Fróðskaparrit - 31.12.2000, Page 91

NØRINGIN HJA TOSKINUM A LANDGRUNNINUM:
GÝTINGARØKI, EGGSPJAÐING OG FØÐIN HJA LARVUNUM
95
horizontal salinity distribution is better in
1999 than in 1995 (Fig. 4). The isohaline
figures indicate that the tidal front was clos-
er to land on the north-eastern part of the
shelf than on the western part in 1999.
Distribution and abundance ofcod eggs
and larvae in April
From the spawning grounds, cod eggs are
advected with the residual currents in a
clockwise direction. In mid-April 1995,
most eggs (the latest stages) and larvae that
were located to the north of the Islands
were close to the salinity gradients that in-
dicate the position of the tidal front (Fig. 4).
However, while drifting eastwards in the
northern region and southwards in the
northeastern shelf region, most larvae were
gradually advected into shallower areas.
While drifting, the eggs develop and hatch
and the larvae start feeding soon after
hatching.
Table 3. Maturity distribution ofmature cod in the
western spawning site on 17 March in 1995 and
1999.
Talva 3. Búningarstig á búnum toski á vestara
gýtingarøkinum hin 17. mars 1995 og 1999.
Maturity stage 1995 1999
3 0 0
4 1 2
5 7 2
6 31 56
7 10 0
Average 6.0 5.9
St. dev. 0.7 0.4
N 49 60
In 1999, the samplings were carried out
two weeks later than they were in 1995.
Now the eggs (latest stages) were located
mainly in the north-eastern shelf region.
On the other hand, the larvae were more
evenly distributed than the eggs, although
the highest abundance was located in the
central and western shelf regions.
In both years, very few eggs and larvae
were found offshore. This indicates that
the loss of eggs and larvae from the ecosys-
tem may have been small during these two
periods of observations.
Cod larval sizes in April 1995 and 1999
Even though the cod larvae in April 1995
were sampled about 12 days earlier relative
to April 1999, the mean length of the larvae
was significantly larger in 1995 than in
1999 (P = 0). The mean length ± standard
deviation in April 1995 was 5.4±0.7 mm,
and in 1999 it was 4.3±0.7 mm. In April
1995, the larval length distribution was
quite large, however, there were two abun-
dance peaks, one around 5.0-5.5 mm and
one about 6-7 mm. No larvae were smaller
than 4.0 mm (Fig. 5). In April 1999, the
length distribution had only one peak,
around 4 mm, and the smallest larvae were
3 mm.
Food content in the cod larvae
In April of both years, almost 50% of the
first feeding larvae had an empty gut (Table
4). Green gut and small, unidentified parti-
cles, about 30 pm in diameter, occurred fre-
quently. In addition, copepod eggs were by
far the most important prey items, while
copepod larvae were only of minor impor-