Population Biology and Behavior of Sea Otters

Science Center Objects

WERC's sea otter researchers are developing and utilizing a variety of methodological and analytical tools to understand the causes of biological and ecological trends in sea otter populations, and to predict the ecological consequences of management practices on these populations and their ecosystems.

Veterinarians examine a sedated sea otter (WERC)

Veterinarians examine a sedated sea otter. (Credit: Ben Young Landis, USGS WERC. Public domain.)

Relevance to USGS Missions:

This research project has direct relevance for the Wildlife program of the Ecosystems Mission Area (ECO), which works with others to provide the scientific understanding and technologies needed to support the sound management and conservation of our Nation's biological resources. Specifically, we are developing and utilizing a variety of methodological and analytical tools to understand the causes of biological and ecological trends in sea otter populations, and to predict the ecological consequences of management practices on these populations and their ecosystems. To accomplish this, we have forged partnerships with scientific collaborators from the Federal, State and private sector, to produce high-quality scientific information on the role of various stressors in limiting sea otter abundance, and to ensure this information's relevance and application to current conservation problems.

Sea otter populations in the North Pacific were decimated by the fur trade of the 18th and 19th century, and continue to recover and re-occupy historical habitat.  Variation in their current status, and in the rate and pattern of recovery, provides an opportunity to use the comparative approach to elucidate how various natural and human-caused stressors affect population health and dynamics.  Moreover, sea otters provide an excellent indicator species for nearshore coastal ecosystems, because the factors that affect individual health and survival of sea otters also affect other vertebrate species in these systems, including humans.  As a keystone predator, sea otters have also been found to exert strong effects on food web structure and dynamics, and their recovery to impaired ecosystems may have important implications for resiliency of nearshore marine ecosystems to emerging threats such as climate change and infectious diseases. Accordingly, this project aims to understand the impact of multiple threats on sea otter abundance and trends, describe critical sea otter habitat needs, and determine the functional roles of sea otters in nearshore ecosystems. To achieve this, we will work with multiple collaborators to conduct a multi-disciplinary investigation of sea otter ecology, health and population biology. We will develop an integrative modeling approach that can be used to combine a broad range of data types including behavior, life history, demography, bio-medical, physiology, pathology, parasitology and epidemiology, in order to arrive at a process-based understanding of the factors affecting sea otter populations, and then use this model to provide resource managers with projections of population dynamics and viability under alternative management scenarios, and/or in response to anticipated environmental change.  

PROJECT GOALS             

  • The goal of this research program is to understand the factors affecting the growth and dynamics of sea otter populations in the western US coastal waters, including listed populations in California and southwestern Alaska.  


Sea otter Elkhorn Slough National Estuarine Research Reserve (WERC)

A sea otter at Elkhorn Slough National Estuarine Research Reserve, near Moss Landing, Calif.(Credit: Robert Scoles, ESNERR/NOAA . Public domain.)

How are sea otters using estuarine habitats and prey resources? Researchers are seeking to understand their role in the estuarine food web and to quantify and understand the effects of human-caused stressors — such as contaminants or nutrient inputs — on sea otters in Elkhorn Slough, California.

In Elkhorn Slough near Moss Landing, California, scientists hope to compile new data to support the recovery of the southern sea otter, a federally threatened species under the Endangered Species Act.

This partnership of federal, state and local institutions is seeking to increase our understanding of estuary habitat use by sea otters — and to help inform the conservation and restoration of suitable habitat and water quality conditions at Elkhorn Slough.

As southern sea otters continue their recovery and expansion into southern and northern reaches of the California coast, they will encounter estuary habitats. But scientists are really not sure how sea otters will respond and thrive in estuary environments, and how their recovery will affect estuary food webs.

For the time being, Elkhorn Slough is our best example in California of sea otters using estuarine habitats — which have different environmental factors than say, kelp forests and other habitats along the coast.

So using a variety of established study methods — radio tracking, veterinary exams, genetic analysis, diet observations — this collaborative group of scientists hopes to uncover new knowledge about this population of California’s iconic sea otters — a population that hasn’t been extensively studied for 15 years.

The research is being led by a partnership of the U.S. Geological Survey, University of California-Santa Cruz, California Department of Fish and Wildlife, the Monterey Bay Aquarium, and the Elkhorn Slough National Estuarine Research Reserve (ESNERR), with assistance from other partners.