Pattern of movements within a home reef in the Chesterfield Islands (Coral Sea) by the endangered Giant Grouper, Epinephelus lanceolatus (original) (raw)
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Marine Ecology Progress Series, 2020
Characterizing the behavior of coral reef fishes at home reef sites can provide insight into the mechanisms of spatial ecology and provide a framework for spatial resource management. In the Caribbean, populations of Nassau grouper Epinephelus striatus have declined due to fishing impacts on spawning aggregations. Despite local and regional efforts by fisheries managers to implement regulations protecting spawning aggregations, few Nassau grouper populations appear to be recovering. In order to improve management strategies for this critically endangered species, it is necessary to understand the spatial ecology of the species across seasons and years. In the Cayman Islands, we used a multi-year, presence/absence, depth-coded acoustic tagging dataset of Nassau grouper to characterize patterns in the species’ behavior and vertical habitat use at home reef sites. Twenty acoustically tagged individuals (56-84 cm, 70.01 ± 7.40 cm; total length, mean ± SD) maintained consistent home reef...
Spatial dynamics of the Nassau grouper Epinephelus striatus in a Caribbean atoll
Marine Ecology Progress Series, 2007
Worldwide, chronic overfishing has depleted populations of large predatory reef fishes and caused unexpected, top-down changes in coral reef ecosystems. Groupers are especially susceptible to overexploitation, because they aggregate to reproduce at specific locations and times. An understanding of the spatial dynamics of these fishes is critical for fisheries management and conservation. However, movements and migration dynamics of endangered reef fishes are poorly known. We show, using acoustic telemetry, that Nassau groupers Epinephelus striatus exhibit highly synchronised migration to spawning sites, despite their otherwise solitary habits. Reproductive adults leave their individual territories in shallow waters near the winter full moons, and migrate to the same spawning site up to 4 times yr-1. At the spawning site, a remarkable population-wide depth change occurs within an hour as individuals dive to a maximum depth of 255 m. Our results greatly expand the previously known migration frequency and depth range of this species, and reveal an unexpected yet predictable complexity of adult fish migration between habitats. Effective conservation of this threatened species requires that deeper reefs and the timing of migration events be incorporated into fisheries management plans.
Marine Ecology Progress Series, 2018
Marine protected areas (MPAs) are considered an effective tool for protecting marine organisms. The precise estimation of home range size, as well as diel differences in home ranges, are essential when considering the appropriate size of an MPA. In addition, behavioral characteristics of spawning migration should also be considered for species that form spawning aggregations. Our aim was to clarify the diel variation in home range size and the degree of precision of the returning ability of white-streaked grouper Epinephelus onus by acoustic telemetry. Seventeen individuals were studied, and nighttime home range sizes that were calculated by 50 and 95% kernel utilization distributions were 5.9-fold and 5.5-fold greater, respectively, than the daytime home ranges. The average inter-center distance between home ranges during the 2 time periods ranged from 3.0 to 67.9 m (22.5 m on average), suggesting that the day−night home range shift within the home ground varied individually. Returning ability for 10 individuals that showed clear spawning migration behavior was also analyzed, and the average inter-center distance between home ranges during the periods before and after spawning was 8.1 m. Eight out of these 10 individuals showed precise returning after the spawning migration to the patchy coral substrates that were used before the spawning migration. The present study suggests that appropriate setting position of the home ground can establish long-term protection of the species due to their precise returning ability after the spawning migration.
Coral Reefs, 2019
Many species of groupers form transient fish spawning aggregations (FSAs) that are both spatially and temporally predictable, making them highly vulnerable to fishing. Consequently, many known aggregations have disappeared, making the collection of additional baseline data imperative to inform management actions and decisions that have the capacity to protect these important areas in the long term. Using acoustic telemetry and underwater observations, we document the spatio-temporal dynamics of the camouflage grouper Epinephelus polyphekadion at a FSA in Fakarava, French Polynesia. We show that grouper arrival at the aggregation site started 2 weeks before the full moon with a core area density that increased from 0.13 to 1.25 fish m-2 during the observation period. Following reproduction, almost all camouflage groupers left the FSA site within 48 h. Among 30 tagged groupers in 2011 and despite a relatively low receiver coverage in the pass, 30% returned to the FSA the following year confirming patterns of FSA site fidelity of the species found in previous studies at other locations. Our results confirm that the current management procedures protecting the FSA under the UNESCO biosphere reserve are critical in maintaining the functional role of the FSA by ensuring the persistence and sustainability of large and healthy populations of groupers and sharks.
Website: http://www. …, 2006
The Cayman Islands Department of Environment needs to assess the effectiveness of Nassau grouper (Epinephelus striatus) spawning aggregation site closures by gaining a better understanding of how local grouper populations use the aggregation sites. During the January 2005 spawning season thirty Nassau grouper were acoustically tagged off the Little Cayman west end aggregation site and during the summer of 2005 an additional twenty Nassau groupers were tagged around Little Cayman. By tagging fish on the aggregation we have been able to determine where fish go after they leave the spawning aggregation. By tagging fish around Little Cayman prior to the 2006 spawning season we will be able to determine the proportion of fish from around the Island that attend the west end spawning aggregation. Also, the frequency of aggregation attendance by individual fishes as a function of demography will be assessed. Initial results show that 60% of the groupers tagged during the January, 2005 aggregation returned to aggregate during the February full moon. Furthermore, these 18 returning fish were amongst the largest of the 30 tagged. Ultimately, this information will allow us to assess the current and future impacts of protections afforded Cayman's spawning aggregations. Moreover, the study will define an aggregation's "sphere of influence" both geographically and demographically and will thus aid in the management of local Nassau grouper populations.
Journal of Marine Science and Engineering
No-take areas are key instruments to promote the effectiveness of Marine Protected Areas (MPAs), particularly concerning the protection of endangered species such as the dusky grouper (Epinephelus marginatus). However, despite the establishment of no-take areas and the prohibition of catching this species in a southwestern Portuguese MPA (SACVMP—‘Sudoeste Alentejano’ and ‘Costa Vicentina’ Marine Park) since 2011, there is still no evidence of population recovery. By using acoustic biotelemetry, this work aimed to evaluate the feasibility of restocking hatchery-reared adult dusky groupers in two no-take areas within the SACVMP. In 2019 and 2021, thirty groupers were tagged with acoustic transmitters and the site attachment and movements of the groupers were assessed in the releasing sites (no-take areas). None of the tagged fish settled down in either of the areas, leaving the no-take areas mainly at dusk and night. Some individuals displayed extended movements of more than a hundred...
Bulletin of Marine Science, 2013
ABSTRACT Populations of the economically and ecologically important Nassau grouper, Epinephelus striatus Bloch, 1792, have declined to the point of being declared "endangered" by the International Union for the Conservation of Nature. Beyond existing efforts to reduce top-down pressure from overfishing, especially on spawning aggregations, recovery of Nassau grouper could be enhanced by preventing bottom-up pressures created by degradation of essential habitats. The design of suitable protection would benefit from knowledge of ontogenetic patterns in habitat use at multiple spatial scales, and this study documented microhabitat associations for late juvenile Nassau grouper in shallow, nearshore lagoons off Little Cayman Island. In total, 82% of juvenile grouper that were 12–26 cm in total length and approximately 1 yr old associated with hardbottom rather than other equally or more widespread microhabitats, i.e., sand, seagrass, and algae. Hardbottom provided crevices, holes, ledges, and other shelters. Approximately 96% of shelters contained a single juvenile grouper, and 10%–66% of these shelters also contained one or more cleaning organisms. These results suggest that protection of hardbottom in Little Cayman Island's lagoons would maintain the >1200 patches of microhabitat suitable for late juvenile Nassau grouper.
Frontiers in Marine Science
Understanding animal space use patterns is critical for ecological research and conservation efforts. An organism’s home range territory serves as the fundamental unit of space use and is the area repeatedly used for routine activities. Nassau grouper, Epinephelus striatus, once of high commercial fishery importance, are now on the IUCN’s Red List designated as Critically Endangered due to overexploitation. Known for the formation of large spawning aggregations, information on their movements and space use dynamics outside of the reproductive period are lacking. In this study, we used acoustic telemetry to quantify the non-spawning horizontal and vertical space use patterns of Nassau grouper at the Bajo de Sico seamount, a seasonally closed marine protected area (MPA) in Puerto Rico. Twenty-nine groupers were tagged with acoustic transmitters, of which, fourteen were tracked continuously over a three-year period. Tagged individuals displayed high site fidelity to home reef locations...
Bulletin of Marine Science, 2013
populations of the economically and ecologically important nassau grouper, Epinephelus striatus bloch, 1792, have declined to the point of being declared "endangered" by the international union for the conservation of nature. beyond existing efforts to reduce top-down pressure from overfishing, especially on spawning aggregations, recovery of nassau grouper could be enhanced by preventing bottom-up pressures created by degradation of essential habitats. The design of suitable protection would benefit from knowledge of ontogenetic patterns in habitat use at multiple spatial scales, and this study documented microhabitat associations for late juvenile nassau grouper in shallow, nearshore lagoons off little cayman island. in total, 82% of juvenile grouper that were 12-26 cm in total length and approximately 1 yr old associated with hardbottom rather than other equally or more widespread microhabitats, i.e., sand, seagrass, and algae. hardbottom provided crevices, holes, ledges, and other shelters. approximately 96% of shelters contained a single juvenile grouper, and 10%-66% of these shelters also contained one or more cleaning organisms. These results suggest that protection of hardbottom in little cayman island's lagoons would maintain the >1200 patches of microhabitat suitable for late juvenile nassau grouper.