Itajara Research Articles

Time-series models and biotelemetry identify behavioral dynamics within a spawning aggregation of a large marine predator

Fish spawning aggregations (FSAs) may persist for months and include behaviors such as spawning and foraging. Acoustic telemetry has been used to measure the movements of fishes to and from FSAs, but behaviors within the aggregation are harder to quantify. We used multi-sensor acoustic telemetry (depth, acceleration) combined with continuous wavelet transformation analysis and hidden Markov models to identify behaviors within a spawning aggregation of the goliath grouper Epinephelus itajara, a vulnerable marine predator. Tagged fish (n = 20) exhibited periods (over 2 spawning seasons, August-October) where multiple individuals displayed variability in depth just after the new moon. These events may represent spawning, and there was always one event each season that included a greater number of individuals and more variability in depth. Grouper were more active during the new moon, in shallow water (<15 m), and at night. We also identified several events with behaviors more consistent with benthic foraging where grouper were highly active while remaining at constant depth. As such, intensive foraging by multiple individuals may occur during more sporadic time periods. Grouper remained close to the seafloor as currents exceeded 0.4 m s-1 but moved up into the water column during cold-water incursions (<24°C). Abiotic conditions may limit vertical habitat use and could potentially influence spawning and foraging behavior. Multi-sensor telemetry combined with time-series analysis can be used to remotely measure individual behavior within spawning aggregations. The timing of these behaviors within the FSA may also have implications for the ecological role groupers play as predators and, potentially, in bottom-up processes.

Review of: "Review of: Estimates of Atlantic Goliath Grouper (Epinephelus Itajara) Bycatch Mortality in Commercial Fisheries of the Southeastern Us From 2002 to 2022"

Review of: "Review of: Estimates of Atlantic Goliath Grouper (Epinephelus Itajara) Bycatch Mortality in Commercial Fisheries of the Southeastern Us From 2002 to 2022"

Estimates of Western Atlantic Goliath Grouper (Epinephelus Itajara) Bycatch Mortality in Commercial Fisheries of the Southeastern United States From 2002 to 2022

The Atlantic Goliath Grouper (_Epinephelus itajara_) in the southeastern United States is in decline due to increasingly large and persistent red tides, loss of juvenile habitat, and severe cold-weather events. In this paper, we address another source of mortality -- bycatch, focusing on data from NOAA Fisheries logbooks for commercial fisheries operating between 2002 to 2022. We calculate capture related mortality based on known patterns of depth-related barotrauma drawn from the literature and assume that all fish captured at depths greater than 30 m died if unvented prior to release. The overall result suggests that 75% (14,124 of 18,770) of Goliath Grouper captures died from barotrauma, as they either hemorrhaged or were unable to return to the bottom because of increased buoyancy due to expanded gas trapped in the swim bladder. While fishers currently use self-reporting to document these mortalities, this approach often results in biases toward lower capture and a higher survival rate. Thus, we strongly urge the Florida Fish and Wildlife Conservation Commission and the National Oceanic and Atmospheric Administration to quit using logbook data and instead require that fishers use paid observers and remote electronic monitoring on all commercial and charter vessels to ensure more effective, timely and reliable bycatch data for this and other protected species.

Seeing further into the early steps of the endangered atlantic goliath grouper (Epinephelus itajara): Eye lenses high resolution isotopic profiles reveal ontogenetic trophic and habitat shifts

Estuarine mangroves are often considered nurseries for the Atlantic Goliath grouper juveniles. Yet, the contributions of different estuarine primary producers and habitats as sources of organic matter during early ontogenetic development remain unclear. Given the species’ critically endangered status and protection in Brazil, obtaining biological samples from recently settled recruits in estuaries is challenging. In this study, we leveraged a local partnership with fishers and used stable isotope (C and N) profiles from the eye lenses of stranded individuals or incidentally caught by fishery to reconstruct the trophic and habitat changes of small juveniles. The eye lens grows by the apposition of protein-rich layers. Once these layers are formed, they become inert, allowing to make inferences on the trophic ecology and habitat use along the development of the individual until its capture. We used correlations between fish size and the entire eye lens size, along with estuarine baselines, to reconstruct the fish size and trophic positions for each of the lens layers obtained. We then used dominant primary producers and basal sources from mangrove sheltered, exposed estuarine and marine habitats to construct an ontogenetic model of trophic and habitat support changes since maternal origins. Our model revealed marine support before the juveniles reached 25 mm (standard length), followed by a rapid increase in reliance on mangrove sheltered sources, coinciding with the expected size at settlement. After reaching 60 mm, individuals began to show variability. Some remained primarily supported by the mangrove sheltered area, while others shifted to rely more on the exposed estuarine area around 150 mm. Our findings indicate that while mangroves are critical for settlement, as Goliath grouper juveniles grow, they can utilize organic matter produced throughout the estuary. This underscores the need for conservation strategies that focus on seascape connectivity, as protecting just one discrete habitat may not be sufficient to preserve this endangered species and safeguard its ecosystem functions.

Physicochemical variables influencing the abundance of Atlantic goliath grouper juveniles (Epinephelus itajara) in a tropical Brazilian mangrove habitat

The purpose of this study was to investigate the relationships between the abundance and occurrence of juvenile Atlantic goliath grouper and physicochemical variables in a tropical mangrove ecosystem, employing a non-lethal methodology. Juvenile Atlantic goliath grouper individuals were captured biweekly, using blue crab traps, across three locations within the São Mateus estuary (18°36′S, 39°44′W), from August 2021 to July 2022. Simultaneously, the physicochemical water variables were assessed during each trap inspection. The physicochemical water variables influence on the abundance and occurrence of Atlantic goliath grouper juveniles were assessed using the Zero-Inflated Binomial (ZIB) and the Poisson (ZIP) generalized linear mixed-effects models (GLMMs). A total of 66 Atlantic goliath grouper juveniles were sampled (Pontal do Sul = 50, Lagoa Creek = 13, and Pitangueiras Creek = 3), ranging from 32 to 319 mm in total length. The best model fitted to presence-absence data (AIC = 278.6) consisted of location, depth, and salinity, with only location having a significant influence on the likelihood of species occurrence. Regarding abundance data, the best model (AIC = 336.4) included location, depth, and turbidity, with only location and depth showing a significant impact on abundance variation, with lower abundance at deeper areas. Although our results indicate a weak significant influence of physicochemical variables on juvenile Atlantic goliath grouper distribution, it is imperative to continue this monitoring effort, considering that additional data may be required to gain a deeper understanding of these patterns.

Estimates of Atlantic Goliath Grouper (Epinephelus Itajara) Bycatch Mortality in Commercial Fisheries of the Southeastern Us From 2002 to 2022

Atlantic Goliath Grouper _Epinephelus itajara _is experiencing a population decline in the southeastern United States currently due to a combination of factors, including increasingly large and persistent red tides, loss of juvenile habitat, severe cold-weather events, and bycatch, the unintended capture by commercial and recreational fishers. In this paper, we review the extent of bycatch in the southeastern United States from 2002 to 2022 resulting from commercial fishing only based on data from NOAA Fisheries logbooks. We calculated depth-of-capture-related mortality based on known patterns of depth-related barotrauma and assumed that all captures deeper than 30 m that were unvented prior to release died based on observations of other researchers. The overall result is that 75% (14,124 of 18,770) _Epinephelus itajara_ captures died from both barotrauma and from inability of the fish to return to the bottom due to trapped swim bladder gas.

Diving for Data: Florida Sea Grant’s Great Goliath Grouper Count

Every summer, divers across Florida don their masks and fins and embark on a mission to provide data about one of the world’s largest groupers. The Atlantic goliath grouper (Epinephelus itajara, hereafter referred to as goliath grouper) is a large, long-lived reef species that can reach lengths exceeding 2 m and ages of at least 37 years (Bullock et al., 1992). Occurring in subtropical/​tropical waters of the South Atlantic and Gulf of Mexico, the species suffered significant overfishing and population declines through the 1980s. In 1990, the harvest of goliath grouper was prohibited in the United States, and the species remains protected from harvest in all federal waters of the United States at this time (although the state of Florida recently approved a limited, highly regulated harvest opportunity for goliath grouper in state waters; FWC, 2022). The state of Florida has historically been a center of abundance for this species, and although numbers have been rebuilding in some areas since the moratorium, stock assessment remains complicated and the status of the population is unclear (Koenig et al., 2011; SEDAR, 2016; Locascio et al., 2023).

Mislabeling, illegal capture, and commercialization of Atlantic goliath grouper (Epinephelus itajara) on the Brazilian coast using DNA barcoding

Abstract The Atlantic goliath grouper Epinephelus itajara is the largest grouper species in the Atlantic Ocean. Despite the conservation status being Vulnerable (VU) globally and Critically Endangered (CR) in Brazil, the species continues to face threats from overfishing throughout its range. We used DNA barcoding employing the mitochondrial Cytochrome c oxidase subunit I (COI) gene to identify the illegal commercialization of E. itajara in fish markets from the northern (NC) and southern (SC) Brazilian coasts. Sampling was conducted in fish markets and aimed to confirm the identification of mischaracterized fish sold as E. itajara in the NC, as well as identifying fish fillets sold as the Dusky grouper in the SC. DNA barcoding allowed the unambiguous identification of 22 (84.6%) of the 26 analyzed fish market samples. Both sampled areas had confirmation of E. itajara illegal commercialization and from the 22 analyzed samples, 17 (77.3%) were confirmed to be E. itajara. Here we report two crimes, the illegal sale of E. itajara and commercial fraud by species substitution. This study has highlighted that the existing legislation that protects E. itajara in Brazilian waters requires the adoption of better public policies for the conservation of the species.

DNA barcode reveals occurrence of threatened species and hidden diversity on Teleost fish trade in the Coastal Amazon

This study aimed to identify the teleost fish species sold in Bragança, a major fishing hub on the north coast of Brazil. The COI gene analysis was performed for the identification of fish species. The local market uses common names that are not accurate and do not reflect the diversity of the species. 204 sequences were obtained, with 119 haplotypes. 83 species were identified by comparing with public databases and constructing phylogenetic trees, with Carangidae being the most prevalent family. The study also found Haemulon atlanticus, Menticirrhus cuiaranensis and Hoplias misioneira, a newly described species from the Amazon basin, among the samples. Additionally, 73 commercial names were recorded, including 10 categories, and the illegal trade of Epinephelus itajara was detected. The DNA Barcode method proved to be effective for discriminating the species. The study highlights that common and commercial names are vague and underestimate the fish diversity, and that Brazil needs to revise its regulations for commercial and scientific names.

Age, Growth, and Functional Gonochorism with a Twist of Diandric Protogyny in Goliath Grouper from the Atlantic Coast of Florida

The lack of data on the age, growth, and reproduction of the Atlantic Goliath Grouper Epinephelus itajara off the coasts of Florida (USA) makes it difficult to estimate the extent of their population recovery following the 1990 fishery closure, as well as the potential effects of the recent (2023) opening of a fishery for juveniles. Goliath Grouper from the Atlantic coast of Florida were non-lethally sampled for size (total length, TL), age (via fin rays), and sex and reproductive stage (via gonad biopsies, milt/egg expression, gonopores) from May to October 2010–2016. Of 653 unique fish captured (not including 118 recaptures), 257 (39.4%) were females (122–228 cm TL; 5–20 years old), 264 (40.0%) were males (104–225 cm TL; 4–22 years old), 100 (15.3%) were unsexed (82–211 cm TL; 3–15 years old), and 32 (4.9%) were protogynous hermaphrodites (108–209 cm TL; 5–20 years old). Protogyny was conclusively determined in two fish recaptured and re-biopsied that had transitioned from female to male. However, an overlap in the age and size of males and females, a 1:1 sex ratio, and the presence of relatively small, young, mature males, in combination with an apparently low functional sex change rate, all indicated that the sexual pattern of Goliath Grouper was functionally gonochoristic with the potential for diandric protogyny. Females > 10 years old were larger-at-age than males, and Goliath Grouper from the Atlantic coast were larger-at-age than fish from the Gulf of Mexico. These differences in age, growth, and reproductive strategy—as well as the nascent fishery for juveniles—need to be monitored closely so that the current and future reproductive capacity of the population continues to ensure growth and sustainability.

Spawning Migrations of the Atlantic Goliath Grouper along the Florida Atlantic Coast

Atlantic goliath grouper (Epinephelus itajara), the largest reef fish in the Western Atlantic, exhibit high site fidelity to home reefs but also undertake annual migrations to distant spawning sites. Once relatively common throughout Florida and the Caribbean, the species; is now considered vulnerable (i.e., threatened with extinction) due to overfishing and loss of juvenile mangrove habitat. Goliath grouper in the southeastern US form annual spawning aggregations on high-relief reefs located offshore of both the Gulf and Atlantic coasts of Florida, US. To determine spawning site fidelity and describe migration patterns to aggregations, we implanted 50 adult goliath grouper with acoustic transmitter tags from 2010 to 2013. Fish were tagged at known spawning sites off the Florida Atlantic coast and tracked as they moved through the FACT Network array of acoustic receivers. From 2010 to 2020, we collected ~7 million detections from tagged goliath grouper at 153 sites along the southeastern US Atlantic coast. Results of this long-term tracking indicate that adult goliath grouper are relatively sedentary during non-spawning months (Nov to June) but move significantly more prior to, during, and immediately after spawning (July to Oct). Inter-annual spawning site fidelity was high: between 80–93% of tagged fish returned to the same spawning sites each year. Arrival timing at spawning sites coincided with the August new moon, with males arriving earlier than females. Some individuals migrated distances greater than 400-km per year, with observed migration rates of up to 44-km per day prior to spawning. Long-term tagging data are critical for understanding movement patterns and developing management strategies for this species of special conservation concern.

Absolute Abundance Estimates of Atlantic Goliath Grouper (Epinephelus itajara) on Spawning Aggregation Sites

Reliable data on Atlantic Goliath Grouper abundance are prerequisite to informed management decisions, particularly as the State of Florida reopened a limited harvest on the species in 2023 after a 32-year moratorium. Limited data exist for this purpose and fisheries data have been unavailable for over three decades due to a fishery closure that began in 1990. The purpose of this study was to compare absolute abundance estimates of Goliath Grouper between two years using an efficient, cost-effective method developed by Koenig. An underwater tagging method was used to collect mark and resight data for use in a Peterson deterministic model. These data were collected at the same spawning aggregation sites off Jupiter, Florida near the time of the new moon in September 2013 and August 2022. We found that Goliath Grouper abundance had declined at all but one of six sites since 2013. Because data were not collected during the intervening years, interannual variability is unknown. However, given the highly age-structured spawning stock of adult Goliath Grouper on the spawning grounds, the lower abundances measured in 2022 may reflect a real decline in the population rather than just representing a weak year of adult recruitment to these spawning sites.

Hydroclimatic influence on the trophic ecology of Atlantic goliath grouper juveniles (Epinephelus itajara) in a tropical estuary using non-lethal methodologies

The Atlantic goliath grouper Epinephelus itajara is the largest species of groupers in the Atlantic Ocean, reaching over 2 m total length and 400 kg. It has an ontogenetic migration, with adults using nearshore and offshore marine areas and juveniles inhabiting estuarine/mangrove areas. Despite of its high ecological relevance and classification as a threatened species for several decades in the IUCN red lists, critical phases of its life cycle, like juveniles inhabiting estuaries, are still poorly investigated. In this study, we evaluated if hydroclimatic changes may affect the trophic ecology of juveniles in a tropical estuary. We described their diet composition, isotopic niche area, food assimilation, and trophic position of juveniles across seasons using two non-lethal techniques: stomach content analysis using a stomach flushing procedure and stable isotope analysis using a dermal biopsy. A total of 87 individuals with TL ranging from 38 to 331 mm had their stomachs analyzed, of which 31 had food content. We identified 11 prey items, shrimp being the most abundant prey group (IRI% = 88.4), followed by fish (6.6), blue crab (2.8), and crab (2.2). A total of 93 specimens had their muscle's carbon (δ13C) and nitrogen (δ15N) stable isotope ratios analyzed (38–332 mm TL). Average δ13C values showed statistically significant changes across seasons, but no significant changes were observed for δ15N. As initially predicted, isotopic niche size of juveniles changed consistently along the entire hydroclimatic cycle, reaching its peak at the end of the wet season. We also observed changes in the proportion of prey assimilation by juveniles between seasons. Shrimp (92.1%) was the most assimilated prey group during the late dry season, whereas tidal crabs (36.7%), blue crab (27.8%), and shrimp (25.1%) were the most important in the late wet season. Average trophic position of juveniles remained similar across wet (3.32 ± 0.10) and dry (3.23 ± 0.11) seasons. These findings provide important information to help decision makers to promote more efficient management and conservation legislations to protect early life stages of the Atlantic goliath grouper in tropical estuaries.

Controversial opening of a limited fishery for Atlantic Goliath Grouper in the United States: Implications for population recovery

Laws protecting the Atlantic Goliath Grouper Epinephelus itajara from fishing in federal and state waters of the United States (US) occurred in 1990 after the species was identified as being severely overfished. Population increases that occurred during the first 20 years of the closure were followed by a decline in the 10 years thereafter. Despite the National Oceanic and Atmospheric Administration’s call to retain full protection for this species in federal waters, the Florida Fish and Wildlife Conservation Commission (FWC) decided to open a limited fishery in state waters for juveniles. Here, we review the literature demonstrating the initial recovery of Goliath Grouper in the U.S., the limits of that recovery, and the ensuing factors that precipitated its subsequent decline; we discuss the risks associated with management decisions that ignore the best available scientific information; and we compare management differences and difficulties among nations within the Atlantic Goliath Grouper’s global range. The major findings are that Goliath Grouper populations have not fully recovered and that FWC has not sought to conserve and protect them. Resolving these problems will require the Governor of the State of Florida to appoint Commissioners that represent a range of stakeholders with expertise in ecology, conservation, and management beyond that provided by the FWC agency; to better train appointees lacking in those areas; and to choose candidates who embrace use of the best available science in making critical decisions that affect Florida ecosystems, native species, and Florida residents.

West African Goliath Grouper: Where Are They between Senegal and Angola?

The Atlantic Goliath Grouper Epinephelus itajara (Lichtenstein, 1822) occurs on both sides of the Atlantic, from the Carolinas (USA) to Brazil in the western Atlantic and historically from North Senegal to North Angola off of West Africa in the eastern Atlantic. While there are relatively good data on their distribution in the western Atlantic, confirmed occurrences, population status, fishing reports, and trade data are almost non-existent for West Africa. Part of the problem is that tropical West African countries largely lack the wherewithal to fund the research needed to evaluate this species, nor do they have laws, management plans, or viable enforcement measures that might lead to effective population recovery or protection for essential juvenile mangrove habitats. Given the lack of published studies on this species in West Africa, the primary objectives of this paper are (1) to describe all known historical and current anecdotal information available on this species and (2) to encourage the increased monitoring of habitats where viable populations might still occur (i.e., mangroves, oil rigs, and oil platforms).

Are the Coastal Waters of French Guiana a Source or Sink Habitat for Atlantic Goliath Grouper Epinephelus itajara?

The coastal waters of French Guiana are amongst the most turbid and nutrient rich in the world, and as such, they favour the settlement and early development of several species of marine fish. Recent work has revealed a high abundance of Atlantic Goliath Grouper (Epinephelus itajara) in these waters, yet little is known about this species’ reproductive biology, which this study aims to complement. During the period from 2010 to 2013, we surveyed Goliath Grouper at three rocky sites along the French Guiana coast and examined 602 individuals for evidence of maturation. Satellite tags were deployed on five individuals and an acoustic survey was conducted to identify potential spawning movements and activity. We found no evidence of sexually active individuals or local spawning aggregations. Most individuals showed high site fidelity, but one fish was located 1150 km away, near Trinidad and Tobago. We discuss these findings in the context of the wider literature and postulate that Goliath Grouper inhabiting French Guiana reefs originate from spawning sites in northern Brazil and disperse to westerly reefs with the onset of maturity. We propose that the Goliath Grouper populations of South America and Caribbean are linked, and that management of Brazilian source populations could have wide-reaching impacts on Goliath Grouper stocks.

Reproductive Success Dynamics Could Limit Precision in Close-Kin Mark–Recapture Abundance Estimation for Atlantic Goliath Grouper (Epinephelus itajara)

Extra-Poisson variance in annual reproductive success can affect the precision of abundance estimates made using ‘close-kin’ mark–recapture procedures. However, empirical evaluation of that variance in natural marine populations can be daunting. Here, a scaling method was used to extend a discrete-time, age-structured model, facilitating investigation of annual and lifetime reproductive success dynamics in Epinephelus itajara. Life tables were synthesized from fishery assessment vital rates and life history measures. For model scaling, a precise empirical estimate of effective population size for the studied population was utilized as the independent variable, and model sensitivity to an informative range of adult abundance was evaluated. The potential for sex reversal to impact reproductive success dynamics was also investigated, albeit in the absence of selective fishing pressure and potential compensatory or depensatory responses. Close-kin relationships in a genetic sample of ~300 adults collected from spawning sites in the Florida Atlantic included numerous full-sibling pairs and multi-sibling families, which is unusual for long-lived, iteroparous marine populations with broadly dispersed larvae. The highly overdispersed reproductive success dynamics modeled for this population and its atypical kinship distribution could have ramifications for planned close-kin mark–recapture analyses. The low observed effective size also has conservation implications. Both issues warrant continued genetic monitoring.

Dorsal Fin Spines and Rays for Nonlethal Ageing of Goliath Grouper Epinephelus itajara

Atlantic Goliath Grouper, Epinephelus itajara, the largest grouper in the western North Atlantic, exhibits life history characteristics (e.g., it is slow-growing, long-lived, and late-maturing) that make it particularly susceptible to fishing pressure. Otoliths, the structure typically processed for age determination, are usually collected as part of fishery monitoring, but otoliths are not available from Goliath Grouper due to a harvest moratorium enacted in 1990 for United States waters. Alternative structures—such as dorsal fin rays or spines—can be acquired for ageing via nonlethal sampling and may provide reliable age estimates. Since 2006, the Florida Fish and Wildlife Conservation Commission (FWC) has been collecting incidental Goliath Grouper samples from mortality events including those from cold kills and red tides. Corresponding otolith, dorsal fin ray and dorsal fin spine samples were compared to determine the accuracy and precision of the external ageing structures. Marginal increment analyses indicated that annulus (translucent zone) deposition occurred primarily in March–June on spines and in April–June on rays. While ages determined from both rays and spines exhibited high precision, the accuracy compared to otolith ages was low as a result of systematic underageing of both external structures, particularly at the oldest age classes. A correction factor was applied to rays and spines that remedied the underageing, but the correction factor was more successful for spines. An analysis of ray and spine section accuracy based on nonlethal structure removal from the fish (i.e., comparing ages from sections at the base of the structure within the body to those sectioned from the external surface of the body) determined that spines can be accurately aged when sampled distal of the base of the structure, but that rays cannot. Nonlethal sampling and ageing of Goliath Grouper spines facilitated by public participation could address management goals and help determine the offshore population age structure. Simultaneously, it could contribute critical data needed for a traditional stock assessment, should such a path be warranted by the recovery or management of the species.

Active acoustic surveys reveal coastal fish community resistance to an environmental perturbation in South Florida.

Coastal fish communities are under increasing levels of stress associated with climate variation and anthropogenic activities. However, the high degree of behavioral plasticity of many species within these communities allow them to cope with altered environmental conditions to some extent. Here, we combine meteorological information, data from hydroacoustic surveys, and recordings of goliath grouper sound production to examine the response of coastal fish communities to heavy rainfall events in South Florida, USA, that resulted in the release of excess storm water into surrounding estuaries and coastal waters. We observed a nearly 12,000% increase in water column acoustic backscatter following a heavy rainfall event of September 16th, 2015. Interestingly, estimates of school backscatter, a proxy for biomass, increased by 172% with the onset of the perturbation. Schooling fish density also increased by 182%, as did acoustically derived estimates of mean schooling fish length (21%). Following the perturbed period, school backscatter decreased by 406%, along with schooling density (272%), and mean schooling fish length (35%). Hydrophone and hydroacoustic data also revealed that goliath grouper (Epinephelus itajara) spawning aggregations were persistent in the region throughout the duration of the study and continued to exhibit courtship behavior during the perturbed period. Our observations demonstrate the high level of resistance common in coastal species but raises new questions regarding the threshold at which fish communities and reproductive activities are disrupted. As coastal land use continues to increase, and the effects of global climate change become more pronounced, more Before-After Control Impact (BACI) studies will provide improved insight into the overall response of nearshore communities to future perturbations and the cumulative effect of repeated perturbations over extended periods.

Residency and Fine-scale Habitat Use of Juvenile Goliath Grouper (Epinephelus Itajara) in a Mangrove Nursery

The Atlantic goliath grouper (Epinephelus itajara) is the largest grouper species in the Atlantic and exhibits high site fidelity and limited range of movement. By 1990, the goliath grouper population in US waters had declined approximately 95% relative to unfished levels, leading to a harvest ban in 1990. Since then, the south Florida population has grown but the magnitude of recovery remains unknown due to uncertainties about life history characteristics. However, despite these unknowns, the state of Florida approved a limited recreational harvest of goliath grouper. In 2021, fine-scale habitat use of three juvenile goliath grouper was investigated using acoustic telemetry and a positioning solver. All three individuals exhibited high site fidelity as well as a diel habitat use pattern, utilizing seagrass habitat during the night and mangrove habitat during the day. Fine-scale acoustic telemetry provides insight into not only habitat use, but broader habitat preferences as well. This study illustrates the need to consider deep seagrass-dominated channels lined with red mangroves when protecting juvenile goliath grouper populations within Florida Bay, especially as the population is opened to harvest.