Goliath grouper are curious and fearless, characteristics that have made them easy targets for fishers, especially when the fish gather in large numbers in July and August to mate. That fishing pressure, coupled with degradation of the mangrove habitats that juvenile goliath grouper need to survive, has driven a dramatic decline in the species throughout its range, which includes the Florida Keys in the United States, the Bahamas, most of the Caribbean and most of the Brazilian coast.
In Cuba however, there is strong hope for a rebound, thanks to the government’s 2018 passage of a resolution to protect the goliath grouper (Epinephelus itajara)—a measure that was based on scientific research from 2012 Pew marine fellow Fabián Pina Amargós.
Pina Amargós, professor at the Center for Marine Research of the University of Havana and an environmental consultant with Avalon Diving operations in Cuba, used his fellowship to develop the data needed to better manage goliath grouper in Cuba.
Diving for data
Over three years, Pina Amargós used underwater surveys and conventional external tags to study goliath grouper growth, reproduction, and diet. He and his collaborators also studied where this species spawns and collected data on catches. They visited 74 sites off the central coast of Cuba and in the Jardines de la Reina (Gardens of the Queen) archipelago.
Pina Amargós and his team made several significant findings, including identifying a previously unknown spawning aggregation site east of Jardines de la Reina. The team estimated population size and structure, and determined movement patterns, habitat use, and whether the grouper revisited spawning sites, a behavior known as site fidelity.
“Spawning is the most critical part of the goliath grouper’s life cycle,” Pina Amargós said. “It’s when these fish gather together, putting them at highest risk of being captured.”
Goliath groupers live up to at least 37 years and reach sexual maturity after four years, when they’re around 40 pounds. Each year, they migrate to gather in reproductive aggregations of up to 100 individuals. Juveniles and adults often return to the same site to spawn year after year, making goliath grouper particularly susceptible to overfishing.
The researchers found that catch of goliath grouper had decreased over the past 20 years, that landings were no longer significant in Cuba, and that no commercial fishing boats were targeting the fish, even during spawning season. This change suggests that as their numbers declined, goliath grouper were no longer a commercial fisheries resource.
Based on their findings, Pina Amargós’ team recommended that the government ban fishing of goliath grouper at the Jardines de la Reina spawning aggregation site and establish a minimum legal size of 110 centimeters (about 43 inches). They also recommended a ban on spearfishing of the species in Cuban waters.
“This is an excellent example of putting science into action by a leading Cuban marine scientist,” said professor Ken Lindeman of the Florida Institute of Technology.
The government went a step further, declaring it illegal to catch and keep a goliath grouper in Cuban waters without an environmental license for research and conservation actions. Previously, Cuba had allowed catches of specimens larger than 40 centimeters (nearly 16 inches), which meant that almost any goliath grouper could be landed.
Internationally, goliath grouper are classified by the IUNC Red List of Threatened Species as vulnerable. The U.S. banned fishing of the species in 1990 and governments in some parts of the Caribbean enacted partial bans in 1993 that often protected the species inside marine parks in the region. Goliath grouper populations have been recovering since those measures took effect, but because of the species’ longevity it will take many years to achieve full recovery.
Through an international exchange, scientists working to protect goliath grouper in the broader Caribbean and Gulf of Mexico ecosystems are using research from Pina Amargós and his team.
Polita Glynn directs the Pew Fellows Program in Marine Conservation.