According to groundbreaking research, Marine Protected Areas (MPAs) are positively impacting fish populations, leading to an increase in the number of ‘trophy-size’ fish found right outside these protected zones, with this impact strengthening over time.
A study conducted by scientists from the University of Hawaiʻi at Mānoa, published today in Science Advances, reveals that Marine Protected Areas contribute significantly to increasing the population of “trophy-size” fish. These are fish that are particularly large or heavy and are often regarded as exceptional catches. This research provides the first comprehensive global evaluation of the advantages of MPAs.
According to Simone Franceschini, the Principal Investigator and Postdoctoral Researcher at HIMB, “This standardized global assessment showcases the advantages that MPAs offer to recreational anglers, verifying that MPAs are effective in boosting fish biomass and supporting local fisheries. Our findings indicate that the tangible benefits of MPAs for adjacent areas may take over 20 years to become evident, helping to set realistic expectations regarding how long it takes for a marine reserve to positively affect surrounding fisheries.”
The Hawaiian Islands boast 13 state and federal Marine Protected Areas (the full list is included below). The state-managed Marine Life Conservation Districts are overseen by the State of Hawaiʻi Division of Aquatic Resources.
While MPAs are recognized as one of the most effective strategies for preserving marine biodiversity, the global influence of these areas on local recreational fisheries has not been thoroughly understood until now. This study offers valuable insights for management agencies, conservationists, and recreational fishers about what to anticipate in the long run from the establishment of MPAs.
This research builds on earlier work by Callum Roberts and colleagues, who conducted a study in Florida two decades ago. They found that the number of trophy fish caught near an MPA (within a 100km radius) surged significantly between 12 and 30 years after the MPA was established.
Co-author Elizabeth Madin, an Associate Professor at HIMB, shares, “In our research, we explored whether the findings of one of the most studied impacts of MPAs on recreational fishing could be confirmed on a global level. Our results indicate that, on average, highly-protected marine ecosystems offer long-lasting, concrete benefits for recreational fishers, creating a win-win for both nature and people. However, we should note that not every MPA will yield the same spillover effects, and the success of MPAs relies on community backing, enforcement, and proficient fishery management.”
The results of this study are crucial for the future of MPAs and the global “30×30” marine conservation initiative, aiming to protect 30% of the world’s oceans by 2030.
Co-author John Lynham, a Professor of Economics at the University of Hawaiʻi at Mānoa, emphasizes, “These findings provide research-backed guidance that can play a key role in promoting the successful establishment and ongoing support of MPAs on a global scale. Interestingly, different MPAs worldwide, even with their varying sizes and features, exhibit a similar positive spillover effect and an approximate ‘waiting period’ of 20 years.”
This research highlights the necessity of setting realistic expectations concerning the advantages of marine reserves for local fisheries. Although MPAs can significantly increase the number of larger fish over time, these benefits often take decades to materialize. Policymakers and local communities need to be patient and commit to a long-term vision to sustain support for conservation initiatives. Nevertheless, as Callum Roberts, the lead author of the initial 2001 study that informed this current investigation, mentions, “Local fishers may start noticing benefits from the spillover of smaller fish long before large trophy fish become evident, as these larger fish require more time to reach notable sizes. As a result, well-managed MPAs can aid local livelihoods within ten years of their establishment.”
