The Nassaugroupercan be identified by three distinct features: 1) its body is covered in five olive-brown vertical bars, and a diagonal bar goes from its snout, across its eye and to the start of its dorsal fin; 2) the top of its head has a tuning-fork shaped marking; and 3) the base of its tail has a large black saddle spot. The fact that the Dutch Caribbean has a healthy population of NassauGrouper is an attestation to the health of our reefs and the success of our marine parks.
One of the biggest threats to this fish species is habitat loss; Nassau groupers inhabit shallow to mid-range coral reefs (typically between 6 and 30 meters) and rocky areas where they can hide in crevices; juveniles are commonly found in seagrass beds. Both coral reefs and seagrass beds have suffered much degradation in parts of the Caribbean within the past few decades.
These large fish are associated with hard structure such as reefs (both natural and artificial), rocks, and ledges. It was easy for commercial and recreational fisherman to catch Nassau grouper and it soon became scarce.
Because their range exceeds national borders, the best approach to their conservation is regional closed seasons. Sampling of fish landed in the U.S. Virgin Islands and Puerto Rico during the 1970s and 1980s indicates that Nassau grouper were commonly caught, mostly from spawning aggregation sites.
Currently, Nassau grouper are occasionally reported during underwater reef surveys at low density. Coloration varies, but adult fish are generally light beige, with five dark brown vertical bars, a large black saddle blotch on top of the base of the tail, and a row of black spots below and behind each eye.
A dark band that forms a tuning-fork pattern on top of the head, beginning at the front of the upper jaw, extending through each eye, and then curving to meet its corresponding band in front of the dorsal fin. They can be distinguished from other groupers by the vertical bars and dark saddle coloring along the dorsal part of the area preceding the tail.
Color pattern can change within minutes from almost white too bicolored to uniformly dark brown, according to the behavioral state of the fish. They take advantage of lower light levels at dawn and dusk, combined with the higher number of prey during changeover between diurnal and nocturnal fishes.
Nassau grouper are found in tropical and subtropical waters of the western North Atlantic. This includes Bermuda, Florida, Bahamas, the Yucatán Peninsula, and throughout the Caribbean to southern Brazil.
There has been one verified report of Nassau grouper in the Gulf of Mexico at Flower Gardens Bank. The Nassau grouper is considered a reef fish, but it transitions as it grows through a series of shifts in both habitat and diet.
As juveniles, they are found in nearshore shallow waters in macro algal and seagrass habitats. The main influences on where they live are not known, though water clarity, habitat, and bent hos (the community of organisms in the seabed) seem to be important.
Nassau grouper tend to spend a lot of time in one spot, often on a high-relief coral reefs or rocks in clear water. Larger fish tend to occupy deeper reef areas with greater vertical relief.
While adult Nassau groupers can change sex after hormone injection, natural sex-change has not been confirmed. Sites have been found near the edges of reefs, as little as 50 yards from the shore, near drop-offs into deeper water across a wide range of depths (20 to 200 feet) and environments (including soft corals, sponges, stony coral outcrops, and sandy depressions).
Some more information on how Nassau grouper get to their spawning sites, based on limited observations: After 1 to 2 months of floating with the ocean currents, the larvae settle in nearshore shallow waters in macro algal and seagrass habitats.
Adults are relatively solitary, living in areas that (patchily) overlap other groupers’ home ranges. In some countries with protective regulations, there are too few enforcement officers to cover a large geographic area with many landing locations.
Meanwhile, fish caught during closed season are held and later marketed as legal capture. “Adult gag grouper live in nearshore waters from coastal North Carolina south to Brazil and as well as in the Gulf of Mexico.
Smaller gag are a lot of lighter in coloring, and have numerous dark brown, or charcoal, kiss-like marks along their sides. “Adult gag grouper, live over on top of low- and high-profile hard bottom such as reefs or shipwrecks in waters between 60-250 feet deep,” said McLean Seward, fisheries biologist with the North Carolina Division of Marine Fisheries.
“Young gag grouper will live in oyster reefs, estuaries and seagrass beds from Massachusetts to Cape Canaveral, Florida. The coloration of red grouper helps to distinguish this species from gag with its head and body being dark reddish brown, shading pink or reddish or even pale pink along the lower part of its body,” Nash said.
“In North Carolina, gag will typically spawn in February and have clear larvae, which then make their way into estuaries. As water temperatures start to go down in the fall, juvenile gag will migrate from estuaries to offshore hard bottom habitat and larger members of their species,” said Seward.
Seward noted that all grouper are considered protogynous intersex, “that is they start their lives as females, and a part of the population will morph, or make the change, to males as they get older. Females start to reach sexual maturity when they are about 24 inches in total length and about 3 years old.
They are voracious predators, and will feed on whatever they can capture including scad, snapper, grunt, sardines, crabs, porgies, shrimp and squid, said Seward. Red grouper sitting on sand habitat 45 degrees to camera full body view mouth open.
In addition to their color, redgroupercan be distinguished from gag by the sloped, straight line of their spiny dorsal fin. “The red grouper is also a protogynous intersex and females are sexually mature by the time they reach 4 years old,” Seward said.
Females typically will let go an average of 1.5 million pelagic eggs that stay at the surface for between 30-40 days before finally settling down to the bottom. “ Red grouper may live to be as old as 25 years of age, with older specimens reaching a size of 32.5 inches and up to 25 pounds.
They will feed on lobster, shrimp, octopus, crabs and fish that are found close to their preferred reef habitat,” Seward said. Bottom fishing is the best way to catch gag grouper, using live bait, including squid and cigar minnows.
Use a depth finder to find deep-water rock ledges, artificial reefs and shipwrecks, a gag grouper ’s favorite hiding place. Recreational and commercial fishermen are required to use hooking tools when fishing for the snapper grouper species.
“This prohibition does not apply to fish harvested, landed and sold before the annual catch limit is reached and held in cold storage by a dealer,” said North Carolina Division of Marine Fisheries Executive Assistant to Councils Steve Poland, who is also a representative with the South Atlantic Fishery Management Council. Charter and head boat and commercial snapper grouper vessels must have National Marine Fisheries Service-approved sea turtle release gear and adhere to small tooth saw fish release protocol, Poland added.
While populations of gag grouper have remained healthy, a 10-year effort to rebuild the red grouper stock has failed, leading to new, stricter rules and regulations taking effect this year. Therefore, on Sept. 27, 2017, NFS sent a letter to the council stating that the South Atlantic red grouper stock was not making adequate progress toward rebuilding.
So, NFS took steps in 2018 to immediately end overfishing of red grouper by reducing the total commercial and recreational annual catch limits, based on the acceptable biological catch recommendation from the council’s Scientific and Statistical Committee. “For red grouper, this final rule extends the closure season formerly from January to April, to January through May of each year for the next ten years for the commercial and recreational portions off North and South Carolina, and establishes a commercial trip limit,” said Poland.
This final rule establishes a commercial trip limit for red grouper harvested in the South Atlantic EEA of 200 pounds, gutted weight. The trip limit is expected to help rebuild the red grouper stock by discouraging directed commercial fishing for the species, although it is not likely to substantially reduce the current level of commercial harvest of red grouper, according to the National Register.
“The council selected a commercial trip limit that in combination with extending the spawning season cloture for red grouper off North Carolina and South Carolina would help keep down harvest numbers to help rebuild the stock,” Poland said. You can help pay some cost by sponsoring a day on CRO for as little as $100 or by donating any amount you're comfortable with.
Which is why there are closed seasons for certain fish, ensuring a time when they can be left alone to breed in peace and to perpetuate their species. They are mostly found in the Northern Bahamas but only the Nassau grouper is on the IUCN Red List as an Endangered Species in need of protection.
Sad to say, mankind is the main cause of the population fragility that has led to the official listing, and the imposition of a strict closed season for 3 months between December 1st and February 28th. Scientific studies have shown that commercial overfishing has reduced a thriving population to fewer than 10,000 mature fish.