C.M. 1997/0:04
International Council for the
Exploration of the Sea
•
REPORT ON THE O-GROUP FISH SURVEY IN
ICELAND AND EAST GREENLAND WATERS,
AUGUST- SEPTEMBER 1997
by
Sveinn Sveinbjörnsson and Siguröur P. J6nsson
Marine Research Institute Reykjavik, Iceland
This paper not to be cited without prior reference to the authors
1. Abstract
This paper is a continuation of annual reports on routine investigations on
hydrography and the distribution and abundance of O-group fish in Icelandic and
East Greenland waters in August-September.
The temperature was relativly high with a strong warming up of the surface
layer.
The 1997 abundance index of cod was very high. The abundance index of
haddock was somewhat above the long term average (excluding the extremely rich
years of 1976 and 1978) and that of capelin was high. The abundance index of
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redfish was not estimated as the survey did not cover the main distribution area of
the O-group redfish in the East Greenland- and the Irminger Sea area.
2. Introduction
Annual surveys on the distribution and abundance of O-group fish in the
Iceland-, East Greenland area have been carried out since 1970. The main aim has
been to obtain a first index of year c1ass strength of the most important
commercial species, Le. cod, haddock, capelin and redfish. Methods and data
handling have been described by Vilhjalmsson and Friögeirsson (1976).
In 1996 only one vessel covered the survey area as folIows:
•
Ami Friöriksson
13.8.-5.9.
The shelf area off W-, N-, E-,
NE-, S-Iceland and the Eastem
Dohm Bank
Survey routes and stations are shown in Figure I. The East Greenland Irminger Sea area was not surveyed this year and only the eastemmost part of the
Dohrn Bank area was surveyed. Acoustic records of O-group fish were obtained
and the density assessed by a 38 kHz Simrad EK 500 split-beam sounder /
integrator system. Species composition as weIl as abundance was, however,
primarly assessed by trawling in the scattering layer for a set distance at a time.
For O-group capelin echo abundance was obtained and an index based purelyon
echo integration was calculated for the O-group capelin as in previous years.
2
Hydrographie stations were worked on standard hydrographie seetions in
Icelandie waters using CTD-sonde.
A total of 255 pelagie trawl stations and 71 hydrographie stations were
worked and 33 juvenile lumpsuekers were tagged during the eruise.
Seientifie staff on RV Arni Friöriksson was: Sveinn Sveinbjörnsson,
Siguröur 1>. Jonsson, Björn Sigurösson, Albert Stefansson, Gfsli Olafsson, PalI
Svavarsson, Heöinn Valdimarsson, John Mortenssen and Siguröur Gunnarsson.
Svend-Aage Malmberg eompiled and eommented on the hydrographie data.
3. Hydrography
In August 1997 the main features of the hydrographie eonditions (Figs. 2-4)
in Icelandie waters were as folIows:
South and west of Iceland salinities and temperatures were relatively high
0
(7-10 C) with a strong warming up in the surface layers. The Atlantic inflow into
North Icelandie waters was also quite pronounced (5-6°C; S>35.0%0), covered by
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a low saline surface layer. A slight relatively cold (4°C) intrusion from the north
was observed in the western part of the area. Off the East coast of Iceland
temperatures were also relatively high (>4°C). In deeper waters northeast and east
of Iceland the cold East Icelandie Current was, on the other hand, pronounced as
earlier this year (0-2°C) but with a strong warming up in the surfaee layer (7-S0C).
Jt is concluded that in the summer of 1997 temperatures were relatively high
in the survey area with a strong warming up in the surfaee layers in general.
4. Distribution and abundance of O-group fish
In the Icelandic area the greatest abundance of O-group eod (87% of the total
index) was reeorded off N-Iceland where the highest densities were observed in
the inshore areas. In other areas the distribution differed from normal years in a
tllat relatively high proportion of the O-group was reeorded off E-Iceland. Some
drift of O-group eod was deteeted aeross the Denmark Strait to the eastern Dohrn
Bank area but time constraints did not permit further eoverage in that area. The
distribution of O-group haddoek was normal and the greatest abundance was
recorded offW- and N-Iceland as in 1996. This is eontrary to the situation in 1994
and 1995 when the 0- group haddock was mainly recorded at
SE~
and SW-Iceland.
The distribution of O-group capelin was very extensive as commonly happens in
rich years. The distribution of O-group redfish in the Icelandie region was normal.
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3
In comparative terms the O-group index of cod was very high, that of
haddock was about average whereas the abundance index of capelin was high,
ranking among the highest on record for the second consecutive year.
4.1. Cod
The 1997 distribution and relative abundance of O-group cod is shown in
Figure 5 and the total abundance index as weB as the contribution by the various
subareas in Table I.
Table I. Abundance indices of O-group cod.
•
Iceland
Dohmbank
4
SE
sw
W
N
E
Total
+
+
97
1005
46
1152
As usual most of the O-group cod were recorded off North Iceland. The total
abundance index ranks among the highest in the series. The size of the distribution
area of the O-group cod is normal for rich years. Some drift of O-group cod across
the Danmark Strait was observed. The condition of the 1997 cod brood as judged
by the length distribution was dose to the long term average. (Fig. 6).
4.2. Haddock
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The distribution and relative abundance of O-group haddock is shown in Figure 7 and the
indices by subareas and the total inde~ is given in Table 2.
Table 2. Abundance indices of O-group haddock.
Iceland
Dohm Bank
+
SE
sw
W
+
+
11
N
15
E
Total
+
26
Almost aB the O-group haddock was recorded off W- and N-Iceland. The
abundance index is close to average and the highest since 1985. The overall mean
length of the O-group haddock (Fig. 8) was considerably above the long term
average.
-.~
4
I
4.3. Capelin
The distribution of O-group capelin is shown in Figure 9. The highest
numbers were recorded off N-Iceland but on the whole the O-group capelin was
widely distributed.
The abundance indices in different areas are given in Table 3.
Table 3. Abundance indices of O-group capelin
Iceland
Dohm Bank
5
SE
SW
W
N
E
3
11
30
II
Total
61
•
The abundance index ranks among the highest in the series but the overall
mean length of the of the O-group was below the long term average (Fig. 10).
The acoustic abundance index of O.,group capelin (Reynisson and
Vilhjeilmsson, 1983) was about 98 which is the second highest obtained.
The acoustic abundance indices in the period 1981 ~ 1997 are given together
with the corresponding CPUE indices in Table 4.
Table 4. Abundance indices of O-group capelin in 1981-1997.
Year
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
Acoustic index ( m2 * 10-5)
15.2
2.8
7.8
3.5
5.6
37.1
21.2
91.8
33.3
24.7
40.2
CPUE index
29
13
22
28
33
37
14
52
40
21
54
•
5
1992
56.8
1993
44.9
35
51
1994
50.5
94
1995
23.0
24
1996
145.0
82
1997
97.8
61
---------------------------------------------------------------------------------------------------,
(
4.4. Redfish
As mentioned before, no survey was conducted in the main distribution area
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of O-group redfish. Consequently it is not possible to give an abundance index for
the species. In Figure 11 the distribution and density of the O-group redfish in the
surveyed area is given. The distribution of the O-group redfish in the Icelandic
region was wider than in recent years, the fry being caught off SE-, N-, W- and
SW-Iceland. The average length of the O-group at SW- and W-Iceland in 1997
was smaller than in 1996.
4.5. Other species
During the O-group survey in 1997 20 species other than already mentioned
of O-group fish and juveniles were recorded.
As in previous years the fry and juveniles of the sand eel species
Ammodytes marill11S and A. tobiall11S were most numerus in the catches of other
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O-group and juvenile fish species. They were recorded at 82 stations from Faxa
Bay at SW-Iceland c10ckwise to the E-Iceland region.
The young stages of lumpsucker were widely distributed this year, as in
1996, and were recorded at 51 stations off W, N, NE and E-Iceland. The greatest
numbers occurred off N-Iceland.
Whiting was widely recorded (38 stations) mainly off W- and N-Iceland
and norway pout was caught at 2 stations offW-Iceland.
0- group wolffish was fairly abundant and was caught at 27 stations, mainly
off N-Iceland. Spotted wolffish was caught off NE-Iceland at 3 stations.
Young stages of herring were present at 14 stations off SW-, W-, N-and EIceland.
Long rough dab was present at 28 stations, being most numerous off NIeeland.
6
Witch was recorded at 6 stations off SE- and SW-Iceland and lemon sole at
1 station off SE-Iceland.
Greenland halibut was recorded at 3 stations off N-Iceland and in the
Dohrn Bank area.
Greater silver smelt were caught at 2 stations off W-Iceland..
O-group and juvenile polar cod was recorded at 10 stations in the Dohrn
Bank area and offW-Iceland and N-Iceland.
Five bearded rockling was recorded at 2 stations off W-Iceland.
Short- spined scorpionfish was recorded at 7 stations off SE- and SWIceland.
Eelpout was recorded at 2 stations off W-Iceland and spotted snake
blenny at one station off N-Iceland.
Atlantic seapoacher was caught at 2 stations off W- and N-Iceland and
anglerflsh at 1 station off SW-Iceland.
Several other species of young and adult fish, not belonging to the O-group and
juvenile stages, were caught in the O-group hauls. They are not commented on in this
paper.
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5. References
Reynisson, P. and H. Vilhjalmsson, 1983: Acoustic index of O-group capelin in the
Iceland-Greenland area. ICES, C.M. 19831B:3.
•
4C1
7~
35"
3Cf
25"
15"
SURVEY ROUTES AND
GRID OF STATIONS
AUG.-SEPT. 1997
x HYDROGRAPHY
o PELAGIC TRAWL
68'
Figure 1. Survey routes and grid of stations, August-September 1997.
10·
- - - - - - - - - - -
3CJ
7(J
2:;
1:;
2(J
10·
tOC 20m
AUG.-SEPT. 1997
6a"
00
7·
11·
""----12"
Figure 2. Temperature at 20 m depth, August-September 1997.
•
25"
35"
20·
15"
tOC 50m
AUG.-SE PT. 1997
'0
0°
.
3. Temperature at 50 m depth , August-Septe mber 1997.
Ftgure
10·
5°
4<1
7(1
,·e
100m
AUG.-SEPT. 1997
68'
-
66"
o
8.5 0
Figure 4. Temperature at 100 m depth, August-September 1997.
15"
2Cf
4CJ
S"
1(f
E
7(f
COD 1997
1<'0
10-100
100-500
>500
GE!
o
.o;'JIlAbo
00
o
-0
o
o
o
t
o~
o
o~o~
00
g
0
o
~
0
o
0
o
0
o
o
0
Figure 5. Distribution and density of O-group eod (n/1 n.m.), August-September 1997.
oOJ
0
L
12
AUG-SEPT 1997
Cod Southwest
NODATA
0
'"
Cod Dohm
N 106
MI 55.93
0
'<t
0
(')
>!!
0
0
'"
~
0
•
0
'"
CodWesl
N 135~
0
'<t
MI 50.27
0
(')
;ft.
0
'"
~
0
0
Il)
Cod North
N 4875
MI 47.96
0
'<t
0
(')
<fi.
0
'"
-
0
0
•
0
Il)
Cod Easl
N 1008
MI 51.58
0
'<t
g
?f2.
~
0
0
,
,
20
40
,
6ctenglh (mm)
,
80
,
100
Cod Southeast
N2
MI35
Figure 6. Length distribution of cod, August-September 1997.
I
120
:JS
7d
25'
10·
15'
2d
HADDOCK 1997
~
<IO
10-100
100-500
68'
o
o
00
0
o
0
0
0
o
~
o
8
8
o
0
,~
8
0..
0
8
'0
0
0
o
o
o
0
8
o
0
0
:":::"'0
0
0
o:P
0
~~~~~~~~ l~
00000=000
/)
~~
o 00
o 0 0
o ,--.
o 0
00000
o
000
o
000000
o
0.%
o
0° 0,
o
0
o
0
0
o
o
o
oc9
o
o
0
o
0
0
0
0
0
Figure 7. Distribution and density of O-group haddock (nIl n.m.), August-September 1997.
l
14
AUG-SEPT 1997
Haddock Southwest
N2
MI 107,5
Haddock Dohrn
Ng
MI 117.5
0
l/)
Haddock West
N340
MI 79.43
0
-r
0
'"
,!!
Q
~
0
.,
0
"
0
l/)
Haddock North
N 518
MI 82.86
0
"t
0
M
cf.
~
0
0
i
20
I
40
,
6<t.ength (mm)
I
8Q
Haddock East
N4
MI 96.25
Haddock Southeast
N1
MI35
Figure 8. Length distribution of haddock, August-September 1997.
•
35"
i
i
2IS
25"
2cJ
15"
10°
I
!===:
7cJ
CAPELIN 1997
1
<1000
1000-10.000
10.000-100.000
>100.000
68"
~}J
~j '}t
66°
VI
j.
64°
62"
-
f
.s:1'
",
t;;)
~
:3
Figure 9. Distribution and density of O-group capelin (nil n.m.), August-September 1997.
16
AUG-SEPT 1997
o
Capelin Southwest
N703
MI 44.75
U'l
g
o~
o
(\I
o
o
o
Capelin Dohm
N 761
MI 47.68
U'l
o
V
o
C')
o~
o
(\I
.,
o
CapelinWest
N2458
MI 47.9:l
g
o~
o
(\j
o
Capelin North
N4534
MI 39.66
o
o
Capelin East
N 1892
MI 38.7
o
o
l()
Capelin Southeast
N 819
MI 34.98
o
C')
0"o
C\I
o
i
6Ct.englh (mm)
80
Figure 10. Length distribution of capelin, August-September 1997.
l
35"
4d'
i
i
70·
f ~
REDFISH
10·
15"
2(1
'~
1997
i<IOO
100-1000
1000-10.000
6a"
o
o
o
o
00
0
8
0
'0
0
0
0
0
0
0
0
0
0
0
0
8
0
8
0
o
o
o
8
o
o
00
o
8
o
0
0
0
~
;
0
WO
0
0:Q)0 0000
00
-
00 000
... ...
...
...
...
o
-l
000
o
000000
o
o
0
19
o
Figure 11. Distribution and density of O-group redfish (nil n.ffi.), August-September 1997.
L
-~
I
18
AUG-SEPT 1997
o
1.0
Redfish Southwest
N 414
MI 47.93
o
....
o
<?
~
o
'"
o
Redfish Dohrn
N38
o
....
MI 36.97
o
<?
o~
o
'"
o
o
l/"l
Redfish West
N243
MI 27.1
o
<?
~
o
'"
o
Redfish North
N3
MI41
Redfish East
NODATA
0
1.0
Redfish Southeast
N 130
0
'<t
MI 25.38
.
0
<?
~
0
'"
~
0
,
20
,
40
6Ct.englh (mm)
- _.
80
100
Figure 12. Length distribution of redfish, August-September 1997.
~
~