Incidence of sib mating, test for inbreeding depression and potential application for reducing the impact of escaped cultivated cod on wild Atlantic cod (Gadus morhua)

Puckrin, Olivia Anne (2015) Incidence of sib mating, test for inbreeding depression and potential application for reducing the impact of escaped cultivated cod on wild Atlantic cod (Gadus morhua). Masters thesis, Memorial University of Newfoundland.

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Abstract

Fish often escape from aquaculture operations raising concerns of interactions with wild individuals. Due to selective breeding and high fecundity among Atlantic cod, few breeding individuals are used in culture, potentially leading to inbreeding among the offspring within the cages. If inbreeding among Atlantic cod reduces offspring survival, this could limit the risk of outbreeding depression from cod escaping as eggs or larvae, maturing and mating with wild cod. To determine if cod inbreed and what effects inbreeding has on offspring, spawned embryos from tanks of sister−brother−unrelated male trios underwent microsatellite analysis to determine parentage. Inbreeding occurred with no significant bias toward one type of male. Percent hatch, deformities, larval size, and mortality were monitored in artificially fertilized inbred and unrelated crosses. Only percent hatch differed significantly, being higher in non-inbred offspring (P = 0.024). One generation of inbreeding is not sufficient to determine if inbreeding would effectively reduce farmed cod offspring survival.

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