Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 8432
Title: Evaluating trophic and non-trophic effects of shellfish aquaculture in a coastal estuarine food web
Author: Bridget E. Ferriss, J. C. P. Reum, P. Sean McDonald, Dara Farrell, C. J. Harvey
Publication Year: 2016
Journal: ICES Journal of Marine Science
Volume: 73
Pages: 429-440
Keywords: aquaculture,bivalves,geoduck,Puget Sound,food webs,ecosystem model

Expansion of the shellfish aquaculture industry has the potential to affect the structure and dynamics of coastal estuarine food webs. To better understand food web tradeoffs, we incorporated both trophic and non-trophic interactions (e.g., habitat facilitation, predator refuge) into a food web model of central Puget Sound to predict the effects of an increase in geoduck (Panopea generosa) aquaculture. At a basin-scale, the food web can support at least 120% increased geoduck aquaculture, above current production levels (landings of 10,546 kg in 2012), with only minor changes in individual species’ biomass and/or metrics of ecosystem resilience. The non-trophic effects of increased geoduck aquaculture, related to the influence of anti-predator structure, had a stronger influence on the food web than the trophic role of cultured geoducks as filter feeders and prey to other species. Increased geoduck culture caused substantial increases in biomass densities of surf perch, nearshore demersal fish, and small crabs, and decreases in seabirds, flatfish, and certain invertebrates (e.g., predatory gastropods and small crustaceans). This study identifies species that should be a priority for additional empirical research and monitoring related to bivalve aquaculture interactions, including demersal fish, small crustaceans, and seabirds. It also provides insights into the benefits and challenges of incorporating habitat-related data into a food web model.  Understanding these relationships can inform management decisions by clarifying tradeoffs in ecosystem functions and services in Puget Sound and facilitates estimation of direct and cumulative effects of bivalve aquaculture at a food web scale.

Theme: Ecosystem approach to improve management of marine resources
Foci: Characterize ecological interactions (e.g. predation, competition, parasitism, disease, etc.) within and among species.
Provide scientific support for the implementation of ecosystem-based management