Limiting Parrotfish Catch Could Save Caribbean Reefs

According to recent study published in the journal Proceedings of the National Academy of Sciences, limiting parrotfish catch could provide a solution to the rapid decline of Caribbean coral reefs. Based on the work of researchers from the University of Queensland, the study is the first of its kind to suggest specific science-based regulations for Caribbean parrotfish fisheries.

The Caribbean is home to 9 percent of the world’s coral reefs, which have been increasingly affected in recent years by a devastating cocktail of factors, including climate change, overfishing and pollution. As a result, coral cover in the Caribbean has decreased by over 80 percent, a statistic that is likely to worsen as the symptoms of climate change continue to plague the region. Coral bleaching as a result of rising sea temperatures is a particular concern, and study co-author Peter Mumby warns that the future of Caribbean reefs depends on how well they are able to recover from bleaching events.

Recovery is possible if new corals are allowed to repopulate and grow on the skeletons of the bleached reef. However, these fragile new structures must compete with algae, which often suffocates the new coral and prevents any further growth. The reefscape becomes barren and lifeless. Herbivorous fish like the parrotfish provide a solution to this problem, acting as crucial gardeners for the reef by removing algae and giving new corals the chance to grow. 

Limiting Parrotfish Catch

In the Caribbean, parrotfish are a key herbivorous species, spending up to 90 percent of their day feeding on algae. However, they are specifically targeted by local fisheries, and as their numbers decline, so too the Caribbean reefs become less likely to survive an increasingly uncertain future. For Mumby and his fellow researchers, the goal was therefore to find out how many parrotfish can be removed from an ecosystem before it is negatively affected in order to ascertain what regulations could ensure that parrotfish fisheries remain sustainable.

To do this, the team developed a model capable of predicting how different fishing regulations could affect parrotfish populations and, in turn, what the knock-on effect for the reefs would be. The scientists tested the accuracy of their model against known case-studies, in which altered fishing regulations triggered a dramatic change in regional fish populations and reef health. As a result of their findings, the team recommends a minimum size restriction of 12 inches (30 cm), as well as limiting total catch to 10 percent of the mass of the Caribbean parrotfish population.

Several Caribbean countries, including Belize, Bonaire and Turks & Caicos, have already banned parrotfish fishing. These countries are home to some of the healthiest reefs in the region, illustrating the positive impact that these suggested fishing regulations could have. According to Mumby, it would be in the best interest of local fishermen to adhere to the regulations if they are implemented, as “the more we do to maintain healthy coral reefs, the more likely it is that fishers’ livelihoods will be sustained into the future.” Failure could see a threefold reduction in future catches.

While the current model is tailored specifically to Caribbean reefs, it could be manipulated to help other areas on a case-by-case basis. In particular, Mumby hopes that it could prove relevant for Australia’s beleaguered Great Barrier Reef, a UNESCO World Heritage Site currently in the middle of a major coral bleaching crisis.

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