The 2017 census of southern sea otters (Enhydra lutris nereis) was conducted between late April and early July along the mainland coast of central California and in April at San Nicolas Island in southern California. The 3-year average of combined counts from the mainland range and San Nicolas Island was 3,186, down by 86 sea otters from the previous year. This is the second year that the official index has exceeded 3,090, the Endangered Species Act delisting threshold identified in the U.S. Fish and Wildlife Service’s Southern Sea Otter Recovery Plan (the threshold would need to be exceeded for 3 consecutive years before delisting consideration). The 5-year average trend in abundance, including both the mainland range and San Nicolas Island populations, remains positive at 2.3 percent per year. Continuing lack of growth in the range peripheries likely explains the cessation of range expansion.
|Title||California sea otter (Enhydra lutris nereis) census results, Spring 2017|
|Authors||M. Tim Tinker, Brian B. Hatfield|
|Publication Subtype||USGS Numbered Series|
|Series Title||Data Series|
|Record Source||USGS Publications Warehouse|
|USGS Organization||Western Ecological Research Center|
Annual California Sea Otter Census - 2017 Spring Census Summary
Brian B Hatfield
Annual California Sea Otter Census - 2017 Spring Census SummaryThe spring 2017 mainland sea otter count began on April 30, and although the shore-based counts were completed by May 12, 2017, the aerial counts were not completed until July 12, 2017. Overall viewing conditions this year were good, although not as good as conditions experienced during the 2016 spring census (View Score 2.4 versus 3.1, where 0=poor, 1=fair, 2=good, 3=very good, and 4=excellent).
Brian B Hatfield