Can conservation‐oriented, captive breeding limit behavioural and growth divergence between offspring of wild and captive origin Atlantic salmon (Salmo salar)?

Abstract

Captive rearing is being used increasingly to maintain demographics and genetic diversity of threatened fish populations and species, but its effectiveness can be hindered by domestication, that is, inadvertent selection for performance in captivity at the cost of that in the wild. Some captive rearing programmes have begun to take steps to limit such domestication, but the results are ambiguous, as the degree of generational exposure to captivity is often difficult to control. Using an endangered population of Atlantic salmon (Salmo salar) currently undergoing conservation‐oriented captive rearing, we tested for domestication effects on dominance (dyadic trials) and growth (seminatural stream channels with differing densities and group proportions) of juvenile offspring of wild and captive origin parents. Pedigree data afforded the ability to compare these effects among three specific study groups: wild, single‐generation captives and two to three generation captives. Our results indicate that, despite conservation breeding practices, a divergence in growth can occur in as little as one generation without divergence in dominance behaviour. Further, evidence suggests that trait divergence did not increase with generations in captivity. Given the experimental design, results and supporting literature, we conclude that this contemporary divergence is likely genetic and driven by a combination of factors, including variation in selective histories influencing behaviour.

European sturgeon (Acipenser sturio L.) young of the year performance in different rearing environments –study within a stocking program

“…This is explained by an increment in muscular development and heart performance that can be beneficial in stocking programs because it might improve survival in the wild (Young and Cech Young and Cech 1993;Davison 1997). Being bigger can also improve survival in the wild (Hutchings 2002;Wilke et al 2014) because bigger fish have wider size ranges of prey items and have a lower predation risk than smaller fish (Juanes et al 2002).…”

Population genomic analyses of early‐phase Atlantic Salmon (Salmo salar) domestication/captive breeding

“…Some practices including minimizing the number of generations spent in captivity and mimicking natural conditions in captive environments have been undertaken to compensate the negative effects of captive breeding, but the results are uncertain (Wilke et al. ).…”

“…Hybridization between fish originating from supplementary stocking or aquaculture escapees with wild fish may reduce the survival rates and population sizes of wild fish populations and is thus a major concern regarding wild population persistence (Ford and Myers 2008;Fleming et al 2011). Some practices including minimizing the number of generations spent in captivity and mimicking natural conditions in captive environments have been undertaken to compensate the negative effects of captive breeding, but the results are uncertain (Wilke et al 2014).…”

Atlantic Salmon Recovery Informing and Informed by Ecosystem‐Based Fisheries Management

“…A river-specific stocking program is used to support the recovery plan and is designed to maintain the genetic integrity of stocks in the different rivers (Wilke et al 2015). A river-specific stocking program is used to support the recovery plan and is designed to maintain the genetic integrity of stocks in the different rivers (Wilke et al 2015).…”