Abstract

The queen conch, Strombus gigas, is one of the most valuable fisheries species throughout the Caribbean, however, the populations have been declining for several decades. Research focused on aquaculture, restocking, and transplanting techniques is being conducted to help replenish wild conch populations. A 38 week experiment to determine the influence of diet and substrate on queen conch growth and survival began at Harbor Branch Oceanographic Institution, Ft. Pierce, Florida in December 2003. Hatcheryreared juvenile queen conch (32.3 ± 2.4 mm shell length) were stocked into six individual recirculating systems at 75 conch/m 2 . There were three treatments, with two replicates per treatment: 1) aragonite sand substrate with 1x calcium feed, 2) aragonite sand substrate with 2x calcium feed, and 3) silicate substrate with 1x calcium feed. Calcium, alkalinity, and pH were measured once per week; and conch length and weight measurements were taken on a biweekly or monthly basis. Results indicate that there is no difference in the growth rate with additional dietary calcium, the 2x feed (0.07 ± 0.01 mm/d) compared to the 1x feed (0.08 ± 0.01 mm/d). However, there appears to be a slower growth rate in those animals stocked on the silicate substrate (0.04 ± 0.02 mm/d) in comparison to the conch grown on aragonite sand substrate (0.07 ± 0.01 mm/ d). Calcium and alkalinity levels remained the same in all treatments. Conch grown on the silicate substrate had a significantly higher mortality (57%) than the 1X and 2x treatment on aragonite (18.7% and 25.8%, respectively). These results can be used to assist in choosing the husbandry techniques best suited to culture queen conch juveniles for stock enhancement purposes.

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