Age and growth of mutton snapper along the east coast of Florida

Abstract

Otoliths of 1191 mutton snappers, Lutjanus analis, 265–860 mm total length ( TL) were examined. The fish were sampled from headboat landings from Jacksonville Beach, Florida, to Key West, Florida, from 1976 to 1981. The oldest fish was aged 14 and measured 824 mm TL. Back-calculated mean lengths of 878 fish ranged from 161 mm at age 1 to 778 mm at age 14. The von Bertalanffy growth equation is L t = 861.5 (1−e −0.1534( t + 0.5788) ), where L = total length in mm and t = years. The lenght-weight relationship is W = 1.0 × 10 −8 TL 3.0449, where W = weight in kg and TL = total length in mm. Mutton snapper are fully recruited to the headboat hook and line fishery at age 3. For all years combined, the total instantaneous mortality rate ( Z) was 0.33 and the total annual mortality rate was 0.28. A Beverton and Holt yield-per-recruit model ( M = 0.20) suggests a maximum yield-per-recruit of 800 g if instantaneous fishing mortality is 0.4–0.5 and recruitment ages are 5–6 years. However, even with the current low levels of fishing mortality (<0.2), 75% of the yield is being harvested.