Final Technical Report: - Southwest Fisheries Science Center - NOAA

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Figure 15. The transect lines used to collect dolphin and oceanographic data in the California Current ecosystem are shown for 1991, 1993, 1996, and 2001. The locations of the largest 20% of temperature fronts at the 120 km resolution are shown as black dots for all years of data. Fronts were defined as the difference between the minimum and maximum temperatures recorded on a segment. Table 12. Number of encounters for the four species and six spatial resolutions considered in our California Current ecosystem analyses. The 120 km resolution has the highest number of encounters for several species because segments with Beaufort sea state values greater than 5.5 were excluded from our analyses. In particular, 2 km segments containing an encounter and occurring in Beaufort sea states greater than 5.5 may not contribute to the analyses at the smaller resolutions but may contribute at the larger resolutions if the average Beaufort sea state on the longer segment was less than or equal to 5.5. Spatial Resolution (km) Striped dolphin Shortbeaked common dolphin Risso’s dolphin Northern right whale dolphin Total number of segments 2 28 177 37 30 8216 10 29 184 38 30 1888 20 29 188 38 30 966 40 29 193 39 30 490 60 29 191 39 30 329 120 29 193 39 30 168 Although the results of these analyses suggest that dolphin-habitat relationships in the CCE are resolution dependent (Fig. 16), instability in the models necessitates further analyses. The variables included in the models, their functional form, and the degree of difference among models built at the various resolutions changed when we looked at 56
different subsets of data. We discovered this result while exploring criteria for the minimum number of temperature and salinity measurements to include in the average for each segment. The variability in the models suggests that the sample size may not be large enough to address the effect of resolution in such a heterogeneous ecosystem. Only short-beaked common dolphin had more than 40 sightings in the total data set. A minimum of 40 sightings has been suggested as a conservative estimate of the sample size needed to build a cetacean-habitat model for species in heterogeneous ecosystems (Becker 2007). We lost a large number of sightings due to the constraints imposed by our analytical design. In particular, we had to restrict our analyses to days on which the ship traveled 120 km and days on which complete oceanographic data were collected; we also had to exclude effort that occurred outside the 120 km segment. The best means for increasing the sample size in these analyses is to use the data collected in the CCE during August-December 2005. We did not complete this extension of the analyses as part of the SERDP project because we are using the 2005 data to validate our final models; it would be circular to use the 2005 data to both determine the appropriate resolution for the models and validate the models. Instead, we compared the results of the models built at the 2-km and 10-km resolutions, which used in situ oceanographic data, to the models built at a 5-km resolution using only remotely sensed data. We found that the models built using only the remotely sensed data performed as well as or better than the in situ models. These results increased our confidence in building models at a 5-km resolution and using remotely sensed oceanographic data for the final CCE models. However, we did find that some species showed a strong response to oceanographic variables for which there are no remotely sensed counterpart, such as measures of water column temperature gradients. Consequently, our final models were derived from a comparison of models built at a 5-km resolution using only remotely sensed habitat variables to those built using both remotely sensed and in situ oceanographic variables. 4.3.2 Extent We explored the effect of extent by building models using data from the ETP and CCE separately, and from both ecosystems combined. The combined models incorporate a larger range for many habitat variables (e.g., temperatures are colder in the CCE than the ETP) and a larger sample size for each species. We were interested in determining whether the combined models had increased predictive power. We used the methods derived for the resolution analyses (see Redfern et al. 2008) to explore the effect of extent. Encounter rate models were built at a 60km resolution for two species that occur in both habitats: striped dolphin and short-beaked common dolphin. 57
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U N I R A P E D T T E M D S E N TA
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C O L A N IO T A N U N C I EA .S. D
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This report was prepared under cont
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Table of Contents Acronyms and Abbr
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C.1 Journal Publications ..........
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Figure 18. Encounter rate models bu
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List of Tables Table 1. Summary of
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Appendix B, Table B-6. Summary of m
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Acknowledgements This project was f
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of these choices as possible and us
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Although our models include most of
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2.0 Background The Navy and other m
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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
Page 38 and 39: “number of individuals” as the
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
Page 52 and 53: overwhelming majority of “Bryde
Page 54 and 55: the genera Ziphius and Mesoplodon.
Page 56 and 57: Table 7. Geographically stratified
Page 58 and 59: above, and the data themselves, are
Page 60 and 61: (hereafter “summer”). SWFSC has
Page 62 and 63: avoid these problems, we decided to
Page 64 and 65: Figure 9. Thermocline depth (m) obs
Page 66 and 67: Attempts to adjust search parameter
Page 68 and 69: CAMMS 1991 PODS 1993 ORCAWALE 1996
Page 70 and 71: 4.2 Modeling Framework : GLM and GA
Page 72 and 73: 4.2.4 Conclusions Regardings Modeli
Page 74 and 75: Table 10 cont. Comparison of the si
Page 76 and 77: Table 11 cont. Comparison of the si
Page 80 and 81: A) Striped dolphin 10 km B) Short-b
Page 82 and 83: dependent. For example, the number
Page 84 and 85: Figure 19. Predicted average densit
Page 86 and 87: ecosystem, eastern spinner dolphins
Page 88 and 89: Table 13. Variables selected for mo
Page 90 and 91: Table 14. Starting and final AIC va
Page 92 and 93: Table 17. Ratios of observed to pre
Page 94 and 95: species represented in the acoustic
Page 96 and 97: 0.29 (Risso’s dolphin) to 3.20 (n
Page 98 and 99: Figure 25. Sample 2005 validation p
Page 100 and 101: Table 18. (continued) 1991 1993 Nor
Page 102 and 103: Blue whales had the greatest deviat
Page 104 and 105: Table 20. Abundance (number of anim
Page 106 and 107: Table 22. Proportion of deviance ex
Page 108 and 109: Figure 27. Average density (AveDens
Page 110 and 111: Table 23. Effective degrees of free
Page 112 and 113: We attempted to build encounter rat
Page 114 and 115: 5.0 Conclusion The field of predict
Page 116 and 117: 6.0 Transition Plan The models of c
Page 118 and 119: needed to ensure that the SDSS rema
Page 120 and 121: Administrative Report LJ-07-02. NOA
Page 122 and 123: Forney KA, Barlow J (1993) Prelimin
Page 124 and 125: Redfern JV, Barlow J, Ballance LT,
Page 126 and 127: 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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