Fróðskaparrit - 01.01.1987, Page 72

Spawning of Atlantic Halibut (hippoglossus
hippoglossus) in Deep Waters on the Continen-
tal Slope South West of the Faroe Islands
Stein Hjalti í Jákupsstovu og Tore Haug
Abstract
From the appearance of fish with running
gonads, and of pelagic eggs in the water
column, it is evident that the Atlantic hali-
but, Hippoglossus hippoglossus, spawns in
late winter in deep waters on the continen-
tal slope southwest of the Faroe Islands.
Almost exclusively sexually mature speci-
mens are present in the spawning area
(mainly depths below 700 m), while in
shallower areas around the Faroes, small
immature halibut are quite abundant.
Temperatures and salinities in the spaw-
ning area are, in February, c. 8° C and
35.25%0 respectively. A possible signifi-
cance of the cold deepwater current runn-
ing north-westwards just north of the spaw-
ning area through the Faroe Bank Chan-
nel, as a clue for halibut to identify the
spawning area, is discussed.
Introduction
In Norwegian coastal inshore waters. At-
lantic halibut, Hippoglossus hippoglossus
(L.), spawning in early winter in deepwater
localities (300-700 m) in certain fjords has
been well documented (see, e.g., Devold
1938, Kjørsvik et al. 1987). From the
occurrence of planktonic eggs and larvae
(Jespersen 1917, Rollefsen 1934, Vedel-
Táning 1936, Mclntyre 1958) and the occa-
sional presence of adult fish with running
or spent gonads in commercial catches
(Hjort 1905, Jespersen 1917, Devold 1938)
it has been inferred that the species most
probably also spawns at certain deepwater
areas laying on the slope of the continental
shelf in various parts of the North Atlantic.
Congregations of adult halibut on defi-
nite continental slope spawning grounds
were not documented, however, until late
1982 - early 1983 when a Faroese trawler
made very good catches of large halibut in
a restricted area at 800-1000 m depth on
the northwestern slope of the Faroe Bank
(Fig.l) (Jákupsstovu 1986). Later research
in this area has revealed that spawning
commenced in January and intensified with
a peak of activity probably occurring later
Fróðskaparrit 34.-35. bók (1986-87): 76-90