The Use of Genetic Analysis in Differentiating Geographic Stocks of Rough-Toothed Dolphin, (Steno bredanensis)

Formica, Palma M., Frank Cipriano, and Hal Markowitz
Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132

Little is known about the life history of the rough-toothed dolphin, Steno bredanensis, except that they are typically found within deep tropical, subtropical, and warm temperate waters, usually above 25º C. Limited information about their distribution has been derived from occasional observations of live individuals and opportunistic studies of stranded animals. Some specimen material and stomach content information has also been collected, mainly by the U.S. tuna fishery observer program in the Eastern Tropical Pacific.

Molecular genetic methods may prove a tool useful in distinguishing genetically distinct stocks of rough-toothed dolphins across their range, using tissue samples collected from strandings, bycatch, and live-display animals. Our preliminary genetic analysis of 17 such samples has already revealed variation between individuals from the Pacific, the Atlantic and the Gulf of Mexico. Such variation may be important in assessment of the potential impact of incidental and directed catches in some portions of the total species range. The continuation of this study will expand the geographic extent of analysis to additional ocean basins and sub-areas within the Pacific and Atlantic. Expansion of the geographic scope of the study will provide a more accurate representation of genetic structure over the range of the rough-toothed dolphin.