A Review of Elasmobranch Reproductive Behavior with a Case Study on the Nurse Shark, Ginglymostoma Cirratum
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Elasmobranch reproductive behavior has been inferred from freshly caught specimens, laboratory examinations of reproductive structures and function, or determined from direct observations of captive or free swimming wild animals. Several general behaviors have been described including seasonal sexual segregation, courtship and copulation. Courtship behavior was inferred for many species from the presence of scars and tooth cuts on the female's body, and noted in more detail from underwater observations. Copulation has been directly observed in captive settings for several species of elasmobranchs in large aquaria, and in the wild for three species of urolophids and for Triaenodon obesus and Ginglymostoma cirratum. A detailed ‘case history’ of nurse shark reproductive behavior is presented that may be used as a template for future work on shark reproductive behavior of other species. Our studies, using diver identifiable tags and in situ behavioral observations, provide unprecedented information on social structure and mating behavior in this species. Since 1993, 115 G. cirratum, 45 adults and 70 juveniles have been tagged in the Dry Tortugas, Florida. Observations show that adult males visit the study site every year with three males dominant. Individual adult females visit the study area to mate in alternate years. Polygyny and polyandry are common. Future research on reproductive behavior of elasmobranchs should address questions on male access to females, sexual selection and dominance hierarchies.
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