An analysis of the distribution of juvenile Atlantic salmon (Salmo salar) in nature as a function of relatedness using microsatellites

The major objective of this study was to test the hypothesis that juvenile Atlantic salmon kin occupy adjacent territories in their natural habitat in order to profit from the benefits associated with kin-biased behaviours, a s has been observed under controlled laboratory conditions. Microsatellites were used to establish the relatedness of salmon fry (in their first summe r of life) and parr (in their second and third summer of life) captured in adjacent territories. We did not observe a relationship between the proximi ty and the relatedness of either parr of the same cohort or fry in their na tural habitat. Although many pairs of fry were identified as being related when sampled immediately after emergence, most family groups did not occupy adjacent territories. The high dispersal potential in rivers, the low occu pation rate of the habitat and the incidence of half-sibs in nature most pr obably reduce the opportunity and advantage of kin-biased behaviour, in con trast to laboratory studies conducted in artificial, high-density condition s.