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Add To Calendar 24/02/2016 11:30:0024/02/2016 11:50:00America/ChicagoAquaculture 2016IDENTIFYING UNCERTAINTY IN ASSESSING FITNESS COMPONENTS OF GROWTH HORMONE TRANSGENIC COHO SALMON: A MARINE EXAMPLE Vendome BThe World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY


Rosalind A. Leggatt* and Robert H. Devlin
Centre for Aquaculture and Environmental Research, Fisheries and Oceans Canada
4160 Marine Drive, West Vancouver, BC, V7V 1N6, Canada

Insertion of a growth hormone (GH) transgene into the genome can result in greatly accelerated growth rates and increased feed conversion in many fish species. As such, GH transgenic (T) fish have potential to improve aquaculture production. However, there is concern over environmental impacts T fish may have should they be inadvertently introduced to natural ecosystems. Previous studies have found culture-reared T coho salmon can have greatly diminished reproductive success relative to non-transgenic (NT) nature-reared fish, suggesting T coho salmon may have limited reproductive impact in nature. However, NT fish reared in equal culture conditions also have greatly diminished reproductive success and behaviour, as well as decreased size and altered morphology at maturation, than nature-reared fish. This raises the question of whether culture conditions are also limiting mature size and reproductive success and behaviour of T fish.

We examined the influence of marine rearing conditions on success of T coho salmon by rearing T and NT salmon in large (350,000 L), semi-natural, seawater tanks (termed mesocosms) designed to minimize effects of standard culture conditions. Rearing in mesocosms partially restored NT mature size, morphology (Fig. 1), and spawning success (Fig. 2) to that of nature-reared fish. T fish had similar spawning behaviour and success (Fig. 2), slightly diminished swimming performance and survival, and greater size than mesocosm-reared NT fish (Fig. 1). As such, we found no evidence to support enhanced fitness of T fish in the marine environment, although they were capable of successful swimming, reproductive behaviour, and spawning with NT fish reared in nature. There was a strong genotype x environment interaction, where NT and T fish had different responses in size and reproductive success to rearing environments (e.g. Fig. 2). Such non-parallel reaction norms complicate predicting fitness and hence ecological effects of T coho salmon in nature with high certainty.

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