The 2016 census of southern sea otters Enhydra lutris nereis was conducted in May 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 3,272. This is the first year that the official index has exceeded 3,090, the Endangered Species Act delisting threshold suggested by the U.S. Fish and Wildlife Service (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, is positive at 3.2 percent per year; however, regional trends vary, with localized declines at the southern and northern peripheries of the mainland range. The lack of population growth in the range peripheries over recent years likely explains the cessation of range expansion, with the range limits remaining almost unchanged from the previous 5 years.
Citation Information
| Publication Year | 2016 |
|---|---|
| Title | California sea otter (Enhydra lutris nereis) census results, Spring 2016 |
| DOI | 10.3133/ds1018 |
| Authors | M. Tim Tinker, Brian B. Hatfield |
| Publication Type | Report |
| Publication Subtype | USGS Numbered Series |
| Series Title | Data Series |
| Series Number | 1018 |
| Index ID | ds1018 |
| Record Source | USGS Publications Warehouse |
| USGS Organization | Western Ecological Research Center |
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Annual California Sea Otter Census: 2016 Spring Census Summary
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