Prepared in cooperation with Bureau of Ocean Energy Management (OCS Study BOEM 2017-002) Southern Sea Otter Range Expansion and Habitat Use in the Santa Barbara Channel, California Open-File Report 2017–1001 U.S. Department of the Interior U.S. Geological Survey Cover: Photograph showing a male sea otter (Enhydra lutris) pausing from grooming to display its uniquely colored flipper tags, used for visual identification. Photograph by Nicole LaRoche, U.S. Geological Survey. Southern Sea Otter Range Expansion and Habitat Use in the Santa Barbara Channel, California By M. Tim Tinker, Joseph Tomoleoni, Nicole LaRoche, Lizabeth Bowen, A. Keith Miles, Mike Murray, Michelle Staedler, and Zach Randell Prepared in cooperation with Bureau of Ocean Energy Management (OCS Study BOEM 2017-002) Open-File Report 2017–1001 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior SALLY JEWELL, Secretary U.S. Geological Survey Suzette M. Kimball, Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit http://www.usgs.gov/ or call 1–888–ASK–USGS (1–888–275–8747). For an overview of USGS information products, including maps, imagery, and publications, visit http://store.usgs.gov/. This product has been technically reviewed and approved for publication by the Bureau of Ocean Energy Management. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Tinker, M.T., Tomoleoni, Joseph, LaRoche, Nicole, Bowen, Lizabeth, Miles, A. Keith, Murray, Mike, Staedler, Michelle, and Randell, Zach, 2017, Southern sea otter range expansion and habitat use in the Santa Barbara Channel, California: U.S. Geological Survey Open-File Report 2017–1001 (OCS Study BOEM 2017-002), 76 p., http://doi.org/10.3133/ofr20171001. ISSN 2331-1258 (online) Contents Abstract ...............................................................................................................................................................................1 Introduction ..........................................................................................................................................................................2 Background ......................................................................................................................................................................2 Primary Objectives ...........................................................................................................................................................4 Secondary Objectives ......................................................................................................................................................4 Methods ...............................................................................................................................................................................5 Live Sea Otter Captures ..................................................................................................................................................5 Processing, Sampling, Health Assessments, and Tagging ..............................................................................................7 Live Sea Otter Surveillance ........................................................................................................................................... 10 Dead Sea Otter Surveillance ......................................................................................................................................... 14 Gene Transcription ........................................................................................................................................................ 15 Captive Reference Otters .......................................................................................................................................... 15 Blood Collection and RNA Extraction ......................................................................................................................... 15 cDNA creation ............................................................................................................................................................ 15 Real-Time PCR .......................................................................................................................................................... 15 Statistical Analysis ..................................................................................................................................................... 17 Movement, Behavior, Home Range, and Habitat Selection—A Synoptic Model............................................................ 18 Synoptic Model Details .............................................................................................................................................. 19 Spatially Explicit Risk Analysis ................................................................................................................................... 22 Dive Behavior and Time-Activity Budgets ...................................................................................................................... 22 Dive Behavior ............................................................................................................................................................. 22 Time-Activity Budgets ................................................................................................................................................ 24 Foraging Ecology and Tool Use ..................................................................................................................................... 25 Body Condition .............................................................................................................................................................. 25 Survival and Reproduction ............................................................................................................................................. 26 Cause of Death—Necropsy Analyses ........................................................................................................................ 26 Results............................................................................................................................................................................... 27 Overview ........................................................................................................................................................................ 27 Gene Transcription ........................................................................................................................................................ 32 Transcript Pattern Analysis ........................................................................................................................................ 32 Within Site: Sex by Year Transcript Differences ........................................................................................................ 35 Gene Specific Patterns .............................................................................................................................................. 35 Heatmap Pattern Analysis ......................................................................................................................................... 35 Movement Behavior, Home Range, and Habitat Use .................................................................................................... 37 Proximity to Man-Made Structures ............................................................................................................................. 44 Dive Behavior, Depth Use, and Time-Activity Budgets .................................................................................................. 44 Foraging Ecology ........................................................................................................................................................... 47 Body Condition .............................................................................................................................................................. 49 Survival and Reproduction ............................................................................................................................................. 49 Preliminary Findings from Necropsy of Tagged Sea Otters ....................................................................................... 59 Discussion ......................................................................................................................................................................... 63 Primary Objectives: Space Use Patterns and Exposure to Oil and Gas Seeps ............................................................. 63 Secondary Objectives: Population Status and Threats to Recovery .............................................................................. 64 Acknowledgments ............................................................................................................................................................