DETERMINING SOCIAL AND ECOLOGICAL CARRYING CAPACITIES FOR SOUTH PUGET SOUND, WASHINGTON, USA

Washington State is a major producer of farmed bivalve shellfish in the United States, producing about 40,000 metric tons valued at more than $100 million annually. The goal of this research was to provide shellfish growers, regional resource managers, and the general public, tools and information for assessing the ecological and social capacities of shellfish aquaculture in south Puget Sound (SPS).

We used local and regional data, predictive modeling tools and stakeholder working groups to provide recommendations for multi-use spatial planning. Physical, production and ecological carrying capacity were assessed using Farm Aquaculture Resource Management (FARM) and EcoWin modeling tools. Ecological and social carrying capacity were assessed using the EcoPath with EcoSim (EwE) modeling framework, in conjunction with stakeholder working groups and the Assessment of Estuarine Trophic Status (ASSETS) tool.

Individual FARM models were prepared for Manila clam (Venerupis philippinarum), Pacific oyster (Crassostrea gigas), and Mediterranean mussel (Mytilus galloprovincialis). Development of an equivalent model for geoduck (Panopea generosa) is underway.

Production scenarios examined various increases in bivalve aquaculture and the effects of certain 'control' fisheries.  We explored using an EcoSim model how a doubling or an order of magnitude increase in each of four aquaculture sectors could influence the availability of phytoplankton and zooplankton to other species groups.

Finally, a public perceptions survey was completed to assess social carrying capacity. It revealed a general view that shellfish farms "neither enhance nor detract from the scenery of coastal areas" and their "greatest benefit" is "providing locally produced seafood." This research was funded through Washington Sea Grant, pursuant to NOAA award #NA14OAR4170078.