INTERNATIONAL COUNCIL FOR THE
CM. 1973/H: 6.
EXPLORATION OF THE SEA
•
P ELAGIC FISH (NORTHERN) COMMITTEE
REPORT ON THE INTERNATIONAL TRAWLING SURVEY
FOR IMMATURE HERRING IN THE NORTH SEA 1973.
by
A. Corten and C.J. Kuiter
Netherlands lnstitue for Fisheries Investigations,
Haringkade 1, IJmuiden (Netherlands)
•
This paper not to be eited without prior referenee to the authors.
International Couneil for the
Exploration of the Sea
C.M. 1973/H : 6'
Pelagic Fish (Northern)Committee
REPORT ON THE INTERNATIONAL TRAWLING SURVEYFOR IMMATUREHERRING
IN THE NORTH SEA 1973.
================================================================
by
A. Corten and C.J. Kuiter
Netherlands Institute for Fisheries Investigations, Haringkade 1,
Ymuiden, The Netherlands.
Introduetion.
The programme,of international young,herringsurveys·in.the·North·Sea·isintended
to provide estimates on the strength of new·year-classesbefore ·they enter the
adult herring fisheries. Apart from being of direct interest to the fishing industri~
this information will also bevital'for a future management ofthe fishery by means
of a eatch quota' system.
,..
.
.
.
eIn
February 1973',the 10th·.survey in\this series.was made. Previous·ones·weremade
in 1960 and 1961, and.then.on a yearly.basisstarting from.1966 •. Results·ofthese
surveys were reported by the North Sea Young Herring .Working Group (Burd 1969, Anon
1971), Zijlstra (1966), Saville (1967), Postuma (1968), Postuma and Zijlstra (1969),
Schubert (1970), Postuma and Kuiter (19?1, 1972).
Methods
Procedures for the 1973 survey were similar to the ones used in previous years.
Each of the participating vessels.was.allocateda number of statistical squares,
and at least one haul was made at a random position within each square. The gear
used was a herring bottom'trawl with a small-mesh codend. Catches of herring were
sampled for' age-composi tionand. racial . characters:
. . .... . '"
The abundance of.year-class.1970and 1971 was expressed innumbers per·one-hour
tow. No correetions were made for differences in fishing powerbetweenthe vessels.
Hean length, VS andK2 were calculated for the'whole area by raisingvalues for'
eachsquare with the c~rresponding density offish.
Coordination of the survey and compilation of final results was done in IJmuiden.
~rhe
following ships participated in the 1973 survey
Country
Ship
Period
Denmark
England
Germany
Netherlands
Scotland
Sweden
U.S.S.R.
Daria
Cirolana
Anton Dohrn
Tridens
Explorer
Skagerrak
Aliot
9 - 23
9 - 24
9-- 20
29 Jan.
17 Jan.
31 Jan.
7 - 25
Hauls
Febr.
Febr.
Febr.
- 16 Febr.
9 Febr.
- 16 Febr.
Febr.
-
19
23
46
38
51
16
30
Herring sampled
1625
600
840
625
890
1020
100
Results
The survey area extended between 52°00 N and 59°00 N, including Skagerrak and Kattegate A total of 223 hauls was made by all vessels, covering 123 squares. Figures
1 - 8 represent numbers per one-hour tow, mean length, VS and K2 of yearclass 1970
and 1971.
The mean density of year-class 1971 for all squares combined was 411. This is slightly
below the long-term average of previous year-elasses.Out of 10 year-classes measured
as I-group fish sinee 1960, 7 were stronger and 3 were smaller than year-class 1971
(table 1).
-2-
-2-
Compared with the two previous year-classes (1969 and 1970), year-class 1971 appears
to be much smaller.
The distribution of year-class 1971 was peculiar since it was limited mainly to the
eastern part of the central North Sea. Very few I-group herring were found in the
western and northern parts of the North Sea, except for same patches along the English
and Scottish coasts.
Tatlc 1 comparcs mcan length, VS and K2 of year-class 1971 with data for previous
;ye'.J.r-classes. Its menn length of 16.40 cm was about normal, but i ts mean VS of
56.29 was the lowest ever recorded since the start of the international young
hcrring surveys.
Herring of year-class 1970 were found along the eastern side of the Dogger Bank,
off Shields and in the Moray Firth. An exceptionally large haul of II-group herring
was made by RV "Cirolana" off Shields in square 2708. This catch has not been used
in calculating menn density, length, VS and K2 for the whole survey area. Thus
excluding square 2708, the menn density of year-class 1970 was found to be 57.
Discussion
•
One problem that needs further consideration is the presence in the North Sea of
jUVenile herring that originated elsewhere. Larval surveys north of Scotland in
1970 and 1971 have shown that substantial numbers of larvae born west of 4° Ware
transported by currents into the North Sea (Zijlstra 1972, Schnack 1973). If same
of these larvae survive, then part of the juvenile herring in the North Sea will
belang to stocks outside the area. In fact, there have been indications of the
presence in the North Sea of juvenile herring that belonged to stocks west of
Scotland (Anon 1969~ Saville 1971).
This theory mayaIso explain the discrepancy between the high abundance of year-class
1969 as measured during the International Young Herring Surveys, and the much lower
abundnnce of the same year-class during the commercial fishing season in the North
Sea in 1972. In view of the good catches of year-class 1969 west of 4° W, it seems
reasonable to assume that part of juvenile fish from the North Sea recruited to
stocks west of 4° W.
Our experience with year-class 1969 shows that caution is needed in interpreting
results of the International Young Herring Surveys. The abundance of juveniles in
the North Sea may be indicative of recruitment to stocks both in the North Sea and
west of Scotland. Results of the 1973 survey thus indicate an overal recruitment
slightly below average to stocks in the North Sea and west of 4° W•
•
-3-
-3REFERENCES
ANON, 1971
BURD, A.C. (ed.) 1969.
PODTID1A, K.H., 1968.
POSTUMA, K.H. and J.J.
ZIJLSTRA, 1969.
•
POSTUMA, K.H. and
C.J. KUITER, 1971.
POSTUMA, K.H. and
C.J. KUITER, 1972.
SAVILLE, A., 1967.
SCHNACK, D., 1973.
SCHUBERT, K., 1970.
~
ZIJLSTRA, J.J., 1966.
ZIJLSTRA, J.J., 1972.
ds
Report of the Working Group on North Sea Young
Herring Surveys. I.C.E.S. Pelagic Fish (Northern)
Committee. C.M. 1971/H : 4 (mimeo).
Report of the North Sea Young Herring Working Group.
I.C.E.S. Coop. Res. Report, Series A, 14 (mimeo).
Report on the International Trawling Survey for
Immature Herring in the North Sea, 1968.
I.C.E.S. Pelagic Fish (Northern) Committee,
C.M. 1968/H : 4 (mimeo).
Report on the International Trawling Survey for
Immature Herring in the North Sea, 1969.
I.C.E.S. Pelagic Fish (Northern) Committee, C.M •
. 1969/H: 9 (mimeo).
Report on the International Trawling Survey for
Immature Herring in the North Sea 1971.
I.C.E.S. Pelagic Fish (Northern) Committee,
C.M. 1971/H : 5 (mimeo) •
Report on the International Trawling Survey for
Immature Herring in the North Sea 1972.
I.C.E.S. Pelagic Fish (Northern) Committee, C.M.
1972/H : 5 (mimeo).
Report on the International Trawling Survey for
Immature Herring in the North Sea in 1967.
I.C.E.S. Pelagic Fish (Northern) Committee, C.M.
1967/H : 28 (mimeo).
Report on the International Surveys of Herring
Larvae in the North Sea and Adjacent Waters in
1971/72. I.C.E.S. Coop. Res. Rep., 34 : 1 - 31.
Report on the International Trawling Survey for
Immature Herring in the North Sea 1970.
I.C.E.S. Pelagic Fish (Northern) Committee, C.M.
1970/H : 13 (mimeo).
Report on the pilot-study for future young herring
research in the North Sea.
I.C.E.S. Pelagic Fish (Northern) Committee, C.M.
1966/H : 9 (mimeo).
Report on the International Surveys of Herring
Larvae in the North Sea and Adjacent Waters in
1970/71. I.C.E.S. Coop. Res. Rep., Series A,
28 (mimeo).
TABLE 1. Mean abundance, mean length and mean number of vertebrae of I Group
Herring in the North Sea and the Skagerrak between 52 0 N.L. and 59 0 N.L.
Yearclass
1958
1959
19G3
:96 4
•
"1965
"'966
1967
1968
1969
1970
1971
Catch/hour
1230
337
2797
714
238
265
455
442
1241
844
411
v.s.
~2
L
56.45
16.05
16.05
-----
-----
56.44
56.49
56.49
56.48
56.51
56.47
56.49
56.47
56.29
14.90
16.73
17.13
16.83
17.32
15.67
15.31
16.54
16.40
TABLE 2. Catch in numbers per hour per statistical rectangle of I and 11
Group herring in the North Sea and Skagerrak.
Yearclass
1957
1958
1959
1962
1963
1964
1965
.1966
1967
1968
1969
1970
1971
I GROUP
1230
337
2797
714
238
265
455
442
1241
844
411
11 GROUP
222
167
28
184
56
10
45
87
73
354
57
•
)
v
5
~
j
•
\'---
I
--"-J'
I
I
I .
. 24.. 25.. 26. . 27. 28..29. 30 . 31 . 32 .33. .3{; . 35 36. 37.. 38.. 39..
-----
--tb,---{
17
---0
0
0
12
0
5
0
0
8
4
~--
2
5
0
0
0
2
48
o
3
0
1
20
0
4
0
7
1
0
1
1
0
48
0
•
o~
1
18
9
0
12
1
0
1
9
1
1
3
3
0
1
o
10
2
0
0
0
1
48 176
o
270 106
o
383
80
0
o
40 120 2147
48
o
09
08
07
06
05
171
1
42
7
0
37
0
1
247
10
04
03
02
01
Figure 2
•
Mean number per square per one
hour tow
YEAR CLASS 1970
Autumn spawners
February 1973
Mean number whole area: 57
(except square 2708)
5~~
I
j
,
I
I
I
I
I
I
24.. 25.. 26.. 27. 28.. 2!J.. 3D.. 31. 32.33 . 3t{ 35.. 36 . 37.. 38.. 39..
-k:\
0
0
2
0
0
2
14 25
1
0
0
•
2
14 2
0
0
0
0
0
0
0
1
0
0
0
0
0
,.
0
0
0
2
0
16.00
0
0
19 12
0
0
0
0
0
0
0
0
0
0
17
4
0
20.87
0
0
0
10
09
-
j)
08
07
06
05
-04
-03
-
- 02
01
Figur. 3
•
Hean length per square
YEAR CLASS 1971
AutU1l1O spawners
February 1973
Hean length whole area: 16.40 cm
I
I
. 24.. 25.. 26.. 21. 28..29.. 30.. 31.. 32.33.. 34.. 35. 36.. 31. 38.. 3[)..
"&
17
I
•
0
0
0
5
22.85
2
24.19
3
20.25
0
0
0
12
0
25.17
8
4
24.75 25.00
0
5
24.03
0
1
0
26.25
4
1
24.25 24.25
1
18
9
25.25 24.64 25.31
9
1
1
3
23.58 26.25 25.75 24.58
0
2
0
0
24.00
106 0
171
.74
22.11
42
40
22.75 19.73
0
7
24.54
0
!J
2
23.75
4
22 50
1
23 25
48
0
23 35
0
7
24 61
0
48
21
0
1
21 25
1
0
20.25
0
176 0
10
09
08
lli.~6
0
0
0
0
0
07
06
05
04
03
02
01
Figurl 4
Mlan length per square
YEAR CLASS 1970
Autumn spawners
February 1973
Mean length whole area: 22.22 es
(Ixcept square 2708)
•
I\--.~
I
I
I
I
I
I
I
. 24.25.. 26.. 27.. 28. .29. 30.. 31.. 32.33.. 34.. 35. 36.. 37. . 38.. 39..
&~"I
~oP
N ~~
1 \)"" ~
0
0
0
2
56.00
~
0
2
1
75
.00
57.14
59.0ll
0
51
1
2
56.33
56.33 56.75
/1
0
0
,---...
~
~.so
2
0
0
0
2
56.00
0
0
0
0
0
;
0
1
0
0
l:r
Z
~c
0
0
0
4
0
56.75
0
0
0
'\0
j
ti
~J
0
11
56.45
v
~~
~~
(
~~f
.....
10
~
;t~
09
~)~~
08
!?rot =07
-06
05
4j1
~~
-
::::::.~
Mean VS per square
YEAR CLASS 1971
Autumn spawners
February 1973
Mean VS whole area: 56.29
(
\~.ro
0
,
\..
I
I
I
I
I
I
I
I
I
I
I
I
I
I
I
04
-03
- 02
-01
5°
Figure 5
)
.
~~ \
~
~!50
O:~
6.4
~
'\
--..r- (
IM
.
?08
56.52
I
35..
1~~t
56
1
Jf
'"
t
Jf
()
V
ff'r'r-B' ~ -
5~
9
56.67
688
56.28 "....
14000 ~
56.18
512
55.95 ~f(
'Il'
244
56.18 ~~)
8318
56.23 (~~
1161
56.35
0
17
173
163
33 I~
56 32 ~8 ~6.35
0
\
~
-
1'"\.(.""-"_J'"
)
•
:/)
4
34
1550
56.25 56.27 56.32
0
54
0
0
0
0
552 2363
2
&48
56.50
56.38 56.42
~.15 56.55
0
1
0
0
0
0
0
147 468
56.35 56.28
0
0
0
0
612
8628 30
\\c
57 00 0
56.38 56.31 56.20
0
25
370
692
910
31
234
11~~ 38
56
56.7 ~29 56.17 56 35
48
56
23
56 55
32
94
91
504 937
210 286
56.25 56.46 56.37
56.45
56.19
p
41
1
80
220
246
91
1
~
.48 56.00
56.37 56.42 56.27 56.39 .~
e;P-'-\.J\~
4
0
5
~.
I
I
~
1Xa
5 .38
!J
-
I
.24.. 25.. 26.. 27. 28.. 29. 30.. 31.. 32.33.. 34.. 35. 36.. 31. 38.. 39..
--~1&1
~n~
N ~l:.
'--.
2
0
58.00
82
5
56.50
2
~ 622 6
.83 56.54 ~6.19 56.63
3
/ 56.25
2
0
57.00
2
1
1
• 1 57.00 57.00
9
79
5 60
~
0
0
0
0
4~~18 2
56.
473~~ 171 270
56.61 ~42 56.41
1
55.00
2
.33
0
}:?
~
)
•
f~~~-~
~V
~
~~'I
5
I
I
(
0
p
48
0
P
",
(J
p~c~
,
.....-...':
~O ,.j[f
~
(
~
t;
~
12
10
09
'1
~)~~
08
1001 =07
-
I
-C
0
35..
.
-
,
I
I
I
I
I
I
I
I
I
I
06
05
-04
-03
02
I
HQure 6
Mean VS per square
YEAR CLASS 1970
Autumn spawners
February 1973
Mean VS whole area: 56.43
(except square 2708)
'--~~
I
0
~6.0
~
.
~
ß~~
~
'\
~.ro
L.J
t
'10
P
0
8
55.63
I
t?'~~,--
V~,"",I
)
___
~
U
p
10
5
56.67 56.9Q
A~
J
C;:) \
176
;5.~
17
~
~
0
262
36.[
56 06 56 4
5
0/
56.80
5°
0
~-1:J
~OO~
1
56.30
54
1
1
1
~O
)
-)
0
() v
V
~':Y
<..
0
~
48
56.31
106 0
383
80
56.26
56.42 56.42
42
40
120 2147
56.43 56.46
56.32
0
37
7
247
56.43
56.33 56.30
0
1
1
\
rcp
0
"
O~
[0
48
0
56.92
0
7
56.43
0
48
17
-
~l./
..._---""
l((
0
!J
--
2
57.00
20
0
4
56.63
57.50
4
1
0
1
1
56.25 58.00
57.00 57.00
18
9
0
12
1
56.56 56.50
56 76
1
1
3
3
0
~6j
~
12
0
56.60
8
4
56.33
0
0
5
0
56.62
0
1
l
~
~}
"I
4 (:j'"" ~5
--- ~ 56.62
1251
.80 56.66
-
I
I
I
I
. 24. .~-'5. : 26.. 21. 28.. 2ß. 30.. 31.. 32. 33. . 34.. 35. 36.. 31. 38.. 39..
01
17
~4~
.J..1~/b
51
0
W.lb
0
0
0
~J-----+=-0-+0=-----+=-0--+1-:-----t-=0---+-=-0
14.) 2
. !Yo81
4
0
14.83
'1
173 n63
33
14.25 ~ 14.23'?,
0
O -t-:~-4.-44--r--r---r-J--r
-t-:::O--r::-
0
0
0
0
0
4
34
1550 688
14.50 14.06 14.30 14.25
p:.
~48 54
0
clA.69 14.13
0
2
0
13.75
0
0
r:.
0
0
552
2363 14000
14.28 14.37 14.38
/
~~~20 A~22
)
~7Q..
\
r:;
4.1~
.1
("tf u
•
0
0
0
0
147
468
512
14.20 14.24 14.09 ~((
t~
t!<,
J
~~
ti
d
~V
JJ
11
48)
14.00 /
~~
5°
-'~'-it--:J-+--tv--c~~
fT'o'r'&"'-~-~
~J
0
t
(
~
----F-iu-re-7- - - - - - -.. . '"
.. Q
Mean K per square
2
YEAR a..ASS 1971
Autumn spawners
February 1973
Hean K whole area: 14.30
2
. 24. . 25.. 26.. 2l.. 28.. 29. 30 . 31.. 32.33.. 34.. 35. 36.. 37. . 38.. 39._
.'
.
6622
c::
i.....2t'
4
10 . . .
~4.\0 0 0 0 0 0 n~04 ~~~~1 ~~.93 {~~29 ~~
~ I<~ i1 09
T-I---+--+----i--t---+--+---+--t---+-7?-i
1126\ 38
25
370
0
692
910
31
234
8318
~ ~)
08
13.80)'~00 14.31 14.09
14.00 14.00
14.34 14.44 \c:'l
u
\ 32
94
91
504
937
210
286
1161
~
14.23 14.18 14.07
13.95
14.30 14.53
10~
D.{ -07
_
241
1
1
220
80
246
91
rJ
06
.19 14.00
14.22 14.38 14.33 13.~&i ~ .-I
)
5
4
0 (/b-~ -I'-' IV
05
V~d=~:---+"IUC--+"'---lh7~:..,-I;~·lf:'-t-7
35. .
04
1
•
1
2
0
13.00 14.00
03
02
01
-&\
~nl::l
~ l!'~
<6V' ~5
~
'--
13.81
1251
1 • 2 14.09
~.
622
...-.."
Vd
0
0
0
14.00
82 5
14;18
0
0
2
12
0
14.67
8
4
14.75
0
0
0
5
14.38
0
1
~
~
\~c'
!J
)
0
V
",0
\
J
~
1>62
~6
~
P/
4.40
fl1r'~~-~
1
10
0
176
0
0
U )
~
~
~
.
\I'
0
0
0
O~c~
48
0
0
~
() ~
-...
~
(
ri
~ ")~t
1Dot =07
-
;'-~
I
t{
\~Oo
I
35..
I
I
-03
50
- 02
-
./
I
06
05
-04
I
~O
8;~
13.
t~
-10
09
08
~
n<J
10
5
14.33 14.~Q,
8
14.25
Autumn spawners
february 1973
Mean K IInole area: 14.27
2
(Except square 2708)
L0
I
9
~
YEAR dASS 1970
.5 ~~
I
1
~3.6~
17
Figur. 8
Mean K per square
"h
W--
0
0
'"
(
)
\
0
17
~
C
~~
i
'-'D~
\
"l
v-~~
-'-i~
tt
~J
0
11
7
13.57 14.22
48
54
~4.59 ~4.4
J,f
.~
•
n
0
(tJ.
\
~
~C ...---- , /
48
14.33
0
~
>{
,)
"
Z
2
15.00
3
20
0
4
1(3
14.16
14.00
J 13.88
2
0
4
0
1
1
1
14.00
14.25 14.00
15.00 15.00
1
18
1
9
0
12
1
84 13.00 14.00 14.11 ~4.06
14.66
79
9
1
1
0
3
ß
.49
0
1
48
P
4~414 2 0
14
14.13
06 P
383 80
47:~ 171 ~70
14.3 14.52 ~4.40 4.29
4.29 14.92
1
20 2147
2
~O
~4.00 4.19 ~4.49
14.25
[l
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4.54 ~4.65
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01