There are naturally reproducing, wild, sea
trout populations in at least 250 rivers in the entire Baltic
area. Besides the naturally spawning sea trout, compensatory rearing
and releases are legally enforced in some rivers utilised for
hydro electric power production. In many rivers enhancement releases
to increase the status of the populations is undertaken. Some
of the wild populations are in a poor shape due to, in
some cases, overexploitation and in other cases due to decreased
spawning opportunities due to human activities. The total production
of sea trout smolt has been estimated to be some 3-3,5 million
annually, of which almost 20% of wild origin. It must be noted
that the production level of wild sea trout is largely unknown
as many populations are not surveyed at all.
The life patterns of sea trout populations
differ depending on the latitude of their home river. It could
be found that the more northern the river, the less migration
distances from the river occur. The southernmost populations have
migration patterns similar to those of salmon and they also reach
much heavier weights than those in the northern part of the Baltic
area.
The fishery of sea trout mostly takes place
in the coastal areas distance from home rivers depending on the
above mentioned migration pattern. However, the southern wide
migrating populations are partly exploited in the salmon fishery
off shore. The total catch of sea trout has been estimated to
be in the level of 1000-1500 tonnes, but this figure is probably
a low estimate as a great part of the catch is taken in recreational
fisheries.
In some rivers, especially in the southern
part of Sweden, there are incidences were the populations are
effected by the M74 syndrome. In the rivers Emån and Mörrumsån,
densities of parr sea trout have decreased even more than those
of salmon parr. There is some evidence that also the sea trout
populations in the Gulf of Finland are affected by M74, but the
extent is not known.
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