Thursday, August 9, 2007

PS 57-26: Pre-enforcement, baseline assessment of queen conch (Strombus gigas) populations in the Sapodilla Cayes Marine Reserve (Belize)

John A. Cigliano1, Bryan S. Bugler2, and April Ridlon2. (1) Cedar Crest College, (2) ReefCI

The Sapodilla Cayes Marine Reserve (SCMR) was established in 1996 at the southern end of the Mesoamerican barrier reef to protect and replenish local fisheries. However, the management plan has not been signed into law and, thus, is not being enforced. The goal of this study is to collect baseline, pre-enforcement data on one of the targeted fisheries, the queen conch (Strombus gigas). We collected data on density and age (size) structure of conch aggregations in all three reserve zones and outside the reserve in both shallow-water (<3m) and deep-water (>15 m). We also tagged conch from each aggregation to determine dispersal and migration patterns. The project and analysis is ongoing but, to date, 1051 conch have been sampled from shallow-water aggregations (n=9). Shallow-water aggregations (mean depth 1.46±0.03 m) were found in seagrass meadows and are nursery (juvenile and sub-adult) aggregations. Three hundred forty-four conch have been sampled in deep-water aggregations (n=3, mean depth 18.7±0.3 m). Deep-water aggregations were found in sand and sand/seagrass habitats and are adult feeding and spawning aggregations. All aggregation densities were relatively high. Currently, 673 conch from shallow-water aggregations and 344 conch from deep-water aggregations have been tagged. Preliminary analysis of “recaptures” (harvested) and re-sightings suggest that juveniles migrate seasonally between shallow (spring-summer) and deep (fall-winter) sites while adult conch from deep-water aggregations are sedentary. It appears that the SCMR contains both significant shallow-water nursery aggregations and deep-water adult aggregations that may act as breeding refugia and a source of recruits for the reserve.