Growth, Mortality, and Condition of Cottonwick in the Gulf of Mexico

Scales and otoliths of cottonwick, Haemulon melanurum, collected on 2 reef sites in the northwestern Gulf of Mexico were examined for usefulness in determining age. Scales were used to estimate age. Back-calculated lengths at annulus formation ranged from 158 mm fork length (FL) (age 1) to 352 mm FL (age 11). No difference in growth was observed between areas, but there was significant year-to-year variation in mean FL for age-classes 2-5. There was no difference in parameters of the von Bertalanffy model due to area of collection.The equation was FLt=350(l-e-0.32(t + 0.1). Annual instantaneous mortality (Z) differed significantly between reefs (0.77 vs 0.95), with a weighted mean of 0.90. The length: weight relationship was W = 0.00013 FL2.6614. Variation in condition between seasons and areas was attributed to normal variation in gonadal weight due to reproductive cycles.

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