We have discovered the easternmost commercial population of hard clams, Mercenaria mercenaria (L.), in the U.S., in the waters of Eastern Maine. In 2007, we received permission from the State of Maine to lease a 6-acre tract in the shallow subtidal of Goose Cove (Trenton) to farm cultured hard clams. This is the first-ever lease of this type in eastern Maine. Working with our research partners from the Downeast Institute for Applied Marine Research & Education in the town of Beals, we received Phase I USDA SBIR funding to examine seasonal growth and survival of cultured seed (6-12 mm shell length, SL) at multiple sites in eastern Maine from Trenton east to Cobscook Bay. That effort demonstrated unambiguously that the waters of far eastern Maine (Washington County) are too cold, and predators such as moon snails and green crabs too numerous to undertake farming operations in that region. Survival and growth of cultured seed in Goose Cove, however, was excellent in small plots where seed was planted in mid-Spring and protected with flexible netting. We observed > 85% survival through December, with animals attaining SL > 20 mm. We propose to extend our experimental approach to larger, pre-commercial scales to test hypotheses concerning both spatial and temporal variation in cultured hard clam growth and survival during the nursery, overwintering, and grow-out phases at Goose Cove and sites west of there in Hancock County. Specifically, we wish to determine what configuration of a field-based nursery system, and which nursery locations, will allow us to produce the largest transplantable hard clam seed; what the most efficient method is to store pre-planting size seed over the winter to optimize survival and growth; what field grow-out methods will produce market size animals in the most effective and efficient manner; and, to what degree interannual variability plays in hard clam growth and survival, both in the field nursery and grow-out phases. Answers to these questions will affect plans to commercialize our rearing methods and procedures. OBJECTIVES: Our goal is to create new economic opportunities for the people of downeast and coastal Mainethrough hard clam farming, but we must first focus on biological and economic efficacy of thenursery, overwintering, and grow-out processes. The project we propose satisfies at least three of USDA's strategic goals. If successful, our work will lead to a new industry and economic boom in one of the most rural coastal areas in the United States. Clam farming will diversify and increase economic opportunities for coastal residents through the sale of seed, distribution of product to market, and spin-offs associated with nursery and field grow-out such as the construction of cages for overwintering clams, soft bags, boat and outboard motor sales, etc. The potential commercial applications of hard clam farming include adding new markets for farmed products both locally and regionally, which will increase demand and likely create additional opportunities for more farming operations. APPROACH: We plan to use an experimental approach for all facets of our work. Generally, we will manipulate two or more factors simultaneously, and in all possible combinations (factorial design), that allows us to examine both main and interactive sources of variation using analysis of variance (ANOVA). This design is efficient, and generally yields greater statistical power to detect differences among treatments than is possible for separate experiments (Underwood, 1997). In addition, several of our tests will incorporate blocking into our experimental design to investigate either spatial or temporal variation with respect to treatment effects. We have had good success with generalized randomized complete block designs (GRCBD; Winer et al., 1991) that use two or more replicates of each treatment within a given block. Unlike the more traditional randomized complete block design (RCBD), the GRCBD does not assume treatment effects operate similarly between blocks, and all main, interactive, or nested sources of variation can be tested We anticipate that our efforts to scale our field results to pre-commercial levels will be successful, that growth and/or survival in our nursery trials will be related to geographic location (with slowest growth occurring in far eastern Maine compared to more centrally located regions along the coast where growth should be higher due to higher overall average temperature), that overwintering of larger volumes of cultured clam per unit area seed will be successful and that new winter storage methods ultimately will enable us greater flexibility in managing field plots. We anticipate that invertebrate predators, especially the invasive European green crab, will beour greatest hindrance to growing clams to market size, but that predator deterrent netting, whenapplied and managed correctly, will combat this predator effectively. Finally, we anticipate that new markets and new branding will enable us to diversify our sales both in Maine, southern New England, and elsewhere.
