Abstract

Goliath grouper, Epinephelus itajara, live in tropical and subtropical waters of the Atlantic Ocean from Florida to the south of Brazil. While their fishing is still allowed in French Guiana, this species is listed as critically endangered on the IUCN red list and is protected in some countries. It is essential to know the age structure of the goliath grouper population in French Guiana to be able to suggest appropriate fisheries management. Groupers are usually aged using their otoliths, which is a lethal method. To avoid this impact, a non-lethal methodology using dorsal finrays was modified for goliath grouper in French Guiana. In a tropical environment such as French Guiana the contrast between seasons is not strong and hence the visualization of the growth zones in the finrays was less than for fish from higher latitudes. Finrays of French Guiana goliath grouper were therefore cut at various thicknesses to enhance the growth rings.Although the reading of the finray sections was difficult due to the presence of false annuli or “checks”, the annular pattern in the finrays was consistently discernible when finrays were sectioned at thicknesses between 1.1 and 1.4 mm. Using this method, a total of 200 fish between 38 to 194 cm total length were aged between 2010 and 2011. Goliath grouper in French Guiana were aged from 1 to 16 years old, with a mean of 4 years old. This highlighted the observation that French Guiana currently houses mostly a juvenile population of goliath grouper.

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