NE shellfish farming candidate: Factors regulating survial & growth of Arcitc surfclam & Mactromeris polynyma in experimental field studies

The Arctic surfclam, Mactromeris polynyma, is a relatively large bivalve (75 - 125 mm) that is similar in appearance to the more common Atlantic surfclam, or hen clam, Spisula solidissima. Its major distinguishing feature, and one that makes it particularly appealing as a culture candidate for consumption in both domestic and Asian markets, is a purple foot and mantle that turns red when cooked, similar to a lobster, crab, or shrimp. This species is marketed for human consumption both domestically and in Asia, where it is known as hokkigai. In addition, Mactromeris produces spisulosine (PharmaMar, ES-285), an anti-cancer agent isolated from its tissues that inhibits prostate cell growth. Previous research culturing this species by our company, although quite successful, left numerous questions that need answering before commercial development can proceed (Davis and Shumway, 1998). Parameters such as estimating its growth, survival, and biomass under commercial-scale, field growout settings are lacking and will be investigated in this study. This Research will 1) use innovative approaches to reduce losses of juveniles during winter months using technologies that have worked well with other commercially-important cultured bivalve seed; 2) investigate multiple methods to reduce losses of small juveniles in the field during the spring-fall growout period by controlling predation in field plots; and, 3) examine means to increase harvesting efficiency of cultured individuals through field studies on the interactive effects of stocking density, position along the shore, and size of planted individuals on clam growth and survival. Specific technical objectives include: 1) determining whether adults of Mactromeris polynyma can be conditioned to spawn in a hatchery setting; 2) determining the effects of sediments on growth and survival of cultured juveniles (ca. 3 mm SL) in a nursery field setting; 3) determining the effects of stocking density on growth and survival of cultured juveniles (ca. 3 mm SL) in a nursery field setting; 4) assessing the effects of planting season on growth and survival of plantable seed (ca. 10 mm SL); 5) evaluating how field plantable Mactromeris juveniles perform over the winter in high density holding containers that are used routinely to hold cultured juveniles of softshell clams, hard clams, and European oysters for spring plantings; 6) estimating the fate of cultured juveniles in on-bottom growout plots in the lower intertidal zone; 7) determining the effects of predators on growth and survival of culture Mactromeris juveniles; and 8) determining interactive effects of stocking density and clam size on the production of commercial size (> 40 mm SL) cultured individuals. Anticipated results of this work will provide the information needed to decide whether to pursue further development of this species. Potential commercial applications from completed Phase I and II studies would position our company to produce and market both juvenile and adult Mactromeris for the wholesale and retail restaurant sectors as well as potential becoming a seed supplier for an emerging aquaculture industry.