Abstract

Effective marine restoration programs require an understanding of the origin of recruits to the population. However, not all managers have access to the emerging technologies that may provide definitive answers to this question. In these cases, low-tech methods may help elucidate the origin of their recruits. We present here the evolution of a strategy designed to restore the depleted population of queen conch (Strombus gigas) in the Florida Keys based upon the results of studies incorporating drift vials and plankton tows. The studies were designed to answer two questions: 1) is the Florida conch population dependent upon upstream sources, and, if not, 2) where in Florida should restoration efforts be focused to maximize the probability that locally produced larvae will be retained. We concluded that few larvae arrive from upstream sources because most of the drifters released in the Keys were recovered in the Keys, almost none of the drifters released outside the Keys were recovered in the Keys, and larval densities in the Gulf Stream were very low while concurrent larval densities in the Keys were much higher. To identify the locations where enhancing reproductive output would have the greatest impact on local larval supply, we examined where drifters that were released in the Keys were recovered and concluded that the target area to increase reproductive output is the lower Keys. Based on these findings, we developed a restoration strategy wherein we translocate adult conch into the existing lower Keys spawning aggregations. To date we estimate that we have increased the spawning stock by approximately 10% while simultaneously observing a significant recovery in the Keys conch population. Despite the well-described drawbacks associated with using drifters, we argue that there is still value in the data they provide and that these data can be applied to address key management issues

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