The Struggle of the Nassau Grouper

What is known about the Nassau grouper? It is thought to be one of the largest fish of the coral reef environment. As a highly prized food source, the grouper also once constituted one of the most commercially valuable exports of Belize. And, due to phenomenal spawning aggregations, this fish has garnered the attention of researchers and fishermen alike. Unfortunately though, the current claim to fame for the Nassau Grouper isn't for any of the aforementioned facts; it is now listed as a candidate for the U.S. Endangered Species list.

The Nassau grouper is found throughout the tropical western Atlantic, distributed throughout the islands of the western Atlantic and along the coasts of central and northern South America. As one of the largest fish of the reef, the Nassau grouper can grow to three feet and weigh up to fifty-five pounds. It is characterized by four to five irregular dark stripes on a gray body with black dots around the eyes and a wide tuning-fork pattern on its forehead. When threatened by predators, the Nassau grouper can camouflage itself to the surrounding environment, blending in with sea whips and coral. More frequently, though, it is the grouper that has the role as the predator. This clever species will find a hiding spot and wait patiently until it eventually pounces on its prey, which most commonly comprise of shrimps, crabs, octopuses, and fish.

Reef Brief is a weekly column published in the San Pedro Sun
As fishermen of this area are well aware, the Nassau grouper was given its name because of a tendency to "group" together in large numbers to reproduce. Annual spawning generally occurs at 20-40 meters in specific locations on the outer reef shelf during the days surrounding the full moon of December and January. These "groups" or spawning aggregations can range from twelve to up to a thousand individuals and are usually in the same site from year to year, thus they are easily targeted by fishermen. Unfortunately, because reproductively active members are often removed, successful spawning is prevented and the growth of the population is consequently limited. Over the past few years, fishermen have also reported that in spawning banks, females continue to be smaller and smaller. This indicates that more mature females are being fished, leaving behind young females carrying fewer eggs to be fertilized.

Although the population of the Nassau grouper has significantly decreased due to over-fishing the past fifteen years, it is still not protected in Belize. In areas such as Glovers Reef and Bacalar Chico, where spawning aggregations are known to occur, there are seasonal fishing closures (five days before and after the full moon in December and January), but this is not always enforced. Moreover, despite the agreement of the U.S. to not import endangered species such as the Nassau grouper, countries such as Japan continue to do so. Belize is one of the few Caribbean countries that still allow for these species to be fished, but the population of the grouper is severely being threatened. If the country of Belize does not wish to completely over-exploit the Nassau grouper population, a management plan needs to be implemented and enforced now. In the meantime, fishermen should continue to abide by regulations set in place at the specific spawning aggregation sites.

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