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Marine Ecology Progress Series

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MEPS 500:281-285 (2014)  -  DOI:

Stable isotope analysis of Humboldt squid prey: Comment on Miller et al. (2013)

John C. Field1,*, Steven Y. Litvin2, Aaron Carlisle2, Julia S. Stewart2,4, William F. Gilly2, Rocio I. Ruiz-Cooley3

1Fisheries Ecology Division, SWFSC/NMFS/NOAA, 110 Shaffer Rd, Santa Cruz, California 95060, USA
2Hopkins Marine Station of Stanford University, 120 Oceanview Dr, Pacific Grove, California 93950, USA
3Ocean Sciences Department, University of California Santa Cruz, 1156 High Street, Santa Cruz, California 95064, USA
4Present address: National Center for Ecological Analysis and Synthesis, Santa Barbara, California 93101, USA
*Corresponding author:

ABSTRACT: Miller et al. (2013; Mar Ecol Prog Ser 477:123-134) used bulk stable isotope analysis (SIA) and a Bayesian isotope-mixing model (SIAR) to assess the diet of the Humboldt squid Dosidicus gigas in the Northern California Current. Their conclusions starkly contrast decades of food habits and other research on this organism. The methods they employed are sensitive to a range of assumptions and parameter estimates, and the trophic model they used is confounded by the interactive effects of movement and diet on D. gigas isotopic values. This is compounded by the sensitivity of the migratory model to critical assumptions of the trophic level of D. gigas (specifically the assumption that large D. gigas are approximately 1 trophic level above copepods), which are inconsistent with the literature. Therefore, Miller et al.’s (2013) conclusions regarding the contribution of specific prey to D. gigas in the northern California Current are unsupported.

KEY WORDS: Humboldt squid · Dosidicus gigas · Stable isotope analysis · Bayesian mixing models · California Current

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Cite this article as: Field JC, Litvin SY, Carlisle A, Stewart JS, Gilly WF, Ruiz-Cooley RI (2014) Stable isotope analysis of Humboldt squid prey: Comment on Miller et al. (2013). Mar Ecol Prog Ser 500:281-285.

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