53 



Abstract.— Nucleotide sequences of a 

 394-396 base pair fragment of mito- 

 chondrial (mt) DNA, including parts of 

 the cytochrome b and threonine tRNA 

 genes, were obtained for eleven species 

 of carcharhiniform sharks important to 

 the U.S. Atlantic large coastal shark 

 fishery. Sequences were used to predict 

 sizes of restriction fragments produced 

 by 118 restriction enzymes with unique 

 recognition sequences. Seven restric- 

 tion enzymes were chosen that produce 

 an array of species-specific fragments 

 for the eleven species. Geographic 

 variation was examined in several spe- 

 cies by surveying specimens from geo- 

 graphically distant regions. Only one 

 of the species, the spinner shark 

 (Carcharhmus brevipinna), exhibited 

 geographic variation in mtDNA restric- 

 tion fragments. The sandbar shark (C. 

 p/(/m6eus) exhibited sequence polymor- 

 phism that did not produce differences 

 in restriction patterns of any of the 

 seven enzymes. We detected numerous 

 differences between observed restric- 

 tion patterns in ten tiger sharks 

 (Galeocerdo cuvier) and patterns pre- 

 dicted from a published sequence. We 

 concluded that the published sequence 

 is incorrect. Amplification of a single 

 PCR product from a sample of meat, 

 digestion of aliquots of the product with 

 restriction enzymes, and sizing of frag- 

 ments on agarose gels is an efficient 

 method for distinguishing among these 

 eleven carcharhiniform sharks. The 

 method can be applied when only a 

 small amount of tissue is available. 



Genetic identification of sharks in the 

 U.S. Atlantic large coastal shark fishery* 



Edward J. Heist 

 John R. Gold 



Center for Biosystematics and Biodiversity 



Texas A&M University, College Station, Texas 77843-2258 



Present address: Cooperative Fisheries Research Laboratory 



Department of Zoology 



Southern Illinois University 



Carbondale, Illinois 62901-6511 

 E-mail addresss (for E J Heist): edheist@siu.edu 



Manuscript accepted 19 March 1998. 

 Fish, Bull. 97:53-61 (1999). 



The U.S. Atlantic large coastal 

 shark fishery grew rapidly during the 

 1980s when commercial landings in- 

 creased from 135 metric tons (t) ih 

 1979 to a high of 7122 t in 1989 

 (NMFS, 1993). In 1993, a quota of 

 2750 1 was established; in 1997 this 

 quota was halved to 1375 t in order 

 to rebuild depleted shark stocks. 

 This fishery targets several species 

 of sharks that are valued for fins 

 (exported to Asia) and meat (sold 

 domestically). Because of the slow 

 growth rate, high age at maturity, 

 and low fecundity of most shark 

 species (Pratt and Casey, 1990), 

 commercial shark fisheries typically 

 collapse after a brief period unless 

 strict conservation measures are 

 implemented (Holden, 1974, 1977; 

 Hoenig and Gruber, 1990). The 1993 

 shark fishery management plan di- 

 vided exploited species into three 

 categories: large coastal sharks, 

 small coastal sharks, and pelagic 

 sharks (NMFS, 1993). The category 

 that grew most rapidly was the 

 large coastal shark fishery, which 

 is dominated by several species of 

 requiem sharks and two species of 

 hammerhead sharks. 



Sound management of a multi- 

 species fishery requires information 

 on the vulnerability of each compo- 

 nent of the fishery. Differences in 

 life history characters, e.g. intrin- 

 sic growth rates, locations of nurs- 

 ery areas, or migration within or 



outside of the fished area, can re- 

 sult in different vulnerabilities to 

 overfishing of exploited species. For 

 example, Musick et al. (1993) re- 

 ported a relative decline in the dusky 

 shark (Carcharhinus obscurus) off 

 Virginia during expansion of the 

 large coastal shark fishery. Thus, it 

 is important to estimate catches on 

 a species-by-species basis and to 

 implement species-specific manage- 

 ment. In the event that regulations 

 (e.g. moratoria or minimum size 

 limits) are applied to individual spe- 

 cies, enforcement will rely on iden- 

 tification of protected species within 

 the catch. The manner in which 

 sharks are processed at sea, how- 

 ever, makes it difficult to accurately 

 identify species at landing. Sharks 

 typically are headed, gutted, and 

 finned (i.e. fins are removed), thus 

 destroying morphological charac- 

 ters necessary for species identifi- 

 cation. Although Castro ( 1993) rec- 

 ommended a suite of characters for 

 identification of shark carcasses, 

 the limited number of available 

 morphological characters makes it 

 difficult to distinguish among sev- 

 eral species. Martin (1993) sug- 

 gested that use of restriction-frag- 



* This paper represents number XVIII in the 

 series "Genetic studies in marine fishes" 

 and contribution number 48 of the Center 

 for Biosystematics and Biodiversity at 

 Texas A&M University, College Station, 

 Texas 77843-2258. 



