Development of a modular submersible mussel raft for use in semi-exposed Maine waters subject to drift ice.

In this SBIR Phase I project, Pemaquid Mussel Farms (PMF) seeks to determine the feasibility of fabricating a submersible mussel raft that will eliminate problems associated with surface mussel rafts (mussel drop off, wave and ice damage to rafts, lower yields, visual impacts) while improving crop production and quality. In the northeast and northwestern U.S., the preferred method of mussel suspension culture is based on the use of floating mussel rafts, first used in Spain (with an annual production of 300,000 metric tons) and modified in Scotland into an easy to assemble "mussel raft kit" form in the 1990's. Rafts, which produce as much as 40 metric tons per 40 by 40 foot raft are used because they are much less susceptible to predation than longline systems. World landings of edible blue mussels (Mytilus edulis) were 1.64 million tons in 2007 (FAO Fisheries and Aquaculture Department) and valued at $1.61 billion. In 2009, the U.S. imported 57 million pounds of mussels (primarily from Canada, Chile and New Zealand) with a value of $72 million (USDA). In contrast, in 2009 total U.S. exports of mussels were 1.6 million pounds with a value of $2.6 million. Production of farmed blue mussels from Maine is only about 10% of total mussel landings (including wild harvested mussels) and equated to approximately 13 million pounds in 2008 Improvements in raft mussel production technology will help the domestic mussel industry take advantage of existing and emerging markets. In this project, we will use a combination of field studies (tidal flows, wave climate, mussel growth trials, CTD profiles), flow modeling (3-dimensional CFD techniques), prototype design, scale model testing, materials selection (including marine composites) and economic analyses to develop a submersible mussel raft for construction and field testing in Phase II. We expect that the results of our efforts will open up new areas for mussel aquaculture, including semi-exposed sites and areas subject to drift ice.