CM_1958_Dragesund.pdf (430.7Kb)

Exploration of the Sea Herring Committee

REMARKS ON THE RECOVERY OF TAGS FROM THE NORWEGIAN HERRING FISHERY OFF NORTH AND EAST ICELAND IN 1958 •

by Olav Drage sund

Introdl.lction.

During this summer, the Norwegian fleet started the herring fishery earlier than usual off north and east Iceland, utilising the fish for the purpose of reducing it into oil and meal. This fishery gave an opportunity for the recovery of tags from this area and enabled to make a comparison of recaptures, with those of the Norwegian winter herring fishery.

The materials.

The fleet started the fishing operations in the middle of June and from this time up to the 10th of July, the fleet was concentrated in the areas 53 and 54

represented in Figure 1, but dl.lring the second half of July, the fishing fleet moved over to area 59 (Figure 1).

All the herring caught in these areas were landed in Norway at 24 oil and meal factories, of which 15 possessed tested magnets for the recovery of the tags.

The quantity of herring (p) in hectolitres thus reduced at these plants and the efficiency (e) of the magnets used are shown in Table 1. The number of tags

recovered in 1958 from the different experiments carried out during the years 1948- 1958, and their distribution in the various factories are also presented in Table 1.

A total number of 168 tags recovered from the factories during the above mentioned season and 207 tags obtained from the Norwegian herring season, form the material for the present report. The recaptures from the present years tagging experiments and the tags received from those factories which do not possess magnets have not been taken into consideration.

The observations.

The composition of these recaptured herring from the north and east coast herring season this summer is partcularly noteworthy. The striking point is that out of these 168 tags,8 were released as spring and large herring at the Norwegian coast, 155 as north and east coast herring, while 5 belong to those herring tagged off south west Iceland.

- 2 -

A comparison of these with those tags recovered during the Norwegian winter herting season in 1958 indicates that the relative proportion between the Norwegian and Icelandic tags is different. ':)ut of the 207 tags from the winter herring season, 125 were Norwegian, whereas only 82 were Icelandic tags (Table 2). The 0/00 return per million hectolitres of herring from the different experiments during the two seasonS are shown in Table 2 (second part).

If we compare the data from the two seasons it wlll be seen that the Icelandic tags show higher

0/

^ob return per million hectolitres off Iceland than the recovery during the Norwegian winter herring season. The recaptures off Iceland show a very high 0/00 return of herring tagged in 1954 and the subsequent years compared with those tagged in 1953 and the previous years.

If the different age groups of the herring population, spawning at the Norwegian coast this winter, have migrated to the feeding grounds off north and east Iceland in the same proportion as to the other feeding grounds in the

Norwegian Sea and without mixing up with the other herring tribes off north and east Iceland, we should expect to find the same proportion in Norwegian and

Icelandic tags during the two Seasons. However, this is not the case. The probable reason for this disproportion may be explained as follows:

If a relatively large number of Icelandic spring spawners were present during the tagging experiments off north Iceland then a fair number of the Icelandic

spring spawners must have been tagged together with the Norwegian spring spawners.

According to Fridriks son (1956) the Icelandic spring spawners contributed only 4.2 - 17.1 per cent of the total catch during the period 1949-53, but the

percentage of their contribution in 1954 and 1955 was 39.1 and 39.6 respectively.

This immigration of Icelandic spring spawners to the north coast herring grounds, may explain the relatively high 0/00 return per million hectolitres of the taggings carried out in 1954 and the subsequent years and also partly explains the disproportion in the number of Norwegian and Icelandic tags recaptured at the Norwegian coast and off Iceland.

The other reason for this disproportion in number may be that the older age groups of the Norwegian herring population, spawning at the Norwegian coast, segregate to the areas north of Iceland, whereas the younger herring migrate to the feeding grounds farther north and east in the Norwegian Sea. The average age of the Norwegian spring spawners during the period 1948 -55 off north Iceland was 14. 1 for the northern type and 11. 1 for the southern type (Fridriksson 1956). This is fairly higher than the mean age for the herring at the Norwegian coast during the winter herring fishery which was 9.38 for the northern and 6.30 for the

southern type during the same period. Then the herring tagged off north Iceland therefore should be composed of relatively older herring. Since this herring return to the areas off Iceland without a contingent of young ones, it may also contribute to the relatively high

0/00

return per million hectolitres during the north and east coast herring fishery off Iceland. The Norwegian spring spawners, however, tagged

off north and east Iceland mix with the younger herring in the spawning grounds at the Norwegian coast and the 0/00 return per million hectolitres will therefore become lower during the Norwegian vvinter herring fishery than the north and east coast herring fishery off Iceland.

According to the strong 1950 yearclass, which showed up in the catches during the Norwegian winter herring fishery in 1955, and also partly in 1954, it should be expected that a great decrease in 0/00 return per million hectolitres both of Norwegian and Icelandic tags should take place, since the recruit spawners have not been tagged neither oif Iceland nor at the Norwegian coast. This decrease in recaptures can be marked with regards to the Icelandic tags, whereas for the Norwegian tags it is not so significant. This can be studied from Figures 2 and 3 and the Table 3.

It can therefore be concluded that both the immigration of spring spawners to the north off Iceland, the segregation of the older age groups from the Atlanto- Scandian herring tribe to the feeding areas off north Iceland together with the strong 1950 yearclass, are the reasons for the decrease in 0./0.0 return per million

hectolitres of Icelandic tags in the winter herring fishery during the period 1955- 1958. It also partly explains the difference in proportion between Icelandic and Norwegian tags recaptured in the Norwegian herring fishery and the herring fishery off Iceland.

Reference:

Fridriksson, A., 1956. "The Tribes in the North Coast Herring of Iceland with Special Reference to the Period 1948 -1955. 11 Rapp.

et Proc. -Verb., 143 (2) : 36-44. Copenhagen,

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Table 1. The number of returns during the Norwegian north and'east ooast herring fishery off Ioe1and in 1959 .

~~. ~

. Year of tagging Factory

4g ~9

51 51 52 52 53 53

5~ 5~

55 56 57 5g 5g

_t!~~~~, p(Jl1.~

.. &_"" _ P

~(hll

NH SH SH NIt SH NH LH NH SH __ NH NH NH NH SH NH Total 11 62 5 3 0,g7

5~,11

2 2 1 5 16 114-5 0,96 1099,20 3 3 lS 12g1 0,94 1204,11+ 1 1 22 4-791 0,70 3353, 70 1 1 1

5

1 9 23 21463 0,g1 173 g5 ,03 1 2 2 3 4- 13

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9 6 26 3g 1957g 0,90 16720,20 1 1 1 1 1

1

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2 42 30692 0,97 29771,24 1 1+ 1 10 5 6 7 37 43 19371 O,g6 16659,06 2 1 4 1 5 1+7 4-260 - 0 56

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0

64 3

515 -0

66 4572 - 0 77 974- -

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east ooast herring SH : Spring herring LH : Large herring

Table 2. Number ot returns in 1959 trom the different experiments. Year ot tagging and the number tagged. Year ot tagging and the number tagged. Season Winter herring

191j.g 1950 1951 1952 1953 19511-L955 1956 1957 191j.g 191j.9 1950 1951 1951 1952 195~ 19p3 19511-19511-19511-1955 1955 1955 1956 1956 1957 1957 1~7 711-75 1ftij1 3065 1730~ 101g! g*ft( 11ka2 gll-1I-3 7gfi9 601g g261 90g5 599g 99g6 10763 100g0 100ijO 10011-2 10291 111-970 10011-5 90g7 1,5g6 it99g 12799 9500 gll-Bb 3 00 L.1. (hl) NH NH NH NH NH N Totg.1 SH SH LU LR eH aH LH SH LH SR FH LH BH P'H LR FH LH BH Total 1.09g.1s1j. 1 2 3 10 10 15 20 21 .. g2 1 1 1 2 2 17 3 2 15 11-16 11-13 11-9 15 15 1 North and east 20!S~ ~e:r:~ _ ,:12

5 ,:

II-Zll-_ 1 3 9 6 22 33 Ij.6 35 .. 155 1 2 1 2 2 0/00 Returns per mill. hl. Winter herring 1.09g.1s1j. 0.69 0.59 0.15 0.g9 1.011-1.16 2.15 2.63 0.15 0.11 0.10 0.30 O.lg 1.1j.Ij. North and oast ooast herr1ng .195.11-711-0.6g NH .. North and east ooast herr1ng SH .. Spring herring LH .. Large herring FH a Fat herring and "Fortangsts11dl

5.01 2.66 3.01 12.g2 11j..39 27.gg 22.67 0.62 -1.02 0.1j.g 1.02

~1 O.lg 1.33 0.211-1.11-5 0.1j.o 0.g70.73 0.611-1.1j.Ij. 1.610.23 0.99

125 g

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1950 Sf 52 5~54 55 5657 58 year of recopture,

Table 3. Number of returns from reduction plants with tested magnets for the different experiments and returns per million hectolitres in 0/00 (in brackets) Year of Number tagging Category. tagged 1950 1951 1952

Year of recapture 1953 1954- 19q.g 19q.g

BH NH 6.01g 7.4-75 8.261

15 (1.36) 9 (0.67) 13 (0.60) 7 (0.35) 26 (1.75) 23 (1.03) 9.065 •• 11.215 • 1.321 . 5.998 • 9.966 •. 3.065 ••

• • 14-(0.57) 9 (0.30) 6 (2.23)

21j. (0.92) 9 (0.26) 25 (0.70) 15 (0.38) 9 (0.16) lit (2.44) 20 (0.77) • 63 (1.4-5) 2S (2,10) 16 (0.78) 9 (0.36) 17 (0.60) 10 (0.32) 6 (0.21) 6 (1.79) 20 (0.96) 61 (1.60) 33 (3.18)

15 (0.1+3) 12 (0.26) 4-5 (0.91t) 17 (0.32) 12 (0.19) 11 (1.4-11-) 29 (0.911-) 75 (1.30) 52 (2.911-) 10.295 • • • • •••••••• 16 (0.52) 26 (0.44) 10.763 17.306 •• 10.Q60 . • 10.04-6 •

. .

,

. .

• • 76 (2.06) 112 (1.60) ••••••••• 24-7 (1t.21) 327 (3.27) • 16 (0.31)

. .

• 4-3 (0.74-) 1955 , 8 (0.29) o (0.00) 16 (0.4-2) 9 (0.22) 5 (0.10) 5 (0.62) 19 (0.65) 57 (1.24-) 16 (1.26) llj. (0.30) 137 (2.77) 116 (1.lt6) 6 (0.17) 1j.7 (1.02) 1956 11 (0.36) 1 (0.03) 21 (0.60) 11 (0.21t) 4-(0.07) 5 (0.74-) 11 (0.35) 38 (0.75) 17 (1.09) 13 (0.25) 110 (2.00) 109 (1. 22) 10 (0.19) 37 (0.72) 1957 10 (0.44) 2 (0.07) 10 (0.32) 4-(0.12) 1 (0.02) 2 (0.1to) 2 (0.88) 27 (0.72) 9 (0.76) 7 (0.16) 62 (2.02) 66 (1.01) 10 (0.26)

1 1 1 1 2 2 1 17 3

194-9 1950 1950 1950 1951 1951 1951 1952 1952 1952 1953 1953 1953 1954- 1964- 1954- 1955

BH LH

eH

NH LH BH NH LH BH NH LH

eH

NH LH

eH

NH LH BH NH LH NH LH SH NU

10.]J61 • , 2g3 (J4..31) 102 (2.]g,) 117 (2.25)

36 (0.95) 1t9 (1.~) 15 (0.1to) 61 (1.57) 4-3 (1.30) 55 (1. 4-5) 31 (0.90)

3 10 1955 1955 1956 1966 1957 1957 1957 LH = Large herring

10.04-2 , 10.291 , 6.783 10.0lj.5 9.067 • • • 11.732 • • 4-.998 • g.443 ' • 9.500 •• 8.11-50 • • •

. .

7.899 • • • • • BH 2 Spring herring NH ,. North and east coast herring

•

. . . . . . . . . . . . . . . . . . . . .

• •

. . . . . . . . . . . . . . . .. .. · . · . . ^{. . .} . . . .

• 21t (0.62) • 86 (1.82) 122 (3.02) 19 (0.35) 80 (1. 52) 67 (1.91t) • 67 (1.70)

2 15 10 16 • 28 (0.60) 161 (2.69) g2 (1.65) ••• 29 (1.51t)

It 15 4-

· . .

• g9 (2.80) 20 • • • • • • 15

. . .

••• 15 • • 21