Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

2001

Journal

Journal of Shellfish Research

Volume

20

Issue

1

First Page

185

Last Page

195

Abstract

Two species of arkshell (''blood'') clams. Noelia ponderosa and Anadara ova/is. have recently been targeted by watermen on the eastern shore of Virginia for sale to both East and West Coast markets in the United States. Until 1991. fishermen caught both species in the harvest of oysters and hard clams, and discarded them as bycatch with little value. Very little is known about either species of blood clam. and preliminary data from a pilot study in 1993 indicated that they were being over-fished. We conducted a survey in September 1994 in the oceanside lagoon system along the eastern shore of Accomac and Nonhampton Counties, Virginia. and collected data on density. abundance. habitat preference. age-size and morphometric relationships. 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 blood clam fishery. The total estimated abundance in the study area was about 16 million N. ponderosa and 6.4 mi llion A. ova/is. Of the clams taken in commercial catches on the oceanside of the eastern shore, M. mercenaria constitutes about 84%, N. ponderosa 15%, and A. ova/is I%. in our field survey, M. mercenaria was the most abundant species (72% of the total catch), followed by N. ponderosa ( 17%) and A. ova/is ( 11 %). Densities for blood clams averaged 0.35 clams m-2, or 3,500 clams per hectare. and were highest in shell and shell/mud substrate (I. I and 1.2 clams m- 2 • respectively). Growth studies and age-size data show that A. ova/is grows about twice as fast as N. ponderosa and that market-size N. ponderosa (about 56 mm in shell height) may be 8+ years old. We also present information on mortality rates and morphometric relationships for both species of blood clams, and recommendations for maintaining and enhancing the fishery.

Keywords

Noelia ponderosa, Anadara ova/is. arkshell, blood clam. growth rate. density, substrate

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