FISHERY BULLETIN: VOL. 81, NO. 1 



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SPRING 



FALL 



Figure 18.— Catch per unit effort (CUE) in sharks/100 hooks 

 per hour and number of Atlantic sharpnose sharks landed dur- 

 ing longline operations. Ninety percent of these offshore land- 

 ings were gravid females. 



Since adult female Atlantic sharpnose sharks 

 were collected inshore only during summer 

 months, the data suggest that females migrate 

 inshore in late spring or summer to pup and 

 mate, whereupon they return offshore again to 

 overwinter. During June and July sharpnose 

 shark pups with a fresh umbilical scar (in some 

 cases the scar was actually an open slit) could be 

 collected from the littoral zone. It is likely that 

 special nursery areas exist for many shark spe- 

 cies (Springer 1967), although the existence of 

 specific pupping or nursery grounds for the At- 

 lantic sharpnose sharks could not be conclusively 

 established from this study. However, since new- 

 born pups were never taken from deep waters in 

 spite of intensive trawling, it is reasonable to 

 suppose that the pups were born in shallow water. 

 Perhaps the shallows of the northern Gulf of 

 Mexico's extensive barrier island system serve 

 as pupping/nursery grounds for the Atlantic 

 sharpnose shark. 



Sex Ratio 



Sex of the Atlantic sharpnose sharks could be 

 determined by clasper examination in embryos 

 as small as 5.0 cm TL. The sex ratio through most 

 of gestation could therefore be determined. The 

 sex ratio early in development and of near-term 

 embryos was found to be 1:1. One-hundred and 

 fifty male and 155 female embryos were exam- 

 ined. These data suggest that the sex ratio at par- 

 turition is also 1:1. 



Among adults sampled, the sex ratio was 



found to be one sided in favor of females. During 

 this study 33 adult male and 91 adult female 

 sharpnose sharks were collected representing a 

 1:2.8 ratio. During offshore longlining 90% of the 

 catch consisted of gravid adult female sharpnose 

 sharks. This condition in sharpnose shark is not 

 without precedent, as it has been observed in 

 other shark species. Springer (1940), discussing 

 Carcharhinus milberti and Carcharhinus ob- 

 scurus, stated that in both species females out- 

 number males. Clark and von Schmidt (1965) 

 found a similar situation in Galeocerdo cuvieri. 



ACKNOWLEDGMENTS 



This research was funded by a fellowship 

 awarded to the author by the Dauphin Island Sea 

 Laboratory. Robert Shipp provided helpful as- 

 sistance. Special thanks are due David Nelson 

 for reviewing the manuscript, Snead Collard for 

 supplying shark rodeo data, Benny Rohr for sup- 

 plying NMFS data, and John Gourley for supply- 

 ing data. 



I am also very grateful for the assistance pro- 

 vided by the faculty and staff of the Dauphin 

 Island Sea Laboratory. Likewise, I wish to thank 

 the graduate students of the University of South 

 Alabama, especially Rick Blaise, Steve Branstet- 

 ter, Don Marley, and Austin Swift. 



LITERATURE CITED 



Bass, A. J., J. D. D'Aubrey, and N. Kistnasamy. 



1975. Sharks of the east coast of southern Africa. III. The 

 families Carcharhinidae (excluding Mustelus and Car- 

 charhinus) and Sphyrnidae. South Afr. Assoc. Mar. 

 Biol. Res., Invest. Rep. 38, 100 p. 

 Baughman, J. L., and S. Springer. 



1950. Biological and economic notes on the sharks of the 

 Gulf of Mexico, with especial reference to those of Texas, 

 and with a key for their identification. Am. Midi. Nat. 

 44:96-152. 

 Bigelow, H. B., and W. C. Schroeder. 



1948. Sharks. In A. E. Parr and Y. H. Olsen (editors), 

 Fishes of the western North Atlantic, Part 1, p. 59-546. 

 Mem. Sears Found. Mar. Res., Yale Univ. 1. 

 Budker, P. 



1971. The life of sharks. Columbia Univ. Press, N.Y., 

 222 p. 

 Clark, E., and K. von Schmidt. 



1965. Sharks of the central Gulf coast of Florida. Bull. 

 Mar. Sci. 15:13-83. 

 Compagno, L. J. V. 



1978. Sharks. In W. Fischer (editor), FAO species iden- 

 tification sheets for fishery management purposes; west- 

 ern central Atlantic, Vol. 5, unpaginated. 

 Lack, D. 



1954. The natural regulation of animal numbers. Ox- 



72 



