448 



Fishery Bulletin 92(2), 1994 



habitat indices to Anganuzzi et al.'s ( 1991) abun- 

 dance estimates. We used a subset of three en- 

 vironmental variables from those used here, to 

 enable use of existing, large data bases on 

 oceanography of the ETP, to allow computation 

 of environmental axes for years prior to 1986. 

 We found that, for some species, environmen- 

 tal variability does appear to influence abun- 

 dance estimates made from tuna vessel observer 

 data. We are now working on using environmen- 

 tal data to reduce error in dolphin abundance 

 estimates derived from both research vessel and 

 tuna vessel sightings data. Gerrodette et al. 1 

 applied the results of this study in a prelimi- 

 nary attempt to account for movements in and 

 out of the study area when estimating total 

 abundance of dolphins. 



Acknowledgments 



The efforts of many people were required to col- 

 lect and process the data used in this analysis. 

 Cetacean sightings were made and recorded by 

 S. Beavers, S. Benson, C. Bisbee, P. Boveng, K. 

 Brownell, S. Buckland, J. Caretta, J. Cotton, A. 

 Dizon, G. Friedrichsen, S. Hill, A. Hohn, W. 

 Irwin, A. Jackson, S. Kruse, C. LeDuc, R. LeDuc, 

 M. Lynn, M. Newcommer, R. Pitman, J. Raffetto, 

 K. Rittmaster, L. Robertson, R. Rowlett, S. 

 Sinclair, D. Skordal, B. Smith, P. Stangl, V. Thayer 

 and M. Webber. Oceanographic data were col- 

 lected by J. Echols, J. Ellingson, J. Fleishman, L. 

 Gearin, L. Lierheimer, B. McDonald, D. Niemer, 

 V. Philbrick, B. Tershey, V. Thayer, G. Thomas and 

 S. Strickland. C. Oliver, R. Holland, A. Jack- 

 son, R. Rasmussen and K. Blum contributed 

 data editing and processing. Holland contrib- 

 uted computer programming for the analyses 

 and produced the figures. We thank these 

 people, plus the officers and crew of the NOAA 

 research vessels David Starr Jordan and 

 McArthur for their contributions. Helpful com- 

 ments on various drafts were made by D. Au, J. 

 Barlow, L. Ballance, D. DeMaster, W. Perrin, 

 W. Perryman, P. Wade and two anonymous re- 

 viewers. Doug DeMaster provided enthusiastic 

 support and encouragement during the course 

 of this study. 



CANONICAL AXIS 2 



1 Gerrodette, T., P. C. Fiedler, and S. B. Reilly. 1991. 

 Including habitat variability in line transect estimation 

 of abundance and trends. NOAA-NMFS Admin. Rep. LJ- 

 91-37. 



1988 



10-1 r 



|» 120 110 '00 



1990 



130 120 110 100 W 80 



• While-belly Spinner dolphin a Eastern Spinner dolphin 



Figure 7 (Continued) 



