Date of Award

Fall 12-2012

Degree Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Chair

Mark S. Peterson

Committee Chair Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 2

Nancy Brown-Peterson

Committee Member 2 Department

Coastal Sciences, Gulf Coast Research Laboratory

Committee Member 3

Chet Rakocinski

Committee Member 3 Department

Coastal Sciences, Gulf Coast Research Laboratory

Abstract

Southern kingfish, Menticirrhus americanus, is a common sciaenid along the north-central Gulf of Mexico (GOM), but annual harvest has declined over the last decade. Little is known about the life history of southern kingfish in the north-central GOM, and thus the objectives of this study are to establish the spawning season, spawning frequency, fecundity, sex ratio, female size at 50% maturity, age, and standard morphometrics. Specimens were collected using hook and line in several locations within the Mississippi Sound. A total of 519 southern kingfish (434 females, 85 males) were captured from April 2008 through May 2009 by hook and line and consisted of age classes from age 0 to 4 with the population dominated by age 1 and 2 individuals. Annuli formation occurred in May and June based on marginal increment data. The size at 50% sexual maturity for females was estimated at 189 rnm TL at age 1, although few immature female fish were captured. GSI values and overall histological ovarian maturity phases indicated that fish begin rapid gonadal development in February and March. Actively spawning females were found from April through September, although some spawning capable fish were still collected in early October. Southern kingfish are batch spawners with asynchronous oocyte development, and mean relative batch fecundity was 231.10 ± 35.68 (mean ± SE) eggs/g ovary-free body weight. Spawning frequency averaged 6.93 days between spawns from April through September, with highest spawning frequency occurring in mid-summer (June and July). The reproductive strategy of M. americanus is similar to that of other sciaenids in the GOM, although both relative batch fecundity and spawning frequency are lower than most other members of the family. The results from this study should strengthen the overall knowledge about this species and will provide resource managers valuable information to better assess population dynamics of the southern kingfish in the north-central GOM.

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