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Population structure of the arkshell clams Noetia ponderosa and Anadara ovalis in the oceanside lagoons and tidal creeks of Virginia and implications for fisheries management
McGraw, Kay A. Castagna, Michael Dennis, Sally D.
McGraw, Kay A.
Castagna, Michael
Dennis, Sally D.
Abstract
Two species of arkshell (blood) clams, Noetia ponderosa and Anadara ovalis, have · recently been targeted by watermen on the Eastern Shore of Virginia for sale to east coast markets. Until 1991 fishermen caught both species in conjunction with the harvest of oysters and hard clams and considered them of little value. Very little is known about either species, and preliminary data from our pilot study in 1993 indicated that blood clams were being overfished. In September, 1994 we conducted a survey in the oceanside lagoon system along the Eastern Shore and collected data on density, abundance, habitat preference, and mortality rates for both species of blood clams, as well as some ancillary data on the hard clam, Mercenaria mercenaria. The study provides baseline data for establishing management practices and regulations for the bloodclam fishery. Mean clam density for all species in the study area was 1.26 clams per m2 , with the majority of clams occurring in shell/mud substrate. The total estimated abundance in the study area was about 15 .2 million Noetia, 9 .6 million Anadara, and 62.2 millionMercenaria. Of the clams taken in commercial catches on the oceanside of the Eastern Shore, Mercenaria constitutes approximately 84%, Noetia 14.7%, andAnadara 1.4%. Length-frequency data from both the field survey and commercial catches indicate that blood clam stocks are being depleted. We also studied relationships between size and age of blood clams using the acetate peel method. These data, along with growth studies, show that Anadara grows about twice as fast as Noetia and that market-size Noetia (approximately 56 mm in height) may be 8 years old or more. We also present information on mortality rates and morphometric relationships for both species of blood clams, and recommendations for maintaining and enhancing the fishery.
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1996-04-05
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Arkshell_Clams_1996.pdf
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Research and Technical Reports
ESL Publications, Clams -- Virginia, Clam fisheries -- Virginia -- Managemen
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Virginia Institute of Marine Science