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Marine Ecology Progress Series

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MEPS 414:209-221 (2010)  -  DOI:

Interdecadal variability in predator–prey interactions of juvenile North Pacific albacore in the California Current System

Sarah M. Glaser

Integrative Oceanography Division, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093-0218, USA
Present address: Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, Kansas 66047, USA

ABSTRACT: Predator–prey interactions are critical components of multispecies models, and most attempts to quantify these interactions in pelagic marine environments rely on observational diet studies. In conjunction with 3 historical studies, a new diet study quantifies decadal patterns of predator–prey interactions for juvenile North Pacific albacore Thunnus alalunga in the California Current System (CCS). Juvenile albacore in the CCS eat young-of-year prey and derive 68 to 89% of nutrition from fishes, 9 to 30% from cephalopods, and the remainder from crustaceans. Despite resurgence in abundance of Pacific sardine Sardinops sagax in the CCS, only Northern anchovy Engraulis mordax, Pacific saury Cololabis saira, and cephalopods have consistently been important to albacore diet. These results support theoretical predictions of optimal foraging models that albacore will prefer hunting in cold, near-shore waters containing anchovy and saury while minimizing foraging in warmer, offshore waters of sardine habitat. A bioenergetics model is used to calculate daily and annual consumption rates. The importance of calculating an ensemble prey energy density (EDn) value for steady-state consumption models is demonstrated, and the relationship between EDn and consumption rates is generalized to other marine predators. Low variability in EDn consumed by juvenile albacore translates into equally stable consumption to biomass (Q:B) ratios over decades.

KEY WORDS: Thunnus alalunga · Predator–prey interaction · Bioenergetics · Ensemble energy density · Diet · Trophic ecology · Pelagic food web · California Current

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Cite this article as: Glaser SM (2010) Interdecadal variability in predator–prey interactions of juvenile North Pacific albacore in the California Current System. Mar Ecol Prog Ser 414:209-221.

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