Figure 1: MMTD Scientists deploying a satellite LIMPET tag on a type-B (“pack-ice killer whale”) in waters off the Antarctic Peninsula. Photo credit to Ken Carlson.
Recent advances in satellite tag electronics have enabled the development of small transmitter tags that can be remotely deployed externally on the dorsal fins of killer whales, using crossbows or pneumatic rifles, without the need for physical capture and restraint (Figure 1). Specifically, SWFSC/MMTD has been involved in the development and application of Low Impact Minimally Percutaneous External Transmitter (LIMPET) tags (Andrews et al. 2008; Figure 2) since 2005, and we have now deployed more than 25 of these 40g tags on Antarctic killer whales. These have been deployed on types A, B (large and small form) and C killer whales in the Antarctic Peninsula and Ross Sea regions, with tag longevity of more than 100 days and tracked individual movements of more than 9000 km. The small size of these LIMPET tags allows them to be deployed high on the dorsal fin of the whale, in comparison to conventional implant tags. This high placement and external mounting of the tags enables relatively frequent transmissions to Argos satellite receivers (www.argos-system.org), resulting is a relatively high resolution tracks of estimated locations (Figure 2). These data are being used to study ranging patterns, migration and foraging behaviors, with comparisons between types and enabling inference about their ecological impacts. Additionally, near real-time tag locations are being used to direct field operations, increasing our understanding of killer whale prey preferences through more regular observations of predation behavior (Pitman and Durban, in press).
Figure 2: Left: A satellite LIMPET tag deployed on the dorsal fin of an adult female Type A killer whale (Pitman and Ensor, 2003). Right: More than 10,000 locations calculated from transmissions by LIMPET satellite tags deployed on Type A and Type B killer whales around the Antarctic Peninsula, 2009-2011. Transmissions were received and processed for location calculations by the Argos Satellite System (www. argos-system.org)
Figure 3: Example of the rapid migration of a type B killer whale from the Antarctic Peninsula to the edge of the tropics and back, in just 42 days. Durban and Pitman 2011
Andrews, R. D. et al. 2008. Satellite tracking reveals distinct movement patterns for Type B and Type C killer whales in the southern Ross Sea, Antarctica. Polar Biology 31: 1461-1468.
Pitman RL, Ensor P. 2003. Three different forms of killer whales in Antarctic waters. Journal of Cetacean Research and Management 5:131–139.
Pitman, R.L and Durban. J.W. Cooperative hunting behavior, prey selectivity and prey handling by pack ice killer whales (Orcinus orca), type B, in Antarctic Peninsula waters. Marine Mammal Science, in press.