Mesoscale distribution patterns of Queen Conch (Strombus gigas linne) in Exuma Sound, Bahamas: Links in recruitment from larvae to fishery yields

Populations of benthic species that produce pelagic larvae are sustained th rough a complex interaction of factors, including larval supply, variable t ransport mechanisms, and a host of postsettlement processes that affect dif ferential recruitment and abundance. We report distributional data for the larvae, juveniles, adults, and a time-averaged index of fishery yield (shel l middens) of the economically important marine gastropod Strombus gigas (q ueen conch) in the Exuma Sound, Bahamas. All life history stages and the fi shery yields were heterogeneously distributed around this semienclosed syst em, with higher densities of benthic stages in the northern part of the sou nd than in the south and east. Distribution of shell middens closely reflec ted abundance patterns of shallow-water juvenile aggregations and abundance of adults in depth-stratified surveys; therefore, midden distribution prov ided a good indicator of long-term productivity around the periphery of the sound. Although patterns of fishery productivity around the system were cl osely related to both juvenile and adult distributions, and density of newl y-hatched larvae reflected the distribution of adults and shell middens, as would be expected, benthic stages and the fishery yields were completely d ecoupled from the abundance of settlement-stage larvae. When transplants of newly settled conch were made to four seagrass sites in the eastern Exuma Sound with characteristics typical of conch nurseries, low growth rates res ulted in all but one location. All of these results suggest that conch abun dance and distribution in Exuma Sound is determined in the benthos, either during settlement or in the first year of postsettlement life. Therefore, a lthough larval supply has been shown to influence benthic recruitment on a small scale (i.e., size and location of juvenile aggregations), and juvenil e populations will always depend upon a reliable source of competent larvae , high quality habitat plays an equally important role in the recruitment o f this important fishery resource.