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The diel, lunar, and seasonal timing of spawning in Atlantic goliath grouper Epinephelus itajara (Lichtenstein, 1822) in the United States is highly specific, occurring at night during new moon phases of August, September, and October. We derive these patterns from four lines of evidence apparent on spawning sites during the known spawning season:...
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Many animal species across different taxa change their habitat during their development. An ontogenetic habitat shift enables the development of early vulnerable‐to‐predation stages in a safe ‘nursery’ habitat with reduced predation mortality, while less vulnerable stages can exploit a more risky, rich feeding habitat. Therefore, the timing of the...
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... These ecosystems serve several essential functions, including carbon sequestration (Donato et al., 2011;Kandasamy et al., 2021), acting as a buffer zone for coastal regions (Hochard et al., 2019), significantly increasing fishing opportunities (Carrasquilla Henao and Juanes, 2017), promoting biological connectivity between estuarine and marine environments Bastos et al., 2022) and providing crucial habitats for fauna (Kathiresan and Bingham, 2001;Borland et al., 2023). Mangroves also serve as vital nursery areas for several commercially important (Moura et al., 2011;Whitfield, 2017) and endangered species (Dahlgren and Eggleston, 2001;Koenig et al., 2017), such as Lutjanids and Epinephelids. Mangroves typically exhibit a high abundance and a diverse assemblage of fish species (Kathiresan and Bingham, 2001;Faunce and Serafy, 2006;Gaines et al., 2022), providing essential shelter for various species during their settlement phase, feeding grounds at different life stages, and areas for reproductive activities (Koenig et al., 2007;Sheaves et al., 2015;Bastos et al., 2022). ...
... PAM variables and PAM-supported results also facilitate communication and increases the credibility of findings, since meagre acoustic behaviour is well known among fishers in the Tagus estuary. A similar confirmatory role of PAM was found for the grouper family, where diver-based visual censuses compared well with PAM in the short-term (Rowell et al. 2012) and the long-term (Koenig et al. 2017). Such congruent results facilitate, in turn, recursive feedbacks between the state of meagre in the estuary and knowledge about the system (Blythe et al. 2017) and increases the legitimacy of potential measures to protect reproduction (Stratoudakis 2021). ...
Passive acoustic monitoring (PAM) is useful for monitoring vocal fish but has had so far limited application in fisheries management. Here, four years (2016–2019) of concurrent daily catch and effort fishery data in Portugal and species-specific vocal activity in the Tagus estuary are compared to describe biological and small-scale fishery dynamics for a large sciaenid fish, the meagre (Argyrosomus regius), that aggregates to spawn. Consistent patterns in seasonality of acoustic and fisheries variables indicate that most fishing takes place within the Tagus estuary in spring and summer months, when higher vocal activity related to spawning aggregations is detected in the PAM station. Good fit of statistical models shows that PAM (sound pressure level in the third-octave band with centre frequency at 500 kHz during dusk) and PAM-supported variables (mean weekly catch per first sale transaction) can provide useful surveillance indicators to improve local management. Signs of overexploitation and hyperstability are detected and communicated to the estuarine fishing communities with the aim to initiate an adaptive local management cycle. The approach can be relevant for fisheries targeting other vocal fish that seasonally aggregate and face similar threats of overexploitation.
Graphical Abstract
... Groupers are known to produce sounds, some of which have been associated with visual courtship behaviours (Bertucci et al., 2015;Koenig et al., 2016;Rowell et al., 2019). Courtship calls are species-specific sounds that can be used to spatially and temporally localize the occurrence of spawning aggregations (Mann et al., 2010;Wall et al., 2014;Locascio & Burton, 2015). ...
Groupers are marine fishes particularly vulnerable to overexploitation owing to their reproduction‐related traits. The dusky grouper Epinephelus marginatus is classified as ‘Endangered’ in the Mediterranean Sea, where protection measures have proven critical for allowing population recovery and persistence of the species. However, knowledge gaps remain regarding its reproductive behaviours and spawning sites. As with other grouper species, the dusky grouper is known to produce courtship‐associated sounds, which were validated in captivity, but no study has ever established a link between sound production and observed behaviours in the wild.
This study aims to characterize, both visually and acoustically, the behavioural patterns of wild dusky grouper, thus specifically linking visual courtship behaviours to the associated sound production. Visual as well as passive acoustic methods were employed at two presumptive spawning sites within a Mediterranean Marine Protected Area (MPA) in the north‐western Mediterranean Sea over two consecutive summer seasons (2017 and 2018).
The temporal patterns of sound production showed site specificity over the month in which reproductive activity was most intense. Courtship calls were mostly recorded around sunset at both study sites and were significantly associated with visual reproductive behaviours. Results also indicated a temporal partitioning in the acoustic activity of the species, with different sound types being recorded at distinct times of the day, likely corresponding to the occurrence of various behaviours during those periods.
These findings have important implications for identifying and monitoring dusky grouper spawning sites using passive acoustic methods, therefore providing valuable information for the development, implementation, and/or enforcement of effective conservation measures therein.
... Acoustic activity, such as chorusing, has been linked to spawning in sciaenids (e.g., field: Mok and Gilmore, 1983;Luczkovich et al., 1999 Montie et al., 2017;Vieira et al., 2019;Bolgan et al., 2020) and in groupers (epinephelids) (field: Koenig et al., 2017, Rowell et al., 2019 through concurrent appearance of eggs and larvae in the water with recordings of fish calls. However, the relationship between acoustic features, male quality, mate choice, and spawning success (offspring number) remains to be tested in these groups. ...
This paper outlines my research path over three decades while providing a review on the role of fish sounds in mate choice and reproduction. It also intends to provide advice to young scientists and point toward future avenues in this field of research. An overview of studies on different fish model species shows that male mating acoustic signals can inform females and male competitors about their size (dominant frequency, amplitude, and sound pulse rate modulation), body condition (calling activity and sound pulse rate), and readiness to mate (calling rate, number of pulses in a sound). At least in species with parental care, such as toadfishes, gobies, and pomacentrids, calling activity seems to be the main driver of reproductive success. Playback experiments ran on a restricted number of species consistently revealed that females prefer vocal to silent males and select for higher calling rates. This personal synthesis concludes with the suggestion to increase knowledge on fish mating signals, especially considering the emerging use of fish sounds to monitor aquatic environments due to increasing threats, like noise pollution.
... The lunar periodicity of spawning was calculated using the proportion of mature individuals during each moon phase. The equation describing the moon phase was based on the data presented in Koenig et al. (2016)). The moon phases are described as follows: New Moon = NM ± 3.5 d; First Quarter (Q1) = NM + 3.5 to NM + 11.5 d; Full Moon = FM ± 3.5 d; Third Quarter (Q3) = FM + 3.5 to FM + 11.5 d. ...
... They are the largest grouper found in coastal regions of the western Atlantic Ocean, with adults reaching 2.5 m in total length (TL) [7] and ages up to at least 37 years [8]. In addition, they form spawning aggregations during specific times of the year at specific sites [9,10], making them targets for harvesting [11]. Goliath Grouper also exhibit an ontogenetic shift in preferred habitat, with juveniles (≤6 years old but up to~1.2 m TL) occurring mostly in coastal mangrove habitats and subadults and adults moving to relatively shallow (<50 m) offshore reefs, ledges, and artificial structures [3,12,13]. ...
... Bullock et al. [8] sampled commercial and recreational catches of Goliath Grouper from 1977 to 1990 in the Gulf of Mexico (GOM) and provided the most comprehensive age, growth, and reproductive study of Goliath Grouper available to date. Within the past 15 years, however, substantial information on the relative abundance, movements, spawning behavior, habitat use, diet, and mercury contamination have been amassed using non-lethal collection methods [10,13,23,[27][28][29][30][31]. These studies have been particularly important in determining the spatiotemporal use of nursery and spawning sites [10,32], with related movements and spawning behavior both in the GOM and off the Atlantic coast of Florida [10,28,32]. ...
... Within the past 15 years, however, substantial information on the relative abundance, movements, spawning behavior, habitat use, diet, and mercury contamination have been amassed using non-lethal collection methods [10,13,23,[27][28][29][30][31]. These studies have been particularly important in determining the spatiotemporal use of nursery and spawning sites [10,32], with related movements and spawning behavior both in the GOM and off the Atlantic coast of Florida [10,28,32]. ...
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.
... Atlantic goliath grouper, Epinephelus itajara (Lichtenstein 1822), exhibit restricted home ranges and high site fidelity, but also form annual spawning aggregations [1][2][3][4][5]. Adult goliath groupers form predictable, repeated concentrations of individuals gathered to spawn at densities far greater than found outside aggregations [5,6]. ...
... Atlantic goliath grouper, Epinephelus itajara (Lichtenstein 1822), exhibit restricted home ranges and high site fidelity, but also form annual spawning aggregations [1][2][3][4][5]. Adult goliath groupers form predictable, repeated concentrations of individuals gathered to spawn at densities far greater than found outside aggregations [5,6]. Fish spawning aggregations (hereafter, "FSAs"), such as those formed by goliath grouper, produce a mass point source of offspring that supports population persistence [6,7]. ...
... In the southeastern United States (US), goliath grouper form predictable spawning aggregations at offshore, high-relief habitats in the late summer to early fall each year in the eastern Gulf of Mexico and along the central Florida Atlantic coast [3,5]. Peak spawning by goliath grouper occurs primarily around the new moons of August and September, based on the collection of hydrated oocytes and/or post-ovulatory follicles from fish captured on-site, collection of fertilized eggs, recording of spawning sounds, and/or observations of aggregations during evening dives [5,12]. ...
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.
... To address the first assumption, Koenig et al. [7,8,10] used 3 divers to conduct a roving diver technique (RDT) one day after fish were tagged and demonstrated that the proportion of marked to unmarked fish was similar among divers which met the assumption of random assortment and therefore an equal chance of tagged fish being sighted. The second assumption was addressed using acoustic telemetry data which showed low movement (<10% of tagged fish) between spawning sites near the time of the new moon [8,11].We assumed these conditions also held for our 2022 surveys. ...
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.
... For fish, less information is available but to date, evidence points toward a similar synchrony between calling activity and spawning. For example, goliath groupers (Epinephelus itajara) produced 'boom' calls on nights when spawning was confirmed by egg collection, but did not call on nights without egg deposits (Koenig et al. 2017). Similarly, plainfin midshipman (Porichthys notatus) males attracted females to their nests with humming sounds, where the females spawned (Brantley and Bass 1994). ...
... Increased light conditions from the moon facilitate multimodal communication, but also increase susceptibility to predation (Dickerson et al. 2023). This trade-off leads some fish species to call more close to full moon (Mccauley 2012;Borie-Mojica et al. 2022), while others restrict their calling to periods with little lunar illumination (Mooney et al. 2016;Parsons et al. 2016;Koenig et al. 2017;Kaplan et al. 2018). This can even vary within species. ...
... Another driving factor could be the predation pressure on offspring. A reef fish species, the Atlantic goliath grouper (Epinephelus itajara), increased its spawning effort on new moon nights, when visually hunting egg predators were less abundant (Koenig et al. 2017). ...
Chorusing is widespread across the animal kingdom. Animal calling behavior is often driven by phenological and environmental factors such as seasonality, lunar period, and temperature. Now, in the Anthropocene, factors such as increased anthropogenic noise levels are also affecting calling behavior. Many fish call in choruses to attract mates, but the dynamics that drive fish calling behavior have rarely been studied in the field. We investigated how seasonality, lunar period, ambient noise, and temperature influenced the calling behavior of two species of toadfish, the plainfin midshipman (Porichthys notatus) and putatively, the Atlantic midshipman (Porichthys plectrodon). Acoustic recordings from a two-year period in eight different locations, spanning two ocean basins showed that midshipman chorus presence was driven by seasonality and lunar period. Furthermore, chorus frequency increased with increasing temperature. Chorus levels were strongly influenced by seasonality and increased somewhat with increasing noise levels. Taken together, these results indicate that midshipman calling behavior was strongly influenced by interacting environmental conditions. Understanding the various impacts of each driver will facilitate predictions of changes in midshipman calling due to future changes in environmental conditions.
... The Atlantic Goliath Grouper Epinephelus itajara (Lichtenstein, 1822)-hereafter referred to as "Goliath Grouper"-is the largest grouper in the western Atlantic where it occurs from the Carolinas (USA) to Brazil and is presumed to occur in the eastern Atlantic from North Senegal to North Angola off of West Africa [1,2]. Throughout its lifespan, this species spends its post-larval and juvenile stages in mangrove habitats [3,4], moving offshore to home and spawning sites on natural and artificial reefs (including oil rigs and platforms) as individuals mature [5,6]. Their diet is primarily composed of invertebrates, particularly crabs off the coast of Florida from which these fish accumulate heavy loads of methyl mercury that is accompanied by health and reproductive consequences [7][8][9]. ...
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).
