The Nassau grouper, a predatory fish inhabiting coral reefs throughout the tropical western Atlantic, including the Cayman Islands, is among the most important fish species on coral reefs throughout the region. Overfishing, however, has driven Nassau grouper to become a threatened species, eliminating them from much of their historic range. The following is provided by the Cayman Islands Department of Environment.
Nassau groupers can live a long time – the oldest ever scientifically aged was 29 years from right here in the Cayman Islands! They are slow growing, reaching lengths of up to three feet, and weighing more than 50lbs. It takes approximately eight years for most individuals to reach sexual maturity, thus eight years = one generation of fish.
For most of the year they live alone on the reef guarding their specific territory. But once or perhaps twice a year, usually around the full moon in January or February, they perform a truly remarkable feat by travelling, sometimes great distances, and historically in great numbers, to specific locations to reproduce together as a group.
These traditional meeting areas are know as spawning aggregations sites, locally known as Grouper Holes. For the Nassau grouper this will be the only time they reproduce during the year and it is critical to the survival of the species.
While rarely caught during their solitary life, such spawning events involving the concentration of many hundreds of large hungry adults, and presents a guaranteed catch for knowledgeable fisherman.
Unfortunately these critical aggregations have been fished for many years, a practice which has led to their rapid decline.
A bit of Cayman’s Nassau grouper history:
Due to fishermen reporting smaller numbers and size of fish, a project began in 1987 to monitor the health of the local grouper fishery. Catch and size data from 1987 to 1995 (approximately one generation) showed that indeed our populations of Nassau grouper were in serious decline, and that fishing the spawning aggregations was unsustainable.
Recommendations to safeguard the grouper at that time went unheeded however, and fishing continued for yet another generation of fish, during which catches of Nassau’s grouper dwindled to almost nothing.
Then, in 2001 and 2002 the rediscovery of a traditional Nassau grouper spawning site in Little Cayman resulted in approximately 4,000 fish being caught. Some of the catch could not be sold and had to be discarded.
Realizing that this was probably our last chance to save our Nassau population, public outcry at this massive slaughter and waste of resource prompted action by Government to pass laws to protect this species. Since 2003, fishing on any of the eight designated Nassau grouper spawning sites is illegal.
How are Nassau groupers doing?
The Nassau grouper is in trouble throughout the Caribbean, and faces the very real possibility of extinction.
They have been taken by the thousands during their spawning season over the last 50 years, and in the Cayman Islands since the late 1960s.
Of the approximately 150 known Nassau grouper spawning sites around the Caribbean, more than half have been fished out of existence and the remaining sites – Cayman included – are in decline and are extremely vulnerable to fishing. This heavy fishing pressure has taken its toll on Cayman’s six known spawning aggregation sites, and today only one remains reproductively viable. The other five sites have very few spawning grouper, or none at all.
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How can we protect our Nassau groupers?
• Protect habitat – Grouper need healthy coral reefs and lagoons to survive.
• Don’t target them while fishing.
• Don’t buy or sell grouper in restaurants or the supermarket.
• Educate others about the plight of the Nassau grouper.