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Occurrence of neonate and juvenile 

 sandbar sharks, Carcharhinus plumbeus, 

 in the northeastern Gulf of Mexico 



John K. Carlson 



Southeast Fistieries Science Center 



National Manne Fisheries Service, NOAA 



3500 Delwood Beach Road, Panama City, Flonda 32408 



E-mail address carlsoniffbiofsuedu 



The sandbar shark, Carcharhinus 

 plumbeus, is a large, coastal spe- 

 cies of the western north Atlantic 

 occurring from Cape Cod, Massa- 

 chusetts, to Brazil, including the 

 Gulf of Mexico and Caribbean 

 (Bigelow and Schroeder, 1948; 

 Springer, 1960). Sandbar sharks 

 are targeted by commercial fisher- 

 ies and account for up to 60*^ of the 

 large coastal shark landings in U.S. 

 southern waters (NMFS, 1993). 

 Adults are highly migratory and 

 mostly congregate offshore. Neo- 

 nate and juvenile sandbar sharks, 

 on the other hand, are commonly 

 found in coastal nursery areas 

 where they feed ( Med vedetal., 1985) 

 and avoid predation ( Springer, 1967; 

 Branstetter, 1990) during summer 

 months. 



The presence of neonate and ju- 

 venile sandbar sharks has been 

 well documented in coastal areas of 

 the eastern United States. Springer 

 (1960) reported juvenile sandbar 

 sharks from Cape Cod, Massachu- 

 setts, to Cape Canaveral. Florida. 

 Juvenile sandbar sharks are abun- 

 dant in Chesapeake Bay and east- 

 ern shore of Virginia in less than 

 10 m (Medved and Marshall, 1981; 

 Musicketal., 1993). Castro (1993) 

 found neonate and juvenile sharks 

 in Bulls Bay, South Carolina. Pratt 

 and Merson' determined Delaware 

 Bay, New Jersey, as a major nurs- 

 ery area for neonate and juvenile 

 sharks. Further attempts to delin- 

 eate the extent of nursery areas for 



sandbar sharks along the U.S. east 

 coast continue (Damon, 1997; Pratt 

 and Merson'). 



Juveniles are not known to occur 

 in coastal areas of the eastern Gulf 

 of Mexico. The direct correlation of 

 juvenile sandbar shark survivor- 

 ship and future stock size (Cortes, 

 in press) requires delineation of 

 sandbar shark nursery areas. Thus, 

 if recruitment to the stock is as- 

 sumed to be entirely from sharks 

 from the U.S. east coast, then un- 

 derestimates of total population 

 size could occur and affect overall 

 stock assessments. This paper re- 

 ports on the occurrence of neonate 

 and juvenile sandbar sharks and 

 the potential nursery area of these 

 sharks in coastal waters of the 

 northeastern Gulf of Mexico. 



Materials and methods 



Sandbar sharks were captured from 

 October 1992 to October 1997 as part 

 of studies on the distribution and 

 abundance of sharks in the eastern 

 Gulf of Mexico. Because sampling 

 had various objectives, the variabil- 

 ity in sampling design and methods 

 precluded quantification of a valid 

 time series of abundance (e.g. CPUE) 

 from 1992 to 1997. In general, gill 

 nets varied in height from 1.52 to 

 3.04 m and ranged in length from 

 30.4 to 273.6 m, and mesh sizes from 

 6.9 to 20.3 cm stretched mesh. Each 

 net, regardless of size, was anchored 



at both ends and fished on the bot- 

 tom. Longlines, which ranged in 

 length from 76 to 335 m and con- 

 sisted of 10-60 hooks, were anchored 

 at both ends and fished so that one 

 half fished the "midwater" and the 

 other the "bottom." Gangions were 

 0.9-1.8 m long and hooks were size 

 3/0 and 12/0 ( Mustad). Usually men- 

 haden (Brevoortia spp. ) was the bait 

 of choice. 



The nets or longlines, or both, were 

 set over a 24-h period at various 

 times. Gill nets and longlines were 

 checked, or checked and pulled, and 

 sharks were removed throughout 

 each sampling period. Surface water 

 temperature (°C), salinity (ppt), and 

 light transmission (cm) were mea- 

 sured daily at each station. 



After they were caught, sharks 

 were sexed and measured (total 

 length, TL) to the nearest mm. 

 Sharks that were in poor condition 

 were euthanized for life history in- 

 formation; those in good condition 

 were tagged with a multirecapture, 

 nylon-head, dart tag (Hueter and 

 Manire'-) and released. Sampling 

 took place April to October of each 

 year, occasionally from November 

 to March. 



Study area 



Sampling sites were located in four 

 major areas along the northeastern 

 portion of the Gulf Apalachee Bay 

 to St. Andrews Bay, Florida (Fig. 1). 



1 Pratt. H. L.. and R. R. Merson. 1996. 

 Delaware Bay sandbar shark nursery pi- 

 lot study. Narragansett Laboratory, Na- 

 tional Marine Fisheries Service. NOAA. 

 Progress report, 23 p. 



- Hueter, R. E., and C. A. Manire. 1994. 

 By-catch and catch-release mortality of 

 small sharks and associated fishes in the 

 estuarine nursery grounds of Tampa Bay 

 and Charlotte Harbor. NOAA NMFS/ 

 MARFIN Program. Project Rep. NA17FF- 

 0378-01, 183 p. 



Manuscript accepted 13 May 1998. 

 Fish. Bull. 97:387-391 (1999). 



