Density, age structure, and length of queen conch (Strombus gigas) in shallow-water aggregations in the Sapodilla Cayes Marine Reserve, Belize

The Sapodilla Cayes Marine Reserve (SCMR) was established in 1996 to protect the queen conch (Strombus gigas) fishery in southern Belize. However, no systematic survey of queen conch populations in the SCMR had been conducted. To determine the state of the queen conch population and to provide a baseline to measure management effectiveness, we conducted shallow-water surveys of historical conch fishing areas from 2006 2008 during July and August. We collected data on habitat, depth, maturity, length, and density. We sampled 1,778 conch at eight sites throughout the reserve. Conch were found primarily in seagrass meadows (88.6%) in an average depth of 1.7 +/- 0.01 m (range: 0.3-4.9 m). 93% of conch were juveniles and the percentage of juveniles in aggregations averaged 85.0 +/- 3.8 (range 28.6 - 100.00%). Average shell length was 14.6 +/- 0.1 cm (range: 6.5-25.0 cm) and varied among aggregations and among years within aggregations. 85% of conch were below the legal harvestable size for Belize. Average density (all age classes) ranged from 0.00 +/- 0.00 to 4014.29 +/- 741.12 conch/ha and varied among sites and year. Average adult density ranged from to 0.00 +/- 0.00 to 75.00 +/- 41.19 conch/ha, subadult density ranged from 0.00 +/- 0.00 to 214.29 +/- 67.01 conch/ha, and juvenile density ranged from 0.00 +/- 0.00 conch/ha to 3785.00 +/- 737.57. Only twice was an aggregation above the density threshold required for reproduction (50 conch/ha). The SCMR appears to be an important nursery area for queen conch.