Abstract

The queen conch is an important fishery resource in the Caribbean, and high fishing pressure has led to its depletion. The Xel-Ha Inlet is a park used for ecotourism, representing a sanctuary for the conch. Most knowledge about its growth was generated in enclosures or derived from population dynamics, but has been studied little by direct methods. Growth appears to be higher under natural conditions than in enclosures or hatcheries. In this study, we compared the growth rates of 1,242 Strombus gigas in two protected nurseries (BN and CU), each with an area of 6,000 m² and average densities of 0.20 ± 0.0981 and 0.16 ± 0.0651 ind./m2, respectively. The particularity of the sanctuary is the freshwater input from underground caves surrounding it. BN is characterized by fine sand/mud, while the bottom of CU is composed of coarser coralline algae rubble. Both sites present dense macroalgae patches. A capture-mark-recapture method was employed during the period from April 2009 to May 2011. Population size and relative density were estimated using Schnabel’s method. Growth was highest in juveniles with an initial shell length of 100 - 149 mm and < 100 mm, increasing 0.29 ± 0.09 mm/day and 0.27 ± 0.07 mm/day, respectively being statistically equivalent. Growth decreased significantly in size classes 150 - 199 mm (0.19 ± 0.09 mm/day) and ? 200 mm (0.08 ± 0.08 mm/day). No differences could be detected between the two sites, except for the class of < 100 mm, with an average growth of 0.32 ± 0.09 mm/day at BN and 0.26 ± 0.06 mm/day at CU. Growth showed seasonal differences. The ecological significance of growth rates is discussed.