Translation Series No.1211

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of almost 29 mm. More than 93 per cent of all fish caught were, however,
more than 60 cm long. Such salmon have a mouth opening of more than 57 mm.
This Means that a mechanically conditioned selection does not take place
in this range of lengths. If there is still some kind of selectivity at
work, it must be conditioned by sensory physiology.
LA. 237]
In contrast to this expectation the trial results showed relat-
ively small differences between the catch results for both kinds of hooks
for lengths of up to 74 cm. For lengths of over 60 cm more salmon were caught
with the large hooks than with the small ones.
Tests for significance for the catch differences between the
two kinds of hooks for the total catch, as well as for fish above 89-cm .
length showed no statistically significant differences. It thus remains
whether
to establish in case a selective effect has been presentlit has been cov-
ered up in the present case by accidental fluctuations in the catch.
2.3. The extent of the pelagic salmen fishery . .
2.3.1. The fishing grounds
It has already been mentioned that the salmon fishery has ex-.
a large extent to the open Baltic Sea only alter the Second
World War. To begih with the fishermen frequented only parts of the
southern Baltic Sea. The most important fishing ground was the Bay of Danzig
(south of 55 ° N). At that time the southern point of Gotland Deep (south .
of 56 ° N) also played already a certain role, as well as the Bornholm Basin.
In the spring months the coast of Pomerania was visited.
During the course of the years it was principally the Danish
fishermen who extended their cruiees to the more distant'fishing grounds.
At the beginning of the fishing season, in August, todayeevere Danish .
and a few German cutters sail past the Land. Islands and . visit:the Gulf
tended to