Progress 07/01/02 to 08/30/04
Outputs
The Recovery of the Southern Sea Otter project (contract # P0275004), funded by USFWS, has allowed and fostered the development of a collaboration between the California Department of Fish and Game and the U.C. Davis Wildlife Health Center aimed at assisting the recovery of a Threatened marine mammal species. U.C. Davis faculty, staff, graduate and veterinary students have assisted with; 1) the field capture, anesthesia, tagging, sampling and release of wild southern sea otters; 2) postmortem examination of dead sea otters; 3) laboratory and diagnostic functions in support of health investigations; and 4) collaboration on a number of specific disease research projects. Specifically : During the summer/fall of 2002, 2003 and 2004 U.C. Davis Veterinary School students, visiting externs and Wildlife Health Center staff assisted with the capture and anesthesia of nearly 100 sea otters which were anesthetized and surgically implanted with temperature sensitive VHF radios and
time depth recorders. These devices have allowed ecologists to determine in much greater detail than ever before the needs of activities of sea otters Graduate students have assisted CDFG with determining what sorts of diseases sea otters are exposed to and where they have significant exposure to contaminants. Veterinary students, seniors on rotations and faculty have assisted CDFGs veterinary pathologist with postmortem examinations and with examination of histopathology slides. UC Davis faculty and staff have assisted with investigations of bacterial infections of sea otters, normal and pathogenic bacterial flora and the development of antibiotic resistance in sea otters. Wildlife Health Center Graduate students have assisted CDFG in determining the accuracy of aerial counting methods used for sea otter population counts. Assistance was provided on investigations of the effects of the red tide toxin domoic acid on sea otters and its role a cardiomyopathy syndrome. A UC Davis School
of Veterinary Medicine doctoral student was central to determining the importance of protozoal parasites as mortality factors in sea otters and in determining the role of fresh water run off and bivalves as sources of infections for sea otters. This program is being continued under other funding sources and has lead to other collaborations such as one currently underway to look at the role of persistent organic pollutants in the health of sea otters.
Impacts
The Recovery of the Southern Sea Otter project helped show that this species is an excellent sentinel of pathogen and chemical pollution and helped improve and advance larger collaborative programs that assist State and Federal agencies in recovery of this species. The comprehensive and collaborative program it has helped establish is a model for endangered species recovery and for interfacing traditional ecology with biomedical and epidemiologic approaches.
Publications
- Miller, M.A.,I.A. Gardner, D. Paradies, K. Worcester, D. Jessup, E. Dodd, M. Harris, J. Ames, A. Packham, P.A. Conrad 2002. Coastal freshwater runoff is a risk factor for Toxoplasma gondii infection of southern sea otters (Enhydra lutris nereis). International Jour. Parasit. 32:997-1006.
- Miller, M.A., I.A. Gardner, A. Packham, J.K. Mazet, K.D. Hanni, D. Jessup, J. Estes, R. Jameson, E. Dodd, B.C. Barr, L.J. Lowenstine, F.M. Gulland, P.A. Conrad. 2002. Evaluation of an indirect fluorescent antibody test (IFAT) for demonstration of antibodies to Toxoplasma gondii in the sea otter (Enhydra lutris). J. Parasit. 88:594-599.
- Jessup, D.A. 2003. Good medicine for conservation: Comments, corrections and connections. Conservation Biology, 17(3) 1-4.
- Hanni, K.D., J.A.K. Mazet, F.M.D. Gulland, J. Estes, M. Staedler, M.J. Murray, D.A. Jessup. 2003. Clinical pathological values and assessment of pathogen exposure in southern and Alaskan sea otters. J. Wildl. Dis. 39(4): 837-850.
- Kreuder, C., M. Miller, D. Jessup, L. Lowenstine M.D. Harris, J. Ames, T.E. Carpenter, P.A. Conrad, J.K. Mazet. 2003. Patterns of mortality in the southern sea otter (Enhydra lutris) from 1998-2001. J Wildl. Dis. 39(3): 495-509.
- Stavely C.M., K.B. Register, M.A. Miller, S.L. Brockmeier, D.A. Jessup, S. Jang. 2003. Molecular and antigenic characterization of Bordetella bronchiseptica isolated from a wild southern sea otter (Enhydra lutris nereis) with severe suppurative bronchopneumonia. Journal of Veterinary Diagnostic Investigation. 15(6): 570-574.
- Jessup, D.A., M. Miller, J. Ames, M. Harris, P. Conrad C. Kreuder and J.A.K. Mazet. 2004. The southern sea otter (Enhydra lutris nereis) as a sentinel of marine ecosystem health. Ecohealth. 1(3):239-245.
- Jessup D.A., M.A. Miller, M.Harris, B. Hatfield, J.A. Estes. 2004. The 2003 southern sea otter (Enhydra lutris nereis) unusual mortality event: A preliminary report to NOAA and USFWS.
- Miller M.A., M.E. Griggs, C. Kreuder, E.R. James, A.C. Melli, P.R. Crosbie, D.A. Jessup, J.C. Boothroyd, D. Brownstein, and P.A. Conrad. 2004. An unusual genotype of Toxoplasma gondii is common in California sea otters (Enhydra lutris nereis) and is associated with mortality. Int. Jour. Parasit. 34:(275-284).
- Hanni, K.D., M. Staedler, J. Estes, F.M.D. Gulland, D.A. Jessup, J.A.K. Mazet. 2004. Survival in juvenile rehabilitated and free-ranging southern sea otters, Enhydra lutris nereis. Behavior. In press.
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Progress 01/01/03 to 12/31/03
Outputs
The southern sea otter (Enhydra lutris nereis) is listed as 'threatened' under the Endangered Species Act. Once thought to be extinct, the remnant Big Sur populations of this subspecies grew steadily during the early half of the 20th century and expanded their range to both the north and south. The recovery appeared to falter during the late 1970's, presumably due to bycatch in the gill net fishery. But, in the early 1980's after government restrictions moved net fisheries away from most sea otter habitats, the recovery continued. Recovery faltered again in 1995 with an approximately 12% decline in the ensuing four years. The overall trend of the California sea otter population since 1995 has been a decline, and as of today there are 9% fewer otters than there were in 1995. The sea otter is a 'keystone species,' one which strongly influences the abundance and diversity of the other species within its kelp forest ecosystem, primarily by its effect on sea urchins which
eat the kelp stipe and holdfast. Sea otters are also a very charismatic species; their antics and feeding and maternal behaviors are very attractive to people. Protection of sea otters may have the classic 'umbrella species' effect, with a popular species providing protection and habitat for less noticeable, but nonetheless biologically important species. The recent southern sea otter decline has been of concern to conservationists and indeed recovery is not likely in the foreseeable future. Higher adult mortality rather than depressed recruitment appears to be a component of the decline. A good deal of debate has centered on the role of infectious diseases and parasites, exposure to contaminants, nutrition and prey availability, net and pot fishery interactions and other sources of mortality. Our studies have focused on evaluating the current survey methods for sea otters to insure proper evaluation of the population size, accurately determining the current causes of death in the
population, and responding to and investigating recent spikes in mortality.
Impacts
Adult sea otter mortality, the contribution of emerging diseases, and population decline and/or failure of recovery are important conservation issues. Beneath these lay the issues of the general health of Californias near shore marine ecosystems and the potential role of sea otters as sentinels of marine ecosystem health.
Publications
- Kreuder, C., M. Miller, D. Jessup, L. Lowenstine, M. Harris, J. Ames, T. Carpenter, P. Conrad, J. Mazet. 2003. Patterns of mortality in southern sea otters (Enhydra lutris nereis) from 1998-2001. Journal of Wildlife Diseases 39:495-509.
- Kreuder-Johnson, C., W.O. Johnson, J.A. Estes, M.D. Harris, J.A. Ames, T.E. Carpenter, and J.A.K. Mazet. 2004. Variability in detection probability of sea otters: a model for evaluating the relative efficacy of survey methods. Ecology (in preparation).
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