Second Workshop Held on Ways to Reduce Shark Predation on Hawaiian Monk Seal Pups

Galapagos sharks pose a threat to Hawaiian monk seal pups at French Frigate Shoals. However, sharks are also valued components of the ecosystem, so reducing monk seal mortality by selectively removing problematic sharks poses a "conservation condundrum".

Predation by sharks on juveniles of the endangered Hawaiian monk seal has been identified as a critical factor in the seal's survival at French Frigate Shoals in the Northwestern Hawaiian Islands. To mitigate mortality caused by sharks, NOAA Fisheries has considered various strategies including selective removal of sharks and shark deterrents. In November, 2008, the second Workshop on Shark Predation of the Hawaiian Monk Seal was held to exchange ideas and views from different science and management perspectives about the predation problem and seek a logical course of action for research and mitigation.

Convened by the PIFSC Protected Species Division (PSD), the meeting was attended by over 35 people, including staff of the Papahānamokuākea Marine National Monument, the US Fish and Wildlife Service, State of Hawaii Department Land and Natural Resources, Marine Mammal Commission (MMC), Hawaiian Monk Seal Recovery Team, and the NOAA Pacific Islands Regional Office. Scientists from PIFSC Hawaii Monk Seal Research Program (HMSRP), Hawaii Institute of Marine Biology (HIMB, University of Hawaii) and Florida State University presented their perspectives on the "conservation conundrum" that arises when protecting the endangered monk seal may involve deliberate removals of another valuable ecosystem component, the Galapagos shark. HMSRP staff presented results of their 2008 shark deterrent pilot study, HIMB scientists discussed their 2008 shark tagging program, and research ideas for the 2009 HMSRP field season were discussed.

Workshop participants evaluated past research and prioritized suggestions for upcoming field seasons. In reviewing the history of research by HMSRP and HIMB, participants agreed on some definitive statements about the predation problem and knowledge gaps that need to be filled. Research and analysis on the behavior of monk seals and sharks, their movement patterns, and spatio-temporal overlap of the species is necessary; however, such information on sharks may not be available until 2010, after a greater number have been tagged within the atoll.

Participants encouraged design of improved deterrents, to be tested a priori, and removal of sharks displaying predatory behavior. Thus, a mitigation strategy for 2009 may need to simultaneously incorporate both non-lethal techniques and traditional lethal means of limiting shark access to monk seal pups. After more is learned about seal and shark behavior, it may be advisable to pursue other avenues of mitigation including creating physical or electro-magnetic barriers to restrict seal and shark movement, translocating seal mother-pup pairs to safer locations, creating additional seal pupping habitat by restoring former pupping sites that have been submerged, and expanding the removal of Galapagos sharks. It was suggested that a cost-benefit analysis of these ideas be undertaken to establish options for future field seasons.

For more information contact: Bud Antonelis