Tímarit Verkfræðingafélags Íslands - 01.12.1967, Page 14

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TÍMARIT VPl 1967
karfaveiðinni á Islandsmiðum verið 20—25% á
ári undanfarið, en stærstan hlut taka Þjóðverj-
ar, en Bretar eru hálfdrættingar á við okkur.
Beztu skýrslur um afla karfa á sóknarein-
ingu eiga Þjóðverjar og sýna þær, að veiðamar
hafa dregið verulega úr stærð karfastofnsins á
Islandsmiðum á undanfömum ámm.
Summary
In this paper the author gives a short summary
of the status of the stocks of herring, cod,
haddock, saithe and redfish in Icelandic waters.
There are three races of herring in Icelandic
waters, two of Icelandic origin and one of
Norwegian.
Fig. 1 shows the annual Icelandic catch from
each of these races and reveals that in the last
years there has been a rather sharp decline in
the Icelandic races compared to a great increase
in the Norwegian one. The increased herring
catches are caused by a great increase in fishing
effort.
Fig. 2 shows the annual landings of cod from
Icelandic waters and also the effort (broken
line) as expressed by number of tons landed
by millions ton-hours fished. There is quite a
good correlation between catch and fishing effort
up to 1958, but after that there has been a steep
rise in effort but a general decrease in catch.
The effect of fishing on the stock is clearly
demonstrated by Fig. 4, which shows the
correlation between mortality and fishing effort.
There is a considerable variation in the strength
of the various yearclasses and this is shown in
Fig. 3, which gives the output of a single year-
class at the age of 7—9 years in the Icelandic
fishery, compared to the fishery 8 years later.
The annual landings of haddock from Icelandic
grounds are shown in Fig. 5. There has been
a substantial increase in total catch in recent
years corresponding to an increase in effort. This
is in apparent conflict with the development of
this fishery before the War, when the haddock
stock was known to be severely reduced by
fishing. It is concluded that the big increase in
catches after the War must be ascribed to better
protection of small fish, partly by changes in the
fishery limit and partly by the larger mesh intro-
duced in recent years.
The annual landings of saithe are shown in
Fig. 6 and they do not give rise to any concern
about the state of this stock. As for the red-
fish (Fig. 7), the fishery seems to have had a
clear adverse effect on abundance.