Abstract

The age and size structure, year class abundance in the fishery and juvenile abundance in the seagrass habitat of gag, Mycteroperca microlepis, in the northeastern Gulf of Mexico were examined from 1989 to 1994. We examined growth marks on otoliths from 1,539 gag (55% commercial and 45% recreational fishery); age ranged from 1 to 26 years for fish 332 to 1,290 mm total length (mm TL). Von Bertalanffy growth equation parameters for 1991-1994 were Lì (maximum attainable length) = 1261.0 mm TL, K (growth coefficient) = 0.139, and to (hypothetical age at zero length) = -1.3143. Juvenile gag absolute abundance was estimated in seagrass habitat of St. George Sound, Florida by using a 5 meter otter trawl with known sampling efficiency. Abundance estimates (number per hectare) for the years 1989-1994 were 388 in 1989, 3.9 in 1990, 460 in 1991, 180 in 1992, 1,035 in 1993,and 11 in 1994. The alternating year pattern of high-low abundance was also evident in the age-structure of the fishery (1989, 1987, 1985 were high and 1988, 1986, 1984 were low), and suggests that juvenile abundance estimates may be useful to forecast future fishery production.

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