Age, Growth, and Mortality of Yellowmouth Grouper from the Southeastern United States

The Yellowmouth Grouper Mycteroperca interstitialis is a member of the snapper–grouper complex that is managed by the South Atlantic Fishery Management Council. There is little published life history information—specifically age–growth parameters—for use in assessing the resource. We sampled Yellowmouth Grouper from the fisheries along the southeastern U.S. coast from 1980 to 2012 ( n = 391), determining ages by counting opaque zones on sectioned sagittal otoliths. Opaque zones were annular, forming in May–August with a peak in May and June. Yellowmouth Grouper age ranged from 3 to 31 years, and the largest fish was 859 mm FL. Body size relationships were as follows: whole weight W (g) = (8.89×10 −6 )(FL, mm) 3.07 ( n = 339; r 2 = 0.96); W (g) = (1.13×10 −5 )(TL, mm) 3.01 ( n = 165; r 2 = 0.96); and TL (mm) = 10.09 + [1.05×(FL, mm)] ( n = 162; r 2 = 0.98). The von Bertalanffy growth equation for Yellowmouth Grouper was L t (length at age t ) = 755[1 − e −0.14( t + 1.42) ] when the model included an adjustment for minimum size limits and was L t = 772[1 − e −0.11( t + 4.18) ] when the model was not adjusted. Natural mortality ( M ) estimated by Hewitt and Hoenig's (2005) longevity‐based method was 0.14. Age‐specific estimates of M were obtained with the Charnov et al. (2013) method. The selection of growth model (size limit adjusted versus unadjusted) had a marked effect on M for the earliest ages: M was 1.22 versus 0.43 for age 0; 0.72 versus 0.35 for age 1; 0.51 versus 0.29 for age 2; 0.40 versus 0.26 for age 3; 0.33 versus 0.23 for age 4; and 0.29 versus 0.21 for age 5. We believe that these life history parameter estimates are accurate for Yellowmouth Grouper in southeastern U.S. fisheries. Received June 6, 2013; accepted November 12, 2013