Humboldt squid (Dosidicus gigas) are large (> 1 m), short-lived (1-2 years), fast-growing (1 mm/d in adults), highly fecund (30 million eggs/female), generalist predators in the eastern Pacific Ocean that support the world's largest invertebrate fishery (FAO 2009). Life history and behavioral characteristics of the Humboldt squid have likely facilitated its range expansion into the northern California Current System. After an initial presence during the 1997/1998 El Niño, Humboldt squid were observed in variable numbers from 2002-2010. Seasonal feeding migrations likely bring them to the productive waters off the coast of Washington and British Columbia to forage before returning to warmer waters to spawn. I investigated the behavior and habitat of Humboldt squid in situ with both electronic tags deployed on individual animals and observations collected by remotely operated vehicles (ROVs) in Monterey Bay that recorded thousands of Humboldt squid from 1997-2010. Several tagged squid dove to depths > 1.25 km, through the core of the oxygen minimum zone (OMZ), and I estimated they can sustain horizontal velocities of > 35 km/day for over two weeks, with maximum velocities > 50 km/day. Further, I integrated observations of Humboldt squid on each ROV dive with information on time-at-depth of the ROV, creating an "encounter rate" metric that can be used in ecosystem and fisheries models, similar to catch per unit effort (CPUE). I used this metric to investigate the seasonality of Humboldt squid presence in the Monterey Bay area in relation to upwelling and found that early evolution of the upwelling season may serve as an indicator for the annual magnitude of their presence. My work reveals capabilities and behaviors of Humboldt squid that will enhance our understanding of their impacts on the ecosystems and fisheries in the California Current System.
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