The Cayman Islands is home to the last known intact spawning aggregations of Nassau grouper in the world. The reason why is a conservation success story! 

Historically, thousands of Nassau grouper gathered in aggregations around the Caribbean to spawn during the January and February full moons. According to REEF, nearly 50 of these aggregation sites have been documented around the region, but due to overfishing, the majority of them are no longer viable. The last remaining site is on the west end of Little Cayman. So far, results have shown that banning fishing at these sites has a direct and positive effect on the Nassau grouper population. That’s why many scientists advise its continued protection. 

Because of the Cayman Islands’ conservation management, this particular spawning aggregation has been protected since 2003. Additionally since 2003, Reef Environmental Education Foundation (REEF) has partnered with the Cayman Islands Department of Environment to better understand and protect the spawning aggregation of Nassau grouper through the Grouper Moon Project. Through studying the Nassau grouper population size, fish lengths, juvenile habitats, genetics, and ocean currents, researchers continue to learn more about the Nassau grouper.

Protecting the Nassau grouper by imposing a fishing ban on the spawning aggregation ensures a healthy fish stock to keep fishermen in business for years to come, and supports a healthy ecosystem on the reef.

For more information on the project, visit https://www.reef.org/programs/grouper-moon-project

A keystone species is a species that a large number of other species in an ecosystem depends on. If a keystone species is removed from a system, the species that it supported will also be impacted, as well as any other dependent species. Nassau grouper are a keystone species and influence both the structure of reef communities and promotes coral health. Unfortunately, it is estimated that 60 to 80% of Nassau grouper aggregations have been wiped out due to overfishing at the spawning aggregation site. Because Grouper don’t reach maturity until four to eight years of age, and juveniles are frequently predated upon, Nassau groupers’ population is slow to rebuild. This is why the protection of the remaining aggregation sites, like the largest known site in Little Cayman so important to the protection and recovery of the species. 

The Cayman Islands government has taken a series of management actions aimed at recovering collapsed stocks of Nassau grouper as a result of overfishing. The government partnered with academic and nonprofit organizations to establish a research and monitoring program (Grouper Moon) aimed at documenting the impacts of conservation action. Over the last 15 years, the Nassau grouper population on Little Cayman has more than tripled in response to conservation efforts. The findings demonstrate that spatial and seasonal fishing closures aimed at rebuilding aggregation-based fisheries can foster conservation success. From 1 December to 30 April there is a closed season for Nassau grouper in the Cayman Islands. In May, the limit is 5 per person or 5 per boat per day, whichever is less. Additionally, once the fishing season begins in May, only Nassau grouper between 16″ and 24″ can be taken, and only with a hook and line.