664 



Abstract. ^The Atlantic sharpnose 

 shark, Rhizoprionodon terraenovae, is 

 a small coastal shark that is harvested 

 in both directed and nondirected fish- 

 eries throughout its range. Because 

 pups of this species are found both 

 along the southeastern U.S. Atlantic 

 coast and the Gulf of Mexico, it is pos- 

 sible that multiple isolated breeding 

 stocks exist. Restriction fragment 

 length polymorphism analysis of mito- 

 chondrial DNA was used to test the 

 hypothesis that Atlantic sharpnose 

 sharks from the U.S. Atlantic coast and 

 the western Gulf of Mexico have iden- 

 tical mitochondrial haplotype frequen- 

 cies and therefore no apparent genetic 

 stock structure. Seven mitochondrial 

 haplotypes were detected among 52 in- 

 dividuals. The distribution of haplo- 

 types between samples did not differ 

 significantly from homogeneity iP= 

 0.694), indicating that the null hypoth- 

 esis of a single breeding population 

 could not be rejected. 



Mitochondrial DNA diversity and 

 divergence among sharpnose sharks, 

 Rhizoprionodon terraenovae, from the 

 Gulf of Mexico and Mid-Atlantic Bight* 



EdwardJ. Heist** 

 John A. Musick 

 John E. Graves 



School of Marine Science, Virginia Institute of Marine Science 

 College of William and Mary, Gloucester Point, Virginia 23062 

 e-mail address E-heist@tamu edu 



Manuscript accepted 14 May 1996. 

 Fishery Bulletin 94:664-668 ( 1996) 



The Atlantic sharpnose shark, 

 Rhizoprionodon terraenovae, is a 

 small (maximum length 110 cm to- 

 tal length) coastal shark that inhab- 

 its the east coast of North America 

 from New Brunswick, Canada, to 

 Yucatan, Mexico (Compagno, 1984). 

 This species is abundant along the 

 southern U.S. Atlantic coast and is 

 second only to the sandbar shark, 

 Carcharhinus plumbeus, in longline 

 catches in Virginia (Musick et al., 

 1993). It supports a large recre- 

 ational fishery off Texas (Parrack 1 ) 

 and is an important species in the 

 Mexican shark longline fishery 

 (Applegate et al., 1993). In addition 

 to being caught in directed fisher- 

 ies, the Atlantic sharpnose shark is 

 frequently taken by shark long- 

 liners targeting large coastal spe- 

 cies (Branstetter and McEachran, 

 1986; Russell, 1993) as well as by 

 commercial shrimp trawlers (Bran- 

 stetter, 1981; Parrack 1 ); however, 

 the implementation of turtle ex- 

 cluder devices (TED's) has produced 

 the additional benefit of reducing 

 bycatch of sharks (Branstetter 2 ). 

 Atlantic sharpnose sharks travel in 

 sex-segregated schools, as noted by 

 the disparate sex ratios of adults 

 captured by longlines (Branstetter, 

 1981; Musick et al., 1993). The ges- 

 tation period for this species is 

 about ten to twelve months, and 



parturition takes place from April 

 to June in the northern Gulf of 

 Mexico (Branstetter, 1981; Parsons, 

 1983) and from May to June in 

 South Carolina (Castro, 1993). 



The most recent fishery manage- 

 ment plan for sharks in the coastal 

 Atlantic waters of the United States 

 (NMFS 3 ) divides sharks into three 

 categories for management pur- 

 poses; pelagic species, large coastal 

 species, and small coastal species. 

 Currently catches of small coastal 

 species (predominantly the Atlantic 

 sharpnose shark) are not regulated 



* Contribution 1933 of the Virginia Insti- 

 tute of Marine Science, School of Marine 

 Science, College of William and Mary, 

 Gloucester Point, Virginia 23062. 

 ** Present address: Department of Wildlife 

 and Fisheries Sciences, Texas A&M Uni- 

 versity, College Station, Texas 77843-2258. 

 E-mail address: E-Heist@tamu.edu. 



1 Parrack, ML. 1990. A study of shark 

 exploitation in U.S. Atlantic coastal wa- 

 ters during 1986-1989. NOAA, Natl. 

 Mar. Fish. Serv., Southeast Fisheries 

 Science Center, Miami, Florida. 



2 Branstetter, S. 1995. Gulf and South 

 Atlantic Fisheries Development Founda- 

 tion, Suite 997, Lincoln Center, 5401 W. 

 Kennedy, Tampa, Florida 33609. 

 Personal commun. 



3 NMFS. 1993. Fishery management 

 plan for sharks of the Atlantic Ocean. 

 U.S. Dep. Commer, NOAA, Southeast 

 Regional Office, St. Petersburg, FL, p. 

 1-167. 



