Stoner and Davis: Outplanting queen conch. Strombus gigas 



391 



site (Stoner and Sandt, 1991, 1992). This research 

 provides further insight into the potential for using 

 cultured conch in a stock enhancement program, and 

 elucidates possible limitations. 



Methods and materials 



Site description 



During the 15-month period from March 1990 to May 

 1991, all field outplant, enclosure, and tether experi- 

 ments were carried out at two different sites desig- 

 nated CI and C2 (Fig. 1). The study sites, each a 

 100-m square area delineated by buoys, were located 

 0.8 km west of Children's Bay Cay and 5.0 km south- 

 east of the Caribbean Marine Research Center field 

 station on Lee Stocking Island, in the southern 

 Exuma Cays, Bahamas (lat. 23°44.5'N, long. 

 76°04.4'W) (Fig. 2). A shallow sand bank is to the 

 southwest. The two sites are in a homogeneous 

 seagrass meadow of Thalassia testudinum with mod- 

 erate shoot density (500-700 shootsrrr 2 ) in 3.2 m 

 depth. Tidal currents run northwest (flood) and 

 southeast (ebb) at velocities to 50 cm-sec -1 with a 

 tidal range of approximately 1.0 m. Clear water from 

 the Exuma Sound flows over the sites on flood tides. 



resulting in high underwater visibility that facili- 

 tated field experiments and recovery of tagged conch. 



Site CI was established within a well-studied 

 queen conch nursery area that has carried as many 

 as 500,000 individuals in densities between 0.5 and 

 2.0 conch-nr 2 since at least 1984 (Wicklund et al., 

 1991; Stoner et al. 1993, unpubl. data). Site CI has 

 been the location of numerous investigations on conch 

 mass migration (Stoner et al., 1988; Stoner 1989a), 

 distribution (Stoner and Waite, 1990), and diet 

 (Stoner and Waite, 1991). 



Site C2 was approximately 0.3 km to the southeast 

 of site CI and had very few juvenile conch (< 0.05 

 conchm -2 ). In 1988, small-scale transplants in en- 

 closures showed that young conch survived and grew 

 at nearly identical rates at sites C 1 and C2 despite the 

 absence of wild conch at the latter (Stoner and Sandt, 

 1992). This suggested that certain unpopulated areas 

 of the extensive seagrass meadows in the Exuma Cays 

 could support outplanted conch stocks. 



Density estimates were obtained by counting the 

 conch (tagged and untagged) in as many as 20 hap- 

 hazardly placed circles of 4-m radius at each site at 

 five different times during the experiment. The pur- 

 pose of these estimates was to assess the natural 

 population of conch prior to the transplant, to exam- 



Burial 



Density o = Macrophyte Analysis s = Survey GP = Growth Penod M = Cumulative Mortality 



Figure 1 



Calendar of free-ranging, enclosure, and tether experiments; showing duration of experiments, 

 data collection points, and time periods for growth and mortality of queen conch, Strombus gigas. 

 The total study period extended from March 1990 to May 1991. See text for descriptions of the 

 measurements and experiments. 



