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Open Access Publications from the University of California

An Analysis of Fish Bycatch in the California Large Mesh Drift Gillnet Fishery


The California Large Mesh Drift Gillnet fishery (CA DGN fishery) has targeted swordfish (Xiphias gladius) within the exclusive economic zone (EEZ) off the West Coast of the United States since the late 1970s. Since its inception, a number of regulatory changes have been implemented to reduce the take of non-target species. Concerns over marine mammal interactions led to the implementation of the Federal Fisheries Observer Program in 1990 to support compliance with the Marine Mammal Protection Act (MMPA). Observer information is used by the National Marine Fisheries Service (NMFS) to inform stock assessments, help construct fishery management plan regulations, develop bycatch reduction devices, and identify the need for protective regulations for protected species. The tremendous dataset collected by fisheries observers since 1990 is rich with information on finfish catch and discards in the CA DGN fishery. This component of the fishery remains largely under-studied in the context of the gear modifications and spatial closures that were originally intended to benefit marine mammals, sea turtles and sharks. This research project therefore aims to explore the fish catch and discard characteristics and disposition of fish species in the CA DGN fishery, using an approach based on biomass wherever possible. In addition, catch trends of various species will be described graphically in order to begin drawing a picture of the fishery’s impact on the major species that constitute its catch. The overall aim of this project is to provide an overview of catch and bycatch composition in the CA DGN fishery.

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