Are Triploid Salmonids the Future for Aquaculture and Fishery Management?

There is increasing interest in using triploid (3n) salmonids for both aquaculture and stock enhancement programmes. In aquaculture, sterile triploid fish are used to mitigate the occurrence of early sexual maturation, and to reduce the environmental impact of escaped fish, as sterile triploids are unable to breed with their wild conspecifics. Triploid fish are also increasingly being used for stock enhancement, again primarily to mitigate the threat of interbreeding with threatened wild populations.  

This paper reviews the economic and welfare implications of using triploid fish in both aquaculture and fisheries management. The major welfare concern of using triploids centers on the reported increased prevalence of skeletal deformities, cataracts and heart defects. Further, there are significant differences in brain morphology between diploid and triploid Atlantic salmon. Compared to diploids, the olfactory bulbs were significantly smaller, and cerebellum and telencephalon significantly larger in triploids. As these brain regions are implicated in the control of a number of fitness-related behaviours, including foraging behaviour, aggression and spatial cognition, this could be a welfare issue (effecting fitness) when using triploids for stock enhancement. However, it is likely that the use of triploid salmonids will increase in the future, both in aquaculture and fisheries management.