Effect of maternal and paternal line on spatial and temporal marine distribution in Atlantic salmon.

We examined the inheritance of the sea migration pattern of Atlantic salmon, Salmo salar, in a crossing and tagging experiment in the Baltic Sea. Individuals from the parental stocks, Neva and Iijoki, and their reciprocal hybrids were released as 2-year-old smolts, into the same estuary of the Bothnian Sea in 1994. Two thousand smolts from each of the four groups were marked with Carlin tags. The recapture rate of the tags was nearly 10%. We used log-linear models to analyse the marine distribution of the salmon groups from the tag recovery data. The pure stocks and their pooled hybrid groups all showed statistically significant differences between each other in spatial and temporal sea distribution. The Iijoki salmon were more frequently (9%) caught outside the Bothnian Sea than were the Neva salmon (2%). The majority of the Iijoki salmon (55%), but fewer Neva salmon (40%), were caught in the second sea year. In spatial distribution, the hybrids seemed to be intermediate between the parental stocks, with no differences between reciprocal female and male lines. In duration of sea migration and age at maturity, however, the hybrids were very similar to their maternal line, the effect of which was thus clearly stronger than that of the paternal line. Copyright 2000 The Association for the Study of Animal Behaviour.