Survival of reared and wild Atlantic salmon smolts: size matters more in bad years

摘要: We compared the marine survival of Carlin-tagged wild and hatchery-reared Atlantic salmon smolts Simojoki river, northern Baltic Sea. All reared released were offspring native spawners returning to river. Reared adipose-fin-clipped from hatchery several weeks before tagging. The simultaneously caught tagged at a smolt trap located river mouth. study was conducted in two years, 1991 1993, when post-smolt Sea different. Tags returned by fishermen return rates used estimate groups. applied generalized linear models with as response variable year, origin, size explanatory variables. On average, had 4.5 times higher rate than fish same size. difference observed tag recovery such only about twofold or less, larger ones compensated for their lower rate. better more pronounced low-survival year (1993 class) high-survival (1991 class).