Age, Growth and Mortality of Gray Snapper Collected from Florida Waters

Otoliths and scales of gray snapper, Lutjanus griseus, sampled from the Florida headboat fishery were examined to see if they could be used to age the species. Scales were not useful, but sectioned otoliths proved to be excellent for determining age and growth. Rings could be identified and counted on 91% of all otoliths examined, and measurements could be made on 86%. The oldest fish encountered was 21 years; 775 mm TL. Back-calculated lengths at annulus formation ranged from 95 mm for age 1 to 772 mm for age 19. The von Bertalanffy equation describing theoretical growth is 1t = 890 (1-e-0.1009(t+0.3161)). Gray snapper were fully recruited to the hook and line fishery as 5 to 7 year olds depending on the area. Total instantaneous mortality estimates for fish landed in North Florida (Mayport and Daytona) and South Florida (Pompano, Boynton and Key West) were significantly different. A yield-per-recruit model is presented and should be useful in the future management of the species along the east cost of Florida. The length-weight relationship is W = 2.4 X 10-8 TL2.9122, where W = weight in kilograms. Length conversions are FL = 3.6476 + 0.9359TL, and SL = 2.7381 + 0.7781TL.

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