Phoca Largha)
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NOAA Technical Memorandum NMFS-AFSC-200 Status Review of the Spotted Seal (Phoca largha) by P. L. Boveng, J. L. Bengtson, T. W. Buckley, M. F. Cameron, S. P. Dahle, B. P. Kelly, B. A. Megrey, J. E. Overland, and N. J. Williamson U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Marine Fisheries Service Alaska Fisheries Science Center October 2009 NOAA Technical Memorandum NMFS The National Marine Fisheries Service's Alaska Fisheries Science Center uses the NOAA Technical Memorandum series to issue informal scientific and technical publications when complete formal review and editorial processing are not appropriate or feasible. Documents within this series reflect sound professional work and may be referenced in the formal scientific and technical literature. The NMFS-AFSC Technical Memorandum series of the Alaska Fisheries Science Center continues the NMFS-F/NWC series established in 1970 by the Northwest Fisheries Center. The NMFS-NWFSC series is currently used by the Northwest Fisheries Science Center. This document should be cited as follows: Boveng, P. L., J. L. Bengtson, T. W. Buckley, M. F. Cameron, S. P. Dahle, B. P. Kelly, B. A. Megrey, J. E. Overland, and N. J. Williamson. 2009. Status review of the spotted seal (Phoca largha). U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-200, 153 p. Reference in this document to trade names does not imply endorsement by the National Marine Fisheries Service, NOAA. NOAA Technical Memorandum NMFS-AFSC-200 Status Review of the Spotted Seal (Phoca largha) by P. L. Boveng1, J. L. Bengtson1, T. W. Buckley1, M. F. Cameron1, S. P. Dahle1, B. P. Kelly1, B. A. Megrey1, J. E. Overland2, and N. J. Williamson1 1Alaska Fisheries Science Center 7600 Sand Point Way NE Seattle, WA 98115 www.afsc.noaa.gov 2 Pacific Marine Environmental Laboratory Office of Oceanic and Atmospheric Research 7600 Sand Point Way NE Seattle, WA 98115 U.S. DEPARTMENT OF COMMERCE Gary F. Locke, Secretary National Oceanic and Atmospheric Administration Jane Lubchenco, Under Secretary and Administrator National Marine Fisheries Service James W. Balsiger, Acting Assistant Administrator for Fisheries October 2009 This document is available to the public through: National Technical Information Service U.S. Department of Commerce 5285 Port Royal Road Springfield, VA 22161 www.ntis.gov STATUS REVIEW OF THE SPOTTED SEAL (Phoca largha) NOAA photo by Michael Cameron Prepared and Edited by: The 2009 Spotted Seal Biological Review Team Peter L. Boveng1 (Chair), John L. Bengtson1, Troy W. Buckley1, Michael F. Cameron1, Shawn P. Dahle1, Brendan P. Kelly1, Bernard A. Megrey1, James E. Overland2, and Neal J. Williamson1 With Contributions by: Josh M. London1, Erin E. Moreland1, Muyin Wang3,2, James M. Wilder4, David E. Withrow1, and Heather L. Ziel1 1 Alaska Fisheries Science Center, National Marine Fisheries Service, 7600 Sand Point Way NE, Seattle, WA 98115 2 Pacific Marine Environmental Laboratory, Office of Oceanic and Atmospheric Research, 7600 Sand Point Way NE, Seattle, WA 98115 3Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Box 355672, Seattle, WA 98195 4 Alaska Regional Office, National Marine Fisheries Service, 222 West 7th Ave., Anchorage, AK 99513 9 October 2009 CONTENTS Contents ...................................................................................................................................................... vii Executive Summary ...................................................................................................................................... ix 1 Introduction .......................................................................................................................................... 1 2 Species Background .............................................................................................................................. 2 2.1 Taxonomy and Phylogeny ................................................................................................................... 2 2.2 Species Description ............................................................................................................................. 3 2.3 Behavior .............................................................................................................................................. 5 2.4 Seasonal Distribution, Habitat‐use, and Movements ......................................................................... 7 2.5 Reproduction and Molting ................................................................................................................ 11 2.6 Vital Parameters ................................................................................................................................ 15 2.7 Feeding Habits ................................................................................................................................... 16 2.8 Historic and Current Abundance and Trends .................................................................................... 23 2.8.1 Yellow Sea .................................................................................................................................. 25 2.8.2 Sea of Japan ............................................................................................................................... 26 2.8.3 Sea of Okhotsk ........................................................................................................................... 26 2.8.4 Bering Sea .................................................................................................................................. 27 2.8.5 Coastal Surveys .......................................................................................................................... 28 2.8.6 Trends ........................................................................................................................................ 29 3 Species Delineation ............................................................................................................................. 29 3.1 Evaluation of Discreteness ................................................................................................................ 31 3.1.1 Separation by Physical, Physiological, Ecological, or Behavioral Factors .................................. 31 3.1.2 Delimitation by International Differences in Management and Regulatory Mechanisms ........ 35 3.2 Evaluation of Significance ................................................................................................................. 36 3.2.1 Persistence in an Unusual or Unique Ecological Setting? .......................................................... 36 3.2.2 Would Loss of a Segment Result in a Significant Gap in the Range? ......................................... 36 3.2.3 Population Segment is the Only Surviving Natural Occurrence? ............................................... 36 3.2.4 Segment Differs Markedly in Genetic Composition? ................................................................. 37 3.3 Determination of Distinct Population Segments .............................................................................. 37 4 Extinction Risk Assessment ................................................................................................................. 39 vii e4.1 Tim Frame: The Foreseeable Future ............................................................................................... 39 4.1.1 Factors in the Forseeability of Threats to Spotted Seals ........................................................... 39 4.1.2 Factors in the Foreseeability of Spotted Seal Responses to Threats ......................................... 41 4.1.3 Lack of a Single Time Frame for the Foreseeable Future ........................................................... 42 4.2 Analysis of Factors Listed Under Section 4(a)(1) of the Endangered Species Act ............................ 42 4.2.1 Present or Threatened Destruction, Modification, or Curtailment of the Species’ Habitat or Range .................................................................................................................................................. 43 4.2.2 Overutilization for Commercial, Recreational, Scientific, or Educational Purposes .................. 76 4.2.3 Diseases, Parasites, and Predation ............................................................................................ 81 4.2.4 Inadequacy of Existing Regulatory Mechanisms ........................................................................ 89 4.2.5 Other Natural or Human Factors Affecting the Species’ Continued Existence .......................... 95 4.3 Analysis of Demographic Risks ........................................................................................................ 108 4.3.1 Abundance ............................................................................................................................... 109 4.3.2 Productivity .............................................................................................................................. 111 4.3.3 Spatial Structure ....................................................................................................................... 112 4.3.4 Diversity ................................................................................................................................... 113 4.3.5 Relevant Modifying or Mitigating Factors ..............................................................................