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Fishery independent standing stock surveys of oyster populations in the Virginia sub estuaries of the Chesapeake Bay and a comparison with continuing estimates obtained from fishery dependent data
Mann, Roger L. Wesson, James
Mann, Roger L.
Wesson, James
Abstract
Extensive description of the Virginia oyster resource and history of its utilization has been given by Haven, Hargis and Kendall (1981), and more recently reviewed by Hargis and Haven (1988). These contributions, among many others, describe a state of continuing decline. To facilitate resource management a fishery independent survey was proposed to and subsequently supported by the Chesapeake Bay Stock Assessment Committee in 1993. This report covers activity on that program for the period October of 1993 through September of 1994. Spatial variability in distribution of oysters within an oyster reef system, and distribution of reefs in the intertidal and/or subtidal regions complicate fishery independent estimation of standing stock. By contrast, fishery dependent estimates of oyster standing stock can be made, where adequate data on effort and temporal changes in landings exist, through application of Leslie-DeLury regression analysis (Barber and Mann, 1991). Intensive, fishery independent estimates are rare but pivotal to examination of spawning capabilities of broodstock supporting commercial fisheries and related requirements for establishment of fishery catch quotas. The James River, Virginia has served as the focal point for the Virginia oyster industry for over a century, being the source of the majority of seed oysters that were transplanted for grow-out to locations within the Virginia portion of the Chesapeake Bay and much further afield in the Middle Atlantic states (Haven et al, 1981). The Rappahannock River in Virginia was, for many years, a source of large and valued oysters for both the shucking and half shell trade. It is surprising that comparatively little effort has been previously expended to estimate standing stock in both the James and Rappahannock Rivers given the acknowledged need for such data in fishery management. Continuing losses of productive oyster reef over the past three decades to Haplosporidium nelsoni, commonly known as MSX, and Perkinsus marinus, commonly known as "Dermo", in the higher salinity regions of both rivers, combined with increased fishing pressure on all remaining stocks, have emphasized the need for working estimates of standing stock. This need has been further exaggerated in the James River by a change in emphasis in the past decade from the harvesting of "seed" oysters to larger "market" oysters, and the reduction in size limit of the latter from three to two-and-one-half inches maximum dimension (although this action was reversed with an increase in minimum market size to three inches for the 1994-1995 season). The fishery is now facing the dilemma of exploiting the limited remaining broodstock from the James River in order to retain a viable fishery for" market" oysters, while simultaneously threatening the long term future of the river as a seed producing location.
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1994-11-04
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MannWesson1994.pdf
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Fisheries Science Reports
Research and Technical Reports, Oyster populations -- Virginia; Oyster fisheries -- Virginia
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Virginia Institute of Marine Science
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https://doi.org/10.25773/x7h1-6132