Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 7615
Title: Pelagic and demersal fish predators on juvenile and adult forage fishes in the California Current:  spatial and temporal variations
Author: Richard D. Brodeur, J. C. Buchanan, Robert L. Emmett
Publication Year: 2014
Journal: California Cooperative Oceanic Fisheries Investigations Reports
Volume: 55
Keywords: forage fish,predators,Groundfish,pelagic nekton,California Current

A requisite for reliable food web models and ecosystem based management in regions such as the California Current is the availability of diet information on key predators. In ecosystems designated as wasp-waist systems believed to be the situation in most upwelling ecosystems, much of the lower trophic level energy is transferred through a relatively small set of very abundant pelagic forage fish taxa, such as anchovies, sardines, smelts, and herring. In addition, the pelagic juvenile stages of some important midwater and demersal fishes (Pacific hake and rockfishes) may act as forage fishes during a more limited time period each year. In this paper, we review what is known about the utilization of these forage species by larger fish predators and elasmobranchs in the Northern California Current (NCC) from northern Washington to northern California (Cape Mendocino) to examine spatial and temporal variations in the kinds and sizes of forage fishes consumed. We found that predation on forage fishes was highly variable in space and time, and was often dependent on the size of the prey available as well as the predator. Pacific hake and spiny dogfish have the potential to be dominant forage fish predators due to their high biomass but other species such as arrowtooth flounder and Pacific halibut can be important due to their high proportion of forage fish in the diet. We also highlight where diet information is poor or lacking, and areas where regular fish diet monitoring could be useful for ecosystem-based management.

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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