Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 4407
Title: Identifying ecological and fishing drivers of bycatch in a U.S. groundfish fishery
Author: Jason E. Jannot, Daniel S. Holland
Publication Year: 2013
Journal: Ecological Applications
Volume: 23
Issue: 7
Pages: 1645-58
Keywords: fishery observer, ecological management, fishing operations, delta model, spatial effects,

The science of fisheries bycatch is challenged with developing analyses that separate the ecological (e.g., area, season) from the social (e.g., fisher behavior) determinants of bycatch. In this paper, we demonstrate how comparing fishery-dependent bycatch to fishery-independent catch can provide insights into the opportunities for and constraints on bycatch management. We use observer data from the U.S. west coast trawl groundfish fishery (fishery-dependent data) and scientific data from the U.S. west coast bottom trawl groundfish survey (fishery-independent data) to compare the relative effects of a suite of ecological and fishing variables on the expected catch of 12 bycatch species of management interest. Our expected catch analysis identifies four alternative relationships between how variables affect expected fishery bycatch vs. survey catch: 1) significant positive correlation between variables and both fishery and survey expected catch; 2) significant positive correlation between variables and fishery expected catch, but no correlation with survey expected catch; 3) significant positive correlation with survey expected catch, but not with fishery expected catch; and (4) no significant correlation with either type of expected catch. The first relationship suggests ecological factors (e.g. location and season) might drive bycatch and therefore constrain management options. The second and third cases indicate that fishing behavior is altering the bycatch amounts, either increasing it or reducing it relative to random catch. Our analysis can be used by managers and fishers to identify opportunities and strategies for bycatch reduction and by researchers interested in comparing bycatch before and after a management shift.

Theme: Recovery, Rebuilding and Sustainability of Marine and Anadromous Species
Foci: Investigate ecological and socio-economic effects of alternative management strategies or governance structures.
Describe the relationship among human activities and species stock status, recovery, rebuilding and sustainability.
Official Citation:

Jannot, J.E. and D.S. Holland 2013. Identifying ecological and fishing drivers of bycatch in a U.S. groundfish fishery. Ecological Applications 23(7):1645-58.