Assessing seasonal changes in stock composition of Atlantic salmon catches in the Baltic Sea with genetic stock identification

Abstract

The feasibility of using genetic stock identification to analyse seasonal changes in stock compositions of Atlantic salmon catches in the Baltic Sea was examined. The analysis employed seven variable allozyme loci from most of the potentially contributing stocks (16) from Finland and Sweden. Catch samples were collected from Finnish salmon fisheries in the eastern Bothnian Sea during the 1992 fishing season. Simulation studies were used to evaluate the feasibility of identifying Baltic salmon stocks with allozyme data. Special attention was paid to analysing the wild production of salmon stocks. Clear seasonal differences in stock composition were found. The estimates were compared with smolt production and Carlin-tag data. The proportions of the Neva and Oulujoki river stocks could be estimated as individual stocks, whereas the contributions of the remaining stocks were estimated as four composite stock groups. One of the groups consisted of wild stocks from the rivers Kalixälven and Simojoki. Identification of this group, which could be used as an index of wild production in the catches, requires catch sample sizes >300 salmon if <15% error is required. 1996 The Fisheries Society of the British Isles

Association between environmental factors, smolt size and the survival of wild and reared Atlantic salmon from the Simojoki River in the Baltic Sea

“…These stocks have adapted to the prevailing environmental conditions and to the brackish water of the Baltic Sea (Lindroth et al ., 1982). All these Atlantic salmon stocks, of both wild and reared origin, migrate to common feeding areas (Christensen & Larsson, 1979; Koljonen & McKinnell, 1996), and are affected by the same climatic factors and food abundance (Kallio‐Nyberg et al ., 1999). Two prey fish species in the main basin of the Baltic Sea, sprat Sprattus sprattus (L.) and herring Clupea harengus L., and herring in the Gulf of Bothnia dominate in the diet of Baltic S. salar (Karlsson et al ., 1999; Salminen et al ., 2001).…”

Genetic mixed‐stock analysis of lake‐run brown trout Salmo trutta fishery catches in the Inari Basin, northern Finland: implications for conservation and management

“…Fourth, it is worth considering how reliable the simulation‐based MSA estimates are. Similar to other studies, simulated mixtures were used to evaluate the potential bias and precision of the MSA (Koljonen & McKinnell, ; Beacham et al , 2000, 2008 c ). Based on these simulations, the observed stock composition estimates were very close to the true proportions and had narrow confidence limits.…”

Diet of post‐smolt and one‐sea‐winter Atlantic salmon in the Bothnian Sea, Northern Baltic

“…The native stocks of the Gulf of Bothnia are more similar to one another, and were treated as one group in the analysis. See Koljonen & McKinnell (1996) for details.…”

“…Ranched Neva salmon accounted for 67% of 44 post-smolts and 27% of 36 1-SW salmon, or 54% of the pooled sample of 84 fish: 44 post-smolts, 36 1-SW fish and four fish of unknown age (cf. Koljonen & McKinnell, 1996).…”

“…However, the post-smolt survival rates of ranched Neva salmon are more variable from year to year (Salminen et al, 1995) and growth rates generally lower than in the Gulf of Finland (Salminen, 1997). In catch samples of feeding salmon, the contribution of ranched Neva salmon off the Finnish coast has varied between 0 and 26% (Koljonen & McKinnell, 1996;Koljonen & Pella, 1997).…”