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Growth hormone (GH) transgenes can significantly accelerate growth rates in fish and cause associated alterations to their physiology and behaviour. Concern exists regarding potential environmental risks of GH transgenic fish, should they enter natural ecosystems. In particular, whether they can reproduce and generate viable offspring under natural conditions is poorly understood. In previous studies, GH transgenic salmon grown under contained culture conditions had lower spawning behaviour and reproductive success relative to wild-type fish reared in nature. However, wild-type salmon cultured in equal conditions also had limited reproductive success. As such, whether decreased reproductive success of GH transgenic salmon is due to the action of the transgene or to secondary effects of culture (or a combination) has not been fully ascertained. Hence, salmon were reared in large (350,000 L), semi-natural, seawater tanks (termed mesocosms) designed to minimize effects of standard laboratory culture conditions, and the reproductive success of wild-type and GH transgenic coho salmon from mesocosms were compared with that of wild-type fish from nature. Mesocosm rearing partially restored spawning behaviour and success of wild-type fish relative to culture rearing, but remained lower overall than those reared in nature. GH transgenic salmon reared in the mesocosm had similar spawning behaviour and success as wild-type fish reared in the mesocosm when in full competition and without competition, but had lower success in male-only competition experiments. There was evidence of genotype×environmental interactions on spawning success, so that spawning success of transgenic fish, should they escape to natural systems in early life, cannot be predicted with low uncertainty. Under the present conditions, we found no evidence to support enhanced mating capabilities of GH transgenic coho salmon compared to wild-type salmon. However, it is clear that GH transgenic salmon are capable of successful spawning, and can reproduce with wild-type fish from natural systems. [ABSTRACT FROM AUTHOR]

Prior to the development of any conservation strategies to mitigate deleterious impacts of environmental change and contamination, there must be a method to make meaningful predictions of the effect of environmental change on organisms. Assessment of relative transcriptomic expression patterns can provide a link between the environment and the physiological response of the organism by identifying genes that respond to environmental stressors; this information could also assist in teasing apart the molecular basis of toxicological effects vs. physiological adaptation. Molecular responses to environmental stressors are probably not restricted to single or few genes, and therefore a more integrative approach is required to examine broad-scale patterns of transcriptomic response. To address this objective, used machine learning tools to link the mechanisms of physiological response to environmental stress; although widely used in clinical applications, such as finding the genetic basis of diseases (), ecological genomics applications of artificial neural networks are just beginning to emerge. Analyses such as these are important to help identify limitations on the adaptive capacity of organisms and to predict impacts of climate change, ocean acidification and anthropogenic contaminants on aquatic organisms. [ABSTRACT FROM AUTHOR]