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Monitoring the prey-field of marine predators: combining digital imaging with datalogging tags

Hooker, Sascha K.; Boyd, Ian L.; Jessopp, Mark; Cox, Oliver; Blackwell, John; Boveng, Peter L.; Bengtson, John L.. 2002 Monitoring the prey-field of marine predators: combining digital imaging with datalogging tags. Marine Mammal Science, 18 (3). 680-697. 10.1111/j.1748-7692.2002.tb01066.x

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Abstract/Summary

There is increasing interest in the diving behavior of marine mammals. However, identifying foraging among recorded dives often requires several assumptions. The simultaneous acquisition of images of the prey encountered, together with records of diving behavior will allow researchers to more fully investigate the nature of subsurface behavior. We tested a novel digital camera linked to a time-depth recorder on Antarctic fur seals (Arctocephalus gazella). During the austral summer 2000-2001, this system was deployed on six lactating female fur seals at Bird Island, South Georgia, each for a single foraging trip. The camera was triggered at depths greater than 10 m. Five deployments recorded still images (640 X 480 pixels) at 3-sec intervals (total 8,288 images), the other recorded movie images at 0.2-sec intervals (total 7,598 frames). Memory limitation (64 MB) restricted sampling to approximately 1.5 d of 5-7 d foraging trips. An average of 8.5% of still pictures (2.4%-11.6%) showed krill (Euphausia superba) distinctly, while at least half the images in each deployment were empty, the remainder containing blurred or indistinct prey, In one deployment krill images were recorded within 2.5 h (16 km, assuming 1.8 m/sec travel speed) of leaving the beach. Five of the six deployments also showed other fur seals foraging in conjunction with the study animal. This system is likely to generate exciting new avenues for interpretation of diving behavior.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1111/j.1748-7692.2002.tb01066.x
Programmes: BAS Programmes > Antarctic Science in the Global Context (2000-2005) > Dynamics and Management of Ocean Ecosystems
ISSN: 0824-0469
Additional Keywords: Antarctic fur seal, Arctocephalus gazella, digital imaging, diving behavior, foraging, time-depth recorder
NORA Subject Terms: Marine Sciences
Zoology
Ecology and Environment
Date made live: 15 Nov 2011 14:55
URI: http://nora.nerc.ac.uk/id/eprint/13404

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