Tuohy, Evan A.

Profile Picture

Filters

20221
Reset filters

Settings

Citations

Publication Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    Publication
    Multi-year spatiotemporal dynamics of Nassau grouper 𝗘𝗽𝗶𝗻𝗲𝗽𝗵𝗲𝗹𝘂𝘀 𝘀𝘁𝗿𝗶𝗮𝘁𝘂𝘀 (Bloch 1792) in Puerto Rico
    (2022-11-05) Tuohy, Evan A.; Appeldoorn, Richard S.; College of Arts and Sciences - Art; Schizas, Nikolaos V.; García Saís, Jorge R.; Nemeth, Richard; Department of Marine Sciences; Almodóvar Rivera, Israel A.
    The Nassau grouper, 𝗘𝗽𝗶𝗻𝗲𝗽𝗵𝗲𝗹𝘂𝘀 𝘀𝘁𝗿𝗶𝗮𝘁𝘂𝘀 (Bloch 1792), is a slow growing, long-lived, and late to mature coral reef grouper widely distributed throughout the tropical and subtropical waters of the western North Atlantic. Of high commercial and economic importance, the species is known for the formation of large fish spawning aggregations (FSAs) once numbering in the thousands to tens-of-thousands individuals. Highly predictable in space and time, many of these aggregations are overfished, and the Nassau grouper is now considered critically endangered. In Puerto Rico, the only documented Nassau grouper FSA occurs on Bajo de Sico (BDS), an isolated seamount off the island's West coast that is part of a six-month seasonal marine protected area (MPA). Relatively small and of considerably deeper depth (> 27 m depth), this location differs in spatial scale compared to other known Nassau grouper FSAs in the region. Management strategies for Nassau grouper have largely focused on protecting FSA sites and spawning populations through seasonal closures and MPAs focused on spawning times and locations. Understanding an organism's spatial ecology is a critical step to designing effective MPAs or closure times that offer adequate protection for these species during all times of the year. Acoustic telemetry was used to characterize the spatial and temporal dynamics of Nassau grouper at BDS during both spawning and non-spawning seasons. Given the depth at which the aggregation occurs (>50 m), an in situ approach using closed-circuit rebreather was developed to reduce the potentially harmful effects of removing the fish from increased depths. A total of 29 Nassau grouper were tagged with high efficiency and survivorship. Nassau grouper formed three to four aggregations per year with variability in the timing of formation found within and between years. Tagged individuals occupied significantly deeper depths during aggregation formation compared to the remainder of the year. Nassau grouper occupied relatively small staging areas (2.7 km2) and courtship arenas (0.67 km2) compared to other aggregations occurring on continental/insular shelves or large atolls. While movements off the seamount are possible, none were explicitly detected. Outside of the spawning season, Nassau grouper occupied small home ranges territories (0.48 ± 0.06 km2 [mean ± SD]) with high site fidelity, and two individuals underwent home reef relocation. Individuals had highly overlapping home reef territories, and in locations where multiple individuals occupied the same home reef, they did so within discrete depth profiles. The current timing of the seasonal MPA at BDS inadequately protects the spawning population and offers limited protection for non-spawning Nassau grouper. The seasonal MPA should be expanded to 12 months afford the greatest protection for spawning and non-spawning populations on BDS. Furthermore, changing the current regulations to no-take would facilitate the limited capacity for enforcement at this remote location. Results indicate the importance of BDS as critical habitat for reproduction and primary home reef sites of Nassau grouper and expand on the knowledge of spatiotemporal dynamics of habitat use that will aid in the local and regional conservation efforts of this species.