426 



Fishery Bulletin 89(3). 1991 



the subspecies. Others include international application 

 of a stock quota, complete bans on this type of fishing, 

 and increased focus on technological efforts to reduce 

 fishing mortality rates, to name a few. 



The Central American spinner 

 ("Costa Rican spinner") 



The number of "Costa Rican" schools sampled was too 

 small for meaningful separate analysis (2 of 1454; Fig. 

 3) and the effect on the analyses of including them in 

 the pooled samples can be considered negligible. In any 

 case, the range of the Central American spinner S. I. 

 centroamericana as presently understood (a coastal 

 strip about 50nmi wide between about 13° and 7°N) 

 does not overlap those of the eastern subspecies or the 

 "whitebelly" hybrid/intergrade forms (Perrin 1990). 

 This range could serve as a management unit for the 

 subspecies. 



Acknowledgments 



The data used in this study were collected by biological 

 technicians aboard commercial tuna seiners. We wish 

 to thank these people and the captains and crews of 

 the seiners; the research would have been impossible 

 without their efforts and support. The sampling pro- 

 grams were supported by the U.S. National Marine 

 Fisheries Service and the Inter-American Tropical 

 Tuna Commission; both agencies gave us full access 

 to data and specimens. R.B. Miller and others pro- 

 cessed reproductive samples to determine sexual 

 maturity. K.E. Wallace and R. Rassmussen provided 

 data extraction services. R.C. Holland gave invaluable 

 assistance with the contouring. J. Barlow carried out 

 the Fisher's exact tests. R.M. Allen drafted the 

 figures. J. Barlow, M. Scott, A.E. Dizon, I. Barrett, 

 and S.B. Reilly reviewed the manuscript and offered 

 many useful suggestions. 



Citations 



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



1985 Dolphin habitats in the eastern tropical Pacific. Fish. 

 Bull., U.S. 83:623-643. 

 Barlow, J. 



1984 Reproductive seasonality in pelagic dolphins (Stenella 

 spp.): Implications for measuring rates. Rep. Int. Whaling 

 Coram. Spec. Issue 6:191-198. 

 Dixon, W.J., M.B. Brown, L. Engelman, and R.I. Jennrich 

 (editors) 



1990 BMDP statistical software manual, vol. 1. Univ. Calif., 

 Berkeley, 629 p. 



Dizon, A.E., S.O. Southern, and W.F. Perrin 



1991 Molecular analysis of mtDN A types in exploited popula- 

 tions of spinner dolphins (Stenella longirostris). In Hoelzel, 

 A.R. (ed.) Genetic ecology of whales and dolphins, p. 183-202. 

 Rep. Int. Whaling Comm. Spec. Issue 13. 



Douglas, M.E., G.D. Schnell, and D.J. Hough 



1986 Variation in spinner dolphins (Stenella longirostris) from 

 the eastern tropical Pacific Ocean: Sexual dimorphism in 

 cranial morphology. J. Mammal. 67:537-544. 



Gilpatrick, J.W. Jr., W.F. Perrin, S. Leatherwood, and 

 L. Shiroma 



1987 Summary of distribution records of the spinner dolphin, 

 Stenella longirostris, and the pantropical spotted dolphin, 



5. attenuata, from the western Pacific Ocean, Indian Ocean 

 and Red Sea. NOAA Tech. Memo. NOAA-TM-NMFS-SWFC- 

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

 42 p. 



Hall, M.A., and S.D. Boyer 



1990 Incidental mortality of dolphins in the tuna purse-seine 



fishery in the eastern Pacific Ocean during 1988. Rep. Int. 



Whaling Comm. 40:461-462. 

 Holt, R.S., and A. Jackson 



1987 Report of a marine mammal survey of the eastern tropical 

 Pacific aboard the research vessel McArthur July 29-December 



6, 1986. NOAA Tech. Memo. NOAA-TM-NMFS-SWFC-77, 

 NMFS Southwest Fish. Sci. Cent., La Jolla, CA 92038, 161 p. 



1988 Report of a marine mammal survey of the eastern tropical 

 Pacific aboard the research vessel McArthur, July 30-Decem- 

 ber 10, 1987. NOAA Tech. Memo. NOAA-TM-NMFS-SWFC- 

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

 143 p. 



Mayr, E. 



1970 Population, species and evolution. Harvard Univ. Press, 

 Cambridge, 453 p. 

 Perrin, W.F. 



1972 Color patterns of spinner porpoises (Stenella cf. S. longi- 

 rostris) of the eastern Pacific and Hawaii, with comments on 

 delphinid pigmentation. Fish. Bull., U.S. 70:983-1003. 



1975 Variation of spotted and spinner porpoise (genus Ste- 

 nella) in the eastern Pacific and Hawaii. Bull. Scripps Inst. 

 Oceanogr. 21, 206 p. 



1990 Subspecies of Stenella longirostris (Mammalia: Cetacea: 

 Delphinidae). Proc. Biol. Soc. Wash. 103:453-463. 

 Perrin, W.F., and J.R. Henderson 



1984 Growth and reproductive rates in two populations of spin- 

 ner dolphins, Stenella longirostris, with different histories of 

 exploitation. Rep. Int. Whaling Comm. Spec. Issue 6:417-430. 

 Perrin, W.F., J.M. Coe, and J.R. Zweifel 



1976 Growth and reproduction of the spotted porpoise, Stenella 

 attenuata, in the offshore eastern tropical Pacific. Fish. Bull., 

 U.S. 74:229-269. 



Perrin, W.F., D.B. Holts, and R.B. Miller 



1977 Growth and reproduction of the eastern spinner dolphin, 

 a geographical form of Stenella longirostris in the eastern 

 tropical Pacific. Fish. Bull., U.S. 75:725-750. 



Perrin, W.F., P. A. Sloan [Akin], and J.R. Henderson 



1979a Taxonomic status of the "southwestern stocks" of spin- 

 ner dolphin Stenella longirostri and spotted dolphin S. attenu- 

 ata. Rep. Int. Whaling Comm. 29:175-184. 

 Perrin, W.F., W.E. Evans, and D.B. Holts 



1979b Movements of pelagic dolphins (Stenella spp.) in the 

 eastern tropical Pacific as indicated by results of tagging, with 

 summary of tagging operations, 1969-76. NOAA Tech. Rep. 

 NMFS SSRF-737, 14 p. 



