Document Type

Article

Department/Program

Virginia Institute of Marine Science

Publication Date

1990

Journal

Journal of Shellfish Research

Volume

9

Issue

1

First Page

165

Last Page

172

Abstract

Oyster shells were planted on four successive months (May to August 1986) in contiguous plots at Jones Shore Bar in the Potomac River, Maryland, to study the effect of differences in time of cultch planting on settlement and survival of oyster spat. The plots were usually sampled at two-week intervals from time of planting through November, 1986, and once in June, 1987. A massive concentration of the tunicate Molgula manhattensis covered the bottom in all plots within four to six or eight weeks following shell planting. A commercially acceptable number of spat per shell, between 1.8 and 2.2 (approximately equivalent to 900-1200 spat per bu), was recorded at three of the plots on June 26, 1987, in spite of the heavy tunicate fouling of 1986. Recruitment of oyster spat was lower in the plot on which cultch was planted earliest, on May 13, than in the other three plots on which cultch was planted 1-3 months later. Number of spat was highest in the plot on which shells were planted on July 14; accidental planting of cultch into two elongated mounds on that plot may have contributed to the high recruitment of spat observed. Mean spat height was lowest in the plot on which cultch was planted on August 12 and highest in the plots on which shell was planted on May 13 and June 16. The lower number of spat found on shells planted on May 13 was probably associated with the early planting date. The data suggest that combined maximum recruitment and growth of oyster spat is most likely to occur at Jones Shore on cultch planted between late June and mid-July, although plantings as early as mid-June and as late as early August may also produce commercially-acceptable results.

Keywords

Crassostrea virginica, oysters, fouling, recruitment, growth

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