These large, oblong fish can change both color and gender, and live at the rocky reef bottom of tropical Western Atlantic waters. They are usually a light buff to pink color with striking darker bars and spots, but can change to very light or very dark quickly. There is some debate, but they are protogynous hermaphrodites, meaning most start out as females and then become males after a few years of spawning. They grow up to 4 feet long and eat mostly crustaceans and other smaller fish by opening their mouths and inhaling them. English language common names include Nassau grouper, day grouper, grouper, hamlet, rockfish, sweet lip, and white grouper.
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Nassau groupers, Epinephelus striatus , can be found in the coastal waters of the Atlantic Ocean as far north as the Carolinas of the United States down the Atlantic seaboard to southern Brazil.
Their range stretches as far west as the Yucatan Peninsula in Mexico. Nassau groupers are considered a migratory species in the Gulf of Mexico and are rarely seen there.
Nassau groupers are most commonly found in shallow water reefs, both natural and artificial. While they have been recorded at depths up to m, they are more prolific in depths above 30 m. Nassau groupers can also be found in beds of sea grasses and prefer areas of high visibility. Late juveniles to young adults prefer corals with large macroalgal populations. This species is also euryhaline, meaning it can tolerate a wide range of salinities.
During spawning, Nassau groupers can be found meters offshore, which has in part led to their exploitation and subsequent placement on the IUCN Red List. Nassau groupers range from tawny to pinkish red in color, and they can change coloration based on mood and behavior. They display five dark, unevenly spaced bars across their body, and a distinctive bar runs from the snout to the dorsal fin. Also characteristic of Nassau groupers is a large black spot at the base of the tail.
In juveniles, the caudal fin is rounded, whereas adults display a truncated fin characteristic of groupers. Nassau groupers can grow up to 1. They weigh between 2 and 27 kg average 12 kg. Once fertilization occurs, eggs of Nassau groupers hatch within 48 hours.
The larval period lasts 35 to 40 days, during which they are not recognizable as groupers. Nassau groupers reach sexual maturity between 4 and 8 years of age. Nassau groupers aggregate to specific spawning sites on the full moon during December and January. This peculiar timing is of particular interest to scientists, who have suggested that, like other marine mammals, the gravitational pull of the moon at this specific time of year inspires migration to breeding grounds.
Spawning aggregates can be as large as , individuals. Like other groupers , Nassau groupers are considered monandric protogynous hermaphrodites, meaning juveniles contain immature gonads for both genders and then directly mature as either male or female.
Nassau groupers congregate once a year at the edge of reef shelves in shallow water to spawn. They are strictly loyal to their spawning sites. This species changes its coloration when receptive to mating, usually becoming bicolor, darker, or incorporating a white belly. Dark coloration is though to be characteristic of males, while bicoloring and dark coloring typically correspond to submissive behaviors.
Spawning peaks 3 to 5 days after the full moon, but can continue up to 8 days after. Eggs hatch 23 to 48 hours after fertilization and mature slowly, reaching reproductive maturity between 4 and 8 years of age average 5 years of age. In captive populations, maturity occurs much sooner, which has been attributed to more abundant food sources and less environmental stress.
In captivity, the average hatchling length of the notochord is 1. Nassau groupers do not invest energy in their offspring post-fertilization.
Nassau groupers generally live 12 to 16 years in the wild, depending on environmental pressures. The oldest recorded Nassau grouper caught in the wild was 29 years of age. Except while spawning, Nassau groupers are a solitary predators that prefer to stay close to reefs, wrecks or other protective cover.
They are typically inactive during the day, as they prefer to feed under the cover of darkness. Members of this species can change their color depending on their mood or behavioral state. While this is often observed in relation to aggression during spawning, this behavior is not reserved to spawning.
For example, when two Nassau groupers of different sizes meet, their body color may change in response to aggression. These color changes are not thought to be a camouflage or anti-predator adaptation. Nassau groupers are loyal to their home reef, returning there to spawn. Over the course of a year, a single Nassau grouper has been reported to move up to km. Nassau groupers primarily communicate by altering their skin colors and patterns, especially when ready to spawn.
Their normal barred color pattern is typically seen, but can become lighter, darker, or change to a bicoloration with a dark top and white bottom. This coloration may signify aggression and reception to spawning. Nassau groupers are generalists which feed predominantly at down and dusk. This species has a unique method of engulfing its prey, quickly moving its gills to create suction, or negative pressure, that draws prey into its open mouth. As age and size increase, so do the preferred prey size.
Juveniles and smaller young adults prey on crustaceans and bivalves, while older Nassau groupers mainly eat fish, lobsters, and gastropods. Given its size and habitat, Nassau groupers have few known predators. Sharks may occasionally attack groups of spawning Nassau groupers, and yellowtail snappers eat their eggs. Other predators may include moray eels , which prey on small groupers , and hammerhead and sandbar sharks , which prey on larger groupers.
Nassau groupers also practice cannibalism on occasion. Humans are the primary predator of Nassau groupers, having greatly reduced populations of this species through commercial fishing. Nassau groupers prey on a variety of marine invertebrates and fish.
They compete with other groupers because of overlapping habitat and also likely compete with snappers , jacks , barracudas , and sharks. Nassau groupers also act as hosts to a number of parasites, including copepods , nematodes in the gonads, several trematodes Lecithochirum parvum and Lecithochirum microstomum in the gut, and larval tapeworms that infest the viscera. Nassau groupers also form a symbiotic relationship with some gobies and shrimp , which remove parasitic copepods from their bodies, fins, mouth, and gill chambers.
Nassau groupers have been heavily fished and were once considered the most economically important fish of the Bahamas In addition to commercial fishing, this species also is a form of ecotourism. Fishing, however, has been limited in recent years do to their endangered status.
Nassau groupers are also good candidates for aquacultures, and spawning can be induced in this species using human chrionic gonadotropin HCG. There are no known adverse effects of Nassau groupers on humans. Fishing regulations mandate fish must not be removed from the water, but rather the line must be cut. Even with these regulations in place, populations are still declining. It is the second largest ocean in the world after the Pacific Ocean.
This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals. Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists.
The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate. Jacksonville, Florida U. Reef Fishes, Corals and Invertebrates of the Caribbean. Knopf, Inc.. South Atlantic Fishery Management Council.
Fishing regulations for south Atlantic federal waters. Long-distance movement of a Nassau grouper Epinephelis striatus to a spawning aggregation in the central Bahamas. Synopsis of biological data on the Nassau grouper, Epinephelus striatus Bloch, , and the Jewfish, E. NMFS July U. Department of Commerce. Dineen, J. Smithsonian Marine Station at Fort Pierce. Eggleston, D. Recruitment in Nassau grouper Epinephelus striatus: post-settlement abundance, microhabitat features, and ontogenetic habitat shifts.
Marine Ecology Progress Series , Gascoigne, J. Grouper and Conch in the Bahamas extinction or management? The choice is now. Gibson, J. Managing a Nassau grouper fishery - a case study from Belize. Proceedings of the 60th Gulf and Caribbean Fisheries Institute, Kobara, S. Geomorphometric patterns of Nassau Grouper Epinephelus striatus spawning aggregation sites in the Cayman Islands. Marine Geodesy , Paz, G. The Nassau gropuer spawning aggregation at Caye Glory, Belize: a brief history.
More on author: Bloch. Short description Morphology Morphometrics Dorsal spines total : 11 - 12; Dorsal soft rays total : ; Anal spines : 3; Anal soft rays : 8. Caudal fin rounded in juveniles. Dorsal fin notched between forward spines; 3rd or 4th spine the longest.
To address patterns of genetic connectivity in a mass-aggregating marine fish, we analyzed genetic variation in mitochondrial DNA mtDNA , microsatellites, and single nucleotide polymorphisms SNPs for Nassau grouper Epinephelus striatus. We expected Nassau grouper to exhibit genetic differentiation among its subpopulations due to its reproductive behavior and retentive oceanographic conditions experienced across the Caribbean basin. All samples were genotyped for two mitochondrial markers and 9 microsatellite loci, and a subset of samples were genotyped for 4, SNPs. Genetically isolated regions identified in our work mirror those seen for other invertebrate and fish species in the Caribbean basin. Oceanographic regimes in the Caribbean may largely explain patterns of genetic differentiation among Nassau grouper subpopulations. Regional patterns observed warrant standardization of fisheries management and conservation initiatives among countries within genetically isolated regions. This is an open-access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.