CM_1996_H_12.pdf (995.7Kb)

International Council for the Exploration of the Sea

C.M. 1996/H: 12 Pelagic Fish Co~ttee

REPORT OF THE JOINT NORWEGIAN-RUSSIAN ACOUSTIC SURVEY ON BLUE WHITING DURING SPRING 1996.

ABSTRACT

by

Terje Monstad

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

Norway and

Sergei V. Belikov and Eugene A. Shamrai

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

Rus sia

In March!April 1996 the sixth Norwegian-Russian joint acoustic survey on the blue whiting spawning stock was carried out. The bank and shelf edge area to the west of The British Isles was covered from south to north by a Norwegian vessel and from north to south by a Russian vessel.

Due to time difference between the coverages by the two vessels it was decided not to combine the data for a common estimate. Although there was difference in the observed abundance, and the stock some below than last year' s le vel, it was found to be in a rather stable condition.

The three yearclasses, 1993, 1994 and 1995 dominated in the total estimate of the blue whiting stock.

The hydrographic situation in the surveyed area was sligthly different from 1995, i.e. the temperature being some higher. Due to this the peak of spawning was earlier and hence the postspawning migration from south to north about a week earlier than usual.

2

INTRODUCTION

Bach spring since 1990 Russia and Norway have carried out joint surveys on the blue whiting spawning stock in the area west of the British Isles, except for 1994 when Norway surveyed the stock alone (Monstad and Belikov, 1993; Monstad et al., 1994, 1995).

However, for several years before 1990, both countries carried out separate surveys, and although the contact was rather informal, an exchange of biological and hydrological information took place. The sixth joint survey on the blue whiting spawning stock was then carried out during 24 March-19 April 1996.

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

The Norwegian survey in 1996 was also included in the SEFOS project (EU-AIR programme), and personell from PML, Plymouth, participated onboard the R.V. "Johan Hjort" for egg-and larvae studies. The results herefrom will be publishes in other reports.

In addition several standard SEFOS hydrographical sections (SSS) were worked.

MATERIAL AND METHODS

The bank and shelf edge area between latitudes 48°30' and 62°00'N, i.e. from south of Ireland to Faroese Islands, was surveyed during the period March 24- April 19 (Figures

lab and 2). One research vessel from each country participated within time period and geographical area (latitudes) as follows:

Norway: "Johan Hjort", 24 March-19 April, 48°30'-62°00'N.

surveying from south to north.

Russia: "Fridtjof Nansen", 01-17 April, 51°00'-62°00'N, surveying from north to south.

Both of the research vessels operated echo sounders of 38 KHz frequency (Simrad EK 500), which were connected to integrator systems and precalibrated by use of a copper sphere (Foote, 1981). When the vessels met, neither the weather conditions nor the recordings were suitable for a ship-to-ship calibration as planned, and due to time limit a calibration was therefore not performed. Instead the result of last years calibration, which gave a relationship of 1:1, was decided to be used as reference (Monstad et al., 1995).

The instrument settings are given in Appendix I.

Pelagic trawl as well as bottom trawl were used for identifying of the echo recordings and collection of biological samples. The Norwegian vessel used a Rock-hopper bottom trawl with 18 x 4 m opening and a pelagic trawl with 25m vertical opening (500m circum- ference), both having an innemet of 11mm mesh size. Russia used a pelagic trawl with 45m vertical opening and an innemet of 16mm mesh size.

For assessment of abundance and biomass the area surveyed was treated on maps as 5

3

separate subareas, which again were divided into rectangles of 0.5 ^o latitude and l ^o

longitude size. The echo recordings were scrutinized for allocation of the integrator values (Sa) to various species or groups of species.

The method for the caculation was the same as used for previous blue whiting surveys described e.g. in Monstad (1986) and Belikov et al. (1990), with the target strength as:

TS = 21.8 log L- 72.8 dB

where L is fish length. This gives the density coefficient value:

For hydrographic observations a CTD sonde was used at a number of stations, in general operated from sea surface to 600 m depth or to bottom if more shallow, and to 1.500 m at the standard sections worked.

In addition to radio comunication the vessels also met once at open sea for exchange of preliminary data and results. Due to rough sea the data was wrapped in water tigh plastic bags attached to floats, dropped into the sea and picked up by the other vessel. When R.V."Fritdtjof Nansen" called at Bergen 23-24 April, a post-survey meeting was held for a final exchange of data and discussion of the results.

RESULTS AND DISCUSSION Distribution

Concentrations of blue whiting were recorded throughout most of the area surveyed, with a distribution pattern very similar to that of previous years.

Norway, which surveyed the area from south to north, recorded blue whiting along the continental slope mostly in a SOm thick "belt" varying between 300m and 500m depths, from about l OOOm bottom depth towards the edge. The highest concentrations were found in the northern part of the Porcupine bank area at the shelf edge between 53°30' and 54°00'N, and less than a week later along the edge off St. K.ilda west of the Hebrides, i.e.

between 57°00' and 58°00'N (Figure 3).

Russia, surveying the area from north to south, obtained a similar picture of the distribution, but with the highest concentration found at the shelf between the latitude 56°30' and 57°00'N (Figure 4).

Stock size

The two countries separate estimates of the total biomass and abundance, as well as mean length and weight at age, are given in Tables 1 and 2, and the corresponding results of the acoustic assessment for each subarea in Tables 3 and 4. The Norwegian estimate of the total blue whiting echo recordings c ame out with a biomass of 5 .l mill. tonnes

representing 52.2 x 10-⁹ individuals. Of this, 4.5 mill tonnes, or 36.2 x 10-⁹ individuals belonged to the spawning stock. The corresponding Russian results were a total of 7 .l mill tonnes biomass representing 57.3 x 10-⁹ individuals, of which 5.8 mill tonnes or 39.0

4

X l

o-

⁹ individuals belonged to the spawning stock. On Figures 5 and 6 the biomass estimate by rectangle are shown for Norway and Russia respectively.

The time difference between the coverages during the spawning season resulted in different biological data due to changes in proportions of fish at various maturity stages and the corresponding weights. The concentrations had moved northwards or partly migrated to areas outside the surveyed ones.

As much as the difference between the to estimates of the spawning stock size appeared to be 1.3 mill. tonnes biomass and 2.8 x l

o-

⁹ individuals, they were not to combined to a common res ult. The size of the spawning stock, however, was found to be at a rather stable level, between 4.5 and 5.8 mill. tonnes.

In the 3 text tables below the total estimates in the spawning area since 1990 are given for the biomass (A), the abundance (B) and the total mean weight and length (C).

Corresponding spawning stock sizes are given in brackets.

A. Biomass in mill.tonnes:

Russia 1990 5.4 (5.1) 1991 4.6 (4.2) 1992 3.6 (3.3) 1993 3.8 (3.7) 1994

1995 6.8 (6.0) 1996 7.1 (5.8)

Norway Combined 6.3 (5.7)

5.1 (4.8) 4.3 (4.2) 5.2 (5.0) 4.1 (4.1)

6.7 (6.1) 5.1 (4.5)

4.7 (4.4) 4.6 (4.3) 5.1 (4.9) 6.9 (6.1)

B. Abundance, N x 10-^9: Russia

1990 39.1 (35.3) 1991 35.8 (29.3) 1992 40.2 (36.9) 1993 39.3 (29.4) 1994

1995 66.4 (44.3) 1996 57.3 (39.0)

Norway 62.9 (56.2) 41.5 (40.9) 38.4 (36.8) 41.5 (39.8) 26.8 (26.1) 62.0 (45.2) 52.2 (36.2)

Combined

38.6 (35.2) 40.2 (36.9) 41.1 (39.3) 67.4 (45.5)

5

C. Total mean weight (g) and length (cm):

Rus sia

w l

Norway

w l

Combined

w l

--- 1990 139.0 28.6 100.7 27.1

1991 124.5 27.5 115.7 27.8 121.8 28.0 1992 113.4 27.5 111.3 27.5 113.0 27.5 1993 123.6 28.1 124.6 28.6 123.6 28.1

1994 152.9 31.1

1995 102.6 25.7 108.2 26.9 102.9 26.0 1996 123.1 27.9 94.9 25.5

Stock composition

The length and and age composition for each sub-area by country are shown on Figures 7 and 8 for Norway and Russia respectively, and the corresponding distributions for the total area on Figures 9 and 10. Norway caught more young fish than Russia, and according to the samples, the 1995 yearclass dominated in the area, contributing with 30% in numbers, while Russia found the 1992, 1993 and 1994 yearclass to be the dominant ones. These yearclasses, however, were also significant in the Norwegian samples, and both countries found them mostly in the middle areas where the highest spawning concentrations were recorded. The one year olds were most numerous in the north and in the south.

This survey verified the strength of the 1995 yearclass, which as 0-group was reported to be abundant in the Norwegian Trench (Tveit~, 1996), and formed a significant portion of the successfull fishery of the Norwegian industrial fisheries in the North Sea autumn 1995 (Lahn-Johannessen, pers.comm.).

Hydrography

Synoptical conditions in the area surveyed had a cyclonic character with a well

pronounced meridional transport of air masses. Winds of southern directions (55%) were predominant at the wind force 3-5 (46%).

In spring 1996 water circulation was in general similar to the long-term rnean. Gcostrophic circulation was weak except for a section westwards from the Shetland Isle~. Over the Porcupine bank the flow, following the slope in a southern direction, formed a cyclonic meander without a closed structure formation.

Distribution of temperatures at O, 200, 400 and 600m depths are given in Figures 11-14 respectively. Compared to 1995 a rise in the temperature by 0.2-0.4° C in the sea surface, was observed over the whole area surveyed. Maximum values for temperature, 11.47° C, were registered in the southern area of operation where, for the first time since 1992, the isoterme of 11° C reached 400m depth. More active penetration of the North Atlantic Current Waters into the mid-water of the shelf was observed in 1996, which was

confirmed by extreme north-eastern position of the 10° C isotherme for the recent 5 years.

6

Mean temperature in the section along 53°00'N (Figure 15) was higher than previous years by 0.25-0.28° C in alllayers, and positive anomalies made up 0.21 ^o C in 0-200m.

Compared to 1995 the temperature was markedly higher, i.e. 0.63° C, in 500-1000m layer on the Porcupine bank western slope, and horizontal gradients in a layer of the most intensive downwelling of waters (650-900m) attained 0.11 o /mile. The peak of blue

whiting spawning in the area was observed to be earlier than usual, which could be due to this. Consequently the postspawning migration from south to north was also earlier, i.e.

about a week.

The temperatures along the section between Faroe Islands and Shetland (Figure 16) were markedly higher than in 1995, showing values of 2-3° C in 500m depth, against 0° C in

1995. V ariaton in circulation, from a cyclonic one observed in 1995 to anticyclonic, was observed in the area between the northem extremity of the British Isles and Faroes, which was confirmed by a variation in a temperature field strucure at 600m depth. Compared to 1995, the area occupied by the Arctic waters with negative temperature in 1996, was essentially reduced. This indicates both a poor upwelling of waters, usually observed in the Faroe-Shetland Channel area, and the most intensive advection of the North Atlantic Current waters along this section for the recent 5 years.

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.

Foote, K. G., 1981. Echo sounder measurements of back-scattering cross sections of elastic spheres. Fisken og 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. 1993. Report of the joint Norwegian-Russian acoustic survey on blue whiting, spring 1993. ICES, Doc. C.M. 1993/H: 10.

Monstad, T., Belikov and Coombs, S.H. 1994. Investigations on blue whiting in the area west of the British Isles, spring 1994. ICES, Doc. C.M. 1994/H:12.

Monstad, T., Belikov, S.V., Shamrai, E.U. and McFadzen, I.R.B. 1995. Investigations on blue whiting in the area west of the British Isles, spring 1995. ICES, Doc. C.M.

1995/H:7.

Tveite, S., 1996. Intern toktrapport, F/F "Michael Sars" i Norskerenna, 13.-30. Okt. 1996.

"Survey report of R.V. 'Michael Sars' in the Norwegian Trench, 13-30 Oct. 1996"

(in Norwegian). IT 1/96, IMR, Bergen.

7

APPENDIX I. Acoustic equipment and settings of the instruments:

"Johan Hjort" "Fridtjof Nansen"

Echo sounder: Simrad EK-500 Simrad EK-500

Frequency: 38kHz 38kHz

Transducer: ES-38B-SK ES-38

Absorbtion coeff: 10 dB/km 10 dB/km

Pulse length: Medium (l ms) Medium (l ms)

Band width: Wide (3.8 kHz) Wide (3.8 kHz)

Transmitter power: 2000W 2000W

Angle sensivity: 21.9 dB 21.9 dB

2-way beam angle: -21.0 dB -21.4 dB

Sv Transducer gain: 28.1 dB 23.1 dB

Ts Transducer gain: 27.8 dB 23.2 dB

3 dB beam width: 7.3 dg 6.5 dg

Range: lOOOm 500m

Tab le l. Abundance estimate of blue whiting west of the British Isles, March/ April 1996.

R.V. "Johan Hjort", Norway.

Number: N ^X 10- 6 Mean 1ength: cm

l .

3

Mean weight: grams Condition: 1000 x weight 1ength Biomass: Thousand tonnes

years Mean

cm _{1 2 3 4 5 6 7 8 9 10 11 12+} N Biomass weight

10 o o

11 o o

12 o o

13 2 2 0.0 10.0

14 96 96 1.4 14.8

15 574 574 9.7 16.9

16 1472 1472 31.5 21.4

17 1847 14 1861 49.2 26.4

18 3921 117 4038 127.7 31.6

19 4901 970 5871 221.3 37.7

20 2965 1709 4674 202.4 43.3

21 819 1794 2613 131.0 50.1

22 32 818 850 48.1 56.6

23 42 676 718 48.6 67.7

24 870 49 8 927 68.6 74.0 ₀₀

25 999 490 1489 125.2 84.1

26 678 1619 184 34 2715 250.5 92.3

27 136 2550 920 23 14 . 30 3673 374.9 102.1

26 1637 2301 76 138 5 4157 .476.3 114.6

29 691 2836 366 312 178 _~ 4411 566.2 126.4

30 186 1330 595. 1313 508 6 3938 562.7 142.9

31 11 559 595 129~ 882 90 105 39 3572 562.5 157.5

32 122 382 670 584 238 66 5 4 2071 358.6 173.2

33 111 158 237 688 176 25 11 11 1417 . 260.3 183.7

34 118 374 479 162 73 9 32 4 1251 246.2 196.8

35 20 54 438 227 37 76 34 5 891 196.2 220.2

36 12 44 196 199 62 12 4 529 122.3 231.1

37 5 55 43 44 6 12 165 . 41.8 253.5

38 3 56 40 28 127 35.3 277.7

39 8 13 6 10 37 11.5 310.1

40 4 5 5 14 ·4.7 336.2

41 8 8 2.8 352.0

42 o 0.0 0.0

43 8 8 3.0 373.0

Number ^{16671 6781 7433 8371 2399 4455 4111 1202 459 162 105 25 54169}

Length 18.9 22.5 27.6 29.3 .31.2 31.6 33.0 34.5 34.6 34.9 35.8 35.0 25.5

Biomass 578.6 519.9 776.8 1037.4 367.5 714.7 736.2 247.1 97.5 35.1 25.4 4.3 5140.5

Weight ^{34.7 59.2 104.5 123.9 153.2 160.4 179.1 205.6 212.5 216.7 242.0 212.4 94.9}

Cond. ^{5.0 5.0 4.9 4.9 5.0 5.1 5.0 5.0 5.1 5.0 5.2 5.5 5 .. 0}

Tab le 2. Abundance estimate of blue whiting in the northem stock, i.e. 51 °30'- 62°00'N, west of the British Isles, April 1996. R.V. "Fridtjof Nansen", Russia.

r.angth AgQ

Cl1l\ l 2 3 4 5 6 7 a

14 . 6.2

15 56.1

16 186.4 17 504.7

18 819.8 83.7

19 680.0 413.6 20 1024.1 1611.1

. 21 2284.4

22 211.0 1561.2 14.3

23 1794.5

24 1895.4 421.7

25 1826.5 614.7 80.5

26 1656.0 1975.2 205.1 10.1

27 697.6 4240.4 711.1

28 34.6 . 3255.0 830.6 32.3

29 82.3 2638.1 1042.2 158.2 25.7

30 1334.5 2323.8 397.9 831.1 110.1

31 382.0 1707.4 854.6 1033.4 101.9

32 169.7 1586.3 1237.3 1196.5 99.6 83.0

33 239.3 1521.7 934.0 1178.8 78.6 221.6

34 510.6 '778.1 785.6 204.4 52.3

35 49.9 337.2 740.2 85.3 85.3

36 130.1 573.0 174.3 130.1

37 20.8 349.6 313.2 5.5

38 38.4 16.7 121.0 16.'7

39 102.4 112.9 20.6

.40 38.5 38.5

41 1e.6

42 43 44

To ta~ 3494.3 13946.8 15284.8 10629.1 4896.9 6839.6 1482.2 653.7

,Langth 18.1 23.1 21.8 30.6 32.4 33.0 35.1 34.6

Bioma~s 123.3 944.1 1122.2 1579.6 869.7 1291.8 345.1 142.1

~ight 35.3 67.7 112.'7 148.6 177.6 188.9 232.8 217.4

e.F. 5.4 5.5 5.3 5.2 5.2 5.2 5.4 5.3

Abundanoø Biomaøs Woight C.F.

9 lO 11+ bln.sp. thou.tonn g

5.2 O.l 13.9 5.1

56.1 1.0 17.6 5.2

186.4 4.1 21.9 5.4

504.7 13.4 26.6 5.4 903.5 21.7 30 .. 6 5.3 1093.5 39.6 36 .. 2 5.3 2541.2 111.2 42.1 5.3 2284.4 111.9 49.0 5.3 1792.5 98.5 54.9 5.2 1794.5 115.5 64.4 . 5.3 2317.1 174.6 75.3 5.4 '2521.7 225.6 89.4 5.7 3845.3 360.8 93.8 5.3 5649.1 562.0 99.5 5.1 4152.4 485.1 116.8 5.3

3946.6 498.4 126.3 5.2 _\.0

4997.4 682.2 136.5 5.1 4079.3 642.9 157 .. 6 5.3 4372.3 731.0 167.2 5.1 4174.0 757.8 181.5 5.1 2391.1 479.0 200.3 5.1 1297.9 305.2 235.2 5.5 1007.5 236.6 234.8 5.0 689.2 180.9 262.5 5.2 192.8 61.1 311.0 5.8 236.0 '79.7 337.6 5.7

77.1 154.2 52.9 343.2 5.41

8.3 25.0 9.0 359.'7 5 .2i

18.6 18.5 7.5 406.1 5

.sl

l

85.4 18.6 57331.4 ^!

40.1 42.0 27.9

29.4 7.5 7055.1

344.8 406.1 123.1

5.3 5 . .5 5.2

Table 3. Assessment factors of blue whiting to the west of the British Isles, spring 1996. R.V."Johan Hjort", Norway.

Subarea Latitude Abundance N x 1

o·

⁶ Biomass thousand tonnes Meanw Meanl north immature mature sum immature mature sum (gram) (cm)

6 60°30' - 62°00' 1587 101 1985 27 14 41 40.7 19.3

5 58°30' - 60°30' 11764 3148 14894 444 468 913 61.3 21.7

4 55°30 - 58°30'

o

¹⁸³⁶² 18362

o

2516 2516 137.0 30.0

3 53°30' - 55°30' 264 7478 7742 10 931 95 121.5 28.8

2 51 °00' - 53°30' 2953 6260 9213 81 528 610 66.2 22.6

1 48°30 - 51 °00' 1032 968 2000 25 57 82 41.1 19.8

All subareas 15995 36216 52211 560 4501 5061 94.9 25.5

Table 4. Assessment factors of blue whiting to the west of the British Isles, spring 1996. R.V."Fridtjof Nansen", Russia.

Subarea Latitude Abundance N x 1

o·

⁶ Biomass thousand tonnes Meanw Meanl north immature mature sum immature mature sum (gram) (cm)

5-6 58°30' - 61 °30' 5640 6350 11990 375 1039 1415 118.0 25.9

4 55°30' - 58°30' 5136 29016 34151 480 4331 4811 140.9 30.0

3 53°30' - 55°30' 3719 2806 6526 241 349 591 90.5 25.3

2 51°30'- 53°30' 3804 861 4665 168 71 238 51.1 21.2

1 48°30' - 51 °30'

- - - - - ^- - -

All subareas 9469 47863 57331 1265 5790 7055 123.1 27.9

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

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Figure 2. Cruise track and stations of R.V."Fridtjof Nansen", Russia, 1-17 April 1996.

13

Figure 3. Echo intensity (Sa-values) in m~/n.mile² x 11100, of blue whiting recorded by R.V."Johan Hjort", spring 1996.

14

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Figure 4. Echo intensity (Sa-values) in m²/n.mile² x 1/1000, of blue whiting recorded by R.V. "Fridtjof Nansen", spring 1996.

2

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Figure 5. Blue whiting biomass (thousand tennes), R.V."Johan Hjort",spring 1996. I-VI are subareas used in the assessment.

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Figure 6. Blue whiting biomass (thousand tonnes), R.V. "Fridtjof Nansen", spring 1996. IT- VI are subareas used in the assessment.

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Omr6 N = 2.0 •10-9

30 35

cm

Omr5 N = 14.9 • 10-9

40 10

Ar

r 80

r ¹⁰

t

^{60 50}

l4o%

l ~ 30

l2o o~----~~----~~==~~---~~~=---_jL-~~~--~__j!o l1o

10 15 20 25 30 35 40 o 10

cm 30-

Omr4 N = 18.4 ·10-9 20

10

Ar

-70

l

⁶⁰

[50 140 [ oy.

l 30

r l 20

l

~ 10

0~1~o---1s _______ 2o--~~-25~---3o _______ 3s~~--

4

^-

0

---o~lØ~~UL~~~o

Ar 10

cm

30 - 70

Omr3 ·60

N = 7.7 •10-9

20 ·50

.4()

'lo %

"/.

'lo 10

10 15 20 25

30

20

10

10 15 20 25

30

20

10

30 35

cm Omr2 N = 9.2 "10-9

30 35

cm

Omr1 N = 2.0 •10-9

40

Ar

40 Ar

.JO .X)

• 10

.ro

!J

ro

.6() . 50 - 40

%

~ 30

~ 20

~ ¹⁰

~10~--~-15---20----~2-5==~~3-0====~3-S ____________ _J~~--~~~--~

cm 40 o Ar 10

Figure 7. Length and age distribution (N%) of blue whiting by subareas (marked on Figure 5) of blue whiting in the area west of the British Isles, R.V."Johan Hjort", spring 1996. N x l 0-9, weighted by abundance.

18

30 30

Area 5

20 20

of' '*

10 10

o

o

14 19 24 29 34 39 44 l 3 5 7 9 11+

cm year:;,

30 .Area 4 ⁴⁰

20 30

-

10 ^{dP 20} 10

o o

14 19 24 29 34 39 44 l 3 5 7 9 11+

en ^year~

30 Area 3 ⁸⁰

20 60

dP '* ⁴⁰

10 20

o o

14 !9 24 29 34 39 44 _l 3 5 7 9 11+

cm. year~

.30 2 100

20 75

o'P of' 50

10 25

o

o

14 19 24 29 34 39 44 _l 3 5 7 9 11+

cm year:s

Figure 8. Length and age distribution (N%) of blue whiting by subareas (marked on Figure 6) of blue whiting in the area west of the British Isles, R.V."Fridtjof Nansen", spring 1996. N x l 0-9, weighted by abundance.

20

<IP

10

12 10

6

2

o

19

N 54.2 X 10-9

15 20 25. 30 35

cm

.40 o ⁵

years ¹⁰

Figure 9. Totallength and age distribution (N%) of blue whiting to the west of the British Isles, spring 1996, by R.V. "Johan Hjort", Norway, weigthed by abundance.

30

N 57.3 X 10- 9

20

..,

lO

o

14 19 24 29 34 39 44 l 2 3 5 6 7 ^B 9 10 11+

c::n years

Figure l O. Total length and age distribution (N%) of blue whiting to the west of the British Isles, spring 1996, by R.V."Fridtjof Nansen", Russia. N x 10-9, weigthed by abundance.

·l7 -16 -IS - H -13 -12 -l J -!O -9 -9 -s -s ^{--1 -:;} -2 -1

l l l l

9 -

. 0 ·.

⁶⁰

~

, . . . . 8 .

t - : ; ( ^~L) '~>P

;;::, l~

. . .

^~

• l ,..{l ,l

r---···=r

, r-s

^,!1 J ,./

\ s)rt.> ) ,.,/

9 '"'._;jN ,( _{..-~ ~}

7

_~

il '"1.L'- , .J

\~ '•J /

L _ ... j

<: .. , c,.l'/• {

-L'> ( ..=>-)-

. ~-

;:A o ^y

^)\·vz v..,..·~---

-r

u\1 -" ^~

9

/--~:;:/-*\ l \

. . l ) ^{i \;...} l'~ _ / ? \

... • \r;7 'l'~ l '-1 ~ ^{( \ _}

• • \"V •

~-·r-~r·-f

^{' \} '""'\.

. . . ^. ~ /

^{\ \}

···v,· .· ... , :, . . .

0

f

1

,....\

1 ~_j

⁵⁴

• 10 • J"t"_

··:: :·'·

^{• •} • ( ^•

_~3-- 7

r ^.

\ ...

l .6--t

~

^{. _l 53}

·.·trf ^{! ) .,}

• \.. _{\ b/} ... c--7 _y . ~ _.. , r _--^JJ ₅₂

9 V"-..-- V \

' \ \ r '-'\...-:? . \...-

_("'}_151

. '10 /

~.r-~-

^r

~ ^{c=~r L}

/ ' ,

H

\'..____-c:-1"

^IlO

. : . · - l l

/--~

lO"

~-.

/ /

/-

l

l l

5'j

53

57

5&

55

Figure 11. Temperature, t° C, at sea surface, spring 1996.

Dots indicate positions of observatiop--

-17 -16 -IS -J-1 -!3 -12 -JJ -lO -9 -B -7 -6 -5 --4 -:i

lO

\

'\'si/I{/X~9 ·~~·

~ )

·~-,

^{/ u}

~p

l~ C.

""~

, ~~----r----·)

c-.. ./~ ^{/ /}

\."J

5 //

u

^>;'J =:;.

~ ^~~ ..J'-1 • -<' l

r,

^~---. l

" .,..., L'-_{\1 '-~·-'/}

l

;

r ~~ (

<:~.' ~-

Æ:- l -

j.·4\

o ~)i\-vz <""~\

'.1

v . ,..

l!li \

\

1\~

j \

(-y ^.r.: 2

\tJ..J/ \_

\Q- ~~ \ \

r-[ / ^{'7 \}

( _~ ~ . \ ~~ '"'l

^_j53

f ) ~ ~')

\r ^{~ J}

10 (....~ _{C:-? ,.r·} ~f

s

_-~

v-v-.l'-' '-\...J7 -

,_,--:...J )

^{l 51}

f

^__,/.f

/~---.)~

^{. l ro}

C...; /-7. ^:!

o

60

..

59 58

57

56

55

/\ \'~

^\

11

~ l''~~

l ^l l l l l l l • l l l • • l :

.l~

• • • • l • l

C. . . ;

^{l l • l l l l l ,} l 48

Figure 12. Temperature, t° C, at 200m depth, spring 1996.

o N

-17 -l& -IS -!-l -J3 -12 -11 -lO -9 -!! -7 -6 -4 -3 -2 -1

i l l

~p

\"), LJ

9 _{l -9} ~'~ _{;-..._,}

i /,El!-~)

~ CJ4 { ,../

; rJ -

^c:::.,

u<<('~

-1::? ""'' _,' l ^l

a~ ⁾

rP.:. 1

..-".<"/( ~

.:Z.> f __.,.,..

. . ...

··~\ ^{j ~J'-v(

\

.).~~

t;u \ \

L

·j \

.l\.. ~ \

..,-p ~ ^\ \~·--'/ ^\_...,

j

~

^{l \ \}

lO

o

'

V:7 > \

_j

~f

⁽

'? l

( _~

_\

l

~t

f ) ~ (

()~

₁₀ ^\

u

S-i

c- ^{l .l}

53

V: /

~ -~ ~ ~_j51 ~ r~

52

"" r .

^{__j 50}

-~ ^{/ /}

·\'----~7

~

^...

...----.~ \

l l

11

/ l l ! 11 l l l l l l t l l

~!

^{l l l l l l l l}

l

^{t J l J ' l I l l l ' l}

49

Figure 13. Temperature, t° C, at 400m depth, spring 1996.

- i7 -iii -iS -l-l -J3 - i2 -!i -Hi -a -7 -b -5 -·i -:i -2 -i

. l l l

L)()

10,/2._/

(

~ ;...-:t

f':.. !.)

~'i

_.,~'--:

~~- )

Il .f /

r..s· ~ ~ ,/

l 5 ; -··

,> ,t~- ~- .:4:---~

\..,.• \ ,-· " l

....-9 -1::? -1"- ( l l

""~y

^J

--2/

^r; '...,.. .

~ l

- c!.. .·\

^_j

9 - 0

~

or <::'-...,

~

{} ~~IVv·l \

.t.• . IJU l (', \ <' ^{l .} \

l : \

.. J . ^l

,.--~~-\ \r--~'-'7 \\

l

~

^{\ \}

<7 ) "vt \

;r---..-f .-' (

~

(}

60

59

53

57

56

55

S-i

.!It '\ )

'?

^t

---1

ⁱ

~

^{\ /_}

J:

^l

~ ^/J

^S2

~ l

^{j /}

n< ,_..,. r -

~ ~ ~ ~P_. ^_:::rjst

53

~ ~

. ,__r-"'

/ ~

~~

^{,/"7' _j 50}

\'·.______..,

~

l 49

....---.~

\ ^{l 43}

... 10 ( ' . ^{l l}

l t,:. L . '

Figure 14. Temperature, t° C, at 600m depth, spring 1996.

N 1--'

29 30 31 32 33 34 35 36 37 39 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 -16.00-15.30 -15.01) -14.30 -14.00-13.30 -13.1]1) -12.30-12.110-11.30

~ r-~

..

l \

l \

l . \

300 L . I .

j ·

l

400 L . f

~ 1 Porcupine Bank

l l

. . . . l

q~ . .

:(~

1000~ wo~

⁷

~

No 29 30 31 32 33 34 35 3& 37 33

Lat 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 53.00 Lng -!6.00 -15.30 -15.00 -I·UO -14.00 -1~.30 -13.00 -IL~O -12.00 -t1.30

ar : ! .

. ^{l : ' 1: '}

. .

^. . ^(\

. .

^,.

^~

^{,. l}

^~

^,.

woL

! _l

·-oo

l

l

L

r

l

_l

300~

400 l

l

t-

500

600

700

:f

lOOOl

l

~ ::,..

. V)

~ N)

. l l

~.

lri

• l • ...., •

·~ ^. \;

'l' ^l

/~\ . l

i \ .

l

l l

. l \ . .

l

/ \ l l

r

^\;_l_j

l

Porcupine Bank

Figure 15. a) Temperature, t° C, and b) salinity, S ^0/₀₀ along 53°00'N over the Porcupine Bank, R.V."Fridtjof Nansen", 12-13 April 1996.

1:\J 1:\J

St 376

a)

Faroe Islands

t° C

---- ---5~~6~==========~

7

l l l l

l l

3 4

2 - l

St 364

100

500

:1000

St 3.Z§ •... St 364

b)

_j ' \ : ' l l l

L - - - . . . - - - - L - - - - L I _ _ ( _ L _ _ _ _ __!_ _ _ _ ~L_---_J_---

1 l

c:___

^35.3

35.2 - - - - ~

A\'

Faroe Islands

- - - 3 5 . 1 35.0

--...~"'>.0''

,,,

o \\\

S /oo

l l \\

l l l \ \ \

. l l l l \ \

l l l l l l \ ' \

l l l l l l l l l

Figure 16. a) Temperature, to C, and b) salinity, S ⁰!₀₀^, in a section from Nolsø (Faroe Islands) to Fluga (Shetland), R.V."Johan· Hjort", 15-16 April 1996.

,,

\\ Shetland

\

100

500

1000

N w

1 1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1 1 1 1 1

1 1