Date of Award
Sean P. Powers, Ph.D.
Gray Snapper (Lutjanus griseus) constitute a significant recreational fishery and minor commercial fishery throughout the Gulf of Mexico, and review of the recent assessment determined that the stock is overfished and has been undergoing overfishing. The absence of regional baseline data in the northcentral Gulf of Mexico, combined with projections of range expansion and subsequent population growth due to climatic warming, highlight the need for the present investigation into the age and growth, mortality, and reproduction of this species in Alabama and Mississippi. Sex-specific growth curves constructed using the von Bertalanffy growth function demonstrated a significantly greater mean asymptotic length achieved by males (𝐿𝑡 = 731.52(1 − 𝑒 −0.15(𝑡+1.34) )) than females (𝐿𝑡 = 704.28(1 − 𝑒 −0.14(𝑡+1.62) )). Mortality rates (Z = 0.30 – 0.38; F = 0.04 – 0.12) indicate relatively low levels of exploitation. Histological analyses determined estimates of total length at 50% maturity (L50M = 181 mm; L50F =273 mm) and age at 50% maturity (A50M < 1.0 yr; A50F = 2.0 yr), spawning seasonality (May – August/September), and spawning interval and frequency (3.9 – 4.5 d; 28.7 – 33.4 events/season). The findings from this study will introduce new data for incorporation in future assessments and provide guidance for informed management decisions.
Kim, Edward, "Characterizing Gray Snapper (Lutjanus Griseus) Life History in the Northcentral Gulf of Mexico: Age and Growth, Mortality, and Reproduction" (2022). Theses and Dissertations. 42.