PRELIMINARY STUDIES ON THE EARLY LIFE HISTORY OF THE 

 QUEEN CONCH Strombus gigas IN THE EXUMA CAYS, BAHAMAS 



Robert I. Wicklund, Lucinda J. Hepp, and Geraldine A. Wenz 



Caribbean Marine Research Center 



Lee Stocking Island, Exuma Cays, Bahamas, and 



Riviera Beach, Florida 33404 



ABSTRACT 



The Caribbean Marine Research Center has initiated a study 

 on the life history of the queen conch Strombus gigas in the 

 Exuma Cays, Bahamas. Nursery grounds of S^ gigas in the 

 southern Exumas are described. Surveys of a major nursery area 

 conducted from October through November 1984 resulted in a count 

 of 570,000 juvenile 0+ and l+-year-class conch within a total 

 area of 386,000 m . Average density of the conch within the area 

 was 1.48/m . Average densities within grass beds and adjacent 

 sand shoals were 1.72/m^ and 0.76/m , respectively. Modes of 

 length-frequency curves were 8.0 cm for May 1985 and 11.0 cm for 

 February 1986. Seasonal distribution and behavior of deepwater 

 adults are also described. 



INTRODUCTION 



The queen conch ( Strombus gigas ) is one of the most 

 important marine species in the Caribbean region. It has been 

 second only to finfish as a harvested resource for the past 

 century (Brownell and Stevely 1981). Its popularity as a food 

 source, however, has resulted in depletion of the species in 

 southern Florida, the Bahamas and most of the Caribbean and 

 Bermuda. The species has been so depleted in Florida that the 

 State has closed the fishery completely. In the Exuma Cays, 

 Bahamas, adult queen conch are no longer found in shallow waters 

 where they were once abundant (Richard Ellis, pers. comm. ). Most 

 adult conch in this area are located in relatively deep channels 

 (>6 m) and offshore, out of reach of most breath-hold divers. 



A paucity of data concerning the life history of the queen 

 conch existed until recently (Berg 1976; Brownell et al . 1976; 

 Hesse 1979; Jory 1982; Ballantine and Appeldoorn 1983; Wood and 

 Olson 1983; Appeldorn 1985; Iversen et al . 1986; Iversen et al. 

 1987). The recent development of hatchery techniques has 

 provided a better understanding of the early life stages of S . 

 gigas (Brownell et al . 1976; Iversen 1983; Siddall 1983; 

 Appeldoorn and Sanders 1984). 



Randall (1964) made some early observations concerning 

 predation on juvenile and adult queen conch and their migration. 

 Recent studies suggest predation to be the most important factor 



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