Hunting behavior of a marine mammal beneath the antarctic fast ice

Science

Volumn 283, Issue 5404, 1999, Pages 993-996

  Davis, R W ^a   Fuiman, L A ^b   Williams, T M ^c   Collier, S O ^a   Hagey, W P ^d   Kanatous, S B ^e   Kohin, S ^e   Horning, M ^a  

^a TEXAS A AND M UNIVERSITY   (United States)

^b UNIVERSITY OF TEXAS AT AUSTIN   (United States)

^c UNIVERSITY OF CALIFORNIA   (United States)

^d Pisces Design   (United States)

^e UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

ICE;

ANIMAL BEHAVIOR; ANTARCTICA; ARTICLE; FISH; LOCOMOTION; NONHUMAN; PREDATOR; PRIORITY JOURNAL; SEAL; VIDEORECORDING; VISION;

EID: 0033548224     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.283.5404.993     Document Type: Article

References (39)

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11. J. P. Croxall, I. Everson, G. L. Kooyman, R. W. Davis, J. Anim. Ecol. 54, 1 (1985); B. J. LeBoeuf, D. P. Costa, A. C. Huntley, S. D. Feldkamp, Can. J. Zool. 66, 446 (1988); I. L. Boyd and T. Arnbom, Polar Biol. 11, 259 (1991); M. A. Hindell, D. J. Slip, H. R. Burton, Aust. J. Zool. 39, 595 (1991); M. A. Fedak and D. Thompson, in Marine Mammals: Advances in Behavioural and Population Biology, Zoology Society of London Symposium 66, I. L. Boyd, Ed. (Clarendon Press, Oxford, UK, 1993), pp. 333-347; D. Thompson, A. R. Hiby, M. A. Fedak, in ibid., pp. 349-367; J. F. Schreer and J. W. Testa, Mar. Mamm. Sci. 11, 85 (1995).
12. J. P. Croxall, I. Everson, G. L. Kooyman, R. W. Davis, J. Anim. Ecol. 54, 1 (1985); B. J. LeBoeuf, D. P. Costa, A. C. Huntley, S. D. Feldkamp, Can. J. Zool. 66, 446 (1988); I. L. Boyd and T. Arnbom, Polar Biol. 11, 259 (1991); M. A. Hindell, D. J. Slip, H. R. Burton, Aust. J. Zool. 39, 595 (1991); M. A. Fedak and D. Thompson, in Marine Mammals: Advances in Behavioural and Population Biology, Zoology Society of London Symposium 66, I. L. Boyd, Ed. (Clarendon Press, Oxford, UK, 1993), pp. 333-347; D. Thompson, A. R. Hiby, M. A. Fedak, in ibid., pp. 349-367; J. F. Schreer and J. W. Testa, Mar. Mamm. Sci. 11, 85 (1995).
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15. E. A. Wilson, Nat. Hist. 2, 1 (1907); G. C. L. Bertram, The Biology of the Weddell and Crabeater Seals, vol. 1, issue 1 (British Museum of Natural History, London, 1940); I. Stirling, N.Z. J. Mar. Freshwater Res. 3, 191 (1969); Ecology 50, 573 (1969); Antarct. Pinnipedia 18, 141 (1971); D. B. Siniff, D. P. DeMaster, R. J. Hoffman, L. L. Eberhardt, Ecol. Monogr. 47, 319 (1977).
16. E. A. Wilson, Nat. Hist. 2, 1 (1907); G. C. L. Bertram, The Biology of the Weddell and Crabeater Seals, vol. 1, issue 1 (British Museum of Natural History, London, 1940); I. Stirling, N.Z. J. Mar. Freshwater Res. 3, 191 (1969); Ecology 50, 573 (1969); Antarct. Pinnipedia 18, 141 (1971); D. B. Siniff, D. P. DeMaster, R. J. Hoffman, L. L. Eberhardt, Ecol. Monogr. 47, 319 (1977).
17. E. A. Wilson, Nat. Hist. 2, 1 (1907); G. C. L. Bertram, The Biology of the Weddell and Crabeater Seals, vol. 1, issue 1 (British Museum of Natural History, London, 1940); I. Stirling, N.Z. J. Mar. Freshwater Res. 3, 191 (1969); Ecology 50, 573 (1969); Antarct. Pinnipedia 18, 141 (1971); D. B. Siniff, D. P. DeMaster, R. J. Hoffman, L. L. Eberhardt, Ecol. Monogr. 47, 319 (1977).
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19. E. A. Wilson, Nat. Hist. 2, 1 (1907); G. C. L. Bertram, The Biology of the Weddell and Crabeater Seals, vol. 1, issue 1 (British Museum of Natural History, London, 1940); I. Stirling, N.Z. J. Mar. Freshwater Res. 3, 191 (1969); Ecology 50, 573 (1969); Antarct. Pinnipedia 18, 141 (1971); D. B. Siniff, D. P. DeMaster, R. J. Hoffman, L. L. Eberhardt, Ecol. Monogr. 47, 319 (1977).
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22. K. Green and H. R. Burton, Aust. Wildl. Res. 14, 475 (1987); J. H. Dearborn, J. Mammal. 48, 37 (1965); I. Calhaem and D. A. Christoffel, N.Z. J. Mar. Freshwater Res. 3, 181 (1969); J. A. Raymond, Mar. Technol. Soc. J. 9, 32 (1975); A. L. DeVries and J. T. Eastman, J. R. Soc. N.Z. 11, 329 (1981); J. W. Testa, D. B. Siniff, M. J. Ross, J. D. Winter, in Antarctic Nutrient Cycles and Food Webs, W. R. Siegfried, P. R. Condy, R. M. Laws, Eds. (Springer-Verlag, Berlin, 1985), pp. 561-565.
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24. K. Green and H. R. Burton, Aust. Wildl. Res. 14, 475 (1987); J. H. Dearborn, J. Mammal. 48, 37 (1965); I. Calhaem and D. A. Christoffel, N.Z. J. Mar. Freshwater Res. 3, 181 (1969); J. A. Raymond, Mar. Technol. Soc. J. 9, 32 (1975); A. L. DeVries and J. T. Eastman, J. R. Soc. N.Z. 11, 329 (1981); J. W. Testa, D. B. Siniff, M. J. Ross, J. D. Winter, in Antarctic Nutrient Cycles and Food Webs, W. R. Siegfried, P. R. Condy, R. M. Laws, Eds. (Springer-Verlag, Berlin, 1985), pp. 561-565.
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26. max = 850 nm) is believed to be invisible to them and their prey (14), as it is to humans. This prevents alterations in the normal behavior of the seals and their prey due to artificial light from the instrument. For some dives, the small (6 cm long by 6 cm in diameter) camera head with LEDs was detached from the main housing and mounted on top of the seal's head to obtain closeup images of the seal's eyes and muzzle and the area in front of the animal. The main housing contains an 8-mm video tape recorder (VTR; Sony EVO-220 VTR), rechargeable lithium ion batteries, and an on-board microcomputer (Onset Computer Corporation, Pocasset, MA) with 4 MB of RAM. The microcomputer controls the VTR and data acquisition from the transducers. The video system is activated by an external switch and can record for 6 hours. Transducers for pressure (Keller-PSI, Hampton, VA), water speed (Ultramarine Instruments, Seattle, WA), and compass bearing (KVH, Middletown, RI) are sampled once per second, and the data are stored on a PCMCIA card. A separate housing (17 cm long and 5.5 cm in diameter) for the gimbaled flux-gate compass is positioned behind the main housing and connected to it with a cable. Sound is recorded on one audio channel of the VTR with a hydrophone with a frequency response of 50 Hz to 16 kHz. Flipper stroke frequency is determined from the lateral motion of a small accelerometer (6 cm by 3 cm by 2 cm; Ultramarine Instruments) mounted near the base of the tail. The analog output from the accelerometer is converted into an audio frequency that is recorded on the other audio channel of the videotape. Weddell seals were captured with a purse-string net on the ice along the west shore of Hut Point Peninsula, Ross Island, and transported to the hut in a sled. Newly captured seals were weighed on a platform scale, placed in the hut, and immobilized to attach the video system and data logger. Seals were immobilized with an intramuscular injection of ketamine hydrochloride (3 mg/kg: Fort Dodge Laboratories, Fort Dodge, IO) and diazepam (0.1 mg/kg Steris Corporation, Phoenix, AZ). After cleaning the fur in the middorsal area of the seal with acetone, a sheet of neoprene rubber (0.5 cm thick and 30 cm in diameter) was glued to the fur along the dorsal midline above the shoulders with neoprene rubber cement. The video housing rested in a molded, noncompressible foam cradle that was attached to the neoprene rubber and positioned overlooking the seal's head. The compass housing and accelerometer were glued to fur in a similar fashion. Once mounted on the animal, the entire video system and data logger were neutrally buoyant. Seals were allowed 18 hours to recover from anesthesia before being released into the breathing hole. All procedures were in accordance with Animal Use Protocols of Texas A&M University. The animals performed voluntary dives from an isolated ice hole located 10 km west of McMurdo Station and 200 m east of the McMurdo Ice Shelf (77.86°S, 166.22°E). This area of McMurdo Sound is about 600 m deep. A research hut was positioned over a 1.2-m-diameter hole drilled through 3-m-thick sea ice. Each instrumented seal was released into the ice hole beneath the hut for 4 to 5 days. The hole was located sufficiently far from other cracks so that the animals could not escape. The seals began performing dives similar to those of free-ranging seals within 24 hours of release (2). The main housing of the video system was removed from the seal every 6 to 12 hours while the animal rested in the ice hole, and the data were downloaded to a computer database. The batteries and videotape were replaced, and the main housing was reattached to the seal. Three-dimensional dive paths were computed from depth, compass bearing, and swim speed after correcting for ocean current direction and speed with standard "dead reckoning" methods (15). We assumed that the current speed and direction were uniform over the duration and depth of each dive. The three-dimensional dive paths were plotted with Systat (SPSS, Chicago, IL).
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39. We thank L Collier for assistance in the field and G. Davis, M. Davis, K. Klay, and J. Sheldon for analyzing the videotapes for seal behavior. W. Evans and J. Thomas provided guidance on the analysis and identification of seal vocalizations. P. Canton assisted with manuscript preparation. We thank the many people with Antarctic Support Associates who provided logistical support in the field. This study was supported by the NSF Division of Polar Programs (grant OPP9614857) and the National Undersea Research Program (grant UAF98-0040). This study is dedicated to G. L. Kooyman on his 65th birthday.