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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.

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. [ABSTRACT FROM AUTHOR]

To be as accurate as possible, stock assessments should account for discard mortality in fisheries if it occurs. Three common approaches to modeling discards in assessments are to lump dead discards with landings, treat dead discards as their own fleet, or link them conversely with landings through use of a retention function. The first approach (lumping) implicitly assumes that the selectivity of landings applies also to discards. In many cases, that assumption is false, for example, if discards comprise smaller fish than do landings. The latter two approaches avoid the assumption by modeling discards explicitly with their own selectivity pattern. Here, we examine these approaches to modeling discards. Using a simulation study, we demonstrate that the two approaches to modeling discards explicitly can provide identical results under both static and time-varying conditions. Then, using a stock assessment case study of red grouper Epinephelus morio in the U.S. Gulf of Mexico, we demonstrate that in practice the approaches to modeling discards can provide different outcomes, with implications for the resultant management advice. We conclude by comparing and contrasting the different approaches, calling for more research to elucidate which approach is most suitable under various sources of error typically encountered in discard data.

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., Competing Interests: The authors declare that they have no competing interests., (© 2023 Oribe-Pérez et al.)

Demographic size- or stage-structure can result in significant heterogeneity in species interactions within populations and ontogenetic shifts in the strength or type of these interactions have important consequences for populations. In the case of the Caribbean spiny lobster, Panulirus argus (Latreille, 1804), and red grouper, Epinephelus morio (Valenciennes, 1928), both are important fishery species commonly found co-occurring in Florida Bay habitats. Red grouper are known to prey upon juvenile lobsters but karst solution holes excavated by red grouper often host large groups of lobsters. A combination of experiments tested the effect of red grouper on different lobster size classes to determine how this interaction changes through lobster ontogeny: red grouper were excluded from solution holes to test the effect of grouper presence on the abundance of each lobster size class; artificial dens were constructed to test the avoidance behaviors of small lobsters to red grouper; and a tethering experiment tested how lobster survival varied across size classes. Lobster abundance in solution holes with red grouper increased more than in holes where the grouper was removed (126% versus 16.9%), but this effect was strongest on adult and large immature lobsters. Experiments with artificial dens showed no effect of caged grouper presence on the abundance of small lobsters. Survival of tethered lobsters was lowest for small juveniles but again differed significantly between size classes. Overall, the distribution of lobsters in solution holes appears to be driven primarily by asymmetrical predation risk from red grouper through lobster ontogeny. Shifts in this interaction across life stages may play an important role in structuring the Caribbean spiny lobster population in Florida Bay. [ABSTRACT FROM AUTHOR]

Ecosystem-based fisheries-management (EBFM) is increasingly used in the United States (U.S.), including in the Gulf of Mexico (GOM). Producing distribution maps for marine organisms is a critical step in the implementation of EBFM. In particular, distribution maps are important inputs for many spatially-explicit ecosystem models, such as OSMOSE models, as well as for biophysical models used to predict annual recruitment anomalies due to oceanographic factors. In this study, we applied a recently proposed statistical modelling framework to produce distribution maps for: (i) younger juveniles (ages 0-1) of red snapper (Lutjanus campechanus), red grouper (Epinephelus morio), and gag (Mycteroperca microlepis), so as to be able to define the potential larval settlement areas of the three species in a biophysical model; and (ii) the functional groups and life stages represented in the OSMOSE model of the West Florida Shelf ("OSMOSE-WFS"). This statistical modelling framework consists of: (i) compiling a large database blending all of the encounter/non-encounter data of the GOM collected by the fisheries-independent and fisheries-dependent surveys using random sampling schemes, referred to as the "comprehensive survey database;" (ii) employing the comprehensive survey database to fit spatio-temporal binomial generalized linear mixed models (GLMMs) that integrate the confounding effects of survey and year; and (iii) using the predictions of the fitted spatio-temporal binomial GLMMs to generate distribution maps. This large endeavour allowed us to produce distribution maps for younger juveniles of red snapper, red grouper and gag and nearly all of the other functional groups and life stages represented in OSMOSE-WFS, at different seasons. Using Pearson residuals, the probabilities of encounter predicted by all spatio-temporal binomial GLMMs were demonstrated to be reasonable. Moreover, the results obtained for younger juvenile fish concur with the literature, provide additional insights into the spatial distribution patterns of these life stages, and highlight important future research avenues. [ABSTRACT FROM AUTHOR]

We investigated the effects of hook soak time on targeted reef species and shark bycatch in the reef fish bottom longline fishery in the Gulf of Mexico. Beginning in 2010, capture time and catch per unit effort (CPUE) for the primary target species red grouper ( Epinephelus morio ) in the fishery were evaluated using hook timers. Findings indicated that typical duration of hook soak times is longer than necessary to efficiently harvest red grouper and a reduction in gear soak times to less than one hour would result in minimal or no reduction in red grouper CPUE. The mean capture time of sharks and red grouper differed significantly, suggesting that a reduction in soak time would likely reduce the bycatch of sharks in the fishery. The study also revealed barometric pressure, lunar phase, and fish size were significant covariates with red grouper capture times and that different bait types significantly affected CPUE. Implementing shorter hook soak times would likely improve fishery profitability and potentially reduce discards of unwanted species in the fishery. [ABSTRACT FROM AUTHOR]

Organisms that either directly or indirectly modify the availability of resources can have profound effects on the structure and function of ecological communities. This holds true for organisms that enhance habitat complexity either as a function of their morphology or through mechanical activities, such as digging or burrowing. The net positive effects of engineers on local species diversity follows from activities that allow more species to live in modified habitats compared to unmodified ones. Here, we present the results of a multiyear observational study evaluating the effects of habitat modifications made by juvenile red grouper, Epinephelus morio (Valenciennes, 1828), on the fishes and motile macroinvertebrates associated with karst solution holes in Florida Bay, FL, USA. Because red grouper have multiple roles in these systems, acting as both habitat engineers and predators that consume a variety of benthic crustaceans and fishes, their influence on associated communities is complex. We found that the presence of red grouper resulted in deeper solution holes, increased abundance and richness of the associated fauna, especially among juvenile coral-reef fishes and motile invertebrates, and significant differences in the structure of faunal communities over time. These results suggest that red grouper shape unique communities, distinct from those of surrounding areas, and strongly influence the composition of communities associated with manipulated habitats. [ABSTRACT FROM AUTHOR]

Mapping the spatial distributions of fish populations is an integral component of ecosystem-based fisheries management (EBFM). Particularly for red grouper ( Epinephelus morio ) and gag grouper (“gag”; Mycteroperca microlepis ), two economically important species, the lack of mapping due to data limitations (i.e., inconsistent capture in research surveys) has left a critical gap in the science needed to assess how ecosystem processes and EBFM measures in the Gulf of Mexico (GOM) impact their population dynamics. We combined multiple fisheries-dependent and fisheries-independent data sources to map the long-term spatial distributions of older juveniles and adults of red and gag groupers in the U.S. GOM, using spatio-temporal binomial generalized linear mixed models (GLMMs). Spatio-temporal binomial GLMMs rely on the idea that probability of encounter at a given site is more similar to probability of encounter at nearby sites than to probability of encounter at geographically remote locations; this tenet allows one to estimate a smoothed surface depicting how probability of encounter varies spatially. Our spatio-temporal binomial GLMMs do not integrate environmental covariates, yet they account for the effects of year and research survey. The distribution maps produced from the predictions of the spatio-temporal binomial GLMMs aligned with the current understanding of the long-term ontogenetic spatial distributions of red and gag groupers in the U.S. GOM. Red grouper was predicted to be encountered throughout the West Florida Shelf (WFS), primarily at depths ranging from 20 to 60 m. Both older juvenile and adult female gags were predicted to be encountered from Apalachicola, Florida, to the region northwest of Tampa, Florida, along the 20 m depth contour, especially in Apalachee Bay. The probability of encounter of adult female gag was also high in the Florida Middle Grounds and in deeper (>40 m) areas of the WFS. The probability of encounter of adult male gag was highest along the edge of the WFS, both inside recognized spawning grounds (including the Madison-Swanson marine protected area) and outside, i.e., below 27°N (including Pulley Ridge). The distribution maps produced are valuable for understanding the ecology of grouper species and can be used as a basis for further analyses. Our spatio-temporal binomial GLMM framework will serve many important EBFM projects, including the construction of reliable distribution maps in bulk for spatially explicit ecosystem models of the GOM, which will improve spatial distributions and species spatial overlaps in spatially explicit ecosystem models and, therefore, the trophic interactions predicted by these models. [ABSTRACT FROM AUTHOR]

The insufficiently known nematode species Philometra margolisi Moravec, Vidal-Martínez et Aguirre-Macedo, 1995 (Philometridae) is redescribed based on light and scanning electron microscopical (SEM) examinations of specimens collected from the gonad of the type host, the red grouper Epinephelus morio (Valenciennes) (Serranidae, Perciformes), in the northern Gulf of Mexico off Florida, USA. Also, new prevalence data for females of P. margolisi were derived from 188 fish, and a subset of these (n = 38) were used to determine prevalence and intensity of male nematodes. The male of this species was studied with SEM for the first time, which revealed some new, taxonomically important morphological features. The male posterior end had a V-shaped caudal mound, four pairs of minute adanal papillae, a pair of large papillae located posterior to the cloacal aperture and a pair of very small phasmids. The distal end of the gubernaculum is unique among all gonad-infecting species of Philometra parasitizing serranids in that its ventral surface is flat, smooth, without the usual two longitudinal grooves; the dorsal lamellate structures on the gubernaculum are also different in this species. In contrast to data in the original species description, the body length of gravid females of P. margolisi was 132-280 mm. Overall prevalence for male nematodes (76.3%) was much higher than for females (15.4%), and female nematode prevalence was higher in samples collected during host spawing season than out of season (27.1% and 3.3%, respectively). [ABSTRACT FROM AUTHOR]

The objectives of this study were to: (1) examine patterns of short- and long-term metal exposure within the otoliths of six offshore fish species in varying states of health, as indicated by the presence of external skin lesions, and (2) determine if there was a change in otolith metal concentrations concurrent with the Deepwater Horizon (DWH) oil spill. Otoliths collected from 2011 to 2013 in the Gulf of Mexico (GOM) were analyzed for a suite of trace metals known to be associated with DWH oil. We found that lesioned fish often had elevated levels of otolith 60 Ni and 64 Zn before, during, and after the DWH oil spill. In addition, metal exposure varied according to species-specific life history patterns. These findings indicate that lesioned individuals were exposed to a persistent source of trace-metals in the GoM prior to the oil spill. [ABSTRACT FROM AUTHOR]

Red and black groupers are large-bodied opportunistic ambush predators commonly found in Southwestern Atlantic tropical reefs. We investigated the diet of both species in order to detail ontogenetic, spatial and temporal trends, and to assess the extent of overlap in resource use between these two sympatric predators on the Abrolhos Bank, Brazil. Decapods and fishes were the main food items of Epinephelus morio while fishes were the main prey of Mycteroperca bonaci. Both diets were significantly influenced by body size and habitat, but only smaller individuals of E. morio feed almost exclusively on crustaceans. While the two groupers rely on many of the same prey types, coexistence may be facilitated by E. morio feeding more heavily on crustaceans, particularly the blackpoint sculling crab Cronius ruber, while black grouper take comparatively few crustaceans but lots of fish prey. Predators like red and black groupers could trigger indirect effects in the community and influence a large range of ecological processes, such as linkages between top and intermediate predators, and intermediate predators and their resources. [ABSTRACT FROM AUTHOR]

Fishery observer data collected from June 2006 through December 2015 in the Gulf of Mexico commercial reef fish fishery were examined to determine if any covariates available affected immediate discard mortality for six species: red grouper Epinephelus morio , red snapper Lutjanus campechanus , vermilion snapper Rhomboplites aurorubens , gag grouper Mycteroperca microlepis , scamp grouper Mycteroperca phenax , and speckled hind Epinephelus drummondhayi . Using logistic regression models, this study predicted immediate discard mortality was positively correlated with increased depths, seasons associated with warmer water temperatures, and external evidence of barotrauma. Additionally, bottom longline gear increased the predicted probability of immediate mortality compared to vertical line gear for all species except vermilion snapper. Air bladder venting significantly decreased the predicted probability of immediate mortality for all species except speckled hind. Future research incorporating tag-recapture data into the current observer program for the commercial reef fish fishery is vital to assess if condition assessment at release can be relied on as an accurate proxy for long-term survival. This research provides information that managers could potentially use to make more informed decisions when implementing measures such as changes to existing size limits, venting requirements, and seasonal, area, or gear restrictions intended to reduce unwanted discard mortality. [ABSTRACT FROM AUTHOR]

Invasive lionfish ( Pterois volitans/miles complex) now permeate the entire tropical western Atlantic, Caribbean Sea, and Gulf of Mexico, but lionfish abundance has been measured only in select locations in the field. Despite its rapid range expansion, a comprehensive meta-population analysis of lionfish 'sources' and 'sinks' and consequentially the invader's potential abundance and impacts on economically important, sympatric reef fishes have not been assessed. These data are urgently needed to spatially direct control efforts and to plan for and perhaps mitigate lionfish-caused damage. Here, we use a biophysical computer model to: (1) forecast larval lionfish sources and sinks that are also delineated as low to high lionfish 'density zones' throughout their invaded range, and (2) assess the potential vulnerability of five grouper and snapper species- Epinephelus morio, Mycteroperca microlepis, Epinephelus flavolimbatus, Lutjanus campechanus, and Rhomboplites aurorubens-to lionfish within these density zones in the Gulf of Mexico. Our results suggest that the west Florida shelf and nearshore waters of Texas, USA, and Guyana, South America, function both as lionfish sources and sinks and should be a high priority for targeted lionfish control. Furthermore, of the five groupers and snappers studied, the high fishery value E. morio (red grouper) is the Gulf of Mexico species most at risk from lionfish. Lacking a comprehensive lionfish control policy, these risk exposure data inform managers where removals should be focused and demonstrate the risk to five sympatric native groupers and snappers in the Gulf of Mexico that may be susceptible to dense lionfish aggregations, should control efforts fail. [ABSTRACT FROM AUTHOR]

Marine connectivity over seascapes enables the persistence of metapopulations and is often regulated in part by an organism's pelagic larval duration (PLD), fecundity, mortality, and ocean conditions. The Campeche Bank (CB) in the southern Gulf of Mexico flanks the strong-flowing Loop Current and is important ecologically and economically in the context of mesoscale connectivity to the Gulf. Here we use a biophysical model to examine connectivity between the CB and the northeastern Gulf (NEGOM) of simulated populations of lionfish ( Pterois volitans/ miles), red grouper ( Epinephelus morio), and a generic marine organism. Our purpose was to assess longitudinal connectivity across the CB to the NEGOM and also to quantify this connectivity over a range of PLDs and organism fecundities. From this work, we find that portions of the northeastern perimeter of the CB in water depths between 50 and 300 m are the majority sources of lionfish and red grouper recruits to the NEGOM. This finding is important as deep waters on the bank are often heavily targeted by commercial fishers and are also beyond the reach of present lionfish control regimes. We also demonstrate that buoyant larvae must remain in the water column for a minimum of ten days to reach the NEGOM from the CB given prevailing water flow, though 45-50 days provides maximum connectivity. These findings are relevant for invasive species control, fisheries management, ecosystem services, and preserving metapopulations of marine fauna sympatric to the both regions. [ABSTRACT FROM AUTHOR]

End-to-end ecosystem modeling platforms, including OSMOSE, are key tools for informing ecosystem-based fisheries management (EBFM). End-to-end models ideally implement two-way interactions between model components, yet two-way interactions between high trophic level (HTL) functional groups and humans (fisheries managers and fishers) are currently missing in OSMOSE. We developed a management strategy evaluation (MSE) framework for OSMOSE, which allows for feedback between HTL functional groups and fisheries managers. This framework couples OSMOSE to a management procedure integrating decision rules and accounting for scientific uncertainty and the acceptable risk of overfishing. We applied the MSE framework to the OSMOSE model of the West Florida Shelf, so as to conduct an evaluation of total allowable catch (TAC) strategies for red grouper ( Epinephelus morio ) in a context of episodic events of natural mortality. Our simulations indicate that TAC strategies that assume higher scientific uncertainty and/or lower acceptable risk of overfishing result in higher biomass-related metrics for red grouper. However, the levels of scientific uncertainty and acceptable risk of overfishing impose a trade-off between biomass-related and catch-related metrics for red grouper. Our simulations also indicate that updating red grouper TAC more frequently in a context of episodic events of natural mortality does not have a large impact on biomass-related and catch-related metrics for red grouper and other functional groups. The MSE we conducted for red grouper is strategic, and its outcomes, which were obtained under a specific set of assumptions, must be considered preliminary. We discuss how future research could help enhance understanding of the possible impacts of TAC strategies for red grouper. The MSE framework designed for OSMOSE links the dynamics of HTL functional groups to that of fisheries managers, thereby allowing OSMOSE to be better suited for informing EBFM. This framework is an invaluable asset in assessing the performance of fisheries management strategies, but could also be used for other purposes, such as the evaluation of research monitoring programs. [ABSTRACT FROM AUTHOR]

The spatial dynamics of the red grouper Epinephelus morio plays a fundamental role in the fishery management on the Campeche Bank, where it is overfished. The objective of this study was to characterize the spatial dynamics of this population. We used a dynamic model of spatial distribution to estimate population movement rates between adjacent areas. The model was applied using information on catch per unit effort and length-frequency distributions for the Mexican mid-sized fleet that operated in the area in the period 1973-1977. These data were chosen to ensure that the information would reflect the condition of the resource before overfishing. It was possible to quantify the spatial dynamics of the red grouper and the results were consistent with previously known movement patterns. The results showed different movement rates and temporal patterns of movement for different population sectors. The spawning aggregations and the seasonal upwelling occurring in the eastern part of the Bank were considered as key factors influencing the pattern of population movements.

The ecosystem model OSMOSE-WFS was employed to evaluate natural mortality rates and fishing scenarios for Gulf of Mexico (GOM) red grouper ( Epinephelus morio ). OSMOSE-WFS represents major high trophic level (HTL) groups of species of the West Florida Shelf, is forced by the biomass of plankton and benthos groups, and has a monthly time step. The present application of the model uses a recently developed ‘stochastic mortality algorithm’ to resolve the mortality processes of HTL groups. OSMOSE-WFS predictions suggest that the natural mortality rate of juveniles of GOM red grouper is high and essentially due to predation, while the bulk of the natural mortality of adult red grouper results from causes not represented in OSMOSE-WFS such as, presumably, red tides. These results were communicated to GOM red grouper stock assessments. Moreover, OSMOSE-WFS indicate that altering the fishing mortality of GOM red grouper may have no global impact on the biomass of the major prey of red grouper, due to the high complexity and high redundancy of the modeled system. By contrast, altering the fishing mortality of GOM red grouper may have a large impact on the biomass of its major competitors. Increasing the fishing mortality of red grouper would increase the biomass of major competitors, due to reduced competition for food. Conversely, decreasing the fishing mortality of red grouper would diminish the biomass of major competitors, due to increased predation pressure on the juveniles of the major competitors by red grouper. The fishing scenarios that we evaluated may have slightly different impacts in the real world, due to some discrepancies between the diets of red grouper and its major competitors predicted by OSMOSE-WFS and the observed ones. Modifications in OSMOSE-WFS are suggested to reduce these discrepancies. [ABSTRACT FROM AUTHOR]

While conducting a standardized fisheries-independent longline survey in the northern Gulf of Mexico on August 20–21, 2014, dead and/or moribund fishes, estimated to number in the thousands, were observed within a well-defined area of the West Florida Shelf. Fishes from 15 families were identified; however, numerous individuals of relatively large-bodied serranid species were decomposed beyond a state that would allow for identification below the family level. Based on survey catch data from previous years and morphological characteristics associated with the decomposing fishes, it was determined that most of the large unidentified fishes were red grouper ( Epinephelus morio ). Water profiler cast data collected within the area demonstrated that when compared to previous years (1995–2013) bottom temperature and salinity were consistent with what would be expected; however, dissolved oxygen concentration was lower than normal, and in some cases, hypoxic and chlorophyll a and transmissivity values were anomalously high and low, respectively. Hypoxia, high chlorophyll a concentrations and low transmissivity are thought to have resulted from a bloom of Karenia brevis , which was documented to have occurred in close proximity to the sampling area. As necropsies were not performed, it was not possible to state a definitive cause of death as the effects of brevetoxins are species-specific. However, numerous individuals of most impacted species were observed floating incapacitated, yet alive, in normoxic surface waters suggesting that the impacts we observed were due to the neurotoxicological and/or hemolytic effects of a harmful algal bloom. [ABSTRACT FROM AUTHOR]

Passive acoustic recorders were used to monitor sound production indicative of the use of spawning habitat by groupers (Serranidae) at Riley's Hump, which is located in the Tortugas South Ecological Reserve (TSER), part of the Florida Keys National Marine Sanctuary. Sound production by black grouper (Mycteroperca bonaci), red grouper (Epinephelus morio), and red hind (E. guttatus) was recorded yearround and at all times of day but occurred more often in the evening during the winter-spring spawning period than during other times of the day and year. This pattern for these species is consistent with results of previous studies that documented the association of sound production with reproductive behavior at spawning sites. Distinct diel and seasonal patterns of sound production by the longspine squirrelfish (Holocentrus rufus) and bicolor damselfish (Stegastes partitus) also were recorded. Riley's Hump is a documented spawning site for mutton snapper (Lutjanus analis), and recordings of black grouper, red grouper, and red hind indicate that it is used for reproductive purposes by these species as well. These results showed the importance of the TSER and the need for continued research to understand its role in the recovery and sustainability of managed fish populations. [ABSTRACT FROM AUTHOR]

Unsaturated fatty acids are of current interest for their potential to reduce cardiovascular disease, the first cause of death worldwide. By its content of essential fatty acids, fish is one of the food products most in demand among the population. One of the most popular processes for fish consumption in Yucatan Peninsula, Mexico is frying. However, studies show that frying food causes changes in the composition generating trans fatty acids. The objective of this study was to evaluate the fatty acid profile of Mero (Epinephelus morio) crude and processed with different types of commercial oil. The results showed a fat content in raw E. morio of 1.68%. The percentage of oil extracted and absorbed by the product to be fried with corn oil, sunflower/canola, soybean and safflower was found in a range of 2.3-3.93 and 26.95-57.25%, respectively. The lipid profile obtained by GC-MS suggested the formation of trans fatty acids by isomerization and effect of temperature frying. However essential fatty acids such as oleic and linoleic acids were absorbed by E. morio being fried in sunflower oil and safflower/ canola, respectively. [ABSTRACT FROM AUTHOR]

The goals of this project were to determine the daily, seasonal and spatial patterns of red grouper Epinephelus morio sound production on the West Florida Shelf ( WFS) using passive acoustics. An 11 month time series of acoustic data from fixed recorders deployed at a known E. morio aggregation site showed that E. morio produce sounds throughout the day and during all months of the year. Increased calling (number of files containing E. morio sound) was correlated to sunrise and sunset, and peaked in late summer (July and August) and early winter (November and December). Due to the ubiquitous production of sound, large-scale spatial mapping across the WFS of E. morio sound production was feasible using recordings from shorter duration-fixed location recorders and autonomous underwater vehicles ( AUVs). Epinephelus morio were primarily recorded in waters 15-93 m deep, with increased sound production detected in hard bottom areas and within the Steamboat Lumps Marine Protected Area (Steamboat Lumps). AUV tracks through Steamboat Lumps, an offshore marine reserve where E. morio hole excavations have been previously mapped, showed that hydrophone-integrated AUVs could accurately map the location of soniferous fish over spatial scales of <1 km. The results show that passive acoustics is an effective, non-invasive tool to map the distribution of this species over large spatial scales. [ABSTRACT FROM AUTHOR]

We evaluated eye lenses as potential recorders of stable isotope histories in fish because they consist of metabolically inert optical proteins that are deposited in successive, concentric circles (laminae) much like otolith circuli and tree rings. We conducted four different tests on lenses from red snapper, red grouper, gag, and white grunt. The first test was a low-resolution screening of multiple individuals (4–5 radial groups of laminae per lens, all species except white grunt). Along the radial axis, all individuals exhibited substantial isotopic variability. Red snapper individuals separated into two groups based on δ15N and gag separated into two groups based on δ13C. Two gag with the greatest variation were chosen for high-resolution temporal analysis using individual laminae from their second eye lenses. The first-order patterns from the high-resolution analysis generally mimicked patterns from the low-resolution screening of grouped laminae, yet the high-resolution plots revealed early-life details that were not apparent in the low-resolution screenings. For the third test, left- versus right-eye variation was compared using high-resolution methods. White grunt left- and right-eye radial isotopic patterns were almost identical for both δ13C and δ15N, suggesting the variations observed among individual fish were not artifacts. The final test evaluated intra-laminar variation; multiple samples were analyzed from different parts of the same lamina. Seven laminae from three individuals of two species were analyzed in this manner; variations among laminae were found to be much higher than variations within laminae. However, nominal intra-laminar variations were comparable to nominal differences between left and right lenses, suggesting intra-laminar variation established measurement precision. Eye lens isotopes appear to be useful for reconstructing the isotopic histories of individual fish; these histories can be compared with spatially-derived isoscapes to reconstruct individual histories for site fidelity, movement and trophic position. [ABSTRACT FROM AUTHOR]

A predator-prey model was applied to the red grouper Epinephelus morio fishery from Yucatan, Mexico, with the aim of understanding the spatial behaviour of a mid-sized fishing fleet. The heterogeneity of the environment was considered, and different habitat quality levels were determined to address environmental differences. The behaviour of the fleet was also evaluated based on a simulation of restricted fishing areas (RFA). The model was applied utilising 5 years of information on catch and fishing effort (1973-1977). Four levels of habitat quality were defined (low, medium, high and exceptional). The total costs and revenue for a fishing expedition in the areas of exceptional habitat quality were higher due to their location farthest from the base port. The fleet was most efficient during the winter at locations in the eastern continental shelf, with the number of these areas clearly decreasing in the autumn. The model simulation of the RFA showed a total revenue reduction of 7-27 % in scenarios of RFA for adult protection. When the RFA was implemented for the protection of juvenile fish, the total revenue was not reduced, indicating that this type of RFA might be a feasible management strategy for a sustainable fishery. [ABSTRACT FROM AUTHOR]

To be as accurate as possible, stock assessments should account for discard mortality in fisheries if it occurs. Three common approaches to modeling discards in assessments are to lump dead discards with landings, treat dead discards as their own fleet, or link them conversely with landings through use of a retention function. The first approach (lumping) implicitly assumes that the selectivity of landings applies also to discards. In many cases, that assumption is false, for example, if discards comprise smaller fish than do landings. The latter two approaches avoid the assumption by modeling discards explicitly with their own selectivity pattern. Here, we examine these approaches to modeling discards. Using a simulation study, we demonstrate that the two approaches to modeling discards explicitly can provide identical results under both static and time-varying conditions. Then, using a stock assessment case study of red grouper Epinephelus morio in the U.S. Gulf of Mexico, we demonstrate that in practice the approaches to modeling discards can provide different outcomes, with implications for the resultant management advice. We conclude by comparing and contrasting the different approaches, calling for more research to elucidate which approach is most suitable under various sources of error typically encountered in discard data. [ABSTRACT FROM AUTHOR]

The population dynamics of sequential hermaphrodites were investigated using three-stage matrix population models. A simple hermaphrodite model with density-dependent reproduction exhibited monotonic asymptotic growth or decline depending on parameter values. After incorporating density-dependent survival and sex change, the model was parameterized for red grouper ( Epinephelus morio), which exhibit protogynous life history, and the model was used to investigate the effects of fishing mortality on offspring production and population density. The sensitivity of offspring production to fishing mortality was less when sex change depended on the relative density of female to male (ratio-dependent sex change) or male density alone compared with either female density alone or no density dependence. Although strong ratio-dependent sex change also resulted in less sensitivity of equilibrium abundance to fishing mortality, it caused the population to fluctuate chaotically. This suggests that the strength and type of density dependence on sex change affect reproductive output, equilibrium abundance, and the types of dynamics exhibited. [ABSTRACT FROM AUTHOR]

Abstract: Understanding the spatial distribution of a species is an important precondition to successfully managing marine populations. For reef fishes, this is of particular importance due to the patchy nature of reef communities. This study estimated the spatial distribution of five reef fish species on the West Florida Shelf: gag grouper (Mycteroperca microlepis), mutton snapper (Lutjanus analis), red grouper (Epinephelus morio), red snapper (Lutjanus campechanus), and vermilion snapper (Rhomboplites aurorubens). Estimation was done by combining large-scale fishery-dependent catch per unit of fishing effort with small scale fishery-independent video survey observation. Catch per unit of fishing effort was obtained from vessel logbook data while video observations of reef fish presence–absence and relative abundance were made by stratified random sampling on known reef and hard-bottom habitat in the Gulf of Mexico. Relative abundance estimates showed different abundance patterns for the five species depending on depth and geographical area. Variogram modeling suggested that gag grouper, mutton snapper, and red grouper were spatially autocorrelated on reef or hard-bottom habitats at short ranges of between 0.87 and 0.95km, while red and vermilion snapper were found to be randomly distributed. Range estimates for gag grouper, mutton snapper and red grouper were supported by variograms of depth soundings in the Gulf which produced range estimates of between 1.56 and 6.34km. Combining the relative estimates of abundance from catch per unit of effort with the spatial autocorrelation parameters from video surveys allowed us to provide stochastic fish abundance estimates at scales of about 2km2. [Copyright &y& Elsevier]

Local fisher knowledge is an important source of information for the adjustment of environmental baselines relative to anthropogenic impacts on marine ecosystems. This knowledge is also susceptible to the shifting baseline syndrome. Four generations of fishers neighbouring a marine park in Eastern Brazil, were surveyed regarding the conservation status of nine reef fish species. Shifts in environmental baselines were detected among fisher generations. Fishers older than 50 years not only caught larger individual fish, but catches of large fish occurred four decades ago, suggesting that bigger fish are in decline in the region. Of nine reef fish species, seven exhibited significant declining catch trends based on information provided by fishers. Such declining status was not reported by all informants of younger generations, so the ability to identify such species increases significantly with fisher age. The fish species most cited as overexploited were Mycteroperca bonaci (Poey), Epinephelus morio (Valenciennes) and Ocyurus chrysurus ( Bloch), emphasising that special attention should be given to the management and conservation of these species in Eastern Brazil. These results also showed that knowledge acquired by elder fishers (> 50 years old) can provide valuable insights into the conservation status of reef fish and the adjustment of environmental baselines for proper management of a marine park. [ABSTRACT FROM AUTHOR]

The article examines the survival of red grouper and red snapper caught on circle and J-hooks by recreational fisheries in Florida. It mentions the difference of delayed hook mortality of both species from blood loss of J-hook nicked internal organs. It notes that the survival rates of the fish correlate with feeding behavior, jaw morphology, and prey residence time. It also emphasizes the higher tag recapture rates for tagged red grouper caught on circle hooks than on J-hooks.

The northeastern Gulf of Mexico contains some of the most diverse and productive marine habitat in the United States. Much of this habitat, located on the shelf edge in depths of 50 to 120 m, supports spawning for many economically important species, including groupers. Here, we couple acoustic surveys with georeferenced videography to describe the primary spatial and geologic features of spawning aggregation sites for four economically important species: gag (Mycteroperca microlepis), scamp (M. phenax), red grouper (Epinephelus morio), and red snapper (Lutjanus campechanus), with notes on fish distribution and abundance and spawning activities. We provide information on movement patterns of reef fish determined using acoustic telemetry. Finally, we discuss the possible coupling of geomorphology with hydrographic features to influence the overall productivity of the region and the importance of spatial fishery management in sustaining that productivity. [ABSTRACT FROM PUBLISHER]

The article highlights the activity of five exploited snapper-grouper species in the diverse coral reef habitat of Dry Tortugas, Florida. Among those included in the study conducted by the authors were red grouper Epinephelus morio, yellowtail snapper Ocyurus chrysurus and mutton snapper Lutjanus analis. The authors disclosed that movement of black groupers were small and infrequent while muttons like to make short and frequent movements. They also discovered that there were relatively small home ranges for red grouper, black grouper and yellowtail snapper.

The article explores the distribution and dynamics of holes red grouper Epinephelus morio in Steamboat Lumps Marine Reserve in the Gulf of Mexico. E. morio are known as ecosystem engineers for the depressions or holes they create in flat sandy bottom parts of the ocean. In the authors' study, they used high-resolution multibeam sonar data obtained in the reserve in 2006 and 2009. The authors found that from 2006-2009 there was an increase in hole density to 141 holes kilometer-squared and an increase in the number of holes from 181 in 2006 to 231 in 2009. They conclude that the use of active acoustic sonar is a effective way to observe red grouper spawning populations.

new species of nematode, Philometra morii sp. nov. (Philometridae), is described from males and gravid females collected from the mouth cavity of the red grouper, Epinephelus morio (Valenciennes) (Serranidae, Perciformes), from the northen Gulf of Mexico, off Florida, USA. The new species is characterized mainly by the length of spicules (84-90 and 72-87 μm) and the length (54 μm) and structure of the gubernaculum in the male, and by the presence of three large oesophageal teeth protruding from the mouth, the number and arrangement of small cephalic papillae (8 papillae in 4 pairs of external circle and 6 single papillae of internal circle), the length (1.09-1.50 mm) and structure of the oesophagus and two large papilla-like caudal projections, and by the length of their bodies (19.34-30.07 mm). Philometra morii is the third species of this genus reported from E. morio in the Gulf of Mexico, differing from the two previously described species, in addition to morphological features, by the site of infection in this host (mouth cavity and sinuses vs oculo-orbits or gonads). From the same region (northern Gulf of Mexico, off Florida), gravid females of Philometra Costa, 1845, morphologically and biometrically similar to those of P. morii, were found in the subcutaneous tissues and sinuses of the head of another serranid fish (gag), Mycteroperca microlepis (Good et Bean). Although their conspecificity with P. morii cannot be excluded, they have been designated as Philometra sp. until conspecific males are discovered and described. Based on light and scanning electron microscopy examination (latter used only for females), both these forms are described. [ABSTRACT FROM AUTHOR]

In this article, we consider the potential effects of anthropogenic disturbances on marine fish species known or suspected to be habitat engineers. The three species of interest inhabit different marine habitats at different life stages, and therefore can have significant influences across the sea floor at broad spatial scales. The primary species include the shallow-water Atlantic goliath grouper (Epinephelus itajara), which inhabits mangrove root systems as juveniles, and caves, shipwrecks, and rocky reefs as adults; red grouper (E. morio), which excavates habitat throughout its benthic life in Karst regions of the Gulf of Mexico and western Atlantic, from the coast to the shelf-edge; and tilefish (Lopholatilus chamaeleonticeps), a species that lives on the continental slope and constructs elaborate, pueblo-esque burrows. The anthropogenic disturbances of greatest interest in the Gulf of Mexico include fishing, hypoxia, red tide, oil and gas exploration, and climatic change. We suggest that to understand the broader effects of both natural and anthropogenic disturbances on biomass and productivity in these species requires that we first understand the strength of interactions between them and the other species residing within their communities (e.g., predators, prey, commensals, and mutualists). [ABSTRACT FROM AUTHOR]

Global temperatures are rising, and are expected to produce a poleward shift in the distribution of many organisms. We quantified changes in fish assemblages within seagrass meadows of the northern Gulf of Mexico (GOM) between the 1970s and 2006–2007, and observed changes consistent with this forecast. During 2006–2007 we sampled seagrass meadows using the same gears and methods previously employed by R. J. Livingston in coastal waters of northwest Florida throughout the 1970s. Comparisons between datasets revealed numerous additions to the fish fauna during 2006–2007 that were completely absent in the 1970s, including: Lutjanus synagris (lane snapper), Epinephelus morio (red grouper), Chaetodon ocellatus (spotfin butterflyfish), Mycteroperca sp (grouper, non gag), Centropristis philadelphica (rock sea bass), Fistularia tabacaria (bluespotted cornetfish), Ocyurus chrysurus (yellowtail snapper), Thalassoma bifasciatum (bluehead wrasse), Abudefduf saxatilis (sergeant major), Acanthuridae spp. (surgeonfishes) and Sparisoma viride (stoplight parrotfish). Several other species showed large increases in abundance during the interval between 1979 and 2006, including Mycteroperca microlepis (gag grouper, up ∼200 ×), Lutjanus griseus (gray snapper, up ∼105 ×), and Nicholsina usta (emerald parrotfish, up ∼22 ×). All of these are tropical or subtropical species that now make up a greater percentage of seagrass-associated fish assemblages in the northern GOM than in the past. Additionally, we observed regional increases in air and sea surface temperatures (> 3 °C) during the ∼30 years that separate Livingston's samples and ours that correlate with northern shifts in the distribution of warm-water fishes. Documenting these range shifts is a critical first step in investigating the consequences of global warming for endemic marine communities and fishery production in the northern GOM. [ABSTRACT FROM AUTHOR]

The article discusses a study which analyzed the spatial-seasonal variation in catchability of the red grouper Epinephelus morio fishery in the Campeche Bank, northern coast of the Yucatan Peninsula using data from 1973 to 1977. It reveals that the adult catchability was higher during the reproductive period in the eastern part of the region. The researchers recommend that coastal areas near Celestún, Dzilam de Bravo, Rio Lagartos, and El Cuyo, be considered as fishing restricted areas to limit fishing mortality and promote stock recovery.

Food poisoning due to ingestion of an unknown red grouper occurred in southern Taiwan. To identify the species of toxic red grouper implicated in food poisoning, a 475-bp sequence of the cytochrome b gene from six species of fresh red grouper meat was amplified by using a pair of primers (L14735/H15149). This fragment could be amplified when fish meat was treated with different heating processes. After sequencing, it was found that no variation in sequences was detected among individuals within each species. The species of toxic red grouper meat implicated in food poisoning was judged to be Lutjanus bohar based on sequence analysis. In addition, restriction enzyme analysis with HaeIII rapidly distinguished these six species of red grouper and the two samples implicated in food poisoning. No toxicity of viscera in 18 specimens of six red grouper species was detected, but two food poisoning samples were found to be toxic. This study indicated that DNA sequence and restriction enzyme analysis are powerful methods for identifying potentially toxic red grouper species as L. bohar. [ABSTRACT FROM AUTHOR]

The red grouper (Epinephelus morio) has historically been one of the most important fisheries of the Campeche Bank area in the Gulf of México, where two fleets from México and one from Cuba participate. Current stocks have been estimated to be a third or less as abundant as in the 1970s; hence, the fishery has been declared to be over-exploited. The federal government of México has expressed the need to investigate the potential use of protected areas as a management tool for recovery of this species. Based on artificial neural network (ANN) modelling, we analysed the spatial distribution of red grouper with respect substrate, considering the demographic structure of the stock. We found a significant relationship between the type of substrate and the three stages of development (juveniles, pre-adults and adults). Juveniles are distributed in shallow waters close to the coast on coral substrates; pre-adults are also associated with coral substrates, but at an intermediate depth; adults are found in deeper waters on sandy substrates. We also identified seasonal reproductive aggregation patterns, always in relation to substrate types. Reproductive aggregation during the winter and early spring in the north-eastern continental shelf and the almost permanent (exception in autumn) concentration of juveniles in coastal waters around the central and eastern coast of Yucatan are of particular importance for management. These patterns represent seasons and areas of high fish vulnerability, which is the basic criterion for further analysis of protected areas. [Copyright &y& Elsevier]

The objective of this study was to arrive at biologically convincing estimates of the natural mortality rate (M) for different life history stages of the red grouper Epinephelus morio on Campeche Bank, Mexico. Estimates of M must be compatible with our knowledge of life histories and are essential as input to analytical assessment models for any exploited stock. Because of difficulties in estimating M directly, M has often been incorrectly assumed to be constant with age for a fishery harvesting different age-groups. The gnomonic interval method (GIM) was applied to this long-lived species to estimate a vector of M-values for successive life history stages. The GIM estimates the vector of M at age from the duration of successive development stages and the mean annual fecundity. Estimates were calibrated using available independent data. We computed the relationship between M and age (t) over a 13-year period as Mt = 0.8976t-0.93. Values of M estimated by GIM for adult red grouper were not significantly different (P > 0.05) from those reported in the literature. [ABSTRACT FROM AUTHOR]

Epinephelus morio (Red Grouper) is an important component of commercial fisheries for the United States and Mexico. Fishery-independent long-line surveys that utilized standardized sampling designs were conducted along the west Florida shelf, Florida and Campeche Bank, Mexico (2001-2002). Detecting true differences in abundance and sizes are difficult, but by using standard collection and aging methodologies, the level of bias was kept at a minimum. Relative abundance was higher in the Campeche Bank compared to the west Florida shelf (1.74 and 0.63 Red Grouper/100 hook hr, respectively). Fish from the Campeche Bank were also significantly smaller at length and weight. Differences in length, weight, and relative abundance of Red Grouper may be because of historical fishing pressure and management regulations, or the available carrying capacity of each area for Red Grouper. These differences have a substantial impact on how an overfished population can recover and be sustained. [ABSTRACT FROM AUTHOR]

Distribution patterns of catchability were evaluated for the red grouper Epinephelus morio (Serranidae) on the Campeche Bank off the northern Yucatan coast of Mexico. Catchability-at-length values were estimated with a method based on a transition matrix. Five years of catch and effort data for the Mexican mid-fleet were used for the estimation procedure. Two main patterns were found within the bank. The first occurred in the deepest areas and in the eastern part of the bank, where catchability increased with size. The second was close to the coasts, where lower values of catchability were observed, even in large sizes. These results suggest that the main area of aggregation for reproduction with higher values of catchability is in the eastern part of the bank (22–23°N, 87–88°W). Catchability differences suggest that spatial management policies must be implemented to allow depleted stock to recover. [ABSTRACT FROM AUTHOR]

Abstract: Red grouper (Epinephelus morio) were collected from the west coast of Florida, the central area of fishery harvest in U.S. waters, by fishery-dependent sources during 2000–2005. The west Florida shelf was divided into two regions: north (capture locations ≥28°N latitude) and south (capture locations <28°N latitude). Significant differences were found for age, length, and size-at-age by region and by gear; red grouper from the north were significantly younger and smaller on average than those from the south. Regional differences were also noted with respect to age progression; year class trends were only detected in the north. The 1996 year class dominated the landings in 2000–2001 (ages 4 and 5) and the 1999 year class dominated in 2004–2005 (ages 5 and 6). Regional data were fit to a size-modified von Bertalanffy growth model indicating smaller asymptotic length (L ∞) and faster growth rate (k) in the north (north: L ∞ =800mm, k =0.23mmyear−1, t 0 =1.12; south: L ∞ =863mm, k =0.15mmyear−1, t 0 =0.05). Mortality estimates derived from catch curves resulted in higher total and fishing mortality in the north for both gears. Alternative explanations of regional differences likely depend on nursery delineation and correlation to periodic environmental events such as red tides and hurricanes; all possibly important factors based upon anecdotal information. Nevertheless, our finding of regional demographic differences in red grouper from the west coast of Florida suggests a more complex population spatial structure for red grouper. [Copyright &y& Elsevier]

The article discusses the life history of the red grouper (Epinephelus morio) in North and South Carolina. The 2,146 sample specimens of red grouper have a total length range of 315 to 851 millimeter with the age range of 2 to 20 years. The von Bertalanffy growth equation was used to describe the length-at-age, while the sex type was assessed using histological analysis. It was determined that red groupers are protogynous hermaphrodite or their sex type changes as they mature.

Abstract: This study describes the historical evolution of the biomass, fishing mortality per age group, annual recruitment, and catchability of the Campeche Bank red grouper population. This fishery is based on three fleets (the Mexican Minor, the Mexican Major or Industrial, and the Cuban) with different capacities, areas of operation, and targeting of different age groups. During the last 10 years, the Minor fleet expanded, resulting in some overlapping with the other fleets areas. The biomass of the population of the red grouper in the Campeche Bank has decreased between 1986 and 2000. This decrease is evident from the commercial landings (from 14,410 to 9797t) and in CPUE from independent research surveys (from 3.8 to 1.5kg/100 hooks). The size of the spawning stock has decreased 25% since the beginning of the period, as well as the recruitment (from 24 to 11 million, 1–2 years old), while the catchability coefficient has increased (from 0.2 to 0.4). [Copyright &y& Elsevier]

The genetic population structure of red grouper, Epinephelus morio (Valenciennes), and scamp, Mycteroperca phenax Jordan and Swain, from the southeastern U.S. Atlantic coast and the Gulf of Mexico was examined using nuclear microsatellite DNA markers in order to test the null hypothesis of panmixia throughout this range. Physical and biological data indicate that relatively isolated populations of these fish exist. Genetic variation was assessed at four microsatellite loci in red grouper and six loci in scamp. The fish were collected on different dates between 1991 and 2001. The microsatellite loci were highly polymorphic, with an average expected heterozygosity of 0.75 in red grouper and 0.68 in scamp. Heterozygote deficiencies (significant deviations from Hardy–Weinberg equilibrium, HWE) were found at two of four loci in all red grouper samples except the eastern Gulf of Mexico, and for all red grouper combined. In contrast, all loci conformed to HWE in the separate scamp samples. Minimal genetic differences distinguished southeastern U.S. Atlantic or Mexican red grouper from other localities, and no indication of genetic differentiation was observed in scamp. This large-scale genetic homogeneity may be attributed to ongoing gene flow and/or historical contact between present-day populations. For management purposes, genetic homogeneity does not necessarily imply a single stock. Because larval dispersal may be sufficient to homogenize gene frequencies but not to replenish depleted stocks, other data must be considered in the management of these species. [ABSTRACT FROM AUTHOR]

This paper develops a precautionary bioeconomic approach for the red grouper (Epinephelus morio) multi-fleet fishery in the Campeche Bank, Gulf of Mexico, based on a long-term analysis covering the years 1980–2000. Population structure was estimated through commercial sampling of the three fishing fleets participating in the fishery: two Mexican (one artisanal and the other industrial) and one Cuban (industrial). Length frequency distributions (LFDs) did not show significant differences between the Mexican industrial and the Cuban fleets, but differed from those of the artisanal fishery, which targets smaller individuals. The lack of differences in the LFDs between years suggests that the population structure was stable during the last two decades. However, the instantaneous coefficient of total mortality Z, estimated through length-converted catch curves, significantly increased during the 21-year period of analysis, being in average 1.22 times higher in 2000 than in 1980. Annual estimates of yield and Z, together with unit costs of effort and ex-vessel prices, were used as inputs to build a bioeconomic yield–mortality model. A sensitivity analysis was performed under three scenarios of natural mortality M (0.16, 0.25 and 0.35 per year). The yield at maximum economic yield (YMEY) and the associated mortality levels ZMEY and FMEY were always the most conservative bioeconomic reference points (BRPs). The yield at maximum biological production (YMBP), YMEY and mortality-related BRPs were substantially lower than those based on maximum sustainable yield (MSY), thus constituting useful target BRPs for precautionary management. The bootstrap method used for determining the uncertainty associated at BRPs, shows that the best targets BRPs were YMEY and YMBP, whereas MSY is confirmed as a risky and limit BRP. A simple approach to the formulation of risk-averse management strategies was explored using the percentiles of cumulative distributions of MSY, YMBP and YMEY estimates generated from bootstrap against Z. We conclude that the red grouper fishery at Campeche Bank is overexploited and that immediate management actions are needed to prevent stock collapse. [Copyright &y& Elsevier]