MEPS 500:281-285 (2014)  -  DOI: https://doi.org/10.3354/meps10533

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