Unstable release strategies in reared Atlantic salmon, Salmo salar L.

The effects of year, size, sexual maturity and release date on the probabil ity of recapture of tagged Atlantic salmon, Salmo salar L., released from a Swedish hatchery in the Baltic Sea were examined. The probability of recap ture varied among years for individuals which were juvenile when released ( 1988, 13.5%; 1989, 4.4%; 1990, 1.2%) or previously mature males (1988, 1.9% ; 1989, 0.5%; 1990, 0.4%). Body size was positively associated with the pro bability of recapture in each release year for both life-history types. Int er-annual changes in recapture rates were similar for both large and small smolts. There was a significant effect of life-history type on recapture ra tes in 1988 and 1989, but not in 1990. There was a significant effect of re lease date on recapture rates in 1988 and 1990, but not in 1989. The maximu m recapture rates were associated with different release dates in each year , i.e. 27 May 1988, 6 June 1989 and 21 June 1990.