Náttúrufræðingurinn - 1950, Blaðsíða 21

SUNNLENZKA SÍLDIN í LJÓSI RANNSÓKNANNA
163
On the Herring in southern Icelandic Waters
by Hermann Einarsson
ABSTRACT:
ln ihis essay the author substantiates an opinion, previously expounded by him,
that fluctuations in tlie year-class strength of the Icelandic herring is the most irn-
porlant cause of fluctuations in the yield. The age distribution of the herring, caught
in southern and western coastal waters of Iceland, is described. It is maintained that
tlie Icelandic herring stock has been on a very low level during recent vears, duc to
poor recruitment. This resulted in an unparalelled failure of the drift-net fishery in
Faxa Bay and adjacent waters during 1946 and 1947.
A renewal of the herring stock startet with the arrival of the year-classes froni 1913
aiid 1944 (summer spawncrs 1913 and spring spawners 1944). These year-classes were
dominant during the herring fishery in Hvalfjörður in 1947 and 1948. A still greater
increase occurred during 1949 when the year-classes from thc summer of 1944 and
the spring of 1945 entered the fishery. These two year-classes constituted about 68%
of the total catch in 1949. These conclusions are incompatible with the views of Frið-
rikssoii, who maintains that the stock has been on a relatively high level and who con-
siders the year-classes mentioned (summer spawners 1943 and 1944, spring spawners
1944 and 1945) one year-class, designated as year-class 1944 by him.
Attcntion is drawn to the paralellism in the strength of the year-classes of summer
and spring spawners. It was found that tlie strength of the summer brood one year
corresponds to the strength of the spring brood the ensuing year.
I'hree years ago the author fonnulated a hypothesis according to which the nursing
areas of tlie Icelandic herring lie in the Irminger Sea, west of Iceland, i. e. in oceanic
waters. This view was recently opposed by Táning tvho considers this improbable
because herring fry has nol been caught in oceauic waters. 'Fhe author is of the
opinion that this is most probably due to deficient fishing methods, the gear used
being unsuitable for catching fry more than about 20 min in lengtli. FSnings investi-
gations on the distribution of herring fry off the north and east coasts of Iceland
support this conclusion, which is also borne out by the size distribution of herring and
sand-eel fry cauglit in this gcar. llevold’s important discovery of young herring in tlie
oceanic waters of the Norwegian Sea seems to support the author’s conclusion, as
similar current conditions are encountered off the west coast of Norway and the wcst
coast of Iceland,