To pit or not to pit?: Comparison of overwintering methods foroysters

摘要

The threat of ice damage has forced intertidal oyster farmers to devise strategies to reduce potential losses. In New England, some oyster farmers move their oysters from the farm location to storage area, or `seed pit', that is typically cold (0-4 degree C) and damp (over 90% relative humidity). Qualitatively, local farmers have reported survival rates of over 90%. We quantified survival and typical time to revival of oyster, (Crassostrea virginica) seed as a function of storage time. While survival was good and did not seem to vary over the course of the experiment, there was a clear step-wise drop in time to revival. Furthermore, a study of survival of seed held in the pits of local farmers suggested survival remained high ( greater than or equal to 86%) for seed held for similar to 4 months but dropped to 82% for those held an additional month. Furthermore, evidence suggests that second year seed do not survive pitting as well as first year seed. Alternatives to pitting include leaving the oysters on the farm location or moving them to deeper water, below any ice that might form. We compared overwintering survival and growth of these three methods, both immediately post-winter and across the 2005 growing season. The lowest survival was in the treatment left on the flats, apparently due to damage from ice, while little to no growth was observed immediately post-winter. More surprisingly, there was a tendency for growth across the season to be slowest in the treatment moved to deeper water, relative to the other two treatments.