Geoducks (Panopea abrupta) are in great demand, particularly in China, selling for as much as $15 per pound (wholesale in the shell). At the present time, geoducks are produced commercially from two different sources: 1) a dive fishery (started in 1970) taking wild geoducks from subtidal waters and 2) geoducks that have been produced from intertidal aquaculture farms (with hatchery seed) since the late 1990s. Expansion of the farmed geoduck industry is necessary to meet the anticipated increase in demand. However, this expansion is severely limited by availability of good intertidal grow-out beaches and conflicts with other beach users. Also, existing farming technology is very limited to date and virtually non-existent in the subtidal area. The project offers increased capability for production of a high-value seafood having high export demand while helping to improve the ecological health of Puget Sound. Algal blooms are a contributing factor to the increasing eutrophication of Puget Sound. Geoducks, as filter feeders, reduce these algal blooms. OBJECTIVES: The overall objective of this project is to determine if methods can be developed for cost effective and environmentally sustainable subtidal culture of the geoduck clam (Panopea abrupta). This would be done with the development of new technology and by adapting farming techniques used in intertidal cultivation. APPROACH: Experiments will primarily be conducted at Seattle Shellfish subtidal farming grounds in Spencer Cove in southern Puget Sound, Washington. All treatment and control plots will be set up and planted within the shortest possible timeframe to ensure that all the plots are seeded under the same environmental conditions. Each replicate site will be thoroughly documented for existing surface sediment, algae cover, and large invertebrate fauna. All plots will be visually monitored by a project biologist at regular intervals during the project period to assess effects of water currents and sediment movement, colonization by macroalgae and interaction with marine animals, and to repair any minor damage of the predator protection medium. Because, it is virtually impossible to visually estimate the abundance of subtidal geoducks during their first year of life, quantitative samples will be taken with the use of diver operated venturi suction devices. The recovered seed will be counted, and the shell length and total body weight measured. The results will be quantified as numbers of seed, and individual length and weight per unit of area. The seed surviving in the various treatments will be compared to the survivorship in the standard inter-tidal treatment and controls. An ANOVA statistical analysis will be used to determine if the differences seen are significant. Data will be assessed using appropriate statistical transformations of the count data and other standard statistical methods. Similar analysis of variance procedures will be used to test for differences in density and size by treatment type. Farming and sampling tools will be developed and tested to improve the seed handling and site development capabilities of farm personnel. These will include: (1) on-site training to improve diver skills for work in shallow and turbid waters, (2) development and testing of seed handling and deployment methods for divers, and (3) development and testing of methods to allow rapid and simplified deployment of predator exclusion methods
