Evaluation of Two Off-Bottom Oyster, Crassostrea virginica, Culture Methods for Use in Oyster Gardening in Alabama

Abstract

Three sample sites on the north side of Dauphin Island, Alabama, were used to evaluate two different types of floats, Taylor (surface area of 0.74 m2) and Eastfields (surface area of 0.35 m2), for the culture of oysters, Crassostrea virginica, for oyster gardening. Three replicated treatments containing 1,014, 676, or 338 oysters/m2 were stocked into Taylor and Eastfields floats. Growth and survival of oysters in each float type were compared and correlated with water quality parameters (temperature, dissolved oxygen, and salinity) for 36 weeks. Oysters in the Eastfields floats demonstrated greater total growth at all densities than oysters in Taylor floats. Survival of oysters was similar in each float type. Average survival of oysters ranged from 30.1% to 56.4% among the three treatments and two float types. There was a very weak positive correlation (r = 0.30) between temperature and mortality, and a moderate positive correlation (r = 0.70) between temperature and growth in both types of floats. The Eastfields floats required more maintenance and were less durable than Taylor floats. However, the Taylor floats were cumbersome and became too heavy to lift without mechanical assistance due to biofouling and the weight of oysters. Modifications and a new cage design have been developed (www.mobilebaynep.com) as a result of these design disadvantages in Eastfields and Taylor floats.