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Fishery Bulletin 92(2). 1994 



adaptation by individuals over the course of the 

 investigation, or is explained simply by differen- 

 tial survivorship (i.e. the most fit hatchery-reared 

 conch survived to the end of the experiments). As 

 discussed earlier, a strong case for adaptation can 

 be made because of the obvious changes in shell 

 morphology over time within individual conch. 

 Second, hatchery-reared conch used in this study 

 were from one season's production in a single 

 hatchery. We know that different hatcheries and 

 different cultures from individual hatcheries can 

 produce conch with different characteristics. For 

 example, Jory and Iversen (1988) found different 

 shell strengths among cultures of queen conch. 

 Because juvenile conch are reared from egg masses 

 collected from the wild, and because both shell 

 morphology and behavior appear to be relatively 

 plastic characteristics in queen conch, we believe 

 that differences shown between hatchery-reared 

 animals and native stocks can be alleviated 

 through modifications in diets, hatchery substrata, 

 and other culture techniques. Field viability must 

 be considered continuously throughout the hatch- 

 ery-rearing process. Third, morphological effects 

 on survival may vary with site because of differ- 

 ences in predator assemblages. For example, at a 

 site where molluscs (such as tulip snails, 

 Fasciolaria tulipa ) are the most important preda- 

 tors, size and escape behavior may be more impor- 

 tant than spine length and shell thickness. More site 

 comparisons and better knowledge of predator-prey 

 relationships are needed. 



Importance of stock enhancement 

 sites 



Site selection for stock enhancement with 

 queen conch is a complex issue and the 

 subject of several earlier papers (Stoner 

 andSandt, 1991, 1992; Stoner etal., 1993; 

 Stoner, in press). It is clear from experi- 

 ments reported here that even carefully 

 chosen locations, such as our non-conch 

 study site C2, may not support juvenile 

 conch over the long term. Conch at this 

 site demonstrated consistently higher 

 growth than conch at the traditional nurs- 

 ery site (CI), but mortality was also higher 

 in both tethered and free-ranging conch. 

 Site differences in mortality could be as- 

 sociated with patterns of predator abun- 

 dance or diversity, or both. Although 

 predators may accumulate where prey 

 density is high, the most likely explana- 

 tion for lower predation rate at site CI 



