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Life History of Bay Scallops, Executive Summary

Bay scallops occur in discrete populations scattered along the coast of Florida. In prehistoric times, scallops could be found from West Palm Beach to Pensacola, but in recent decades, that range has contracted considerably. Now, dense aggregations of bay scallops are found only in the area between Tarpon Springs and Port St. Joe.

On the west coast of Florida, the multiple local scallop populations that comprise the metapopulation are isolated from one another by areas of inhospitable adult habitat. However, those local populations are interdependent via larval exchange. Because bay scallops are an annual species, local populations periodically collapse due to natural events. Natural restoration of a collapsed population requires import of larvae from neighboring populations. The stability of the metapopulation is defined by the existence of multiple, healthy, local populations because more local populations increase the opportunities for resupply. Thus, increasing the number of healthy local populations will increase the stability of the metapopulation.

The results of ongoing scallop population monitoring reveal three characteristics of a healthy scallop population: 1) density > 25 scallops per 600-mē survey transect, 2) a broad distribution of scallops within the survey area, and 3) a rapid rebuilding of the population following a collapse. Applying those criteria, only two sites in Florida, Steinhatchee and St. Joe Bay, supported healthy scallop populations through 1999.

The FWC has taken a two-pronged approach to increasing the number of healthy local populations in Florida waters. Beginning in 1994, scallop harvest regulations were modified to reduce take, and beginning in 1998, the FMRI initiated a scallop restoration program. Those programs appear to have been successful. Scallop abundance has increased considerably in the area between Tarpon Springs and Crystal River where restoration efforts have been focused. In areas where scallop populations have collapsed, where no restoration has been implemented, a similar resurgence has not been observed.

Prior to July 1, 2004, the Fish and Wildlife Research Institute was known as the Florida Marine Research Institute.