Life-History Characteristics and Fishery Dynamics of Red Drum ( Sciaenops ocellatus ), in the North-Central Gulf of Mexico

• Main Author: Bennetts, Corbin
• Format: Text
• Language: unknown
• Published: The Aquila Digital Community 2018
• Subjects: age and growth; reproduction; stable isotope analysis; escapement rate; Marine Biology; Population Biology; Statistical Models; Red drum; Sciaenops ocellatus
• Online Access: https://aquila.usm.edu/masters_theses/348; https://aquila.usm.edu/context/masters_theses/article/1391/viewcontent/auto_convert.pdf

Red Drum (Sciaenops ocellatus) are highly targeted recreationally in the Gulf of Mexico, and support a small commercial fishery in Mississippi. Despite their popularity, the stock is assessed using data limited approaches that necessitate accurate life history information. I estimated the year-specific and year-aggregated escapement rates for the Mississippi stock (years 2004 to 2015), which were sensitive to mortality estimation methods; year-aggregated estimates were 6.9 to 28.2 % depending on the method, but temporal patterns were consistent. I then addressed concerns with previously estimated life-history characteristics by describing the sex-specific growth and reproductive dynamics. The three-parameter von Bertalanffy growth function was the best candidate length-at-age model, with no significant difference in overall growth between sex-specific relationships, but females had a larger mean asymptotic length, and four candidate models showed significant sexual dimorphism. I described Red Drum as batch spawners, with 3.7 days between successive spawns during the spawning season (August and September). The age at 50% maturity was around age-3 y in both sexes, but spawning capability was not evident until around age-6 y. The carbon (delta C-13) and nitrogen (delta N-15) stable isotope composition of Red Drum muscle tissue was more enriched in carbon offshore and was significantly different with respect to reproductive phase. Mean and variance of delta N-15 and variance of delta C-13 was significantly different between fish < age-7 y and those older. When accounting for muscle turnover rates, this coincides with the age of spawning capability, indicating an ontogenetic migration at age-6 y.