Sea Otter, Enhydra lutris, mortalities in California, 1968 through 1993

Pattison, Christine A. and Harris, Michael D. and Wendell, Frederick E. (1997) Sea Otter, Enhydra lutris, mortalities in California, 1968 through 1993. Morro Park, CA, California Department of Fish and Game Marine Resources Divison, (Marine Resources Division Administrative Report, 97-5)

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Abstract

Sea otter, Enhydra lutris, mortality in California and the relative contribution from specific causes was assessed for the 26 years from 1968 through 1993. There were 2,082 dead sea otters recorded from Tomales Bay (Marin County) south to Bluff Cove (Los Angeles County) during that period. The average number of carcasses recorded was 80 per year and seven per month. Sex was identified in 87% (n=1,819) of the cases and was composed of 47% female and 53% male. A relative age was assigned to 97% (n=2,017) of the cases and was composed of 28% pup, 18% subadult and 54% adult. Specific causes of death were determined for 26% (n=55 1) of the cases. The majority of these (n=381) were considered to be due to natural causes and included the following specific causes: shark bitten (n=78), probably shark bitten (n=106), other natural causes (n=140), and mating wounds (n=57). The remaining (n=170) were considered to be due to human-related causes and included the following specific causes: shot (n=72), probably shot (n=8), net drowned (n=76), and other human causes (n=14). The large proportion of carcasses without an identified specific cause of death prompted a more detailed necropsy effort in 1992 and 1993. During that period, 78 of the 232 recovered carcasses were examined by veterinary pathologists and a specific cause of death was determined in 76% (n=59) of the cases. This effort identified a wide range of specific causes of death that otherwise may have been categorized as "unknown without trauma". Considering the variety of diseases diagnosed in this expanded necropsy program, it would be prudent to continue this level of examination to refine our knowledge of sea otter pathology. (48pp.)

Item Type: Monograph or Serial Issue
Title: Sea Otter, Enhydra lutris, mortalities in California, 1968 through 1993
Personal Creator/Author:
CreatorsEmail
Pattison, Christine A.
Harris, Michael D.
Wendell, Frederick E.
Series Name: Marine Resources Division Administrative Report
Number: 97-5
Date: 1997
Publisher: California Department of Fish and Game Marine Resources Divison
Place of Publication: Morro Park, CA
Issuing Agency: California Department of Fish and Game
Uncontrolled Keywords: Sea otter; Enhydra lutris; California
Subjects: Health
Fisheries
Biology
Item ID: 393
Depositing User: Joan Parker
Date Deposited: 26 Oct 2007 13:07
Last Modified: 29 Sep 2011 22:07
URI: http://aquaticcommons.org/id/eprint/393

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