Feasibility of Hard Clam, Mercenaria mercenaria, Culture in Grand Bay, Alabama

Abstract

The northern hard clam, Mercenaria mercenaria, has proven to be a profitable aquaculture species along the Eastern seaboard as well as the west coast of Florida. The potential for M. mercenaria aquaculture in the North Central Gulf of Mexico has not been thoroughly investigated. The biological and production feasibility of clam culture was analyzed using two bivalve grow-out systems in the coastal waters of Grand Bay, Alabama. Clams were stocked into mesh bags in a belt system placed on the bottom and in bags suspended from an adjustable long-line system. The stocking densities used for each treatment were 188/m², 375/m², 750/m², and 938/m². Each bag density was replicated three times for the adjustable long-line system and five times for the belt system on bottom. The mesh bags placed on the bottom allowed clams to burrow into the sediment as they would naturally. The clams placed in the adjustable long-line system were suspended mid-water column approximately 0.5 m from the bottom. The belt system and the long-line system were stocked with clams of an average size of 15.3 mm and 17.9 mm, respectively. Over a period of seven months clams in the belt system showed a 25.0% increase in size with 42.6% survival compared to only a 14.6% increase in size for clams in the long-line system with a 24.3% survival. While the belt system performed significantly better than the adjustable long-line system, both system’s growth and survival were lower when compared to published data for similar periods of time along the east coast of Georgia, Florida and South Carolina. The low growth rate and survival may be due to excessive stresses from tunicate and polycheate bio-fouling on the belt system and siphon nipping by fish and crabs in the suspended long-line system.