Age, Growth, and Reproduction of Gag, Mycteroperca Microlepis (Pisces: Serranidae), in the Eastern Gulf of Mexico
Abstract:A total of 1,331 gag, Mycteroperca microlepis, captured in the eastern Gulf of Mexico from November 1977 to May 1980 were sampled for life history analysis. Gag captured in waters less than 30 m deep by commercial and nearshore recreational fishermen were significantly smaller (TL ≤ 739 mm) than those captured in greater depths (TL ≥ 832 mm). Analyses of marginal increments, annulus spacing, and the relationship of otolith size to fish length suggested that a ring forms on the sagittae once each year during the summer. Growth of gag was greatest during the first 10 years, after which mean size approached an apparent maximum of about 1, 100 mm TL. Estimates of the von Bertalanffy growth equation parameters (standard error) for gag were as follows: L∞ = 1,190 mm TL (22 mm), K = 0.166 (0.009), and to = −0.62 (0.13). Growth rate estimates determined from monthly length-frequency data for juveniles and from historical tagging data for adults agreed with the estimate determined by analyzing otolith sections. Gag are protogynous hermaphrodites, and females in the sample outnumbered males 6:1. Females became mature between ages III and VI, and no males less than age V were observed. Histological and gravimetric analyses of gonad condition suggested that gag spawn from December to May, with peak activity occurring during February and March.
Document Type: Research Article
Publication date: November 1, 1992
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