Population biology and ecology of marine mammals, population estimation, predator/prey relations, carnivora, coastal marine ecology, marine conservation.
Professional Experience
2013 - Present Research Wildlife Biologist Emeritus, USGS, Alaska Science Center, Anchorage, Alaska
1990 - 2013 Research Wildlife Biologist, USGS, Alaska Science Center, Anchorage, Alaska
1989 - 1990 Wildlife Biologist, U.S. Fish & Wildlife Service, Koyukuk Wildlife Refuge, Galena, AK
1986 - 1989 Fish and Wildlife Biologist, National Ecology Research Center, Santa Cruz, CA
Education and Certifications
M.S. 1986 California Polytechnical University, San Luis Obispo, CA Biology
B.S. 1975 California State University, Long Beach, CA Wildlife Biology
Affiliations and Memberships*
Society for Conservation Biology
American Society of Mammalogy
Society for Marine Mammalogy
The Wildlife Society
Science and Products
Filter Total Items: 133
Population genetic studies of the sea otter (Enhydra lutris): A review and interpretation of available data
Current information about the utility of genetic markers for estimating population structuring in sea otters (Enhydra lutris) is reviewed. Analyses of spatial population structuring with biochemical and molecular genetic markers are discussed in the context of the species' ecology and history of exploitation. Studies that have used a diversity of genetic markers including allozymes, mitochondrial
Comparative demography of sea otter populations
Population trends are poorly documented and demographic information is typically lacking for many carnivorous mammals. The sea otter (Enhydru lutris) has a well known history of decline and recovery, and while many other species have declined as precipitously, few have recovered so spectacularly. Generally speaking, northern populations (remnants within the range of E. l. lutris and E. l. kenyoni)
Sea otter predation on Dungeness crabs in Glacier Bay, Alaska
Sea otter (Enhydra lutris) populations are increasing and expanding into areas of Southeast Alaska where Dungeness crabs (Cancer magister) are commercially harvested. Although sea otters are known to feed on Dungeness crabs, their effects upon crab demography have not been quantified. We censused Dungeness crabs in adjacent areas within Glacier Bay National Park and Preserve with and without sea o
Mitochondrial-DNA variation among subspecies and populations of sea otters (Enhydra lutris)
We used restriction-enzyme analysis of polymerase-chain reaction-amplified, mitochondrial DNA (mtDNA) to assess genetic differentiation of subspecies and populations of sea otters, Enhydra lutris, throughout the range of the species. There were several haplotypes of mtDNA in each subspecies and geographically separate populations. MtDNA sequence divergence of haplotypes of sea otters was 0.0004–0.
Sea otters in the northern Pacific Ocean
About 250 years ago sea otters (Enhydra lutris) were distributed continuously from central Baja California, north and west along the Pacific Rim to Machatka Peninsula in Russia, and south along the Kuril Island to northern Japan (Kenyon 1969; Fig. 1a). Several hundred thousand sea otters may have occurred in the north Pacific region when commercial hunting began in the 18th century (Riedman and Es
Detection of sea otters in boat-based surveys of Prince William Sound, Alaska
Boat-based surveys have been commonly used to monitor sea otter populations, but there has been little quantitative work to evaluate detection biases that may affect these surveys. We used ground-based observers to investigate sea otter detection probabilities in a boat-based survey of Prince William Sound, Alaska. We estimated that 30% of the otters present on surveyed transects were not detected
California sea otters
Information on the size, distribution, and productivity of the California sea otter population is broadly relevant to two federally mandated goals: removing the population’s listing as threatened under the Endangered Species Act (ESA) and obtaining an “optimal sustainable population” under the Marine Mammal Protection Act. Except for the population in central California, sea otters (Enhydra lutri
An overview of sea otter studies
The Exxron Valdez oil spill (EVOS) on 24 March 1989 threatened extensive areas of prime sea otter (Enhydra lutris) habitat along the coasts of south-central Alaska. The spill occurred in northeastern Prince William Sound (PWS), and oil moved rapidly south and west through PWS into the Gulf of Alaska. Much of the coastline of western PWS was heavily oiled, and the slick eventually spread as far sou
Sea otter foraging behavior and hydrocarbon levels in prey
Following the Exxon Valdez oil spill (EVOS), Prudhoe Bay crude oil from the vessel spread on the sea surface and covered coastal shores from western Prince William Sound (PWS) to the Alaska Peninsula. In PWS alone. acute mortality of sca otters at the time of the spill was estimated to be greater than 2000 (Doroff et al. 1993; Garrott et al. 1993).Shoreline oiling was observed on approximately 24%
An intersection model for estimating sea otter mortality along the Kenai Peninsula
We developed an intersection model to integrate parameters estimated from three distinct data sets that resulted from the Exxon Valdez oil spill: (1) the distribution,
amount, and movements of spilled oil; (2) the distribution and abundance of sea otters along the Kenai Peninsula; and (3) the estimates of site-specific sea otter
mortality relative to oil exposure from otters captured for rehabil
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Filter Total Items: 133
Population genetic studies of the sea otter (Enhydra lutris): A review and interpretation of available data
Current information about the utility of genetic markers for estimating population structuring in sea otters (Enhydra lutris) is reviewed. Analyses of spatial population structuring with biochemical and molecular genetic markers are discussed in the context of the species' ecology and history of exploitation. Studies that have used a diversity of genetic markers including allozymes, mitochondrialComparative demography of sea otter populations
Population trends are poorly documented and demographic information is typically lacking for many carnivorous mammals. The sea otter (Enhydru lutris) has a well known history of decline and recovery, and while many other species have declined as precipitously, few have recovered so spectacularly. Generally speaking, northern populations (remnants within the range of E. l. lutris and E. l. kenyoni)Sea otter predation on Dungeness crabs in Glacier Bay, Alaska
Sea otter (Enhydra lutris) populations are increasing and expanding into areas of Southeast Alaska where Dungeness crabs (Cancer magister) are commercially harvested. Although sea otters are known to feed on Dungeness crabs, their effects upon crab demography have not been quantified. We censused Dungeness crabs in adjacent areas within Glacier Bay National Park and Preserve with and without sea oMitochondrial-DNA variation among subspecies and populations of sea otters (Enhydra lutris)
We used restriction-enzyme analysis of polymerase-chain reaction-amplified, mitochondrial DNA (mtDNA) to assess genetic differentiation of subspecies and populations of sea otters, Enhydra lutris, throughout the range of the species. There were several haplotypes of mtDNA in each subspecies and geographically separate populations. MtDNA sequence divergence of haplotypes of sea otters was 0.0004–0.Sea otters in the northern Pacific Ocean
About 250 years ago sea otters (Enhydra lutris) were distributed continuously from central Baja California, north and west along the Pacific Rim to Machatka Peninsula in Russia, and south along the Kuril Island to northern Japan (Kenyon 1969; Fig. 1a). Several hundred thousand sea otters may have occurred in the north Pacific region when commercial hunting began in the 18th century (Riedman and EsDetection of sea otters in boat-based surveys of Prince William Sound, Alaska
Boat-based surveys have been commonly used to monitor sea otter populations, but there has been little quantitative work to evaluate detection biases that may affect these surveys. We used ground-based observers to investigate sea otter detection probabilities in a boat-based survey of Prince William Sound, Alaska. We estimated that 30% of the otters present on surveyed transects were not detectedCalifornia sea otters
Information on the size, distribution, and productivity of the California sea otter population is broadly relevant to two federally mandated goals: removing the population’s listing as threatened under the Endangered Species Act (ESA) and obtaining an “optimal sustainable population” under the Marine Mammal Protection Act. Except for the population in central California, sea otters (Enhydra lutriAn overview of sea otter studies
The Exxron Valdez oil spill (EVOS) on 24 March 1989 threatened extensive areas of prime sea otter (Enhydra lutris) habitat along the coasts of south-central Alaska. The spill occurred in northeastern Prince William Sound (PWS), and oil moved rapidly south and west through PWS into the Gulf of Alaska. Much of the coastline of western PWS was heavily oiled, and the slick eventually spread as far souSea otter foraging behavior and hydrocarbon levels in prey
Following the Exxon Valdez oil spill (EVOS), Prudhoe Bay crude oil from the vessel spread on the sea surface and covered coastal shores from western Prince William Sound (PWS) to the Alaska Peninsula. In PWS alone. acute mortality of sca otters at the time of the spill was estimated to be greater than 2000 (Doroff et al. 1993; Garrott et al. 1993).Shoreline oiling was observed on approximately 24%An intersection model for estimating sea otter mortality along the Kenai Peninsula
We developed an intersection model to integrate parameters estimated from three distinct data sets that resulted from the Exxon Valdez oil spill: (1) the distribution, amount, and movements of spilled oil; (2) the distribution and abundance of sea otters along the Kenai Peninsula; and (3) the estimates of site-specific sea otter mortality relative to oil exposure from otters captured for rehabil
*Disclaimer: Listing outside positions with professional scientific organizations on this Staff Profile are for informational purposes only and do not constitute an endorsement of those professional scientific organizations or their activities by the USGS, Department of the Interior, or U.S. Government