Published in:
The Open Fish Science Journal, 7 (2014) 1, Seite 46-58
Language:
English
DOI:
10.2174/1874401x01407010046
ISSN:
1874-401X
Origination:
Footnote:
Description:
Origin and age was determined for individual fish caught in offshore catches of Atlantic salmon stocks (Salmosalar L.) in the Baltic Sea over the years 2000–2009. DNA microsatellite loci and smolt age were used to probabilisticallyassign returning spawners to their stock of origin. Data for this study were based on approximately 2600 catch samples ofthe five most common wild and four sea-ranched, hatchery-reared stocks. Spawning age, and sex ratio differed bothwithin and between these wild, and sea-ranched groups. The females were mainly (78.7%) two sea-winters old and themales usually (68.7%) only one sea-winter old. In both sexes, the mean age at maturity was lower in the hatchery-reared,sea-ranched stocks than in naturally reproducing stocks. In the 2000s, there was a weak decreasing trend in the malespawning age, but not in that of females. The sex-ratio of the spawners was female dominant in the naturally reproducingstocks, but male dominant in hatchery-reared stocks. Published historical data from two of the same rivers suggest that themajority of males were multi-sea-winter spawners in the 1930s, and variation in the age distribution of the spawners hasbecome narrower and skewed towards a younger age in the present data (2000–2009) compared to the earlier situation.