What is the Potential for Horse Conch (emTriplofusus giganteus/em) Populations to Recover from Increasing Fishing Pressure?

The horse conch ( Triplofusus giganteus ) is the second largest extant gastropod in the world and is the state shell of Florida. There is demand for these mollusks among commercial and recreational fishers and avocational shell collectors. Despite harvest, life history traits such as age at reproductive maturity and lifetime fecundity are unknown. In this study, we use oxygen isotope sclerochronology of two large shells close to record size to measure annual growth cycles that are recorded seasonally in the shell, a process similar to dendrochronology in trees. Data from this method will provide information on size-at-age from which life history traits might be estimated. Growth breaks along the shell suggest that these snails live > 10 years, a hypothesis supported by two oxygen isotope profiles from large specimens. The von Bertalanffy growth curves constructed from the data will also be used to estimate the age of the largest known horse conch, 606 mm, currently on display in the Bailey-Matthews National Shell Museum.