Abstract

The absolute abundance and survival of early juvenile gag grouper, (Mycteroperca microlepis) in a 15.4 km2 shallow seagrass meadow in St. George Sound. Florida were estimated by the Jolly-S&r mark-recapture method. The method was used within each of three square sampling stations, each 150 m on a side, by standard (150 m, 1.8 km/hr) tows with a 5-m otter trawl The average absolute abundances for the three stations sampled every l-2 weeks from June to mid-September 1991 were 496, 424, and 549 juveniles per hectare. Trawl capture efficiencies (catch per unit area/estimated number per unit area) were calculated and the effects of seagrass habitat conditions and size of juvenile gag on those efficiencies were estimated. We estimated absolute abundance outside the sampling stations by trawling in those areas and dividing gag captures per standard tow by trawl - capture - efficiency estimates. The estimated absolute abundance of juvenile gag for the entire 15.4 km2 area was 943,615 juveniles. Survival estimates were generally variable but were confounded by emigration from the sampling areas. The small-scale spatial pattern of juvenile gag was random. The results of this work are discussed in relation to habitat alteration, recruitment indices, and enhancement potential

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