Size of wild and hatchery-reared Atlantic salmon populations in the northern Baltic Sea estimated by a stratified mark-recapture method

Abstract

J. 2006. Size of wild and hatchery-reared Atlantic salmon populations in the northern Baltic Sea estimated by a stratified mark-recapture method. e ICES Journal of Marine Science, 63: 1477e1487.We estimated the total size of the Atlantic salmon (Salmo salar) population complex (wild and cultured) in the Gulf of Bothnia, northern Baltic Sea, using a stratified mark-recapture method. In 2001In , 1970 salmon were captured by the commercial trapnet fishery and tagged with external arrow tags. A total of 349 tagged fish was later recaptured among 65 180 salmon screened for tags. Recoveries were gathered by the commercial trapnets and by screening fish entering counting facilities in rivers and broodstock fisheries at the river mouths. In addition, tags were recovered from recreational river catches. Our estimates suggest that the total size of the migrating population in both years was about 230 000 fish. Proportions of wild and cultured salmon differed between the two years. In 2001, the proportion of wild salmon was 37%; the corresponding figure for 2002 was 62%. Based on estimates of wild salmon smolt production and the number of released smolts, the estimated proportion of cultured smolts that survived the feeding migration and returned to the Gulf of Bothnia (2e4%) was approximately 2.5e4.5 times lower than that of wild smolts (9e10%).

A Synthesis of Tagging Studies Examining the Behaviour and Survival of Anadromous Salmonids in Marine Environments

“…Survival estimates for wild fish tend to be higher than those for hatchery juveniles [19], [57], [68], [75], [76], [81], [92]–[95]. In one study, survival of wild steelhead smolts during migration away from inshore waters ranged from 18–39%, while hatchery smolt survival was 3% [76].…”

“…pink, masu) are underrepresented in the literature. Most of the research we analyzed examined hatchery fish rather than wild fish, and relatively few tagging studies compared the two (except see [19] , [49] , [50] , [57] , [68] , [75] , [76] , [81] , [92] – [95] , [164] , [165] ), despite known differences in behaviour and survival. For example, wild populations commonly display adaptive plasticity in migration timing due to environmental variation and as a means of avoiding interspecies competition [81] , while hatchery raised fish are manually released according to a hatchery schedule [92] .…”

Migratory connectivity of two Baltic Sea salmon populations: retrospective analysis using stable isotopes of scales

“…In many situations power industry is forced to compensate the loss of wild salmon via hatchery-reared salmon stockings. However, it has been observed that reared salmon might be less viable than wild (Siira et al 2006), and there are some indications that wild and reared salmon do not necessarily display similar migratory behaviour (Salminen et al 1994, Kallio-Nyberg et al 2006.…”

Species‐ and origin‐specific susceptibility to bird predation among juvenile salmonids

“…To this end, it is generally believed that hatchery-reared fish are more prone to predation than wild fish due to lower levels of anti-predator behavior in the hatchery-reared fish (Einum & Fleming, 2001;Pedersen et al, 2008;Serrano et al, 2009). However, despite that a strong effect of origin (hatchery compared with wild) on juvenile to adult survival has been found in Baltic sea salmon (Kallio-Nyberg et al, 2006;Saloniemi et al, 2004;Siira et al, 2006), a difference in mortality and predation risk between hatchery-reared and wild fish during the juvenile life stages has generally not been documented for Atlantic salmon (Fl avio et al, 2021;Gudjonsson et al, 2005;Hvidsten & Lund, 1988;Hyvärinen et al, 2006;Kennedy & Greek, 1988;Lacroix, 2008;Thorstad et al, 2007). For sea trout, on the other hand, a difference in juvenile survival between hatchery-reared and wild fish has been found, with wild juveniles often having a higher survival and lower predation mortality than hatchery-reared juveniles (Aarestrup et al, 2014;Dieperink et al, 2001;Serrano et al, 2009).…”