Large-scale Marine Protected Areas (MPAs) are delivering large-scale benefits for fish catch rates, a new report published this week in Science has determined, even spilling outside of the protection zones themselves to positively impact upon species like the bigeye tuna, notorious for its high mobility across the ocean expanse.

The result is being chalked up as a win for both conservation and the economy, providing crucial evidence that “MPAs are essential for protecting both species and fisheries,” said MPA Project Europe, a platform currently mapping the optimal locations for MPAs in European seas.

Research conducted by a team of scientists, including lead author, John Lynham, an economics professor from the University of Hawai’i at Mānoa, has found that Increases in catch rates for fish – particularly the bigeye tuna – have been demonstrated near recently created large-scale MPAs, including Revillagigedo in Mexico.

A species that makes a vital economic contribution to a global industry worth over $40 billion, the importance of establishing an increased number of tuna such as ‘ahi and skipjack in and around such protected areas cannot be overestimated.

“In 2004, there was only one large-scale MPA in the world – the Galapagos Marine Reserve in Ecuador. Today, there are more than 20, including Papahānaumokuākea in the Northwest Hawaiian islands. Most of these protected areas are in waters where tuna fisheries operate,” said Lynham. 

“This means we can now test, for the first time, the impact of these marine protected areas, especially on tuna species.”

Understanding the interactions between large-scale MPAs, tuna stocks, and tuna fisheries is timely given the current international goals to protect 30% of the world’s ocean area by 2030 and the United Nations’ Biodiversity Beyond National Jurisdiction Agreement – an international treaty aimed at protecting biodiversity on the high seas.

To reach their conclusions, Lynham and the study’s co-author, Juan Carlos Villaseñor-Derbez, a professor at the University of Miami’s Rosenstiel School of Marine, Atmospheric, and Earth Science, reviewed data from nine large-scale MPAs across the Pacific and Indian oceans.

“We found that the spillover benefits, measured as the chance in catch rates, are strongest just outside the boundaries of these MPAs and get stronger over time,” said Villaseñor-Derbez. “The effects were strongest for the MPAs that were heavily fished prior to protection and are now well-enforced.

“Using publicly available data from nine large-scale MPAs across the Pacific and Indian oceans, we found that catch-per-unit effort in tune purse seine fisheries has increased by an average of 12 to 18% near protected area boundaries. This increase declines with distance from the boundaries.”

Results across various species of tuna are relatively consistent, too. All species displayed some evidence of positive spillover ranging from 2% to 11% with the strongest benefits evidenced for bigeye tuna. The research also found that nations engaged in conservation are also reaping the majority of economic benefits. It was found, for example, that close to 100% of the spillover benefits from the Revillagigedo area in Mexican waters flow to Mexican fishing vessels.

Lynham has suggested that while marine protected areas in Hawai’i weren’t the focus of this particular study, his research has displayed positive impacts on local waters revealing that the Papahānaumokuākea Marine National Monument – the world’s largest no-fishing zone – has caused a 10% increase in bigeye tuna catch rates near the monument. 

“[This was] in line with a recent finding of a 13% increase by researchers from the University of Washington and the Western Pacific Regional Fisheries Management Council,” he said. 

As a result of the research, the pair have now built a global database on tuna catch using only publicly available data, meaning that anyone in the world can now download the same dataset and replicate the analysis – something that was not previously possible with studies on large-scale MPAs impacts. The research, therefore, could just indicate a bold new future for the gathering momentum in the between marine conservation and sustainable fishing practices.

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