Marine Management Areas can restore Hawai‘i’s depleted nearshore fisheries

A comprehensive study, led by SOEST researchers, finds Hawai‘i’s nearshore waters need more effective management and that a diverse integrated system of marine management areas can help restore the state’s declining coral reef fisheries and boost the resilience of our coral reefs in a changing climate.

Well-designed marine management areas are a proven tool that can restore coral reef fisheries, increase coastal protection and provide recreational, cultural and economic opportunities. In collaboration with the Hawai‘i Department of Land and Natural Resources, the study found that while Hawai‘i has many marine management areas, most are too small and allow some form of human use within their boundaries that can limit their ability to restore depleted fisheries.

“We need to improve the marine management areas we already have and effectively manage additional areas if we are to protect and restore Hawai‘i’s unique and valuable marine environment,” said Alan Friedlander, fisheries researcher at SOEST’s Hawai‘i Institute of Marine Biology and lead author of the study. “That includes setting aside some areas where fishing is prohibited, because we know that replenishes fish stocks. It also includes areas where the State co-manages resources with coastal communities that want to implement more sustainable traditional management practices.”

The study provides critical information for the State’s initiative to effectively manage 30% of Hawai‘i’s nearshore waters by 2030. Key in reaching this goal is to create an ecologically connected network of marine management areas that can rebuild and sustain productive nearshore fisheries. According to Friedlander, reef fish populations have declined dramatically in Hawai‘i over the last century, with some important food fish populations reduced by more than 90%.

The study also shows that, overall, marine management areas in Hawai‘i are too small and that the average marine management area size is minuscule compared with the geographic extent of the species they are designed to protect. Hawai‘i’s marine management areas vary in size and levels of governance, enforcement and effectiveness. They comprise only 5% of State waters, extending out to 3 nautical miles from the shore, limiting their ability to sustain fish abundance across the state. Of that 5%, fully and highly protected waters cover only 1.4% of nearshore areas, with Kaho‘olawe Island Reserve accounting for most it. Less than 0.1% are within marine protected areas, which provide full protection for fish to grow large and reproduce.   

When fish can mature in protected waters, they grow much larger and can produce exponentially more eggs than smaller, younger fish. The larger fish and their larvae can spill over into neighboring areas that are open to fishing.

“Many fishers already know this and engage in what’s called ‘fishing the line’ between MPAs and open fishing areas,” Friedlander said. “In general, fishers can get the greatest benefit by protecting the largest spawning fishes in larger no-fishing areas.”

Recent surveys in the Molokini Reserve offshore of Maui found more fish and larger predators (which are a sign of a healthy ecosystem) such as ulua, omilu, and reef sharks had returned in the few months since boat traffic was restricted due to COVID-19.

According to Friedlander who was part of the survey team, “While these increases are likely temporary and will probably disappear once visitors return to Molokini, our surveys show just how quickly our marine systems can rebound if given a chance.”

Larger marine management areas protect a diverse range of habitats and help maintain the health and function of marine ecosystems. They provide protection for a wider range of species and serve as a buffer against environmental fluctuations and disturbances. With climate change and increased coral bleaching already occurring in the islands, establishing more and larger management areas will help protect the state’s nearshore resources into the future, the study says. Fortunately, the size and boundaries of current marine management areas can be designed as effective components of a larger network.