Fróðskaparrit - 31.12.2000, Blaðsíða 92

96
REPRODUCTION OF FAROE PLATEAU COD:
SPAWNING GROUNDS, EGG ADVECTION AND LARVAL FEEDING
10-14 April 1995
N = 76
15
10
Q.
22-27 April 1999
N = 599
-llll....llllll.l |B| | l-l |f|
3 4 5 6
Length (mm)
7 8
Fig. 5. Length distribution of cod larvae during 10-14
April 1995 and 22-27 April 1999.
Mynd 5. Longdarspjaðing av toskalarvum í tíðarskeið-
inum 10.-14. apríl 1995 og 22.-27. apríl 1999.
tance. In April 1995, about 13%, and, in
1999, about 26% of the cod larvae had
copepod eggs in their gut. Copepod nauplii
were, on the other hand, not found in the
cod larvae in 1995 and were found in only
4% of the larvae in 1999. Other zooplank-
ton (e.g. Cirripedia nauplii, Podon sp.
(Cladocera), and small copepodite stages)
were only rarely found. The mean gut con-
tent of these prey items per larvae in April
1999 was 0.37 copepod eggs, 0.06 copepod
nauplii, and 0.01 other zooplankton.
Most of the copepod eggs (~ 80-90%)
found in the gut of the cod larvae were
about 130-140pm in diameter and most
likely were Calanus finmarchicus eggs.
The rest of the eggs were smaller in size
and most likely belonged to the neritic
copepod species that occurred in the water.
These were mainly Acartia and Temora.
Thus, the first feeding cod larvae on the
Faroe Shelf seem to have predated mainly
on C. fmmarchicus eggs during April 1995
and 1999.
In late May 1995, the gut content had
changed considerably. Copepod eggs were
only rarely found, and, instead, cod larvae
preferred larger prey (Table 5). Copepod
nauplii were commonly found, but the most
frequently found food items were small and
medium-sized copepodites, mainly within
the size range of 0.6 to 1 mm. In 11% of
these cod larvae, the gut was either empty
or the content so well digested that the food
could not be identified.
Table 4. Frequency of prey groups in the gut ofcod
larvae in April of 1995 and 1999.
Talva 4. Títtleiki av ymiskari føði hjá toskalarvum
í apríl 1995 og 1999.
Date_______________10-14 April 1995 22-27 April 1999
Copepod eggs 12.7% 26.7%
Copepod nauplii 0.0% 4.0%
Other zooplankton 0.0% 1.2%
Phytoplankton a.o. unidentified 39.7% 21.8%
Empty gut 47.6% 46.4%
Number of larvae 63 524