Published by Bulletin of Marine Science

Allan W Stoner, Martha H Davis, and Catherine J Booker

ABSTRACT

Relationships between density of mature adults and mating frequency in queen conch (Strombus gigas Linnaeus, 1758) were observed at three sites in the central Bahamas including one no-take marine reserve (Exuma Cays Land and Sea Park) and two historically important fishing grounds (Berry Islands and Andros Island). No mating was observed in any one count with density < 47 adults ha−1 , consistent with an earlier study suggesting a mate-finding Allee effect in queen conch. #e unfished site had larger and older conch, and mating at that site increased rapidly with adult density, reaching an asymptote at 12%–14% of the population mating at highest density levels. Logistic modeling showed that a 90% probability of mating occurred at 100 adults ha−1 . Mating frequencies increased more slowly with density on the fishing grounds; asymptotic mating frequencies were 6.3% in the Berry Islands and just 2.3% at Andros Island. In contrast to the marine reserve, 90% probability of mating required 350 and 570 adults ha−1 at Andros Island and the Berry Islands, respectively. Higher densities required for successful mating in the fished areas were associated with numerical dominance by small, thick-shelled adults. #e small phenotype in adults appears to result from selectivity imposed by fishing pressure, and those adults had low mating frequencies, compounding the density effect on reproduction. Because releases of hatchery-reared queen conch have not been successful, preserving the integrity of spawner density and population structure will be critical for conch conservation.

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