Length-weight relationships for 

 1 3 species of sharks from the 

 western North Atlantic 



Nancy E. Kohler 

 John G. Casey 

 Patricia A. Turner 



Narragansett Laboratory, Northeast Fisheries Science Center 

 National Marine Fisheries Service, NOAA 

 Narragansett, Rl 02882-1 199 



The rapid expansion of sport and 

 commercial fisheries for sharks in 

 the western North Atlantic has cre- 

 ated the need to manage the stocks 

 of several species of large sharks. 

 A fishery management plan for 

 sharks within the U.S. exclusive 

 economic zone (EEZ) of the Atlan- 

 tic Ocean (USDOC, 1992) was 

 implemented in 1993. The 39 spe- 

 cies of sharks included in the fish- 

 ery management plan are not man- 

 aged on an individual species ba- 

 sis, but are grouped into three spe- 

 cies groups — large coastal, small 

 coastal, and pelagic. Basic biologi- 

 cal information needed for stock 

 assessment is lacking for many of 

 these Atlantic sharks, including 

 minimum, maximum, and average 

 sizes, as well as length-to-weight 

 and length-to-length relationships. 

 These data are essential for under- 

 standing the growth rate, age struc- 

 ture, and other aspects of shark 

 population dynamics. 



Size conversions also have a prac- 

 tical value in fisheries. One mea- 

 sure currently in practice at nearly 

 all shark tournaments on the At- 

 lantic coast is the establishment of 

 minimum size limits and usually a 

 minimum weight. Since sizes must 

 be estimated at sea, means for con- 

 verting lengths to weights are es- 

 sential to anglers. Moreover, the 

 National Marine Fisheries Service 

 (NMFS) conducts an extensive At- 



lantic Shark Tagging Program us- 

 ing volunteer assistance of recre- 

 ational and commercial fishermen. 

 Commercial fishermen generally 

 are more confident in estimating 

 the weight of sharks being released, 

 and recreational fishermen in esti- 

 mating lengths. Conversions are 

 needed to change these estimates 

 into common size units for analysis. 



Length data on sharks worldwide 

 have been reported as total length 

 (Strasburg, 1958; Stevens, 1975, 

 1983; Stevens and Wiley, 1986; 

 Stevens and Lyle, 1989), alternate 

 length (Cailliet and Bedford, 1983; 

 Stick and Hreha, 1989), dorsal 

 length (Aasen, 1963, 1966), pre- 

 caudal length (Nakano et al., 1985; 

 Cliff et al., 1989), standard length 

 (Guitart Manday, 1975) and fork 

 length (Mejuto and Garces, 1984; 

 Casey and Pratt, 1985; Berkeley 

 and Campos, 1988). Most studies 

 include formulas to convert their 

 measurements to total length. To- 

 tal length measurements, however, 

 can vary considerably depending on 

 the placement of the caudal fin 

 (Branstetter et al., 1987). 



Published size relationships for 

 sharks from various regions of the 

 Atlantic Ocean and Gulf of Mexico 

 include studies on the blue shark, 

 Prionace glauca (Aasen, 1966; 

 Stevens, 1975); tiger shark, Galeo- 

 cerdo cuvier (Branstetter, 1981; 

 Branstetter et al., 1987); silky 



shark, Carcharhinus falciformis 

 (Guitart Manday, 1975; Bran- 

 stetter, 1987; Berkeley and Cam- 

 pos, 1988); bull shark, C. leucas 

 (Branstetter, 1981); spinner shark, 

 C. brevipinna (Branstetter, 1981); 

 night shark, C. signatus (Guitart 

 Manday, 1975; Berkeley and Cam- 

 pos, 1988); oceanic whitetip shark, 

 C. longimanus (Guitart Manday, 

 1975); finetooth shark, C. isodon 

 (Castro 1993); shortfin mako, 

 Isurus oxyrinchus (Guitart Man- 

 day, 1975; Mejuto and Garces, 

 1984); white shark, Carcharodon 

 carcharias (Casey and Pratt, 1985); 

 porbeagle shark, Lamna nasus 

 (Aasen, 1963; Mejuto and Garces, 

 1984); bignose shark, C. altimus 

 (Berkeley and Campos, 1988); big- 

 eye thresher shark, Alopias super- 

 ciliosus (Guitart Manday, 1975); and 

 scalloped hammerhead, Sphyrna 

 lewini (Branstetter, 1987). In re- 

 sponse to the immediate needs of 

 tournament officials and fisher- 

 men, and for management initia- 

 tives, we present length and weight 

 data for thirteen species of large 

 Atlantic sharks collected by the 

 Apex Predator Investigation (API) 

 of NMFS over a 29-year period. 



Materials and methods 



Length and weight data were col- 

 lected from sharks caught by rec- 

 reational and commercial fisher- 

 men and biologists along the U.S. 

 Atlantic coast from the Gulf of 

 Maine to the Florida keys during 

 1961 through 1989. Sharks were 

 caught primarily on rod and reel at 

 sport fishing tournaments and on 

 longline gear aboard research ves- 

 sels and commercial fishing boats. 

 Some data were obtained from 

 sharks that were harpooned or 

 taken in gill nets. Measurements 

 from a large white shark captured 

 off Rhode Island in 1991 were also 



Manuscript accepted 29 August 1994. 

 Fishery Bulletin 93:412-418 (1995). 



412 



