Nassau Grouper

Nassau Grouper

N is for Nassau Grouper

This grouper is a candidate for the endangered species category due to overfishing of aggregate spawning sites. The Nassau grouper is generally identified by 4-5 irregular dark stripes on a pale tan or gray body, black dots around their eyes, a large black saddle patch on their tail and a wide "tuning-fork" pattern on their forehead. They grow to lengths of approximately 3-4 feet and weigh up to 55 pounds. They have the ability to change color to camouflage themselves with their surroundings.

Nassau groupers live in offshore and inshore reefs, wrecks and pilings in depths up to 300 feet. In Belize, these top-level predators are usually found near shallow, high relief coral reefs and rocky bottoms to depths of 90 feet. Nassau groupers live a solitary existence, frequently resting on the reef or sea bottom, blending in with their surroundings. They aggregate only for spawning.

Adult Nassau groupers generally eat a diet of mainly fish: parrotfish, wrasses, damselfish, squirrelfish, snapper and grunts. Juveniles, on the other hand, eat a diet composed mainly of crustaceans: crab, stomatopod, hermit crab, lobster, and shrimp. These juvenile groupers are usually found around coral clumps covered with macroalgae and over sea grass beds. As with other grouper, they open their wide jaws to take in their prey whole.

Nassau groupers leave their solitary homes to come together in large aggregations of several thousand individuals for spawning once a year. Spawning usually occurs in December and January during the full moon. When spawning, both color and gender changes occur. The females release planktonic eggs that are externally fertilized in the water by the males. Each female can produce up to 6 million eggs. Nassau groupers exhibit no sexual dimorphism in body shape or color, so it is impossible from a glance to determine if a particular fish is male or female. They possess some degree of protogynous hermaphroditism, which means they change from female to male when they are between 1 and 2 1/2 feet long. These aggregation banks are site specific; Nassau grouper return to the same site each time they spawn. The sites are usually in 65-130 feet of water at specific locations at the outer reef shelf.

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