Acoustic Transmitter-Integrated Remote Sedation for Improved Recovery of Wild Pinnipeds
IAAAM 2014
Greg F. Frankfurter1; Shawn P. Johnson1*
1The Marine Mammal Center, Sausalito, CA, USA


Wild pinnipeds often require capture for disentanglement, rehabilitation, or research studies. Capture of these animals has been accomplished on land or in water with a combination of nets, divers, or traps.1,2 More recently, the use of remote sedation delivered by dart has been used for captures.3,4 This technique can improve targeting of specific individuals and easier handling of larger animals such as adult California sea lions (Zalophus californianus).3,5 Recent studies have shown that some animals that are sedated on land and subsequently reenter the water continue to resurface to breathe, even in a sedated state.4 However, there is still risk of drowning due to entrapment, or of injury from other animals or boats in the area. Furthermore, it can be difficult to relocate sedated animals, as they may swim long distances or be located within a group of conspecifics. To aid in tracking and recovery of wild pinnipeds, we have developed a remote sedation dart with an integrated acoustic transmitter that allows for tracking of a darted animal up to 1 kilometer away. Using a portable, directional hydrophone we have successfully tracked darted animals by boat, which allows for approach and recovery once the animal is sedated. We selected the transmitter based on size, weight, and frequency to allow for efficient delivery, while taking care to mitigate further risk to the animal. The selected frequency is outside the hearing range of tested pinnipeds species in air or water.6,7 We hypothesize that acoustic-transmitter darts will increase capture success while decreasing negative outcomes in remotely sedated animals. Early results support this hypothesis. This technique can be applied to targeted capture of many pinnipeds species for research, disentanglement or rescue of pinnipeds.

* Presenting author

Literature Cited

1.  McAllister DC, Calkins DG, Pitcher KW. Underwater capture of juvenile Steller sea lions with scuba: a narrated video presentation. Cold water diving for science. In: Proceedings of the 21st Annual Scientific Diving Symposium, American Academy of Underwater Sciences [AK-SG-01-06]. University of Alaska Sea Grant, Fairbanks, AK, USA. 2001:53–56.

2.  Wright BE, Tennis MJ, Brown RF. Movements of male California sea lions captured in the Columbia River. Northwest Science. 2010;84:60–72.

3.  Geschke K, Chilvers BL. Managing big boys: a case study on remote anaesthesia and satellite tracking of adult male New Zealand sea lions (Phocarctos hookeri). Wildlife Research. 2010;36:666–674.

4.  Beckmen K, Fadely BS, Lander ME, McAllister D, Melin SR, Rea LD, Rehberg MJ, Snedgen G, et al. Remotely-delivered chemical immobilization of adult female Steller sea lions (Eumetopias jubatus) for physiological sampling and satellite telemetry attachment. In: Mazzaro LM, ed. IAAAM. Las Vegas, NV; 2011.

5.  Spelman LH. Reversible anesthesia of captive California sea lions (Zalophus californianus) with medetomidine, midazolam, butorphanol, and isoflurane. Journal of Zoo and Wildlife Medicine. 2004;35:65–69.

6.  Southall BL, Schusterman RJ, Kastak D, Kastak CR. Reliability of underwater hearing thresholds in pinnipeds. Acoustics Research Letters Online. 2005;6:243.

7.  Mulsow J, Finneran JJ, Houser DS. California sea lion (Zalophus californianus) aerial hearing sensitivity measured using auditory steady-state response and psychophysical methods. Journal of the Acoustical Society of America. 2011;129:2298.


Speaker Information
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Shawn P. Johnson
The Marine Mammal Center
Sausalito, CA, USA

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