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Study: Without crowds, bigger fish back at Molokini

Confirms research that management areas too small, allow human use

Healthy coral and reef fish can be found at the ‘Ahihi-Kina‘u National Area Reserve off South Maui. A new study says that larger marine management areas can restore the state’s depleted nearshore fisheries. JIM PETRUZZI photo

The Maui News

More fish and larger predators, such as ulua, omilu and reef sharks, have returned to the waters off Molokini in the few months that commercial boat traffic has been halted due to COVID-19 emergency orders, said a researcher who was part of a survey team of the preserve.

“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,” said Alan Friedlander, a chief scientist with National Geographic and head of the University of Hawaii Fisheries Ecology Research Laboratory, in a news release Tuesday.

The recent data of Molokini provided further evidence of findings in a study published in October, which found that many marine management areas in Hawaii are too small and allow some form of human use. This can limit their ability to restore depleted fisheries.

Friedlander was lead author of the study titled “Characteristics of effective marine protected areas in Hawai’i,” published in Aquatic Conservation: Marine and Freshwater Ecosystems.

The average marine management area size in Hawaii is almost a half square mile, “minuscule compared with the geographic extent of the species they are designed to protect,” the news release about the study said. Marine management areas comprise 5 percent of state waters, which extend out to 3 nautical miles from shore. Of that percentage, only 1.4 percent of nearshore areas are fully and highly protected waters — and most of that area is the Kaho’olawe Island Reserve.

“We need to improve the marine management areas we already have and effectively manage additional areas if we are to protect and restore Hawaii’s unique and valuable marine environment,” said Friedlander. “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.”

According to Friedlander, reef fish populations have declined dramatically in Hawaii over the last century, with some important food fish populations reduced by more than 90 percent. The establishment of an ecologically integrated system of marine management areas can help restore declining coral reef fisheries and boost the health of coral reefs amid a changing climate, the study said.

Studies show that when fish can mature in protected waters, they grow much larger and can produce exponentially more eggs than smaller, younger fish, the study said. 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 (marine protected areas) 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.”

Larger marine management areas protect a diverse range of habitats and help maintain the health and function of marine ecosystems, the study said. 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. The size and boundaries of current marine management areas can be designed as effective components of a larger network.

Other authors on the paper include Mary Donovan and Whitney Goodell of the University of Hawaii, and Haruko Koike and Paul Murakawa of the state Department of Land and Natural Resources Division of Aquatic Resources.

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