Stoner and Davis: Outplanting queen conch. Strombus gigas 



405 



(Berg, 1976) to 10 cm or larger (Jory and Iversen, 

 1983). Even with the use of 8-12 cm shell length test 

 animals in this investigation, hatchery-reared conch 

 on tethers were killed at a rate nearly twice the rate 

 of wild conch early in the study. Morphological and 

 behavioral differences are probably the most impor- 

 tant factors influencing mortality. Thin shells and 

 short apical spines observed in the hatchery-reared 

 conch would present a smaller, more vulnerable prey 

 to predators. Palmer's (1979) experiments have 

 shown that spination is an important shell charac- 

 teristic for minimizing predation in intertidal gas- 

 tropods. 



Shell weight and spination are malleable traits in 

 queen conch. Alcolado ( 1976) observed that shell form 

 in the species was related to water depth and habi- 

 tat type, with thin shells and short-spines being as- 

 sociated with rapid growth in shallow water. Envi- 

 ronmental mediation of shell form was tested experi- 

 mentally by Martin-Mora (1992) near Lee Stocking 

 Island. She found that transplanted wild conch took 



o 

 -w 

 o 



o 



-M 



D 



-4— ' 



o 



80 



60 



-• Wild - C1 

 -» Wild - C2 

 -O Hatchery - C1 

 -A Hatchery - C2 



80 100 



Figure 14 



Cumulative mortality curves for tether experi- 

 ment I. Hatchery-reared and wild queen conch, 

 Strombus gigas, were compared at sites CI and 

 C2. Forty conch of each stock type were teth- 

 ered at each site. 



on the morphology of local conch within several 

 months, and that high shell weight and long spines 

 were associated with slow growth rate. Given the 

 importance of shell quality in molluscan biology, 

 attention has been given to relationships between 

 shell properties and diets, substrata, temperature, 

 salinity, and other physical factors (Wilbur, 1964; 

 Carter, 1980). It is likely, therefore, that culture 

 techniques can be developed to provide seed conch 

 which are less vulnerable to predation. 



Survivorship of hatchery-reared conch may also 

 have been influenced by their low burial frequency. 

 Wild conch tend to shelter under detritus or al- 

 gae, and remain partially buried and unmoving 

 for long periods of time. This probably provides a 

 certain degree of protection from larger visual 

 predators. Low burial frequency in hatchery- 

 reared conch may be related to the fact that the 

 field grow-out area in the Caicos Islands, where 

 they spent several months before being transplanted 

 to the Exuma Cays, was primarily a hard-bottom 

 environment. Behavioral differences between hatch- 

 ery-reared and wild stocks are rarely documented; 

 however, Schiel and Welden ( 1987) found that hatch- 

 ery-reared red abalone, Haliotis rufescens, did not 

 move to concealed locations as did wild abalone, re- 

 sulting in higher predatory mortality. 



There are at least three limitations of the pre- 

 sent investigation. One is not knowing whether 

 convergence in the morphology and survivorship 

 of wild and hatchery-reared conch was related to 



