An Update on the Ongoing Oyster Summer Mortality Study: Mortality of the Pacific Oyster, Crassostrea gigas: Health Screening, Environmental Links and Management Options
Cheney DP, Elston RA, MacDonald BF, Cherr GN, Hamdoun AM, Jacobsen JL. 2000. An Update on the Ongoing Oyster Summer Mortality Study: Mortality of the Pacific Oyster, Crassostrea gigas: Health Screening, Environmental Links and Management Options. Journal of Shellfish Research. 19(1):685
This project tests hypotheses relating to mortalities of Pacific oysters on the West Coast. Four sites in Puget Sound experienced limited mortality at all stations through the end of June 1999. By the end of August increasing mortalities of up to 15% between sample dates were seen in several treatment groups. These mortalities paralleled a similar pattern of very high seed oyster mortalities in Tomales Bay. Puget Sound ambient air and water temperatures through late spring 1999 were similar to 1998; however after June, peak air temperatures were below 1998 levels. Dissolved oxygen, pH and salinity levels at all stations remained nominal throughout most of this period. There was a correlation between densities of Gymnodinium sanguineum, Ceratium spp., Pseudo-nitzschia spp. and other dominant taxa with the onset of summer mortality. In addition, moribund oysters had lesions consistent with an acute toxic effect. A biotoxin, most likely of algal origin, was considered as a probable cause. No infectious diseases considered certifiable or reportable by regulatory agencies were observed in these oysters. Investigations into the physiological responses of oysters to stress are now underway to provide further insights into the survival process. We are currently field testing outplants to see if a correlation exists between the biochemical response and the organismal response. This research is supported by a grant from the National Sea Grant College Oyster Disease Research Program and matching contributions from West Coast shellfish growers.
- Type
- Journal Article
- Authors
- Cheney, D; Elston, R; MacDonald, B; Cherr, G; Hamdoun, A; Jacobsen, J
- Units
- PORE
- Keywords
- California, ceratium, Crassostrea gigas, Diseases, ecology/community studies, Fish diseases, Fishery Management, Gymnodinium sanguineum, Mortality causes, Oyster fisheries, Pacific giant oyster, Parasites, Pseudo-nitzschia, Puget Sound, species interactions, Tomales Bay, Washington