Age, growth, and mortality of the Atlantic goliath grouper Epinephelus itajara in French Guiana

The age and growth of the Critically Endangered Atlantic goliath grouper Epinephelus itajara of equatorial French Guiana was determined by a non-lethal aging method using dorsal fin rays. Goliath grouper deposit 1 complete annulus per year, with the translucent zone of the annulus laid down at the beginning of the dry season (July). Two readers independently applied the method; there was full agreement between the two for 52% of the fish, and agreement of +/- 1 yr for 82%. Comparison of ages derived from paired samples of otoliths and fin rays were identical (n = 6). The mean age of goliath grouper was 4.2 yr (range = 1 to 17 yr; n = 229); 82% of the individuals were under the size/age of sexual maturity. Goliath grouper in French Guiana are larger at a given age and reach their asymptotic length (L-infinity = 192.3 cm) faster (k = 0.20 yr(-1)) than goliath grouper from the west coast of Florida, USA (L-infinity = 200.6 cm, k = 0.126). Total mortality, estimated from a catch curve of the age distribution, was about 0.65 both in the Grand Connetable Island marine protected area in French Guiana (where fishing is prohibited) and outside of the reserve, suggesting that the reserve does not protect goliath grouper from illegal fishing. However, the estimates of total mortality in both fished and protected sites likely includes emigration, because goliath grouper may use rocky sites in French Guiana as a nursery habitat and may not remain there once they mature.