IVERSEN ET AL.: BIOLOGICAL DATA ON QUEEN CONCHS 



measure market weight. Significant differences in 

 weight-length and whole animal weight-market 

 weight relationships of conchs among cays were 

 determined by analysis of covariance. Survival rates 

 were obtained from the decrease in numbers of 

 tagged queen conch at each of the tagging sites 

 using Jackson's formula for monthly estimates and 

 Heincke's formula for annual estimates as described 

 in Everhart et al. (1975). 



We used pens and cages of varying sizes to 

 evaluate the feasibility of intensive mariculture. Six 

 pens, each 25 m-, were constructed with walls of 

 monofilament webbing 30 cm high, held up by buoys. 

 Pen walls were held in close contact with the bottom 

 by heavy chains and stakes driven into the bottom, 

 and were stocked with conchs 10-15 cm at densities 

 of 1 or 2 conchs/m^. Tagged conchs in this size 

 range released in the vicinity of the pens served as 

 controls. 



Two additional large pens, 90 and 100 m^ in 

 area, were planted with 1 conch/m^, the conch 

 in the size range of 10-15 cm. Various studies 

 on growth and survival in pens ran from 1 to 15 

 months. 



Three wooden floating cages were used to mea- 

 sure growth and survival of small conchs (2-5 cm) 

 over a 1-yr period. They were covered with fine 

 NITEX 4 mm screening and measured 1 x 1 x 0.6 

 m, stocked with 50 conchs; 0.61 x 0.61 x 0.61 m, 

 stocked with 10 conchs; and 1.6 x 1.2 x 0.6 m, 

 stocked with 100 conchs. 



Searches for small, young-of-the-year queen conch 

 (<3 cm) were made by towing a dredge, by siev- 

 ing sand samples with 4 mm mesh, by towing 

 divers, by walking and digging on tide flats, by tow- 

 ing a shrimp try net (3 m opening and 1.3 cm 

 stretched mesh), and by a suction dredge (Iversen 

 et al. 1986). 



To assess density of wild queen conch stocks in 

 shallow water, counts were made along 100 m 

 transects perpendicular and parallel to the shore. 

 All queen conchs lying within 1 m of either side of 

 the transect were counted. Significant differences 

 in density of conchs among cays were tested by 

 analysis of variance. 



Most searches for queen conch were made dur- 

 ing the day. To determine if this animal's bury- 

 ing activity varied between day and night, we con- 

 ducted day-night counts at several cays and in our 

 pens, and found no differential burying activity. 

 Previous studies in the Virgin Islands (Randall 1964) 

 and Puerto Rico (Appeldoorn and Ballantine 1983) 

 reported no day-night differences in burying 

 activity. 



RESULTS AND DISCUSSION 



Queen Conch Distribution 

 and Movement 



Queen conchs sampled ranged from 2 to 26 cm in 

 length (Fig. 2). The smallest conchs (<10 cm) were 

 found on tidal flats, in shallow waters (<1 m), mostly 

 on sandy bottoms with depressions. The largest 

 juveniles were found in high concentrations near 

 shores of cays, many exposed on low tides. Concen- 

 trations of adults with flared lips almost without ex- 

 ception were found in deep water (>3 m). Juveniles 

 were found associated with cays having tidal flats, 

 available food (microalgae and detritus), beaches 

 with a gradual slope, and good water circulation. 

 None was found in the large, open shallow- water 

 areas between cays. 



On all 23 field trips, young-of-the-year queen 

 conchs were sought in the course of our regular field 

 activities. The largest concentrations of young were 

 found on the tidal flats between Bird Cay and Cat 

 Cay (Iversen et al. 1986). Lack of shell epibionts on 

 conchs and extensive searching suggested that small 

 queen conchs live in the substrate and in rubble 

 depressions until they are about 0.5 yr old, or about 

 3-5 cm long, at which time they are found on the 

 tidal flats and nearshore areas in the Berry Islands. 

 Size-frequency distributions (Table 1) showed that 

 smallest individuals spawned the previous year 

 (estimate based on laboratory-reared queen conchs 

 by Siddall [1983], Brownell [1977], and others) ap- 

 peared in winter, spring, and early summer. 



Large juvenile queen conchs (10-18 cm) were 

 easily located on the substrate surface all year long, 

 generally in shallow water. Relatively few lipped 

 queen conchs (A'' = 109; mean size = 19.3 ± 0.5 cm) 

 were found during the study, most in channels 6 m 

 deep although a few individuals were seen in shallow 

 waters characteristic of most of our study sites. At 

 least one lipped conch was recorded for all areas ex- 

 cept Frazer's Hog Cay and Bird Cay-Cat Cay tidal 

 flats. The smallest lipped conchs were found at Cat 

 Cay (Z = 14.8 ± 2.6 cm; AT = 6). Lipped conchs 

 were found every month except February, July, 

 September, and December, with most found in April 

 {N = 46) and October (A = 39). The distribution and 

 seasonal occurrence of lipped conchs may reflect 

 fishing pressure as much as potential reproductive 

 activity. 



Studies by Randall (1964), D'Asaro (1965), Brown- 

 ell (1977), and Weil and Laughlin (1984) indicated 

 that queen conchs have a protracted spawning 

 season as long as March to October. Average length 



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