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An understanding of lifetime trophic changes and ontogenetic habitat shifts is essential to the preservation of marine fish species. We used carbon and nitrogen stable isotope values (δ13C and δ15N) recorded within the laminar structure of fish eye lenses, reflecting both diet and location over time, to compare the lifetime trends of 2 demersal mesopredators. Tilefish Lopholatilus chamaeleonticeps inhabit burrows on the outer continental shelf, which results in exceptional site fidelity. Red grouper Epinephelus morio are spawned on the middle to outer continental shelf, move to the inner shelf for the juvenile period, and return offshore upon sexual maturity. Both species inhabit the eastern Gulf of Mexico, a region with a distinctive offshore–inshore gradient in background δ13C values. Within individual tilefish (n = 36), sequences of δ13C values and δ15N values had strong, positive correlations with eye-lens diameter, and strong correlations between the 2 isotopes (mean Spearman r = 0.86), reflecting an increase in trophic position with growth and little lifetime movement. In red grouper (n = 30), δ15N values positively correlated with eye-lens diameter, but correlations between δ15N and δ13C were weak (mean Spearman r = 0.29), suggesting cross-shelf ontogenetic movements. Linear mixed model results indicated strong relationships between δ15N and δ13C values in tilefish eye lenses but no convergence in the red grouper model. Collectively, these results are consistent with previously established differences in the life histories of the 2 species, demonstrating the potential utility of eye-lens isotope records, particularly for investigating the life histories of lesser-known species.

The ecological impacts of invasive species are highly variable and mediated by many factors, including both habitat and population abundance. Lionfish Pterois volitans are an invasive marine species which have high reported detrimental effects on prey populations, but whose effects relative to native predators are currently unknown for the recently colonized eastern Gulf of Mexico. We used functional response (FR) methodology to assess the ecological impact of lionfish relative to 2 functionally similar native species (red grouper Epinephelus morio and graysby grouper Cephalopholis cruentata ) foraging in a heterogeneous environment. We then combined the per capita impact of each species with their field abundance to obtain a Relative Impact Potential (RIP). RIP assesses the broader ecological impact of invasive relative to native predators, the magnitude of which predicts community-level negative effects of invasive species. Lionfish FR and overall consumption rate was intermediate to that of red grouper (higher) and graysby grouper (lower). However, lionfish had the highest capture efficiency of all species, which was invariant of habitat. Much higher field abundance of lionfish resulted in high RIPs relative to both grouper species, demonstrating that the ecological impact of lionfish in this region will be driven mainly by high abundance and high predator efficiency rather than per capita effect. Our comparative study is the first empirical assessment of lionfish per capita impact and RIP in this region and is one of few such studies to quantify the FR of a marine predator.

Many predatory marine fishes undergo ontogenetic diet and habitat shifts as they grow. Most fishery datasets, such as catch records, length frequencies, and stomach contents, create a series of snapshots, with each captured fish representing a single timepoint during the lifespan. Chemical archives, such as eye lenses, preserve information regarding several life stages for each individual. By combining these disparate datasets, conclusions are strengthened through weight of evidence. We combined a novel archive, δ13C and δ15N bulk values in sequential eye-lens laminae, with fishery-independent catch records and stomach contents for red grouper Epinephelus morio (Valenciennes 1828) from the eastern Gulf of Mexico, USA. Eye-lens core isotope values suggest that successful individuals spend their larval period on the mid-to-outer continental shelf and locations do not vary substantially year-to-year. Profiles of δ15N values indicate that trophic position increases with size following a logarithmic growth model, while stomach contents indicate a simultaneous increase in fish proportion in the diet. Stomach contents and δ13C values together suggest that most red grouper move to nearshore waters at settlement, spend several months in shallow water with heavy benthic diet dependence, then slowly cross the continental shelf toward deeper water as they mature. With this work, we demonstrate that eye-lens isotope value profiles can enhance fisheries datasets and may provide a method of recreating diet and movement histories for species without long-term biological information.

The red grouper, Epinephelus morio, locally known as \"mero rojo\", represents one of the most important commercial fish species in the Yucatán Peninsula, although they have been overfished. Populations of this economically important fish have been studied in the wild, and the presence of a wide array of metazoan parasite taxa has been reported. The technology for producing red grouper seed for a complete aquaculture cycle is being assessed at the pilot system of the Unidad Multidisciplinaria de Docencia e Investigación (UMDIUNAM) facility, in Sisal, in northwest Yucatán, Mexico. In two isolated events that occurred at the facility in 2021 and 2023, 14 individuals of E. morio, intended to be introduced into the system, died during the quarantine period; our sampling for parasites was opportunistic. Specimens were necropsied, and their metazoan parasites Were recovered. Here, we report on the parasite fauna of these individuals. Parasite identification was conducted using morphological traits and, in some cases, molecular data. Nine species were found, including 1 monogenean, 3 trematodes, 1 cestode, 1 acanthocephalan, 2 nematodes, and 1 copepod. The highest prevalence of infection was observed in the acanthocephalan Gorgorhynchus medius and the monogenean Pseudorhabdosynochus yucatanensis, With rates of 70 and 75% for the first and second mortality events, respectively. The parasite fauna of fishes from the aquaculture system is akin to that of wild populations of E. morio in the Yucatán Peninsula. A brief discussion on the importance of considering parasitic diseases in aquaculture systems is presented, and we briefly discuss the potential zoonotic importance of the larvae of the nematode Pseudoterranova sp.

The East Continental Shelf (ECS) of Brazil is a hotspot of endemism and biodiversity of reef biota in the South Atlantic, hosting a number of Marine Protected Areas (MPAs). Connectivity of MPAs through larval dispersal influences recruitment, population dynamics, genetic structure and biogeography in coral reef ecosystems. Connectivity of protected reef ecosystem in the ECS was investigated with a hydrodynamic model (ROMS) forcing an Individual Based Model (IBM-Ichthyop), and used groupers (genus Mycteroperca) as functional group. The hydrodynamic output from ROMS was compared with satellite data and showed good agreement with observed surface fields. Eggs were released, in IBM experiments, from April to September along six years (2002-2007) in five MPAs along the ECS. Intrannual variability in recruitment and self-recruitment of grouper larvae was observed, as well as a negative correlation of these population parameters with total Kinetic Energy (KE) used as a metric of the physical environment. Higher KE leads to increased offshore advection of larvae, reduced total recruitment and connectivity of MPAs. Our results indicate high and uni-directional connectivity between MPAs from north to south influenced by the Brazil Current flowing in the same direction. Results also showed that some MPAs act predominantly as \"sink\" while others are mainly \"source\" areas.

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 northward; a maximum size of 200 cm was reported south of the Bahia, besides Rio de Janeiro and São Paulo coasts, 20 years ago (or longer) by 12 fishers. Local knowledge of fishers was important for grouper data of habitat and diet; the reproduction period was identified by fishers as September to March. Conclusions Groupers can be considered as a cultural and ecological keystone species. We suggest protective measures: 1) fishing zoning, 2) islands (MPAs) with the surveillance of fishers, 3) late Spring and early Summer as key periods for management (grouper reproduction), 4) studies on grouper larvae, 5) mapping of fishing spots, 6) studies on local knowledge. Collaboration with small-scale fishers and local knowledge could contribute to low-conflict management measures. In that regard, integrative models of management from Latin America, by using local knowledge and citizen science, could produce successful grouper management for Brazilian data-poor fisheries, a contrasting reality to the Mediterranean areas. Finally, the distribution of E. marginatus in Brazil leave us with questions: a) Have dusky groupers disappeared from Bahia because of a decline in the population? b) Was it uncommon in Northeast Brazil? c) Did changes in water temperatures forced a movement southward?

Home ranges, activity patterns, and habitat preferences in and around no-take marine reserves (NTMRs) were evaluated for 5 exploited snapper-grouper species in diverse coral reef habitats in the Dry Tortugas, Florida. Movements of ultrasonic tagged reef fish were determined using a calibrated array of omnidirectional hydroacoustic receivers. Average home range sizes were 2.09 ± 0.39 km² (n = 28; total length, TL = 45 to 66 cm) for red grouperEpinephelus morio, 4.17 ± 1.75 km² (n = 5, TL = 48 to 55 cm) for yellowtail snapperOcyurus chrysurus, 1.44 ± 1.04 km² (n = 2, TL = 57 to 75 cm) for black grouperMycteroperca bonaci, and 7.64 km² (n = 1, TL = 70 cm) for mutton snapperLutjanus analis. Red grouper and yellowtail snapper moved moderate distances (from 700 to 900 m) with moderate frequency. Observed movements for black groupers were relatively small and infrequent. Mutton snappers appeared to make short, frequent movements. A tracked gray snapperL. griseusmade long-distance nocturnal migrations. Several exploited-phase groupers and snappers crossed into and out of reserve boundaries. They were most likely to do so in locations where boundaries were positioned over contiguous coral reef and close to home-range centers. We found that home ranges for red grouper, black grouper, and yellowtail snapper were relatively small in comparison to NTMR area. Our observations suggest that the Dry Tortugas NTMRs may reduce exposure to exploitation for these and other species with limited home ranges, especially where NTMR boundaries do not overlie contiguous reef.

In tropical regions, temperature is the fundamental environmental factor controlling the reproduction-related physiological activities of fish. Tropical fish are particularly sensitive to climate change since they develop in a relatively stable thermal environment. A review was done to assess the potential effect of temperature rise on reproduction and population structure in the commercially important hermaphrodite grouper and wrasse species, and in gonochoric snapper species in the southern Gulf of Mexico. Temperature increase can disturb the aromatase synthesis and/or activity, which can affect the reproductive cycle and sexual differentiation in all studied species and the sexual inversion process in sequential hermaphrodites. Moreover, a mistiming or discontinuity in spawning seasonality could occur, with an alteration in the sex ratio in favor of males and a consequent reduction in populations’ fecundity. Furthermore, if the level of fishing exploitation enhances species’ sensitivity to environmental changes, then the stock of red grouper Epinephelus morio would be more affected by temperature increases than other species because it is the only fish population in the Campeche Bank currently assessed as overexploited.

The most important fisheries are recording catches below their historical averages despite increased effort. This level of overfishing is worrying and requires the establishment of feasible and precise measures to prevent a continuing decrease in biomass. Determining the factors that lead to changes in the abundance and distribution of overfished resources would allow us to identify the strengths and weaknesses of management schemes; this approach would also make it possible to estimate more accurate parameters for their evaluation. We hypothesize that environmental, temporal, spatial, and operational components contribute to the variation in the relative abundance. Thus, we analyzed the red grouper fishery, the most important demersal fishery in the southeastern Gulf of Mexico (SGM); it is locally known as escama . We employed the catch per unit effort (CPUE) as an index of relative abundance recorded by the semi-industrial fleet (kilogram per effective fishing day) and the small-scale fleet (kilogram per effective fishing hour) during the overexploitation phase (from 1996 to 2019). We fitted several variables of the components using generalized additive models (GAM) and used multi-model inference to determine the best GAM for each fleet. For both fleets, the operational and temporal components (fishing gear and year) have had a greater impact on the distribution and abundance of red grouper in the SGM than the spatial and environmental components (the place of origin and sea surface temperature). These findings encourage the exploration of métier schemes for more efficient fishery management. In addition, we have identified several strategies that would support the recovery of the resource, such as restricting fishing in the quadrants located to the northeast or regulating scuba diving. We recommend that in the future, researchers use the indices we have generated in the present study to evaluate the red grouper fishery.

Autonomous gliders are a relatively new technology for studying oceanography over large time and space scales. We integrated a hydrophone into the aft cowling of a glider and used it in a 1 wk, shelf-scale deployment on the West Florida Shelf to detect and map fish sounds in the ocean over a large spatial scale. In addition to red grouper and toadfish sounds, at least 3 unknown biological sounds suspected to be produced by fish were identified through manual analysis of the acoustic files. The biogeography of these fishes was identified by mapping the occurrence of sounds along the glider track. Sounds produced by red grouper and toadfish were detected throughout the day predominately in bottom depths >40 m. Conversely, the 3 unknown biological sounds were detected exclusively at night over varying bottom depths. Glider technology provides a reliable and relatively inexpensive method to collect acoustic and environmental data over large spatial scales while maintaining a high rate of successful retrieval.