Growth, production, and reproduction in bay scallops Argopecten irradians concentricus (Say) from the northern Gulf of Mexico

The bay scallop, Argopecten irradians, is a commercially and recreationally important fisheries species on the Atlantic and Gulf Coasts of the United States. Surprisingly, little information exists on northern Gulf of Mexico populations. This research assessed growth, production, and reproduction in a population from St. Joseph Bay, Florida. Specifically, scallops exhibited high initial growth rates (Gw day^-1), with rates declining as individual size increased. Additionally, significant interannual variability existed for both scallop growth and production. These differences may be attributable, in part, to a reduction in salinity (21‰) associated with Tropical Storm Alberto, which resulted in significantly lower growth rates and a mass mortality event. Reproductive assessment of A. irradians showed significant peaks in spawning condition, gonad weight, and gonadal-somatic index (GSI) during the winter (December, January, February) compared to other seasons. However, the salinity minima in July 1994 (11‰) significantly reduced gonad weight and GSI from winter 1994/1995, suggesting that a single storm event had a dramatic but short-term reproductive impact on the population. Assessment of gonad condition and GSI, coupled with field observations, showed spawning occurred in the spring and fall as well, but the presence of small individuals (<4 mm shell height) during July, August, and September suggests that reproduction may occur throughout the year in St. Joseph Bay, Florida.