Insights into the foraging behavior of Steller sea lions using an animal-borne video and data

recorder

Paul Olivier – Texas A&M UniversityRuss Andrews – Univ. of Alaska Fairbanks and the Alaska Sealife Center

Don Calkins – North Pacific Wildlife Consulting, LLC

Vladimir Burkanov – National Marine Mammal Laboratory, NMFS, NOAA

Randall Davis – Texas A&M University at Galveston

S F O SSchool of Fisheries and Ocean Sciences

Project Description

• Objective– Describe the foraging strategies

of lactating SSL

• Location– Kuril Islands, Russia– SSL/NFS Rookery on

Lovushki Island– June 20-23, 2008

• Test Subject Selection– Lactating Female– Healthy, Large Pup

InstrumentationVideo Data Recorder (VDR)

• Equipment in deployed VDRs– Head Mount

• B&W CCD camera with near-infrared LEDs• GPS

– Backpack• Digital video recorder and Flash memory for

data• Pressure sensor (depth)

• Other sensors– Thermistor– Conductivity sensor– Illuminance sensor– Water (swim) speed– 3-axis accelerometer (pitch, roll,

yaw)– 3-axis magnetometer

Example of Time-Depth Record

Dive Depths(Max dive depths for all three animals)

Dive Durations(Combined data for three animals)

Mean = 200 seconds (3.3 min)

Time Budget(from approximately 7.5 hours of video data)

Atka MackerelPleurogrammus monopterygius

• Display diurnal vertical migration1

– Active vertical movement away from “settling depth” (near 100 m) during daylight hours

– Returned to “settling depth” in late afternoon

• Vertical migration may increase susceptibility to SSL predation during daylight hours1

1Nichol and Somerton, 2002; Mar Ecol Prog Ser 239: 193–207

Clip 1: Bottom Foraging (Depth: 60-70m, Time: 18:45)

Clip 2: Bottom Foraging (Depth: 130m, Time: 19:37)

Clip 3: Bottom Foraging (Depth: 120m, Time: 01:00)

Clip 4: Backlight Feeding (Depth: 125m, Time: 19:45)

Estimated Foraging Success(from approximately 7.5 hours of video data)

Consumption rate for SSL 2– Combination of darkness, speed and camera placement made it

difficult to identify which of the fish “encountered” were consumed and which escaped out the bottom of the video frame.

Captures Time (min) No. Dives Captures / DiveCaptures /

min

SSL 1 7 105 24 0.29 0.07

SSL 2 49 250 12 4.08 0.20

SSL 5 10 86 12 0.83 0.12

Conclusion:• SSL exploit Atka mackerel behavior• Prey detection appears primarily by

vision• Vibrissae may be used with vision in

low light conditions

Acknowledgements

Bill Hagey, Sarah Norberg,Petr Permyakov

Oksana Savenko, John Skinner, Tatiana Shulezhko

Boris Solovyev, Andrey Tretiyakov, Jason Waite

The captain and crew of the R/V Georg Steller

FundingNOAA grant to the Alaska Sealife Center Pinniped Program

Texas A&M University

National Science Foundation

National Marine Fisheries Service

National Undersea Research Program