Despite the devastating impact of the lionfish (Pterois volitans) invasion on NW Atlantic ecosystems, little genetic information about the invasion process is available. We applied Genotyping by Sequencing techniques to identify 1,220 single nucleotide polymorphic sites (SNPs) from 162 lionfish samples collected between 2013 and 2015 from two areas chronologically identified as the first and last invaded areas in US waters: the east coast of Florida and the Gulf of Mexico. We used population genomic analyses, including phylogenetic reconstruction, Bayesian clustering, genetic distances, Discriminant Analyses of Principal Components, and coalescence simulations for detection of outlier SNPs, to understand genetic trends relevant to the lionfish’s long-term persistence. We found no significant differences in genetic structure or diversity between the two areas (FSTp-values > 0.01, and t-test p-values > 0.05). In fact, our genomic analyses showed genetic homogeneity, with enough gene flow between the east coast of Florida and Gulf of Mexico to erase previous signals of genetic divergence detected between these areas, secondary spreading, and bottlenecks in the Gulf of Mexico. These findings suggest rapid genetic changes over space and time during the invasion, resulting in one panmictic population with no signs of divergence between areas due to local adaptation.
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), 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.
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).
1 May 2014 in International Oil Spill Conference Proceedings
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.