Humboldt Squid (Dosidicus gigas) in the Monterey Bay National Marine Sanctuary: Electronic Tagging Reveals Behavior and Habitat Use JS Stewart1, WF Gilly1, JAT Booth1,2, JC Field3, KA Baltz3 1Hopkins Marine Station, Stanford University, Pacific Grove, 2Moss Landing Marine Laboratories, Moss Landing, 3Fisheries Ecology Division, NOAA Fisheries Service, Santa Cruz

Humboldt squid have expanded their northern habitat range from Mexico to Alaska. They have been present in Monterey Bay since 1997 (Zeidberg & Robison, 2007), although their abundance fluctuates annually and interannually.

Humboldt squid feed mainly on myctophids and other mesopelagic micronekton. In California, they supplement their diet with Pacific hake, pelagic rockfish, and market squid--all ecologically and economically important species (Field et al. 2007).

Here we report data from the first Humboldt squid tagged in California waters. Our work aims to m .75 ~0 identify Humboldt squid behaviors in relation to various physical features, as well as to determine their diet and impacts on ecosystems and fisheries. Tagging Humboldt squid in California follows

MBARI previous tagging studies in Mexico (Gilly et al. 2006; Bazzino et al. 2010) and provides new information on diving behavior and habitat use.

Daily Vertical Migrations Displayed by Tag 5 Tagging Humboldt Squid 2008-2009

100 9 squid were tagged in the fall in Monterey Bay and Cordell Bank National Marine Sanctuaries. Useful data (> 2.5 days) were 200 38° 200 obtained from 5 tags. 1 400

300 Depth (m)

Day Night 600 Depth (m) All tagged squid swam in a south 400 or southerly direction

Night 36° 3 500 Day 4 2 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2 4 6 8 10 12 14 16 Date (November 2009) Percent of Time at Depth Tag 5 traveled half the length 4 6 8 10 12 14 16 Characteristic behavior involves midwater depths Temperature ($C) of California in 2.5 weeks! until dusk and shallower depths until dawn

34° All Tagged Squid Made Daily Vertical Migrations

200

400 Daytime medians ranged from 280-432 m (overall median = 310 m) Nighttime medians ranged from 27-100 m (overall median = 90 m) 600 32° 5 800 Squid spent 47-83% of nighttime hours at depths < 100 meters.

Depth (m) Occupation of such shallow depths in Mexico is only seen in 1000 wintertime, when surface temperatures are cooler (Gilly et al. in prep). Tag Release 1200 Day Night 1400 # Tag Pop off 1 2 3 4 5 1 2 3 4 5 lines drawn as visual aids Tag Number -124° -122° -120° -118°

sampling min. dist. minimum rate Humboldt Squid Spend Time in the Oxygen Minimum Zone Tag # time (days) traveled (km) (km/day) The oxygen minimum zone (OMZ) is a midwater environment where dissolved oxygen concentrations drop below 1 2.7 54 20 Tag 5 traveled at least 0.5 mL/L (~20 µmol/kg), which is beyond the physiological scope of many marine organisms (Childress 1995). 2 13 108 6.35 595 km in 17.5 days: a minimum average velocity 3 7 118 21 Deep Dives Through the OMZ Displayed by Tag 4 of 35 km/day. 4 3 45 15 5 17.5 595 35 200

400 Deep dives through the OMZ Humboldt squid swimming veolcities of > 30 km/day have been observed in Mexico, oxygen minimum zone to ~1400 m were observed 600 but Tag 5 provides the first evidence of such speeds sustained for > 3 days. in two of the five tagged squid. 800 Tag 4 spent 28.3% of the This behavior is consistent with a fall/winter migration to spawn in warmer waters. Depth (m) daytime in the OMZ. 1000 38° 1200 NightNight 1 DayDay 1400 6 7 8 5 10 15 20 25 30 Date (November 2009) 3 Thanks to: Percent of Time at Depth Investigating Horizontal36° Migrations4 2 4 6 8 10 12 14 16 0.5 1 2 3 4 5 6 7 8 9 10 Our colleagues at the Dissolved Oxygen (mL/L) Temperature (°C) Monterey Bay Aquarium, MBARI, and NMFS; oxygen data courtesy of MBARI 34° Ian Wilson and Alex Norton; x Lorraine Anglin and the Daytime in the OMZ Displayed by Tag 3 100 wonderful crews of the NOAA vessels R/V Fulmar, 32° 5 R/V SRVx and R/V R4107. 100 Tag Release 200 # Tag Pop off CalCOFI Funding support from Three tags spent portions 200 -124° -122° -120°sampling-118° grid California SeaGrant; Hopkins Marine Station of the daytime in the OMZ 300 Marine Life Observatory; as part of their characteristic 300 400 Myers Grant vertical migration, without Depth (m) Next steps: to estimate making deep dives. Depth (m) 500 horizontal migration routes 400 Tag 3 spent 44.3% of 600 the daytime in the OMZ. 700 NightNight We will compare data from DayDay 500 the tags with data from 800 6 7 8 9 10 11 5 10 15 20 25 shipboard surveys, along Date (November 2009) Percent of Time at Depth with estimated velocities 4 6 8 10 12 14 16 0.5 1 2 3 4 5 6 7 8 9 10 Dissolved Oxygen (mL/L) Temperature (°C) 600 and local bathymetry. Squid temperature profile &DO&2),WHPSHUDWXUH near x SURILOHDW[ OMZs in California are shoaling, perhaps facilitating the range expansion of Humboldt squid (Bograd et al. 2008). with D. Foley and S. Bograd, NOAA Pacific Grove G. Auger