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Habitat utilization, behavior and food habits of the jumbo or Humboldt squid, Dosidicusgigas, were compared between an area recently inhabited in the northern California Current System (CCS) and a historically established area of residence in the Gulf of California (GOC). Low dissolved oxygen concentrations at midwater depths define the oxygenminimum zone (OMZ), an important environmental feature in both areas. We analyzed vertical diving behavior and diet of D. gigas and hydrographic properties of the water column to ascertain the extent to which squid utilized the OMZ in the two areas. The upper boundary of the OMZ has been shoaling in recent decades in the CCS, and this phenomenon has been proposed to vertically compress the pelagic environment inhabited by aerobic predators. A shoaling OMZ will also bring mesopelagic communities into a depth range with more illumination during daytime, making these organisms more vulnerable to predation by visual predators (i.e. jumbosquid). Because the OMZ in the GOC is considerably shallower than in the CCS, our study provides insight into the behavioral plasticity of jumbosquid and how they may respond to a shoaling OMZ in the CCS. We propose that shoaling OMZs are likely to be favorable to jumbosquid and could be a key indirect factor behind the recent range expansion of this highly migratory predator. Inglés

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