Tasmanian Atlantic salmon (Salmo salar) broodstock can encounter temperatures above 20 °C, which has a marked negative effect on reproductive development. Broodstock management strategies are needed in order to maintain egg quality in the face of thermal challenge either due to seasonal fluctuation or climate change, where temperatures are expected to rise even further. In Tasmania, the Atlantic salmon industry uses maiden fish for approximately 75 % of egg production due to their smaller size and the lower cost associated with their husbandry relative to repeats. However, maidens appear to be more susceptible than repeat fish to the effects of elevated temperature. The salmon industry’s ability to cope with rising temperature is hindered by the lack of understanding of the effects of thermal challenge on the endocrine system, which ultimately determines egg quality. Therefore the aims of the present research were to: (1) determine how temperature influences endocrine function and reproductive development in maiden and repeat spawning female Atlantic salmon; (2) understand the molecular mechanisms that determine egg quality in broodstock maintained at elevated temperature; and (3) develop management strategies to maintain endocrine function and egg quality under thermally challenging conditions.
Submitted in the fulfilment of the requirements of the degree of Doctor of Philosophy, University of the Sunshine Coast, 2011.