Age, growth, and reproduction of Southern Kingfish (Menticirrhus americanus): a multivariate comparison with life history patterns in other sciaenids


Clardy, Samuel D., Nancy J. Brown-Peterson, Mark S. Peterson, and Robert T. Leaf
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Southern Kingfish (Menticirrhus americanus) is an abundant sciaenid in the northcentral Gulf of Mexico, but little is known of its life history. Our objectives were to describe demographic traits and compare the characteristics of this population with those of other recreationally and commercially important populations in the U.S. Exclusive Economic Zone (U.S. EEZ). We report significant differences in sex-specific weight at length. Otolith annulus formation occurred in April and May and maximum age was 4+ years for both sexes. Length-at-age analysis indicated that mean asymptotic total length (TL; TL∞, male=244 mm, TL∞, female=303 mm) and mean instantaneous growth rates (kmale=1.12 y−1 and kfemale=0.95 y−1) were significantly different between sexes. The mean length at 50% maturity (TL50) for females was 171 mm TL, corresponding to an age at maturity of 1 year. Gonadosomatic indices and histological examination of ovarian maturity phases indicated rapid gonadal development in February and March with females actively spawning from April to September. The interval between spawning averaged 6.9 days, and the most frequent spawning occurred in June and July. Mean relative batch fecundity was 231.1 number of eggs g−1 of ovary-free body weight (±standard error 35.7). Principal component analysis (PCA) of 5 variables from 17 sciaenid populations in the U.S. EEZ identified 2 principal components that explained 68.1% of variation among populations; these components represent a size-related gradient and a gradient of spawning season dynamics. Five distinct groups were identified on the basis of fish size, age at maturity, spawning-season duration, and batch fecundity.