Movements of Hatchery-Reared Dusky Groupers Released in a Northeast Atlantic Coastal Marine Protected Area (original) (raw)
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Comptes Rendus Biologies, 2009
The Marine Reserve of Cerbère-Banyuls represents a refuge for dusky grouper populations (Epinephelus marginatus). Density survey and observation of the reproductive behavior of this species have been conducted there for the last 30 years. However, information on the behavior or habitat utilization for this species during winter time is limited. We conducted acoustic telemetry surveys from September 2005 to June 2006 in the Marine Reserve of Cerbère-Banyuls for a dusky grouper population. Six groupers were tagged and followed within the integral reserve and in the adjacent partial reserve. The results from the tracking of these individuals indicated that the largest dusky groupers are sedentary fishes with a high degree of site fidelity and a high sensitivity to variations of environmental conditions such as storms. This together with the life history characteristics of this species encourages the conservation and the protection of essential habitats of this species. Acoustic tracking coupled to the use of a fixed Kernel can be proposed to follow fish populations.
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 Coastal Zone Management, 2016
The dusky grouper (Epinephelus marginatus) is a reef fish with high market, cultural and ecological values. Therefore, it is an important species to the food security of small-scale fishers in Brazil and in other coastal regions. Nevertheless, groupers can be susceptible to overfishing because they are large, sedentary and with delayed maturity. The lack of data on fishery catches and on the biology of dusky grouper can be an obstacle for the success of management measures. The main goal of this study was to collect information on dusky grouper catches, morphometry (length and weight) and spawning period (observations of its gonads), through a collaboration with local fishers in the Copacabana Beach ("Posto 6"), southeastern Brazilian coast. Two fishers were trained to measure the total length (TL, in cm), weight (kg), and to observe the gonads (whether mature or not, and with or without visible eggs) of all individuals of dusky grouper caught at Copacabana, from September 2013 to June 2015. During the 21 months of data collection, 800 individuals of dusky grouper were examined by the trained fishers, yielding 793 individuals with both length and weight data. The mean length of dusky grouper caught by fishers (N = 796) was 52.4 cm (standard deviation of 12.4 cm, range from 17-130 cm). Most of the individuals caught ranged between 45 and 65 cm, being thus above both the minimum allowed size in Brazil (47 cm) and above the size at first maturity for this fish according to the literature (range of 35-60 cm for females). Although many individuals were adults, only a few individuals (18 of 800) of dusky grouper had mature gonads. This indicates that large spawning fish may be located at deeper sites or at distant spots, out of the reach of these small-scale fishers. Most dusky groupers were caught by spear fishing, in a single island. The collaboration with local fishers greatly improved the amount of data collected; so, we suggest that this approach should be adopted in future studies. These results show a valuable opportunity to properly manage the dusky grouper population at the southeastern Brazilian coast.
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...
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...
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.
Scientia Marina, 2008
a pilot experiment of stock enhancement based on the release of hatchery-reared juveniles of dusky grouper, Epinephelus marginatus, was carried out at two artificial reefs located 0.9 km offshore the southwestern sicilian coast (central Mediterranean). The fish assemblages inhabiting the reefs were characterized using underwater visual census (Uvc) surveys. despite some differences in fish species richness, diversity and abundance, both artificial reefs provide suitable feeding resources and shelter opportunities for the settlement of dusky grouper juveniles. a total of 95 dusky grouper juveniles, which were 3 and 4 years old, were released. no stress-related effects on fish swimming or behaviour were observed during the step by step transportation to the sea-bottom at 20 m depth. after release, several groupers showed very low reactivity; freezing and schooling were the most common behaviours. The sighting rate after one month of Uvc surveys was 15.7% and 20% at the two artificial reefs. no effect of fish size at release on grouper survival was observed. some groupers were not recorded on the pyramid of release but elsewhere in the same artificial reef, which demonstrated their ability to move around the reef. The extent of dispersal of the released juveniles largely exceeded the area encompassed by the reefs, which was shown by recaptures of tagged groupers by local fishermen up to 13 km from the release site. This result provides a first insight into the potential of stock enhancement of hatchery reared dusky grouper juveniles for marine ranching and conservation purposes.
The dusky grouper (Epinephelus marginatus) is a species whose stock management deserves special attention. It has an important role in hard-bottom ecosystems and, as a protogynous hermaphrodite; it is especially susceptible to overfishing. Data on the species’ use of habitat, and on the way environmental and behaviour parameters influence its abundance can help to improve management and conservation strategies. The aim of this study was to evaluate the influence of bottom type, temperature and species behaviour on the abundance of E. marginatus, using a quadrat for visual census. An area of 80 m2, divided between rocky shore, rocky outcrop and sandy habitats was surveyed monthly. Densities of juveniles were: 1.16 groupers m-2 over the rocky shore and 1.47 groupers m-2 over the rocky outcrop, while no groupers were found over sand. Analysis of the yearly variation in abundance revealed a migratory pattern of dispersal and gathering. All size groups observed in this study were below the first maturation length.
Journal of Ethnobiology and Ethnomedicine
Background Groupers are a vulnerable but economically important group of fish, especially for small-scale fisheries. We investigated catches and local ecological knowledge (LEK) of diet, habitat, and past fishing experiences. Methods Landings, prices, interviews, and restaurants demand for two species, Epinephelus marginatus (dusky grouper) and Epinephelus morio (red grouper), were registered. Results We visited 74 markets and 79 sites on the coast of Brazil in 2017–2018, and we interviewed 71 fishers: Bahia (NE), Rio de Janeiro and São Paulo (SE), and Santa Catarina (S). The landings sampled of dusky grouper (2016–2017) in Rio de Janeiro were: n = 222, size 38–109 cm, weight 1–24 kg, average 3.84 kg; in São Paulo, São Sebastião were: n = 47, size 39–106 cm, weight 2–8 kg, average of 2.77 kg; and at Santos: n = 80, 26–120 cm, weight 0.36–15 kg, average 2.72 kg. Red grouper was observed in markets in the northeastern Brazil. We did not observe Epinephelus marginatus from Bahia northw...