NOAA/Saltonstall-Kennedy Grant Program: Evaluation and Development of Advanced Farm Management and Harvesting Tools for Economically Efficient and Environmentally Sustainable Production of Manila Clams

Purpose or Scope:

Currently approximately 4,500 metric tons of Manila clams are harvested annually in Washington State, most from aquaculture facilities (WDFW, 2009). This production accounts for all clams of this species harvested in the U.S.  While most Manila clams are sold domestically within the U.S., an increasing number are being exported to meet demands in Europe. With a couple of exceptions, all farm-reared Manila clams in Washington are grown  semi-intensively using open or net-protected culture systems, or net-bag culture for smaller scale production. Although these conventional tactics will allow Manila clam aquaculture to expand, production costs are generally increasing and overseas competitors are driving profits down. A new technology for Manila clam farming is now available that could mitigate production and market risk, thereby enhancing the economic stability and growth of the industry. This technology, which uses a combination of culture methods and tools more commonly associated with land-based culture, has been successfully adapted on a small scale at two farm sites in north Puget Sound. 

Approach:

The primary goal of this proposed project is to assess the environmental effects of this new technology and improve the technology through on-farm experiments and observations, analyses of production data, and production capacity modeling. Specific objectives are:

  1. Examine the effects of planting bed preparation, predator nets, predator net maintenance and clam harvest on water quality, sediments, benthic communities, and macro fauna;
  2. Compare yield in terms of clam growth, mortality and quality between conventional and mechanized Manila clam culture and harvest;
  3. Incorporate the results into a Farm Aquaculture Resource Management (FARM) model to simulate potential harvest, sustainable carrying capacity, economic optimization, key financial data, and positive (e.g. eutrophication abatement) and negative (e.g. biodeposition) externalities at the farm-scale; and
  4. Provide recommendations for changes or improvements in the culture technologies, with outreach to Manila clam farmers in the region, and other clam farmers and harvesters in the U.S.

Map of Samish Bay research areaManila clams (Ruditapes philippinarum) are widely grown and harvested from Puget Sound and coastal estuaries in Washington State and protected embayments in British Columbia. Culture typically occurs between the +2 to +5 tidal elevations in gravelly substrate. Conventional harvest is done by hand using short-handled rakes at low tide.  New and advanced technologies for Manila clam farming have recently become available. They promise reduced production costs and mitigate market risk, thereby enhancing the economic stability and growth of the industry. These technologies, which employ a combination of culture methods and tools more commonly associated with land-based culture have been successfully applied on a modest scale at two commercial farm sites in north Puget Sound. The overall goal of this proposed project is utilize one of the farms as a demonstration facility to assess and improve cultural tactics, featuring mechanized harvest, through on-farm experiments and observations, analyses of production data, environmental monitoring and subsequent farm-scale modeling and scenario development. 

Two primary hypotheses will be tested:

  1. Advanced intensive culture and mechanical harvest of Manila clams will not alter key environmental parameters beyond the area of the farm.
  2. The economic costs and benefits are at least as great as achieved with conventional Manila clam cultivation methods, when calculated through the entire farm production cycle.

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