 53°30' 12862 4656 8674 13330 161 1273 1434

Ill 53°30' - 55°30' 5661 7480 18611 26091 270 2501 2771

IV 55°30' - 58°30' 4800 145 11037 11182 8 1531 1539

V 58°30' - 62°00' 7436 2259 4648 6907 110 530 640

All sub areas 36605 21884 45485 67369 778 6149 6927

~--

Mean Mean

weight length (g) (cm) 56,8 20,7 107,6 26,1 106,1 26,7 136,8 29,9 92,5 24,9 102,9 26,0

Density tonn es/

sq.n.mile 93 111 489 321 86 189

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50

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Russian result 22 March-23 April. Hatched line:

Norwegian result 27 March-18 April.

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48 L_l__j___L__j__.J___J___j____L___.l___l____t__--L:---l..._~~~___:,_~_..__~ 48

-18 -16 -14- -12 -10 -8 -6 -4 -2

o

2

Fig. 5. Blue whiting biomass (in thousand tonnes) obtained by Russia, March/April 1995. Markings of subareas I-V used in the assessment.

15

._ .. _.:-1.8 _{-16 -1~1 -12} -10 -8 -6 -4 -2

o

^{,.., ')}

·. ^'.•

....

l l ^l

... ,

l

'l

^l '

l

.. '

l l

62

l l

l ~~~~

~~~~~---~4-~-+~~--~~~~~~13-+-1~~~--r.-~,--~62

~~-+--~~-+--~~-r~--~-~~~---+-~-+~~~~~

..

.. l l ^l

. .

l l

^{4 22 .18}

l

l

..

l l

. .

l

¹

l

^{72 49}

l

⁸

l ~ .

.· ...

l l

: ..

^~o

l l l

. .. ..

1Z' l 1- la2l243 12 .~:-. lj--:---iJ~ .

l

⁴

2

^{9' 5}

'l . l

⁶⁰

l l l

^{4 1 5}

l ~i

C".--+--+---+--+---!

. I

<w ~

-~58·. ~~~~~,~~88~:~5 ~

^{.. 7}

~~~'~~

⁵⁸

l •

~:

^{: : : · ;}

~( '~)ll-j,.

- - ! - - - t - - t - 1

JSZ' 140

^.A

l

,

~

r ·

~-+--i-+---+---1

l .

^{2 2 1}

^o

⁶

l ·- o ) -!-i--,.

^-+--+---i

l l

⁷

136. / ~~~

· \ 1 ' · ·l

l ^r·

⁵⁶

4.8~ 55

l

^l

tf'\._

l ,l_~

. ..

_···:··_ . .

~

... - - + _ .

----+-m--+----1--+,.~,5-08+-,29~3~ 1 ^~

^.

^~

^{. . . . .}

·5:· .. ··· .·

^l

77

^9357961

~' l·~,.\'' ^l

56.:

:

41 2 1 7 1 8 'g' 1 5 7 9

J

^{l /'}

l

⁵⁴

::. .. . 1:38 345 4 27' 4 ¹

~, 1

^{·,.,..- .}

l

¹

~)

22: ·112

46

44

l

^-~

^f-'

^~

^.

c. ;._

1f ___;( . ^v-il

~<~~r .. ^< 4 -~~ .1r 1:~ ~a~: ~

¹

~

^.

~:52

.. .. .. .. 64 l·

^l -=:/~~~

.. ·

;~:~9-.: -~= .. ~:~I_· ~~~~;~~~~::~;~~~~_;-~_-++---i~,_-_--1-t-c:-....--i-· ¹ -_~-;_~-=r"=.-=.-;-:=.·-=_;·-:=~-:==;=· ~

^5o

."• ... ^·~ l l ., l

-· .. : · ... .

!-:...!-~--t--l--~-+--+-~-+--f---+l-+--+---1r---t---r-r---r---r--1 48L_~--~_L~~~-L--L-J-~--~~~~~~~--~~~~~~ l 48

. -18 -16 -14 -12 -10 -8 -6 -4 -2

o

²

. -. :· ..

Fig. 6. Blue whiting biomass (in thousand tonnes) obtained by Norway, March/April 1995. Markings of subareas I-V used in the assessment .

~

16

20 30

N

=

^62.0 _!Norway

l

₂₅

15

20

%lO ¹⁵

10 5

5

o o

15 20 25 30 35 40 l ^{2 3} 4 56 7 8 9101112

cm Age

20 31%

30.

N

=

^66.3 _jRussia

25 15

20

%lO 15

10 5

5

o o. l .. _

15 20 25 30 35 40 2 3 4 5 6 7 8 9 101112

cm Age

20 30.

N

=

^64.2

!Total 25

15

20.

%10 15

10.

5

5·

o o

"T

la-

15 20 25 30 35 40 l 2 3 4 5 6 7 ~ 9101112

cm ge

Fig. 7. Total length and age compositions (N%)of blue whiting to the west of the British Isles, ?Pring 1995, obtained by Norway and Russia respectively and their combined

results. N x 10-^9, weighted by abundance.

20 -lB -l& -14 -12 -10 -8 -6 -4 -2 o -20 -18 -16 -14 -12 -10 -8 -li -4 . -2 o

l l l l l l l l l l l l l l l l l l l l l l l l l l

~\ ^{.... - 62} ~~\'; ^{. _j 62}

~

. ) r

^~

.

~~ ( ^~ (QI• ^//f\

P

^S

^{~ n}

^{lit 60}

^{~ ~ ~s 9 :;:;;}

^{d _1&1 _Ho}

Q ~~ l l / ? . ~~

.._/9~ ~~. ^{4 "} r ~/l ~~ -' "

. L1 :)!7_ " lZ ^{V ' /}

^_158

~ ~\ r

^9--.

_~ 't:1J

~

.

^~

J

^{J _j~}

~ ~

~

^{,= \ " <'} _'7

r~

^t~ _;t

r)· \

^_,55

~~

)

?

r""

~

⁵¹

~ ~ ^r

10---

Q ~1

^{• \ . .}

<L--, ^l

V _~ t ^{J . .}

^{53 10 .}

^{1:· ~ ~}

^)J53

/ ) . 52

LrAc ^{t .~ ~}

^_152

~~, ~ ~-e~~ ~

. r_

⁵¹

r_

^_(51

~ ^-1

⁵⁰

~

^e-v

^l"

~11 ~.. ~ j4,

. Il

4S 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 l 1 1 , l , l 1 l 1 l ,

L-'-~

⁴⁸

Fig. 8. Temperature, t° C, at sea surface Fig. 9. Temperature, t° C, at 200m depth

22 March-23 April 1995. 22 March-23 April 1995.

-18

l -1 ^l l ^l

-16

9"

. ../

u

-H

V

-12 -10 -8 -6 -:4 ^-2 o

~'

_~ ⁶²

~ 3g~

ep~~

^{61 6(.1}

5 rJ n

9r ~~·t-7

l ~~·

f.'.J\{j ,(W(

~

. "Y·

u>

^{l .}

c~~\_

r7 ) \

( z ) \. . 7 . 5

^1..153

r _~--·r ^./__1 _~ ^"'

_jst

~ISO

<:>..,;3

-.::. ~Cl ~ 59

58

57

56

ss

54

49

l ·l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l .l 43

Fig. 10. Temperature, t° C, at 400m depth 22 March-23 April 1995.

-20 -18 -16 -H '-12 -to ^{-8 .:.6} -4 -2 o

61

l l l , - . -·

~-'~'\lo., ^{l l}

~~ ^~

~~·

^:

!'o.

B~v ¹

-· li2.

60

~Cl ~~

-.::. ~ 59

rJ .)(/

⁵⁸

~ ~17

57

l . .."_~t> ^{\ .}

C\{~\

56

55

8?

l

\ -9-"1

~

^..._

'

. l

,/ l

Ir\

[,_~

(

~ (~. ^.•

~ J

r _{~---= /} ^·~ _~-

54

53

52

~ r_

Sl

~50

-·· 49

l l l . l l l l l l l l l l l l ' l l l ^l l l l l l l l ^l l l l l l l l l l l l __,___1_Il 43 i

Fig. 11. Temperature, t° C, at 600m depth 22 Mc--~h-23 April 1995.

1--'

en

No ~3 ~3 so ':1 t ~2 95 ~ 95 95 '37 Lat ·s3.00 53.C:l S3.CJO S.Ulil 53.00. 53.00 53.00 53.00 53.00 S:U:a

Lng -l6.0G-15.30-15.0~-14.3!J-14.00-B.30-13.00-n.31J-12.00-11.ZO

o . . . .

~.';'•) ~.S1

100 Z..?o) ;c.;t 9 .. t.s ~.~.!4 ~.:.:c

~-·~· ^{? .. €;.} i4 .. !!-1 9.E.S ~·.s-s

200 ^~

.

^.::~

-~.t.l

300 ^·~ .. s;

400 L ? .. t.•:r

\ l l

.,

'-..

""

soo L ~.::~ ~.H ~ .. ~s.

'"- '-

-~

^'-

BDO Lq ',, ;.·.; ,..,

'

'-

"

700 L 8" ...

"-

""'-

""

... '-..

800 L ^;.'\1

"·

i

8DOL

1

" \

bo

IOOOL S-.. , .•.. _, 'f,f!:·

^{.. ~.:} ~ ^~;

^'

·].52

l·i .. •:.7 ;o.ai 1.,. ;3 j{,;~;1 fC;;~~ lt::H

IO.iil 10.<.0 IO.JC:

!Q.t.S !'.l,oJS

Fig. 12. Temperature, t° C, in a section along 53°00'N over the Porcupine Bank, "Fridtjof Nansen" 3-4 April 1995.

u~ nu ~t S~ SfJ 91 92 ~3 ~4 55 St. ~7

Lo.t Lr:g

:iJ.iitl 5?;.!)() 53.00 )3.0\l 53.03 53.lltJ 53.00 ~3.UO 55.GiJ 53.W -It;. 00-15.3!!-15.0~-14.3~-14. O!J-13.30-13.0!}-12.30-12.!l:.l-11.&0

o ^~.::.::1

~Hi ~~:~~ ~~=n ;.E .• ::.:; ::! .• ::.7

.,: oj.j

HIH

:::"31 ""·"" ::-s.?-3 =!:.3~ 3~-:; :;: .. :;:: ::s .. :;·~

::l:~s.Lf

IDO

l~ii:.~:

=·~-,.::i ?~--::·:r ::: .:.s =·~··==· ::.-: .. :: ... :~.=~

;.:: .. ^:;.~ .:::..,;~. : . .: .• ~s. ::s..;l ;~.!-:<

::·~ -==· ::·=··=~· ;·.: .• ;::: ;::.;s. ;~ .. =,.. ::::: .. :·~

:.:.::3 200 :r: • .:.s. ~.: ... ;::.

?;,;! ;s .. z=

;:: ... ~·; :.5,E·i

'

5(;0 1-- :: .<~: =·~. \::: :-~~(·

'

\

\

600 L :.3.;:;; \

'\

\

\

' '

700 '-35,2 \

\ \

800 ::·s-::.:.

"

' ~

800 ·-

lODD

35.]'

~

~~"..Jl ~

^\

Fig. 13. Salinity, S ⁰/oo, in a section

· along 53°00'N over the Porcupine Bank, "Fridtjof Nansen" 3-4 April 1995.

l--' to

st.383 ' ___.!.__ ' 7 ' . ....,...• •, l 1 t m

Faroe Islands

Shetland

Fig. 14. Temperature, t° C, in a section from Nolsø (Faroe

Islands) to Fluga (Shetland), "Johan Hjort" 13-14 April 1995.

St 371

1000

f

Sf 383

'l l l . ' \ l . l l i:::_~: o

,,,,, .

,,,llllillli~l ~~~~Q

. \ \ \ l l . ,, . . ^34.9

. l.

l,

11\. ~34

//~/ ^. l l

l l l l

l l l

' ' l ^{l , , .} l

r

l

·f l l . l l .

l l l l l ! 1·1 l Ill

Faroe Islands

Fig. 15. Salinity, S ⁰/oo, in a section from Nolsø (Faroe

Islands) to Fluga (Shetland), "Johan Hjort" 13-14 April 1995.

Shetland

-1000

o N

o·-

-

55~

so·-

l

• ⁸

• •

+

1s· 1o·

⁵⁰

l l l l _j l --_1_ _ _ _ 1 ^{l l} l

,,--

-

...

1,, ' ...

( ~~

;.

l ~· , _ ,

\ ~ ,','',

'

...

" , 'l+

~ ,' , .... , ,

',, .· ...

~

+

,, .. ·, ', '

,--

100 -1000 10 -100

' ' l

,-, ~ , .. i '• .. , ';- •

~ ... ! ,_.' ... ~

+ + .... --·

+ ... -·- ~(J

1 -10

<1

o

, ...

l l

l ,•

,' •' ..,'

\ __ ,'

• +

,

-~·::

,_, 8 , .. ,_,! :

+ + " ... · + ~.+.. .. ·•'

t__,'

'A

" " . ~ø

~ Q r

.

~60"

1-

t-55.

l l

,' ,

l

'-, ... t

~

^...

ll ^rso

.... 4: ^Q

~-

....

l -.---.- - l - l

15.

,~ --.---.

-:.,,,,wl••·: .. ,,

'~.

1o·

-T

~=~;~tf;:

.. ~~--.. ^,

-

l l ,

50 Fig. 16. Distribution of blue whiting

eggs, nm-², R.V. "Johan Hjort"

27 March-17 April 1995.

1- .!.:.

"'\

15.

to·

⁵⁰

'QØ' 1000 >

• 100-1000

,_,,--.... ^,

(

' l ^{4'~ -~~} ,_, l

~ t-.0 ,' ,, .... ,

.. ' " .<-:·'

_'4 'l ... " +

,, ..

-

^{,,, ' ...}

,.

, , '

.

/ '... ' l

+ + ,.

+ , .. --'

,•

- 10-100

,-,

.

^{' " '}

~ .. } ·._,.·· .... ·~ +

,_,

-

⁺

,•

+ ,J-' (J

+ + ... _,l

~Q

6o·i •

^{1 -1o} ₊ ^{+ ,- .}

.f.. .. •'/

• <1

+ o

... ,

• l

l '

l '.

. ^{. .}

l •

, __ ,'

+ ~··l

+ ,/

l

+ .:

e +~

•

+ ;

•

+ ^~

,'

• + · .

• -1

+. ,.' ~

, l

,.

.. ~~~

·

•

• • -

r.:-n~···

,_.._ + •' r.·:·:·:"!·:·:·::::::·:·:·:=::::·:·:·:=:=:t~

••• ++./ ···'-''''·

• • l

.__ø. : ..

... ^'\

•• •J.

l l

15.

.

.

, ,

l

' ... ,_,~

-:.. ... ,._1---: ..

10°

... ~ ..

' ..

~o 'A

50 Fig. 17. Distribution of blue whiting

larvae, nm·^2, R. V. "Johan Hjort"

27 March-17 April 1995.

6o·

ss·

^N _1--'

22

140 120 100

~ u 80 c Cl)

:s a"

~ 60 u.

40 20

o

1.6-2.0 2.6-3.0 3.6-4.0 4.6-5.0 5.6-6.0 6.6-7.0 Size in mm

Fig. 18. Length distribution of blue whiting larvae, R.V."Johan Hjort" 27 March-17 April 1995.