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Fishery Bulletin 92(1). 1994 



Figure 1 



Map of the survey area near Lee Stocking Island, Exuma Cays, Bahamas. Flood tidal cur- 

 rents (arrows) and the locations of queen conch, Strombus gigas, nursery habitats (cross- 

 hatched) are shown. Dashed lines separate the inner and outer bank regions and delineate 

 the study site. Areas south and west of the Brigantine Cays were not surveyed. 



bank was divided into an inner section from the 

 Brigantine Cays to a line mid-way between the Brig- 

 antines and Lee Stocking Island, and an outer sec- 

 tion from the mid-line to the cays at the eastern side 

 of the bank (Fig. 1). Each section is approximately 

 5 km wide. The rationale for this division was that 

 the outer section of the bank is flushed with oceanic 

 water on every tide, while the inner bank is flushed 

 only on extreme tides. Virtually all queen conch nurs- 

 eries in the Exuma Cays are found within the outer 

 5.0 km of the bank (Stoner et al., in press.) (Fig. 1). 

 The eastern shores of the Exuma Cays are char- 

 acterized primarily by steep aeolianite cliffs and 

 beach rock interspersed with a few high-energy 

 sandy beaches in coves, particularly on Lee Stock- 

 ing Island and Children's Bay Cay. The seagrass 

 Thalassia testudinum is found on shallow, soft-sedi- 

 ment platforms extending a short distance off the 

 sandy beaches. Most of the shallow nearshore, how- 

 ever, is hard-bottom covered with a short turf of the 

 green alga Cladophoropsis sp. The hard-bottom 

 habitat, interspersed with small patches of sand and 

 hard corals, is characteristic to 10-m depth. From 



10 to 20 m the bottom comprises mixed hard-bottom 

 and bare sand. Off Lee Stocking Island, corals form 

 a 2-km long steep ledge from 10 to about 18 m, but 

 a gradual slope to 25 m is typical of most of the 

 study area. Patchy sand, coral, and hard-bottom are 

 found between 20 and 30 m. 



Detailed hydrographic charts are not available for 

 the Exuma Cays; therefore, shelf bathymetry was 

 mapped with 540 electronic depth-sounder points, 

 corrected for tidal state, and positions acquired with 

 Global Positioning System (GPS) from the RV Chal- 

 lenger during summer 1991. GPS positions taken at 

 close intervals along the eastern shores of the is- 

 lands were used as zero-depth data points. Three- 

 dimensional plotting features of Systat 5.0 software 

 were used to provide a bathymetric chart for the 

 shelf region with 0, 2.5, 5, 10, 15, 20, 25 and 30 m 

 contours for depth at mean low tide. Total surface 

 area for each of the seven depth intervals was cal- 

 culated with a digitizing board and SigmaScan 3.9 

 software. The surface area of the inner and outer 

 bank regions was determined in a similar way with 

 the aid of topographic maps. 



