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What does a decline in healthy coral reefs mean for fisheries? A new study published in Marine Resource Economics, led by the Woods Hole Oceanographic Institution (WHOI), examines the correlation between fish yield and live coral habitats. Researchers analyzed the yields of nine fisheries dependent on Australia's Great Barrier Reef from 2016 to 2020. Results show that substantial losses could occur if the restoration of coral reefs is not prioritized.

In 2024, the Great Barrier Reef experienced one of the worst bleaching events in its history. According to the Australian Marine Institute, an aerial survey of the Great Barrier Marine Park showed bleaching across 73% of surveyed reefs. These vulnerable ecosystems rely on the microscopic algae called zooxanthellae for survival. These algae also contribute to coral's vibrant colors.

Elevated ocean temperatures stress corals, causing them to expel the algae, resulting in bleaching. If warming persists, the algae may not return, leaving the coral bleached and at risk of dying. In the past 30 years, coral bleaching caused by ocean warming has contributed to a 19% loss of the world's coral reef area.

"This rapid loss of coral will force fish capable of living independently of them to move elsewhere. Less concentrated populations can lead to smaller yields for fisheries," said Marine (Yaqin) Liu, an environmental economist at WHOI. "For fish that rely on reefs for food or shelter, such as butterflyfish and coral trout, yields will shrink as their populations do."

The study identifies coral trout and saddletail snappers as the two most vulnerable fisheries, both relying on outer-shelf reefs as their primary habitats. The study shows that if the live coral cover of the Great Barrier Reef were to be reduced from 30% to 25%, the maximum sustainable yield of coral trout would drop by 8% and 19% for saddletail snappers. With a drop of live coral cover from 10% to 5%, the maximum sustainable yield of the coral trout fishery would drop by 27% and saddletail snapper would drop 56%.

"Coral trout and saddletail snapper are part of Queensland, Australia's line fishery, an industry with $27–31 million gross value," explained Qingran Li, an assistant professor of economics and financial studies at Clarkson University in New York.

"While the methodology of this study does not lend itself to making dollar predictions, we can expect a decline in fishing yields to have substantial economic impacts, such as loss of jobs and reduced export."

As ocean temperatures continue to rise, coral casualty events such as bleaching are more likely to occur. Reefs host 25% of marine life and protect coastal communities from the impacts of major storms. They also support millions in tourism and fishing annually.

"It is important to support claims about climate change with hard data. Responsible fisheries are already safeguarding coral reefs by integrating sustainable approaches, but human impacts like ocean warming and acidification further threaten coral reefs and fisheries yields," Liu continued.

"WHOI's Reef Solutions Team continues to study and develop innovative ways to restore and strengthen coral reefs, with a goal of taking successful learnings and implementing them globally."