Early winter foraging success, swimming performance, and morphology of juvenile landlocked Atlantic salmon reared under semi-wild and hatchery conditions

Abstract

Several Finnish populations of salmonids have been maintained exclusively by stocking hatchery-reared fish for several generations, and it is crucial to know whether domestication has affected fitness-related traits and to assess how the developmental environment influences fish phenotypes. Here, we focused on Lake Saimaa landlocked salmon (Salmo salar m. sebago) and studied the role of the early rearing environment in trait formation by comparing juveniles (fingerlings) from three backgrounds: (i) semi-wild (stocked as alevins), (ii) standard hatchery, and (iii) enriched hatchery conditions We compared juvenile morphology, swimming performance, and capability of feeding on natural prey in early winter. We found no differences between standard and enriched hatchery conditions. Semi-wild fish consumed more prey items, but wet mass of stomach contents did not differ among backgrounds. Swimming endurance was comparable among backgrounds. Semi-wild fish had slenderer body shape and longer fins than hatchery-reared fish. The lack of performance differences between hatchery juveniles and their semi-wild conspecifics is possibly due to reduced phenotypic plasticity caused by extremely low levels of genetic diversity in this population.

Life-history genotype explains variation in migration activity in Atlantic salmon ( Salmo salar )

“…The bottom of the stream was covered with gravel (30-80 mm grain size). The system has been running uninterruptedly for years, which allowed establishment of a natural food supply of benthic invertebrates in the tanks, supplemented also by additional natural food via incoming water [27,28].…”

Sperm motility and offspring pre- and posthatching survival in hybridization crosses among a landlocked and two anadromous Atlantic salmon populations: implications for conservation

“…To reduce the unequal distribution of food availability, three separate water inlets with equal distances were set in each channel. The fish were feeding on natural live prey (Rodewald et al 2011;Hatanpää et al 2020), a part of which was developing inside the semi-natural channels, and a part of which was drifting in with the water flowing from the nearby lake (Lake Kivesjärvi). Survival to fry stage was determined as the proportion of young that were alive at the termination of the experiment on 3 July 2018.…”

On the relevance of animal behavior to the management and conservation of fishes and fisheries

“…The epigenetic link between rearing conditions and phenotype spawned a thriving field of research into hatchery enrichment (Huntingford 2004). In general, enriched hatchery conditions offering greater structural complexity (Cogliati et al 2019a), live prey in addition to commercial fish feed (Brown et al 2003), realistic flow characteristics (Pedersen et al 2008), and exposure to the outdoor environment under seminatural conditions (Hatanpää et al 2020) may provide valuable "life skills" training (Brown and Laland 2001;Hawkins et al 2008) to fish prior to release. Enriched rearing has been associated not only with greater rates of survival (Alioravainen et al 2018), growth (Vainikka et al 2010), and performance (Hatanpää et al 2020), but also migratory tendencies and phenologies more closely matching those of wild conspecifics (Hyvärinen and Rodewald 2013;Pedersen et al 2008).…”

“…In general, enriched hatchery conditions offering greater structural complexity (Cogliati et al 2019a), live prey in addition to commercial fish feed (Brown et al 2003), realistic flow characteristics (Pedersen et al 2008), and exposure to the outdoor environment under seminatural conditions (Hatanpää et al 2020) may provide valuable "life skills" training (Brown and Laland 2001;Hawkins et al 2008) to fish prior to release. Enriched rearing has been associated not only with greater rates of survival (Alioravainen et al 2018), growth (Vainikka et al 2010), and performance (Hatanpää et al 2020), but also migratory tendencies and phenologies more closely matching those of wild conspecifics (Hyvärinen and Rodewald 2013;Pedersen et al 2008). Hatchery exposure to site-specific factors like biofilm communities and associated water chemistry may allow fish to "imprint" on their intended habitat and increase stocking success (Dittman et al 2015;Putman et al 2014a;Ueda 2011).…”