The effect of extended holding under ambient water temperatures on the condition, physiology and stress response of cultured blue mussels (Mytolys edulis L. 1758) following commercial harvest in Northeastern Newfoundland

Wyatt, Jessica L. (2012) The effect of extended holding under ambient water temperatures on the condition, physiology and stress response of cultured blue mussels (Mytolys edulis L. 1758) following commercial harvest in Northeastern Newfoundland. Masters thesis, Memorial University of Newfoundland.

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Abstract

Effects of extended holding under ambient water temperature on the physiology and stress response of cultured blue mussels (Mytilus edulis) in northeastern Newfoundland were examined over the course of four seasons. Changes in tissue weight, condition index, stress response, oxidative stress and immune gene expression were assessed over a period of two to three months in live-holding under ambient water temperatures. Animals in holding were compared to field control mussels collected from the original lease at each sample time. Condition and dry tissue weight decreased over time in holding during the summer, fall, and spring seasons; however the effect was only significant after one month. The summer and fall represented the most stressful seasons to maintain animals in extended live holding under ambient water temperatures as indicated by the significant decline in condition and increase in stress response as indicated by the neutral red assay. In the field, condition index and tissue weight varied seasonally and was lowest during winter peaking to a high during the spring (April). Seasonality of antioxidant and immune genes were noted however there was no consistent increased expression due to holding. Only in the spring did extended holding cause any change to digestive gland structure. -- We recommend mussels be maintained in extended holding for no longer than a period of one month to reduce the impact on their physiology and an overall loss in quality. After this point there is a significant increase in stress response coupled with a decline in condition and meat weight which could result in a loss of profit for the grower

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