Shellfish growing capacity in S. Puget Sound

Planning for Sustainable Shellfish Aquaculture in Complex Multiple Use Environments: Determining Social and Ecological Carrying Capacity for South Puget Sound, Washington

Researchers investigated the physical conditions and coastal-community views that determine ecological and social carrying capacity for shellfish aquaculture.

Principal Investigator

Daniel Cheney, Pacific Shellfish Institute

Co-Principal Investigators

Suzanne Bricker, NOAA National Ocean Service

Jonathan Davis, Baywater, Inc.

Joao Ferreira, Longline Environment, Ltd.

Teri King, University of Washington, Washington Sea Grant

David Preikshot, Department of Fisheries & Oceans, Canada

Mindy Roberts, Washington Department of Ecology

John Tarnai, Washington State University, Social & Economic Research Center


With national strategic initiative funding, Washington Sea Grant-supported researchers began an assessment of south Puget Sound’s production, ecological, and social carrying capacity for shellfish aquaculture in 2012. They collected farm production records and shellfish species metrics, industry assessments of aquaculture-related policies and regulations, and information on regional constraints and incentives. They also reviewed nutrient and dissolved-oxygen models, examined model outputs, and initiated ongoing research into nitrogen removal and natural shellfish recruitment at one inlet. They held the first of three planned stakeholder meetings and disseminated the project’s goals via an article in the Pacific Coast Shellfish Growers Association’s newsletter and a flyer distributed at its joint annual meeting with the National Shellfisheries Association in 2013.

Research Updates

National Sea Grant-funded researchers considered physical, ecological, social and production capacities in determining South Puget Sound’s shellfish carrying capacity. They incorporated farm production records, shellfish species metrics, water resource data, policy and regulation assessments, and stakeholder information. Ecopath modeling was used to create past and recent biomass snapshots of multiple plant and animal species and Ecosim modeling forecast changes out to the year 2054 according to various production and management scenarios. Researchers used Farm Aquaculture Resource Management (FARM) modeling to simulate shellfish growth, harvests, and algae and detritus removal.

FARM modeling accurately predicted actual harvests. Ecopath modeling indicated current growing practices had neutral or beneficial effects on most key species’ biomass. Doubling bivalve production, even increasing it 10 times in most cases, had little impact. Model results for South Puget Sound suggest shellfish harvest removed as much nitrogen as 40,000 humans produce, saving $1.6 million a year in waste treatment. The results helped researchers calculate the ecosystem services aquaculture provides, particularly in controlling eutrophication.


Determining social and ecological carrying capacity for South Puget Sound (2013) Pacific Shellfish Institute.