Wild origin and enriched environment promote foraging rate and learning to forage on natural prey of captive reared Atlantic salmon parr

Abstract

– After release to the wild, captive reared salmon have shown lower foraging rates on natural prey and impaired ability to avoid natural predators and thus lower survival compared with wild‐born conspecifics. Here, we examine whether captive breeding influences learning of foraging on natural prey and how enriched rearing methods may improve foraging on natural prey by Atlantic salmon (Salmo salar) parr. We reared offspring of hatchery or wild salmon of the same population in either a standard or enriched environment at production‐scale densities. The enriched environment featured submerged overhead shelter, varying water current, depth and direction and consequently alterations in food dispersion. Parr reared in the enriched environment expressed higher feeding rates, and parr of wild origin started to forage earlier on natural prey. The enriched method promoted foraging of hatchery reared parr on natural prey and is easily applicable to commercial production of salmonids for reintroduction or stock enhancement purposes.

Conclusions: Aquaculture and Behaviour

“…The final example is provided by a study of the effects of environmental enrichment on the behaviour of cultured Atlantic salmon parr held at production densities (Rodewald et al 2011). Experimental fish were the offspring of either wild salmon or hatchery-bred fish, raised either in standard or in enriched tanks; enriched tanks contained submerged shelters (black PVC plates placed on top of bricks) of two sizes and the water current varied in speed, depth and direction.…”

Does environmental enrichment promote recovery from stress in rainbow trout?

“…As reviewed in Näslund and Johnsson (2014), there are several studies demonstrating the positive effects of environmental enrichment on welfare across many fish species. Compared with captive-held fish in barren environments, those provided with some form of enrichment have been found to have increased brain development (Marchetti and Nevitt, 2003;Kihslinger and Nevitt, 2006;von Krogh et al, 2010;Salvanes et al, 2013), reduced impact from stressors (Braithwaite and Salvanes, 2005;Naslund et al, 2013;Batzina et al, 2014), improved foraging ability (Brown et al, 2003;Strand et al, 2010;Rodewald et al, 2011), improved post-release survival (D'Anna et al, 2012) and positive effects on growth (Leon, 1975;Hansen and Moller, 1985;Batzina et al, 2014). This general increase in neural plasticity results in the development of behaviourally flexible fish that are better at coping with a variety of situations.…”

Use of Bottom Structure and Tank Cover during Rainbow Trout Rearing in Circular Tanks

“…Previous studies examining environmental enrichment techniques have noted that the addition of structure may increase competitive behavior and foraging skills in domesticated fish [2][3][4] as well as improve fish swimming ability and adaptability to new environments [5]. Vertically-suspended structure has also been observed to improve fish weight gain during hatchery rearing [6].…”