Virginia Institute of Marine Science
Proceedings of the National Shellfisheries Association
Five series of studies were made to test for differences in condition index of oysters grown in the York and Rappahannock Rivers. Oysters were cultured in elevated trays and on the bottom from 1956 through 1961. All groups came from a single source and were selected for uniformity in size. Rappahannock oysters showed high indices in late spring and fall with a low in late summer; the level of condition of bottom groups was below that of trays. York River oysters showed a peak of condition in late spring; in most years there was no increase in quality in late fall; bottom oysters were generally of lower quality than those in trays, but differences were not as large as in the Rappahannock. In general, the level of quality in the York was almost always lower than in the Rappahannock. Differences in level of index between tray and bottom oysters were not associated with presence of Dermocystidium or Pinnotheres ostreum or with age or crowding, but were probably the result of factors associated with the bottom.
Haven, Dexter, Seasonal cycle of condition index on oysters in the York and Rappahannock Rivers (1960). Proceedings of the National Shellfisheries Association, 51, 42-66.