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Abundance and Distribution of Sea Otters (Enhydra lutris) in the Southcentral Alaska Stock, 2014, 2017, and 2019

Open-File Report 2021-1122
Prepared in cooperation with U.S. Fish and Wildlife Service
By: , , , , , , and 
https://doi.org/10.3133/ofr20211122

Links

  • Document: Report (26 MB pdf)
  • Data Releases:
    • Data Release - Sea otter aerial survey data from the outer Kenai Peninsula, Alaska, 2019
    • Data Release - Sea otter aerial survey data from western Prince William Sound, Alaska, 2017
    • Data Release - Sea otter aerial survey data from lower Cook Inlet, Alaska, 2017
    • Data Release - Sea otter aerial survey data from northern and eastern Prince William Sound, Alaska, 2014
    • USGS data release - Sea Otter Aerial Survey Data from Northern and Eastern Prince William Sound, Alaska, 2014
  • Download citation as: RIS | Dublin Core

Abstract

The Southcentral Alaska (SCAK) sea otter (Enhydra lutris) stock is the northernmost stock of sea otters, a keystone predator known for structuring nearshore marine ecosystems. We conducted aerial surveys within the range of the SCAK sea otter stock to provide recent estimates of sea otter abundance and distribution. We defined three survey regions: (1) Eastern Cook Inlet (2017), (2) Outer Kenai Peninsula (2019), and (3) Prince William Sound (2014 and 2017). Combined, the three regional estimates yielded an overall abundance estimate of 21,617 sea otters (standard error [SE] = 2,190) with an average density of 1.96 sea otters per square kilometer (km2; SE = 0.55). Sea otters were distributed unevenly across the survey regions and densities varied from 0.52 sea otters/km2 (SE = 0.18) in the deep rock-walled glacial fjords along parts of the Outer Kenai Peninsula to nearly 20 sea otters/km2 (SE = 6.70) in shallow soft-bottom communities such as those in Orca Inlet and Kachemak Bay. These survey results represent the best available contemporary information concerning the distribution, density, and abundance of sea otters across the range of the SCAK stock. Survey data files have been standardized and formatted in data releases associated with this report so that they can be queried and displayed with standard geographic information system and database management software. In addition to providing contemporary information on sea otter populations, this report details how an observer-based aerial survey method has been applied in Alaska over 2 decades.

Suggested Citation

Esslinger, G.G., Robinson, B.H., Monson, D.H., Taylor, R.L., Esler, D., Weitzman, B.P., and Garlich-Miller, J., 2021, Abundance and distribution of sea otters (Enhydra lutris) in the southcentral Alaska stock, 2014, 2017, and 2019: U.S. Geological Survey Open-File Report 2021–1122, 19 p., https://doi.org/10.3133/ofr20211122.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Abstract  
  • Introduction  
  • Methods  
  • Summary of Aerial Survey Results by Region  
  • Discussion  
  • Acknowledgments  
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Abundance and distribution of sea otters (Enhydra lutris) in the southcentral Alaska stock, 2014, 2017, and 2019
Series title Open-File Report
Series number 2021-1122
DOI 10.3133/ofr20211122
Year Published 2022
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Alaska Science Center
Description Report: iv, 19 p.; 4 Data Releases
Country United States
State Alaska
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
Additional publication details