Sea otter population status and changes in Alaska

With the exception of 13 small remnant populations, sea otters were extirpated from their historic range in the north Pacific Ocean during the 18th and 19th centuries. Since the beginning of the 20th century, through protection and reintroduction, sea otter populations have increased in abundance and distribution such that most of their range in Alaska, with the exception of southeast Alaska, is currently occupied. Although data are incomplete, there is evidence of increasing, stable and declining sea otter populations in different areas of the Pacific. The cause, magnitude and geographic extent of the declining populations are unknown. Additionally, harvest levels of sea otters for subsistence have increased over the past 10 years. Population level effect of the harvest at current levels are unknown. Because sea otter populations occur over vast and remote areas, determining population status and trends through traditional survey methods is logistically difficult and fiscally expensive.

APPLICATION OF RESEARCH: Studies of sea otter population status and trends are important to assess the recovery of the populations and the potential effects of human perturbations (e.g., harvest, contaminants, and habitat modifications) on population status and trends. This information is important to resource managers in identifying potential conflicts, identifying mechanisms of change and improve the ability to detect change from human induced sources. The objectives of this study are: 1) develop and test methods to identify the degree of population structuring among north Pacific sea otter populations, 2) evaluate the effects of population reductions and translocations on sea otter genetic variability, 3) develop and test techniques to accurately and precisely estimate the status of sea otter populations, 4) develop and test methods to identify cause(s) of change in the status and numeric trends of sea otter populations, and 5) develop and test methods to determine the ecological consequences of changes in sea otter populations.

Publications:

Bodkin, J. L, K. A. Kloecker, G. G. Esslinger, D. H. Monson, DeGroot, J. D., and J. Doherty. 2002. Sea otter studies in Glacier Bay National Park and Preserve. 2001 Annual Report. U.S. Geological Survey, Biological Resources Division, Anchorage, AK. [pdf file - 1.8 MB]

Bodkin, J. L, K. A. Kloecker, G. G. Esslinger, D. H. Monson, and J. D. DeGroot. 2001. Sea otter studies in Glacier Bay National Park and Preserve: Aerial surveys, foraging observations, and intertidal clam sampling. 2000 Annual Report. U.S. Geological Survey, Biological Resources Division, Anchorage, AK. [pdf file - 11.2 MB]

Bodkin, J. L. and D. H. Monson.  1999.  Sea otter distribution and relative abundance, Cross Sound - Icy Strait survey summary.  U.S. Geological Survey, Biological Resources Division, Anchorage, AK. [PDF file - 14 KB]

Bodkin, J. L., G. G. Esslinger, and D. H. Monson. 1999.  Estimated sea otter population size in Glacier Bay.  U.S. Geological Survey, Biological Resources Division, Anchorage, AK.  [PDF file - 414 KB]

Bodkin, J. L., K. A. Kloecker, and A. Burdin.  1999.  Fluctuating asymmetry and genetic diversity in sea otters (Enhydra lutris).  U.S. Geological Survey, Biological Resources Division, Anchorage, AK, poster presentation.  [PDF file - 329 KB]