Intra-Seasonal (March-June) Dynamics of the Mutton Snapper (Lutjanus analis) Spawning Aggregation Fishery At Gladden Spit, Belize

Since the 1950s, artisanal fishers have harvested mutton snapper (Lutjanus analis) at Gladden Spit, southern Belize Barrier Reef. The fishery targets the peak of the species spawning aggregations, which recurs annually in March-June, 10-12 days around the full moon days. In order to characterize for the first time the size, age, and maturation structures of reproductive mutton snapper at Gladden Spit, we sampled the landings of the fishery between -2 and 7 days relative to full moon (drfm) in March-June 2011. We measured, weighted, and macroscopically examined the gonad state of 5,047 individuals and randomly collected 115 pair of sagittae for age determination. Relative abundances of mutton snapper varied significantly in relation to drfm and among months. Individual sizes ranged between 315-905 mm TL, weights 0.5-11.8 kg, otolith-based ages 2-16 years, and von-Bertalanffy-growth-model projected ages 2-50 years. PERMANOVAs revealed significant monthly variations in the size, age, and maturation structures of aggregating individuals. Older individuals dominated in March-May, while younger individuals in June. Most males were mature throughout the season, while most females were predominantly immature in June. Our results suggest that the reproductive output from mutton snapper that aggregate to spawn at Gladden Spit is seasonally structured and that most females harvested in June missed their chance to spawn in 2011.