Home range, movement rates, and habitat use of queen conch, Strombus gigas, in St. John, U.S. Virgin Islands

摘要

The queen conch, Strombus gigas, is a highly valued fishery resource in the Caribbean basin, historically second only to the spiny lobster. Currently listed in Appendix II of CITES, historical surveys from the U.S. Virgin Islands have documented wide-spread reductions in population densities. Habitat use and movement patterns of queen conch differ by size and maturity status, making it important to identify areas and habitat types that can play a role in the recovery of this species. We tracked long-term movements and spatial distributions of conch in St. John, USVI, using visual surveys coupled with mark-and-recapture techniques. Juvenile conch exhibited the smallest mean home range (95 contour) and core area (50 contour) at 8470 m~2 and 2083 m~2, respectively, but had the largest aggregate home range (115,410 m~2) and aggregate core area (55,055 m~2). Transitional conch had the largest mean home range and core area at 18,203 m~2 and 4944 m~2, respectively, with an aggregate home range and core area of 113,147 m~2 and 59,067 m~2. Adults had an aggregate home range and core area of 65,045 m~2 and 29,178 m~2, with a mean home range and core area of 14,987 m~2,and 3929 m~2. Adults exhibited the highest daily movement rate at 11.36 m per day, with juvenile and transitional conch having similar rates of 4.66 m per day and 3.44 m per day, respectively. Multiple recapture events of tagged conch showed an ontogenetic shift in habitat use as maturing individuals moved from shallow seagrass habitats into deeper-water macroalgae plains.