Fishery Bulletin 90|l). 1992 



Year 



Figure 13 



Unsraoothed abundance trends of eastern stock of spinner 

 dolphin Stenella longirostris in the eastern tropical Pacific, 

 estimated from research (solid line) and tuna vessel data. Ver- 

 tical bars are ±2 standard errors. 



IX 8 



o 



c 



(0 



■□ 

 c 



< 



> 



^ 2 



0) 



a: 



Figure 15 



Unsmoothed abundance trends of northern, central, and 

 southern stocks of common dolphin Delphinus delphis in the 

 eastern tropical Pacific, estimated from research (solid line) 

 and tuna vessel data. Vertical bars are ± 2 standard errors. 



Acknowledgments 



We are grateful to Dr. J. Joseph, Dr. M. Hall, and 

 Dr. M. Scott for comments on the methods outlined 

 here, and to two reviewers and Dr. L. Jones for their 

 constructive comments and criticisms. We also ac- 

 knowledge the recent and continuing efforts of the 

 Southwest Fisheries Science Center to evaluate 

 methods for analyzing tuna vessel and research vessel 

 sightings data; their program of work forced us to 

 address more carefully the issue of how to estimate and 

 test for trends in abundance. 



Citations 



Anganuzzi, A. A., and S.T. Buckland 



1989 Reducing bias in estimated trends from dolphin abun- 

 dance indices derived from tuna vessel data. Rep. Int. Whal- 

 ing Comm. 39:323-334. 

 Anganuzzi, A. A., S.T. Buckland. and K.L. Cattanach 



1991 Relative abundance of dolphins associated with tuna in 

 the eastern tropical Pacific, estimated from tuna vessel sight- 

 ings data for 1988 and 1989. Rep. Int. Whaling Comm. 41: 

 497-506. 

 Au, D., W.L. Perryman, and W. Perrin 



1979 Dolphin distribution and the relationship to environmental 

 features in the eastern tropical Pacific. Admin. Rep. LJ-79-43, 

 Southwest Fish. Sci. Cent., NMFS, NOAA, La Jolla, CA 92038, 

 59 p. 



