[MARMAM] New evidence of Pacific sleeper shark predation on Steller sea lions in Alaska

Horning, Markus Markus.Horning at oregonstate.edu
Thu Oct 2 11:02:53 PDT 2014


Dear Colleagues,



we are pleased to announce a new publication in the journal Fishery Bulletin:

Horning M, Mellish JE. 2014. In cold blood: evidence of Pacific sleeper shark (Somniosus pacificus) predation on Steller sea lions (Eumetopias jubatus) in the Gulf of Alaska. Fishery Bulletin 112:297-310.
doi:10.7755/FB.112.4.6



This publication is available for open download and distribution via Fishery Bulletin:
http://fishbull.noaa.gov/1124/horning.pdf



Abstract—Temperature data received post mortem in 2008–13 from 15 of 36 juvenile Steller sea lions (Eumetopias jubatus) that had been surgically implanted in 2005–11 with dual life history transmitters (LHX tags) indicated that all 15 animals died by predation. In 3 of those 15 cases, at least 1 of the 2 LHX tags was ingested by a cold-blooded predator, and those tags recorded, immediately after the sea lion’s death, temperatures that corresponded to deepwater values. These tags were regurgitated or passed 5–11 days later by predators. Once they sensed light and air, the tags commenced transmissions as they floated at the ocean surface, reporting temperatures that corresponded to regional sea-surface estimates. The circumstances related to the tag in a fourth case were ambiguous. In the remaining 11 cases, tags sensed light and air immediately after the sea lion’s death and reported temperatures that corresponded to estimates of regional sea-surface temperatures. In these 11 cases, circumstances did not allow for inferences on the species of predator. Among reported poikilotherm predators of Steller sea lions, only the Pacific sleeper shark (Somniosus pacificus) is known to have body core temperatures that are near ambient. The data from this study indicate that Pacific sleeper sharks need to be considered as a possible source of mortality of juvenile Steller sea lions in the region of the Gulf of Alaska.





Best Regards,

Markus Horning



__________________________________________________
Dr. Markus Horning, Pinniped Ecology Applied Research Lab
Marine Mammal Institute, Oregon State University
2030 SE Marine Science Drive, Newport, OR 97365, USA
Tel. 541.867.0202  Fax 541.867.0128
markus.horning at oregonstate.edu<mailto:markus.horning at oregonstate.edu>
http://mmi.oregonstate.edu/pearl/
www.sealtag.org<http://www.sealtag.org/>


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