Tropical Aquaculture

EFFECT OF DIETARY CALCIUM AND SUBSTRATE ON JUVENILE QUEEN CONCH GROWTH RATE AND SHELL STRENGTH

Research Team:
Ashley Spring - (Florida Tech Graduate Student)
Megan Davis (HBOI) - Master's Committee Chairperson

Queen conch, Strombus gigas, are overfished throughout Florida and the Caribbean. In an attempt to curtail the depleted wild stocks, queen conch aquaculture has developed through the last 40 years. Whether the goal is to culture queen conch for stock enhancement or commercial purposes, there remain a number of fundamental aquaculture methods to improve upon to enhance the quality of cultured conch and reduce costs. This study aimed to improve survival, growth, shell strength, and culture costs of juvenile queen conch by manipulating stocking density and tank substrate. Three experiments were designed to test the effects of five stocking densities (20, 50, 75, 200, and 400 conch/m_) and three tank substrates (crushed coral aragonite, plastic liner, and aragonite chips) in recirculating water systems over 16 months.

Conch grown at low densities grew significantly faster (0.11-0.13 mm/day) than conch grown at high densities (0.05-0.08 mm/day). On the other hand, conch grown at high densities possessed stronger shells. High mortalities occurred in conch grown on plastic liner (68 %) versus aragonite chips (98 %) and crushed coral aragonite (98 %). There were no significant differences in growth between conch grown on the two sand substrates. Crushed coral aragonite costs one-third of the price of aragonite chips and is therefore suggested as a less expensive substrate option.

To culture juvenile queen conch for stock enhancement purposes, it is recommended that conch are grown at a stocking density of 200 to 400 conch/m_ to provide the animals with the strongest shell strengths and on aragonite chips which may increase burying behavior. Commercial markets are not concerned with shell morphology; therefore, the fastest and least expensive culture conditions are recommended. Conch grown for commercial will grow the fastest at stocking densities of 20 to 50 conch/m_ and can be grown inexpensively on crushed coral aragonite. The recommended culture conditions may benefit aquaculture facilities, fishery managers, and commercial industries with higher quality stocks at lower costs.

This research was partially funded by Link Foundation and Astronaut Trail Shell Club.