Quantifying food web interactions in the North Pacific – a data-based approach

Abstract

As part of its annual bottom-trawl survey program, the Alaska Fisheries Science Center (AFSC) has been collecting and analyzing the stomach contents of groundfish predators since 1981. Between 1981 and 2011, a total of 233,451 fish stomachs were collected and analyzed from the eastern Bering Sea, the Gulf of Alaska, and the Aleutian Islands large marine ecosystems; these data are now available online as AFSC’s Groundfish Trophic Interactions Database. Here, we discuss features of the survey and data to aid in the interpretation and use of this extensive dataset for the Alaska region. The primary fish sampled include walleye pollock (Gadus chalcogrammus), Pacific cod (Gadus macrocephalus), Pacific halibut (Hippoglossus stenolepis), and arrowtooth flounder (Atheresthes stomias), although 159 predator species have been included in the stomach content analysis. Prey length measurements are included for important commercial prey and can identify age or size classes of prey prior to their recruitment into fisheries and most other surveys. With these data, one can track time trends in growth, mortality, and prey composition as ecosystem indicators, and include food web interactions in fish stock assessments for ecosystem-based fisheries management.