Spatial distribution of migratory Salmo trutta in the northern Baltic Sea

Abstract

<p>Spatial distribution of brown trout (Salmo trutta) was studied on the Finnish coast of the<br />northern Baltic Sea in 1998–2010 based on smolt tagging. The studied trout stocks were<br />hatchery reared, and smolts were tagged with Carlin tags before release into the rivers. The<br />distance between the release and recapture sites as well as location of the recapture site in<br />relation to the release site (north, south, west, east) were analysed, taking the stock and<br />sea age of the trout into account. The most important tag recovery areas at sea were the<br />estuaries of the spawning rivers and coastal areas surrounding them. The natural direction<br />of movement was along the coast line, north or south on the western coast and east or west<br />in the Gulf of Finland. The release site and age affected migration direction. The distance<br />of recoveries from the release sites varied for the same genetic stock released at different<br />sites. The longest median recapture distances were recorded during the second sea year.<br />The stocked brown trout (80%–95%) were mainly caught during their first two years in the<br />sea before they become mature. Knowledge of spatial dispersal of sea trout is important for<br />the management of the stocks and fisheries.<br /></p>