Abstract

Twenty years ago, surveys conducted in the Exuma Cays, Bahamas, showed that the density of adult queen conch in the shallow bank habitat at the Exuma Cays Land and Sea Park (ECLSP) (> 50 adults/ha2) was 17 times higher than in a fished area near Lee Stocking Island (LSI). Differences in deeper shelf environment (10 - 30 m) were about three times. When identical surveys were repeated in 2011, it was discovered that the density of conch in the bank habitat of LSI had increased slightly, but numbers in shelf habitat had declined 91%, to densities below capacity to support reproduction. At ECLSP, bank densities declined by 69% to just 16 adults/ha. The population in shelf environment declined a smaller amount (6.4%), but the ECLSP population is also becoming older, indicating recruitment limitation. Histological studies on reproductive readiness in ECLSP revealed that males and females were not spawning capable until at minimum 10 - 15 mm lip thickness, respectively. Although these surveys represent two specific areas in the Exuma Cays, it is clear that queen conch populations have declined precipitously since the 1990s, that conch inside even a large protected area like ECLSP are vulnerable to fishing that occurs outside the reserve, and that in the Bahamas conch are legally allowed to be harvested before reaching sexual maturity. We propose that a single marine reserve cannot work in isolation for species with pelagic larvae. We recommend that a network of reserves and a minimum lip thickness criteria of 10 - 15 mm be implemented for sustainable harvest of queen conch (and other species with pelagic larvae) in the Bahamas and other nations of the Caribbean.