Abstract

The Nassau grouper, Epinephelus striatus, were once considered the most commercially important grouper species in the Caribbean. However, decades of overexploitation has led to their virtual disappearance within the coastal waters of Puerto Rico, despite being fully protected since 1990. The only known Nassau grouper spawning aggregation in Puerto Rico occurs at Bajo de Sico, an isolated seamount located within the Mona Passage. During the 2013 and 2014 spawning seasons, 29 Nassau grouper were surgically implanted with acoustic tags in situ using closed-circuit rebreathers. Simultaneous data were collected at the aggregation site using passive acoustic recorders and underwater visual census to compare temporal patterns and estimate population size. Results for this location indicated three peaks in abundances of Nassau grouper occurring shortly after the full moons during the months of January - March, with the duration and timing of peak abundances varying between months. The majority of tagged individuals (24 of 29) were detected at the aggregation site during multiple peaks through the spawning season. Tagged fish displayed greater variability in the day of arrival than timing of departure, but patterns in the time of day of arrival and departure were predictable. Results from passive acoustic recordings and underwater visual censes coincided with tag detection data, with the maximum number of courtship associated calls (CAS), number of individuals observed, and tag detections occurring on similar days.

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