Final Technical Report: - Southwest Fisheries Science Center - NOAA

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Acknowledgements This project was funded by the Strategic Environmental Research and Development Program (SERDP) and by the National Oceanic and Atmospheric Administration (NOAA). Initial funding for cetacean habitat modeling was provided by the U.S. Navy’s Office of Naval Operations (N45), and we particularly thank Frank Stone and Ernie Young for their early support of this project. The marine mammal survey data and oceanographic data used to model cetacean density were collected by a large dedicated team at the Protected Resources Division of NOAA’s Southwest Fisheries Science Center. We particularly thank the cruise leaders, marine mammal observers, oceanographers, survey coordinators, ship’s crew, and officers who have worked hard over the past 20 years collecting the data that we use here. Physical oceanographic and midtropic data were collected and processed by Candice Hall, Melinda Kelley, Liz Zele, Bill Watson, Thomas J. Moore, Robert Holland, Valerie Andreassi, David Demer, Kerry Koptisky, George Watters, and Lindsey Peavey. We also thank Lucy Dunn, Barbara MacCall and Ioana Ionescu who collectively spent hundreds of hours sorting Bongo and Manta samples. Aerial survey efforts were lead by Jim Carretta. Steve Reilly and Robert Brownell were leaders of the Protected Resources Division during most of the surveys and were instrumental in providing the foundations upon which this project were based. We thank Dave Foley at SWFSC's Environmental Research Division for sharing his extensive knowledge of physical oceanography and providing code to automate the acquisition of remotely sensed data and Ray Smith at the University of California, Santa Barbara, for his thoughtful comments and insights on the results of our analyses. Our project benefitted greatly from our close collaboration with the SERDP Team at Duke University (SI-1390), particularly Ben Best, Andy Read, and Pat Halpin. We thank John Hall and an anonymous reviewer for their helpful suggestions on the draft final report. xiv
Executive Summary The Navy and other users of the marine environment conduct many activities that can potentially harm marine mammals. Consequently, these entities are required to complete Environmental Assessments and Environmental Impact Statements to determine the likely impact of their activities. Specifically, those documents require an estimate of the number of animals that might be harmed or disturbed. A key element of this estimation is knowledge of cetacean (whale, dolphin, and porpoise) densities in specific areas where those activities will occur. Cetacean densities are typically estimated by line-transect surveys. Within United States Exclusive Economic Zone (US EEZ) waters and in the Eastern Tropical Pacific (ETP), most cetacean surveys have been conducted by the US National Marine Fisheries Service as part of their stock assessment research and typically result in estimates of cetacean densities in very large geographic strata (e.g., the entire US West Coast). Although estimates are sometimes available for smaller strata (e.g., the waters off southern California), these areas are still much larger than the operational areas where impacts may occur (e.g., the Navy’s Southern California Offshore Range (SCORE) off San Clemente Island). Stratification methods cannot provide accurate density estimates for small areas because sample size (i.e., the number of cetacean sightings) becomes limiting as areas become smaller. Recently, habitat modeling has been developed as a method to estimate cetacean densities. These models allow predictions of cetacean densities on a finer spatial scale than traditional line-transect analyses because cetacean densities are estimated as a continuous function of habitat variables (i.e., sea surface temperature, seafloor depth, distance from shore, prey density, etc.). Cetacean densities can then be predicted wherever these habitat variables can be measured or estimated, within the area that was modeled. We use data from 16 ship-based cetacean and ecosystem assessment surveys to develop habitat models to predict density for 15 cetacean species in the ETP and for 12 cetacean species in the California Current Ecosystem (CCE). All data were collected by NOAA’s Southwest Fisheries Science Center (SWFSC) from 1986-2006 using accepted, peer-reviewed survey methods. Data include over 17,000 sightings of cetacean groups on transects covering over 400,000 km. The expected number of groups seen per transect segment and the expected size of groups were modeled separately as functions of habitat variables. Model predictions were then used in standard line-transect formulae to estimate density for each transect segment for each survey year. Predicted densities for each year were smoothed with geospatial methods to obtain a continuous grid of density estimates for the surveyed area. These annual grids were then averaged to obtain a composite grid that represents our best estimates of cetacean density over the past 20 years in the ETP and the past 15 years in the CCE. Many methodological choices were required for every aspect of this modeling. In completing this project, we explored as many xv
Page 1 and 2: U N I R A P E D T T E M D S E N TA
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Page 6 and 7: This report was prepared under cont
Page 8 and 9: Table of Contents Acronyms and Abbr
Page 10 and 11: C.1 Journal Publications ..........
Page 12 and 13: Figure 18. Encounter rate models bu
Page 14 and 15: List of Tables Table 1. Summary of
Page 16 and 17: Appendix B, Table B-6. Summary of m
Page 20 and 21: of these choices as possible and us
Page 22 and 23: Although our models include most of
Page 24 and 25: 2.0 Background The Navy and other m
Page 26 and 27: comparison is based on a separate s
Page 28 and 29: Figure 1. Transects (green lines) s
Page 30 and 31: used to evaluate the ability of sum
Page 32 and 33: 3.1.5 Mid-trophic Sampling with Net
Page 34 and 35: variable. Interpolated maps of the
Page 36 and 37: Table 2. Variogram model results. A
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Page 40 and 41: Encounter Rate and Group Size Model
Page 42 and 43: were built separately for each of t
Page 44 and 45: Expanding models to the entire U.S.
Page 46 and 47: Table 4. Summary of the weighted ef
Page 48 and 49: Consistent with Barlow and Forney (
Page 50 and 51: incorporation of geographic coordin
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Page 54 and 55: the genera Ziphius and Mesoplodon.
Page 56 and 57: Table 7. Geographically stratified
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Page 62 and 63: avoid these problems, we decided to
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CAMMS 1991 PODS 1993 ORCAWALE 1996
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4.2 Modeling Framework : GLM and GA
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4.2.4 Conclusions Regardings Modeli
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Table 10 cont. Comparison of the si
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Table 11 cont. Comparison of the si
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Figure 15. The transect lines used
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A) Striped dolphin 10 km B) Short-b
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dependent. For example, the number
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Figure 19. Predicted average densit
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ecosystem, eastern spinner dolphins
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Table 13. Variables selected for mo
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Table 14. Starting and final AIC va
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Table 17. Ratios of observed to pre
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species represented in the acoustic
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0.29 (Risso’s dolphin) to 3.20 (n
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Figure 25. Sample 2005 validation p
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Table 18. (continued) 1991 1993 Nor
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Blue whales had the greatest deviat
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Table 20. Abundance (number of anim
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Table 22. Proportion of deviance ex
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Figure 27. Average density (AveDens
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Table 23. Effective degrees of free
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We attempted to build encounter rat
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5.0 Conclusion The field of predict
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6.0 Transition Plan The models of c
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needed to ensure that the SDSS rema
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Administrative Report LJ-07-02. NOA
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Forney KA, Barlow J (1993) Prelimin
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Redfern JV, Barlow J, Ballance LT,
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Appendix A: Detailed Model Results
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Table A-1 (continued) Blue whale 19
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Figure A-1a. Striped dolphin 108
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Figure A-1c. Risso’s dolphin 110
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Figure A-1e. Northern right whale d
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Figure A-1g. Sperm whale 114
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Figure A-1i. Blue whale 116
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Figure A-1k. Baird’s beaked whale
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Figure A-2. Predicted average densi
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Figure A-2b. Short-beaked common do
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Figure A-2d. Pacific white-sided do
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Figure A-2f. Dall’s porpoise 126
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Figure A-2h. Fin whale 128
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Figure A-2j. Humpback whale 130
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Figure A-2l. Small beaked whales 13
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Table B-2. Summary of model validat
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Table B-10. Summary of model valida
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Figure B-1. Predicted yearly and av
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Figure B-1. b) Eastern spinner dolp
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Figure B-1. c) Whitebelly spinner d
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Figure B-1. d) Striped dolphin 168
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Figure B-1. e) Rough-toothed dolphi
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Figure B-1. f) Short-beaked common
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Figure B-1. g) Bottlenose dolphin 1
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Figure B-1. h) Risso’s dolphin 17
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Figure B-1. i) Cuvier’s beaked wh
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Figure B-1. j) Blue whale 180
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Figure B-1. k) Bryde’s whale 182
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Figure B-1. l) Short-finned pilot w
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Figure B-1. m) Dwarf sperm whale 18
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Figure B-1. n) Mesoplodon beaked wh
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Figure B-1. o) Small beaked whales
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Figure B-2. Predicted average densi
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Figure B-2. (cont.) c) Whitebelly s
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Figure B-2. (cont.) g) Bottlenose d
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Figure B-2. (cont.) k) Bryde’s wh
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Figure B-2. (cont.) o) Small beaked
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Ferguson MC (2005) Cetacean Populat
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Barlow J, Kahru M, Mitchell BG (In
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Memorandum NMFS-SWFSC-374, U.S. Dep
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