U.S. DEPARTMENT OF COMMERCE
National Oceanic and Atmospheric Administration
National Marine Fisheries Service NOAA Technical Memorandum NMFS-NWFSC-54 Status Review of Southern Resident
Killer Whales ( Orcinus orca) under the Endangered Species Act December 2002 NOAA Technical Memorandum NMFS Series The Northwest Fisheries Science Center of the National
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does not imply endorsement by the National Marine
Fisheries Service, NOAA. This document should be cited as follows: Krahn, M.M., et al. 2002. Status review of Southern
Resident killer whales (Orcinus orca) under the
Endangered Species Act. U.S. Dept. Commer., NOAA
Tech. Memo. NMFS-NWFSC-54, 133 p. NOAA Technical Memorandum NMFS-NWFSC-54 Status Review of Southern Resident
Killer Whales ( Orcinus orca) under the Endangered Species Act Margaret M. Krahn 1 , Paul R. Wade 2 , Steven T. Kalinowski 1 , Marilyn E. Dahlheim 2 , Barbara L. Taylor 3 , M. Bradley Hanson 2 , Gina M. Ylitalo 1 , Robyn P. Angliss 2 , John E. Stein 1 , and Robin S. Waples 1 Northwest Fisheries Science Center
2725 Montlake Boulevard East
Seattle, Washington 98112 Alaska Fisheries Science Center
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Seattle, Washington 98115 Southwest Fisheries Science Center
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La Jolla, California 92037 December 2002 U.S. DEPARTMENT OF COMMERCE Donald L. Evans, Secretary National Oceanic and Atmospheric Administration Vice Admiral Conrad C. Lautenbacher, Jr. USN (Ret), Administrator National Marine Fisheries Service William T. Hogarth, Assistant Administrator for Fisheries 1 3 2 ii Most NOAA Technical Memorandums NMFS-NWFSC
are available on-line at the Northwest Fisheries Science
Center web site (http://www.nwfsc.noaa.gov) Copies are also available from: National Technical Information Service
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e-mail orders (orders@ntis.fedworld.gov) iii TABLE OF CONTENTS LIST OF FIGURES ...................................................................................................................................... v LIST OF TABLES...................................................................................................................................... vii EXECUTIVE SUMMARY ......................................................................................................................... ix ACKNOWLEDGMENTS ........................................................................................................................ .xxi 1. INTRODUCTION................................................................................................................................ 1 1.1. Scope and Intent of the Status Review ....................................................................................... . 1 1.2. Key Questions in ESA Evaluations ............................................................................................. 3 1.2.1. The Species Question ..................................................................................................... . 3 1.2.2. The Extinction Risk Question ......................................................................................... 3 1.2.3. Factors Not Considered in ESA Evaluations ...................................................................... 4 1.3. Summary of Information Presented by the Petitioners................................................................ 5 1.3.1. The DPS Question: Discreteness..................................................................................... 5 1.3.2. The DPS Question: Significance..................................................................................... 7 1.3.3. Abundance and Population Trends .................................................................................... . 8 1.3.4. Risk Factors ........................................................................................................................ 8 1.3.5. Risk of Extinction .............................................................................................................. . 9 1.4. New InformationNot Included in the Petition and Not Considered by the BRT..................... 9 2. BACKGROUND INFORMATION ON BIOLOGY AND HABITAT OF KILLER WHALES ...... 11 2.1. General Killer Whale Biology.................................................................................................. . 11 2.1.1. Identifying Characteristics ................................................................................................ 11 2.1.2. TaxonomyGenus and Species: Orcinus Orca (Linnaeus, 1758).................................. . 13 2.1.3. Global Distribution .......................................................................................................... . 14 2.1.4. Regional and Global Nomenclature of Killer Whales ...................................................... 17 2.1.5. Feeding Ecology and Food Requirements ........................................................................ 19 2.1.6. Diving Behavior................................................................................................................ 20 2.1.7. Social Behavior................................................................................................................. 20 2.2. Genetics of Killer Whales.......................................................................................................... 22 2.2.1. Introduction to the Interpretation of Genetic Data........................................................... . 22 2.2.2. Microsatellite Genetic Data .............................................................................................. 24 2.2.3. Mitochondrial Genetic Data.............................................................................................. 27 2.2.4. Morphological Data .......................................................................................................... 30 2.2.5. Nuclear DNA, mtDNA, and Morphological Genetic Data............................................... 30 2.3. Features and Environmental History of the Northeast Pacific Ocean and Inland Waters of Washington and British Columbia.......................................................................................................... 31 2.3.1. General Features ............................................................................................................... 31 2.3.2. Environmental History...................................................................................................... 31 2.3.3. Geological and Climatic History ...................................................................................... 32 2.3.4. Geomorphological and Oceanographic Features .............................................................. 33 2.3.5. Marine Species in the Northeast Pacific .......................................................................... . 34 2.4. Ecology of Southern Resident Killer Whales............................................................................ 35 2.4.1. Current Range and Distribution ........................................................................................ 35 2.4.2. Population Dynamics........................................................................................................ 37 2.4.3. Potential Risk Factors ....................................................................................................... 50 2.4.4. Historical Population Size, Carrying Capacity, and Range .............................................. 68 3. DETERMINATION OF DPS ............................................................................................................ 71 3.1. Taxonomic Uncertainty ............................................................................................................. 71 3.2. Data Relevant to Determining ESA Discreteness and Significance.......................................... 72 iv 3.2.1. Other Information ............................................................................................................ . 73 3.2.2. Population Units of Killer Whales Considered as either a Taxon or a DPS .................... . 74 3.3. BRT Determinations of ESA Discreteness................................................................................ 77 3.4. BRT Determinations of ESA Significance ............................................................................... . 77 3.4.1. BRT Deliberations Process ............................................................................................... 77 3.4.2. Are Southern Residents a DPS of the Global Species? .................................................... 79 3.4.3. What is the DPS (Global Species Taxon) to which Southern Residents Belong? ............ 82 3.4.4. Would Southern Residents Be a DPS of an Alternative Taxon? ..................................... . 82 3.4.5. DPS Summary................................................................................................................... 85 4. ASSESSMENT OF EXTINCTION RISK ........................................................................................ . 87 4.1. Previous Assessments of Extinction Risk ................................................................................. 87 4.2. Population Viability Analysis: Approach.................................................................................. 87 4.3. Surrogates for Extinction Risk .................................................................................................. 88 4.4. Population Viability Analysis: Models and Inputs.................................................................... 88 4.5. Population Viability Analysis: Results..................................................................................... . 91 4.5.1. Southern Residents as the Population Unit....................................................................... 91 4.5.2. Southern, Northern, and Alaska Residents as the Population Unit................................... 92 4.5.3. Differences between NMFS PVA and Petitioners PVA............................................... . 105 4.5.4. Discussion and Conclusions for Risk Analysis .............................................................. 106 5. CONCLUSIONS OF THE STATUS REVIEW .............................................................................. 111 CITATIONS ............................................................................................................................................. 113 v LIST OF FIGURES Figure 1 . Ranges of resident killer whales in the Northeast Pacific Ocean. ................................................ 2 Figure 2. Multidimensional scaling plot of pair-wise F ST estimated from 11 microsatellite loci. ............. 29 Figure 3 . Southern Resident killer whale population size through time. ................................................... 39 Figure 4 . Southern Resident killer whale annual crude survival estimates................................................ 42 Figure 5 . Best fitting model of crude survival, 6-year periods of constant survival, starting with a full 6- year period in 1974. .................................................................................................................................... 43 Figure 6. Best fitting model overall, an additive model with 6-year periods of constant survival, starting with a full 6-year period in 1974, scaled differently for each age and sex category................................... 45 Figure 7 . Fraction of adult males (15 or older) in the population per year. ............................................... 48 Figure 8. Best fitting model of fecundity (recruited calves per reproductive age female), a periodic function with about 8 years between peaks. ............................................................................................... 49 Figure 9 . Ratio DDTs / PCBs in killer whales and potential prey. ......................................................63 Figure 10 . Mean concentrations of PCBs and DDTs (ng/g lipid) measured in blubber biopsy samples of sexually mature male resident killer whales from Prince William Sound and Kenai Fjords, Alaska,
grouped by birth order. ............................................................................................................................... 64 Figure 11 . Decision tree for determining taxa and DPS used in evaluating significance criteria under the ESA. ...................................................................................................................................................... 78 Figure 12. Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19742000 survival rates continue, with no catastrophes........................................ 93 Figure 13 . Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19742000 survival rates continue, with a 1% probability of a catastrophe with an
average of a 10% decline in survival for 1 year.......................................................................................... 94 Figure 14 . Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19742000 survival rates continue, with a 1% probability of a catastrophe with an
average of a 20% decline in survival for 1 year.......................................................................................... 95 Figure 15. Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19742000 survival rates continue, with a 2% probability of a catastrophe with an
average of a 20% decline in survival for 1 year.......................................................................................... 96 Figure 16. Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19922000 survival rates continue, with no catastrophes........................................ 97 Figure 17. Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19922000 survival rates continue, with a 1% probability of a catastrophe with an
average of a 10% decline in survival for 1 year.......................................................................................... 98 vi Figure 18 . Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19922000 survival rates continue, with a 1% probability of a catastrophe with an
average of a 20% decline in survival for 1 year.......................................................................................... 99 Figure 19. Estimated risk of extinction at 50, 100, 200, and 300 years for the Southern Resident population, assuming 19922000 survival rates continue, with a 2% probability of a catastrophe with an
average of a 20% decline in survival for 1 year........................................................................................ 100 Figure 20. Estimated risk of extinction at 50, 100, 200, and 300 years for the combined populations of Southern, Northern, and Alaska Residents, assuming 19742000 survival rates of Southern Residents are
experienced by both Southern and Northern Residents. Carrying capacity was set at 800 whales. ........ 101 Figure 21. Estimated risk of extinction at 50, 100, 200, and 300 years for the combined populations of Southern, Northern, and Alaska Residents, assuming 19742000 survival rates of Southern Residents are
experienced by both Southern and Northern Residents. Carrying capacity was set at 1,600 whales. ..... 102 Figure 22. Estimated risk of extinction at 50, 100, 200, and 300 years for the combined populations of Southern, Northern, and Alaska Residents, assuming 19922000 survival rates of Southern Residents are
experienced by both Southern and Northern Residents. Carrying capacity was set at 800 whales. ........ 103 Figure 23. Estimated risk of extinction at 50, 100, 200, and 300 years for the combined populations of Southern, Northern, and Alaska Residents, assuming 19922000 survival rates of Southern Residents are
experienced by both Southern and Northern Residents. Carrying capacity was set at 1,600 whales. ..... 104 vii LIST OF TABLES Table 1 . Summary of known sightings of Southern Resident killer whales along the outer Pacific Ocean coast. ........................................................................................................................................................... 15 Table 2. Identities of Southern Resident killer whales sampled for chemical and genetic analyses. ........ 25 Table 3 . Estimates of F ST for killer whales obtained from 11 microsatellite loci. ..................................... 28 Table 4. Estimates of annual survival (19742000) of Southern Resident killer whales. ......................... 41 Table 5. Estimates of annual survival from the model that provided best fit to the data: 6-year periods of constant survival, scaled differently for each age and sex category, starting with a full period in 1974.... 44 Table 6. Summary of historical and recent estimates of numbers of salmon produced by west coast North American river systems between the Strait of Georgia and Central California. ........................................ . 53 Table 7. Concentrations (mean