Northwest Fisheries Science Center

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Document Type: Technical Memorandum
Center: NWFSC
Document ID: 8554
Title: Wild Animal Mortality Investigation: Southern Resident Killer Whale L-112 Final Report
Author/Editor: Deborah A. Duffield, J. K. Gaydos, S. Raverty, Kristin Wilkinson, B. Norberg, L. Barre, M. B. Hanson, Peggy Foreman, Amy Traxler, Dyanna M. Lambourn, Jessie Huggins, J. Calambokidis, Tori McKlveen, Sophie Dennison, Hans Brubaker
Publication Year: 2016
Tech Memo Number: NMFS-NWFSC-133
Pages: 122

On 11 February 2012, a 3.75-m juvenile female Southern Resident killer whale (SRKW, Orcinus orca), identified as L-112, stranded just north of the town of Long Beach, Washington. A full necropsy was conducted by biologists and volunteers from the Northwest Marine Mammal Stranding Network (Network). This report reviews the data from the necropsy, histopathology, and computed tomography (CT) examinations, as well as results from ancillary diagnostic tests. Based on findings from the gross examination of the carcass and the absence of conclusive histopathology or ancillary test results, the investigative team identified blunt force trauma as the primary consideration for the acute death of the animal. Available information on environmental data and human activities was compiled and evaluated to assess possible contributions to the loss of the animal.    The Network investigators examined the circumstances of the stranding (single individual), environmental evidence, and information about human activities, and ruled out several possible sources of the traumatic injury, including sonar or military training activity, and in-water construction. There were no reports of fishery interactions or vessel strikes coincident with the stranding. In conclusion, blunt trauma to the head and neck is the prime consideration for the cause of mortality, however, despite extensive diagnostic evaluation, the cause of the head and neck injuries could not be determined.  L-112 was hit, struck, or rammed in the head or neck, but the animate or inanimate source of the blow could not be determined based on postmortem examination.

Theme: Recovery and rebuilding of marine and coastal species
Foci: Describe the relationships between human activities and species recovery, rebuilding and sustainability.
Official Citation:

Duffield, D., J. K. Gaydos, S. Raverty, K. Wilkinson, B. Norberg, L. Barre, M. B. Hanson, P. Foreman, A. Traxler, D. M. Lambourn, J. Huggins, J. Calambokidis, T. McKlveen, S. Dennison, and H. Brubaker. 2016. Wild animal mortality investigation: Southern Resident killer whale L-112 final report. U.S. Dept. Commer., NOAA Tech. Memo. NMFS-NWFSC-133, 122 p.