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Project Information

Title: River Otter Component of the Oiled Mussel Bed Study

Project Year and Number: 1992: R103-3

Other Fiscal Years and Numbers for this Project: None

Principal Investigator (PI): James Faro

Assisting Personnel: Gail Irvine

Research Location: All Spill Affected Areas

Restoration Category: Damage Assessment

Injured Resources Addressed: Mussels , River Otters

Abstract: River otters (Lutra canadensis) in Prince William Sound have been impacted as a result of the Exxon Valdez oil spill (Faro et al. 1991 status report on river otters). Mussels (Mytilus spp.) have been recovered from scats of river otters (unpublished data) and mussels reported in the diet of river otters (Solf, 1989). In 1991 the highest oil concentrations found in Prince William Sound animals or sediments were from mussels and substrates underlying oiled mussel beds (Babcock, 1991 status report on oiled mussel beds). River otters are a species with a documented sensitivity to a number of aquatic pollutants (Table 1) so a connection between contaminated mussels and documented sub-lethal impacts is reasonable.

River otters utilize land for many of their life functions but feed exclusively from aquatic habitats, placing them directly at risk to remaining Exxon Valdez oil. Although some feeding may occur in fresh water, in Prince William Sound (Faro et al. 1991 status report on river otters) and Southeast Alaska (Larsen 1983, Woolington 1984), marine populations are dependent on a diet of fish, gastropods, and bivalves. Foraging occurs in shallow water at depths typically occupied by mussel beds. The river otter's sensitivity to pollutants and their high position on the food chain are factors that allow them to serve as an indicator species for the presence of hydrocarbon toxicity in the ecosystem. Unlike other species that may directly or secondarily acquire hydrocarbons from mussels, river otters have smaller home ranges and remain year round in close proximity to contaminated mussel beds.

This study will use nonlethal methods to obtain data on the health of river otters and their diet. River otters will be live captured during the spring breeding season when they are most vulnerable to capture. Trapping will occur in oiled habitat in close proximity to mussel beds providing data for interpretation with other information from the oiled mussel bed study. The home range of captured river otters should include one or more contaminated mussel bed. For control data, some animals will also be caught in an area with mussel beds present but not exposed to oil. Captured animals will be briefly immobilized, measured and a blood sample drawn. Procedures used will be approved by the Animal Care and Use committee under the authority of the University of Alaska Fairbanks. River otters will be released in the vicinity of their capture site when recovered from the immobilizing agent. These techniques were employed in 1991 with no known loss of animals.

Blood samples will be analyzed from components that reflect physiological stress in individual animals. These data will be compared to control data as well as to data obtained in 1990 and 1991. Weights and measurements will be compared between "control" and "oiled" data and between years.

River otter scats will be collected in the two intensive study areas (Esther Passage control area and Herring Bay/Lewis Bay oiled area) established for the impact assessment study. These samples will be examined to identify the "species" that are present. Data analysis will compare the 1992 diet in the two study areas and test for differences or similarities to dietary information from 1989 and 1990 on oiled and unoiled areas.

When gathering scat materials from the intensive study areas, information on the current use of latrine sites by otters will be recorded. Site use data for 1991 and 1992 in the 2 areas will be compared.


Geographic Regions Prince William Sound
Fields of Expertise Contaminants/Toxicology

Proposal: PDF Not Available

Funding Recommendations: View

Funding Detail For: 1992

Quarterly Project Tasks For: 1992

Annual Report: 1992: Not Applicable

Final Report: Not Available - For Current Status Please Contact Us

Publications from this Project: None Available