Potential for ecological effects and gene flow resulting from growth hormone transgenic Atlantic salmon (Salmo salar) interactions with wild conspecifics

Moreau, Darek T. R. (2011) Potential for ecological effects and gene flow resulting from growth hormone transgenic Atlantic salmon (Salmo salar) interactions with wild conspecifics. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Growth hormone (GH) transgenic Atlantic salmon (Salmo salar) exhibit tremendous growth rates under hatchery conditions. This phenotypic response has created interest within the aquaculture industry; however, possible escapee events have raised concerns regarding their potential ecological impacts. This thesis applied an eco-evolutionary approach to empirically assess the potential ecological effects of GH transgenic Atlantic salmon on non-transgenic intraspecific populations. Specifically, my goal was to explore the relative survival and reproductive success of GH transgenic and non-transgenic salmon under near-natural conditions. To accomplish this, key fitness-related traits were compared between GH transgenic and non-transgenic Atlantic salmon over periods of their life cycle when natural selection is typically intense. Specifically, this thesis focused on the young-of-the-year stream and the breeding periods. -- Two studies (Chapters 2 and 3) compared fitness-related traits between transgenic and non-transgenic Atlantic salmon during early life history. Chapter two explored the potential differences in developmental rate and respiratory metabolism between transgenic and non-transgenic siblings at three early stages of life; the eyed-embryo, alevin (larval) and first-feeding fry (juvenile) stages. Chapter three explored the foraging behaviour and the growth and survival of transgenic and non-transgenic first-feeding fry reared under low feed, stream-like conditions. Collectively, the result of these chapters suggest that there is an ontogenetic delay in the phenotypic response induced by the transgene, such that biologically significant differences in fitness-related traits between GH transgenic and non-transgenic Atlantic salmon are minimal during this critical early life history period. -- The final two studies (Chapters 4 and 5) compared fitness-related traits between transgenic and non-transgenic Atlantic salmon during the reproductive phase of the life cycle. The fourth chapter compared the breeding performance of growth hormone transgenic and non-transgenic Atlantic salmon males of both alternative reproductive phenotypes to test for the potential of the transgene to introgress into wild populations. The fifth chapter used populations of GH transgenic and non-transgenic Atlantic salmon siblings to elucidate the effects of growth on precocious parr maturation. Collectively, these data suggest that transgenic males may experience reduced reproductive success relative to non-transgenic individuals. However, the potential for the transgene to introgress into wild populations was demonstrated. The empirical contributions of this thesis inform decisions regarding the potential ecological impacts associated with GH transgenic Atlantic salmon.

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