Blue Chromis Epinephelus striatus
Large, deep-bodied fish with rounded fins and prominent dorsal spines (1), often with yellow tips. The body has a pattern of wide bars that appear green to brown on a pale background (2), with a large black saddle-spot at the base of the tail (3). These fish can pale, darken will. Sexes appear similar and juveniles resemble adults.
1.2 m (4 ft)
Up to 30 years
6 – 30 m (20 – 100 ft)
Nassau groupers are most commonly found in rocky areas of the back reef, fore reef, and drop-off zones where there are plenty of caves and crevices for shelter.
Approximately half of the known Nassau grouper spawning sites have been fished to the point of collapse. Once extinguished, there is no evidence to show that spawning aggregations ever re-form, since young fish are thought to learn their location from experienced adults.
Nassau Groupers are eaten by sharks, barracudas, and other large groupers, including other Nassau groupers.
When predators are nearby, Nassau groupers settle into the reef and change colour to camouflage themselves. If confronted, Nassau groupers can produce a variety of loud booming sounds, created by vibrating their swim bladder, in an attempt to intimidate predators.
Nassau gro upers are usually solitary, but gather in large numbers, sometimes thousands of individuals, to reproduce during the breeding season (November to December). In the days leading up to the full moon, Nassau groupers migrate to traditional spawning grounds and form schools. As dusk approaches, females darken in colour and are chased by several males. Small schools periodically break away from the main aggregation and rush towards the surface where they release gametes (eggs and sperm) into the water. Spawning aggregations often last for about one week.
The Nassau grouper was once the most important food fish in the Caribbean, but overfishing of vulnerable breeding sites has made them endangered. Nassau groupers have declined in number by around 60% over the last three generations. Catching and selling Nassau groupers is banned in several countries, but not everywhere. Avoid purchasing Nassau groupers in supermarkets, fish markets and restaurants where possible.