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Reproductive performance of growth-enhanced transgenic coho salmon (Oncorhynchus kisutch) Bessey, Cindy

Abstract

The reproductive performance of growth-enhanced transgenic and nontransgenic coho salmon (Oncorhynchus kisutch) was examined to address concerns associated with using genetically modified fish in aquaculture. A major concern is the initial reproductive interaction between transgenic and wild fish that may occur if transgenic salmon escape into the natural environment. This thesis attempted to obtain an indication of reproductive allocation, effort and success for transgenic and nontransgenic salmon in a simulated natural environment. Several aspects of reproduction are examined for both transgenic and nontransgenic fish to provide an indication of gamete quantity and quality, courtship behaviour, spawning success, transgene transmission to offspring, and male competitive ability. Female and male body size, shape, and gonadal somatic index (GSI) provided a measure of phenotype and reproductive allocation. Female fecundity and egg diameter, as well as male sperm production, fertility and competition examined gamete quantity and quality. Female digging, probing, and covering, as well as male quivering examined courtship behaviour of ovulated females and ripe males paired together in spawning channels. Spawning success was recorded and fertilized eggs were collected and raised to alevin in order to examine offspring viability. Polymerase chain reactions were conducted on offspring blood samples to determine transgene transmission. Biting, chasing and spawning success of male pairs placed together with an ovulated female were analysed to determine male competitive interactions. Results from these studies found several differences between transgenic and nontransgenic fish. At maturation, transgenic males lacked red coloration and had a less developed kype compared to nontransgenic fish, but no differences in male gamete quantity or quality were observed. Transgenic females were more fecund than nontransgenic females, but may have inferior quality gametes due to reduced egg size. Transgenic females spawned less frequently and displayed consistently low levels of courtship behaviour. No courtship behaviour differences between transgenic and nontrangenic males were observed, however, during competition, transgenic males were inferior; obtaining no spawnings, and displaying less courtship and competitive behaviour. These studies are the first to show that in a simulated natural environment, growth enhanced transgenic coho salmon display courtship behaviour and can spawn producing viable transgenic offspring.

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