Comparison of absorption efficiency and metabolic rate between wild and aquaculture oysters (Crassostrea virginica)

In Eastern Canada, discussions about the adaptation of a hatchery-based industry for oyster aquaculture has led to the implementation of selective breeding programs. As part of this process, traits of interest related to physiological energetics-absorption efficiency and metabolic rate, were compared between two oyster sources (wild, aquaculture) originating from the Bouctouche estuary (NB, Canada). Both trials were carried out separately following a thermal challenge (20, 30 degrees C). Absorption efficiency was not significantly different for oyster source or temperature, but a high level of inter-individual variability was found with a range observed between -37.8 to 95.2 %, which indicates the potential for selection and improvement of this trait within the industry's existing oyster production stocks. Metabolic rate, in terms of aerobic capacity, was also not considered significantly different; however, standard and maximum metabolic rates were highly significant for oyster source with lower values for individuals from aquaculture. These results indicate that wild and aquaculture oysters are not significantly different in terms of growth capacity, but that aquaculture oysters have a lower oxygen demand than wild oysters, suggesting a reduced ecological footprint. The lower standard metabolism of aquaculture oysters also suggests that these individuals could be more resistant to stressful conditions, as their minimal energy level to maintain their vital function is lower.