Horizontal movements, vertical-habitat utilization and diet of the jumbo squid (Dosidicus gigas) in the Pacific Ocean off Baja California Sur, Mexico

Locomotion and behavior of Humboldt squid,Dosidicus gigas, in relation to natural hypoxia in the Gulf of California, Mexico

“…Previous studies have indicated that D. gigas spends considerable time at cold, hypoxic depths, both in the Gulf of California (Gilly et al, 2006) and in the Pacific Ocean (Bazzino et al, 2010;Zeidberg and Robison, 2007). This paper provides an expanded and refined assessment of this feature by exploring squid swimming behavior in the Guaymas Basin of the Gulf of California in locations that are characterized by large seasonal differences in surface temperature and depth of the upper boundary of the OMZ.…”

“…Thus, D. gigas is potentially exposed to prey on a constant basis and may therefore be able to forage during both the day and the night. Although D. gigas can greatly reduce its resting metabolic rate in response to a cold, hypoxic challenge (Gilly et al, 2006;Rosa and Seibel, 2008;Rosa and Seibel, 2010), a previous tagging study did not detect any reduction in vertical velocities during daytime hours that were spent at very low oxygen (Bazzino et al, 2010). Effects of hypoxia on the metabolic rate of D. gigas during active swimming are not known, but presumably highly aerobic activity such as high-velocity jetting would be significantly impaired in the OMZ.…”

“…Throughout its large range (Canada to Chile) D. gigas plays an important ecological role as both predator and prey. In the Gulf of California, prey consists primarily of mesopelagic micronekton, including myctophid fishes, squids, pteropods and crustaceans (Markaida and Sosa-Nishizaki, 2003;Markaida et al, 2008), but this menu expands to include a variety of neritic and pelagic fishes in continental shelf and slope environments along the Pacific coast in the northern hemisphere (Field et al, 2007;Bazzino et al, 2010). In turn, D. gigas is a major prey item for sperm whales and other marine mammals, large teleost fishes and sharks, and is thus an important transitional organism in trophic webs, transferring energy from micronekton to the largest apex predators.…”

“…Dosidicus gigas also migrates vertically in the water column, in a generally parallel fashion to that of the DSL, spending nighttime at shallow depths and daytime near the upper OMZ in the Gulf of California (Gilly et al, 2006) as well as in the Pacific Ocean off Baja California (Bazzino et al, 2010). Thus, D. gigas is potentially exposed to prey on a constant basis and may therefore be able to forage during both the day and the night.…”

Growth model selection for the jumbo squid Dosidicus gigas from the Gulf of California, Mexico

“…Changes in the ions, pH, and organic or inorganic components are related to individual metabolism, diel activity patterns and environmental conditions (Pauly 1998, Bettencourt & Guerra 2000. For D. gigas in the Gulf of California, the vertical and horizontal movements (Gilly et al 2006, Bazzino et al 2010, Hoving et al 2013, Rosa et al 2013) and largescale migrations in and out of the Gulf are caused by environmental changes such as El Niño and La Niña events (Morales-Bojórquez et al 2001a, Rosa et al 2013. These could affect the deposition process of statoliths and the daily formation of the growth rings.…”