Study: Overfishing has less impact on Molokai

Menpachi are among the food fish species found in Hawaii waters. A recent study pointed to overfishing as the primary cause of reef fish decline in Hawaii, particularly around Maui and Oahu. National Oceanic and Atmospheric Administration photo

A few years ago, catching lobster on Molokai’s north shore was like “the circus,” said Kelson “Mac” Poepoe. When the lobster season would open, people would flock to the shoreline to lay down their nets.

Poepoe thought that if something weren’t done, the island would lose its lobster population, so he and others in the community tried to spread awareness and encourage people to harvest responsibly. Eventually, the circus stopped.

“People are aware that we are collecting data, and we do have information on the activities that go on,” said Poepoe, a longtime fisherman and conservationist. “No need be greedy. Everybody can have one share in the food that comes out of the ocean.”

It’s not only lobster that Poepoe keeps an eye on, but all marine resources on the island’s north shore, and it’s efforts like these that have helped keep Molokai’s fish species among the least impacted by overfishing, according to a recently released 17-year study.

The multiagency study that began in 2000 and encompassed 25,000 in-water surveys highlighted overfishing as the primary cause of reef fish declines in Hawaii. Maui and Oahu were most impacted by overfishing.

According to the study, the abundance of food fish species — those primarily caught for human consumption — is lower in populated areas, while there is no difference in the abundance of nonfood fish species — those not generally targeted by fishing — between populated and unpopulated areas. Scientists believe that suggests that fishing, rather than other human influences such as pollution or habitat degradation, is primarily responsible for the differences.

Alan M. Friedlander, a University of Hawaii marine ecologist and National Geographic’s Pristine Seas chief scientist, said in a news release that the data set is the largest ever compiled for Hawaii, and called it “the most compelling evidence that overfishing is the primary driver of reef fish declines in the main Hawaiian Islands.” The study was published recently in the peer-reviewed journal Aquatic Conservation.

“There have been arguments for decades about the impacts of other factors on reef fish populations, such as sediment, sewage and physical damage to reefs,” said co-author Eric Conklin, marine science director for The Nature Conservancy of Hawaii. “But these threats would affect all fish similarly. The only impact that would affect food fish and nonfood fish differently would be direct fishing pressure.”

To calculate fish populations, scientists examined each of the islands by moku. In more than 6,400 sites, divers noted the numbers, species and sizes of the fish to determine biomass, the total weight of all fish in an area.

Of the 37 moku analyzed, the 10 lowest biomass totals were all off Oahu and Maui, mostly around West and South Maui. Meanwhile, the moku of Molokai Koolau, along the island’s north shore, had the highest biomass in the main Hawaiian Islands. Molokai’s north and east shores, as well as all of Kahoolawe made up half of the top 10 highest biomass totals.

Meanwhile, the food fish biomass in the Northwestern Hawaiian Islands was nearly three times higher than in the main Hawaiian Islands, and nearly 10 times higher than areas around Maui and Oahu.

But Basil Oshiro, president of the Maui Cooperative Fishing Association, said that people are often too quick to single out fishermen for the decline of fish populations.

“I believe that the fish stock is depleted, but not because of overfishing,” Oshiro said. “You got to look at what’s happening on the land-based stuff. Whatever happens on land is going to affect the ocean.”

Oshiro pointed to a number of factors, from development that causes pollution and interrupts freshwater flows to the ocean to things like injection wells that contaminate the waters.

“We all got to share the blame,” Oshiro said. “We got to get the streams to flow. When the streams flow, the reef can replenish itself. When the reef can replenish itself, there’s food for the fish.”

Poepoe said that if he had to pick one thing as the source of fish decline, he’d say overfishing. But, like Oshiro, he’s mostly concerned about the bigger picture, particularly stream flow from the mountains that helps to spawn fish.

“I try not to put the blame on any one thing, because it is a combination of things,” he said. “Nobody’s been thinking about the water. The (fresh) water is major for the whole ecosystem. If we lose that, we lose a big part of the reef without even taking fish.”

Molokai is fortunate; it has the country’s longest contiguous fringing reefs and is relatively free of the development that plagues other islands. But Poepoe said that the island still has issues with runoff and overfishing.

“What look like plenty to other people is not plenty to me, because I know what the baseline should be,” Poepoe said. “We get plenty fish compared to the rest of the islands. But when you compare Molokai to Molokai, we do have problems.”

Conklin said that the study doesn’t mean nutrients, sediment and other threats can be ignored.

“With climate change impacts predicted to increase in coming years, it is more important than ever to manage all the factors stressing our reefs, including overfishing,” he said.

Marine protected areas are “a proven way to restore declining fish populations,” as well as community-managed fisheries, Friedlander said. West Maui has the Kahekili Marine Reserve, and community members on Molokai are working to get Moomomi on the island’s north shore designated as a community-based subsistence fishing area, with restricted take on certain species.

Poepoe said that educating people on the declining species and teaching them to avoid harvesting during spawning times has gone a long way toward helping protect marine resources.

“You can’t just take and no pay attention,” he said. “The recovery is more important than the take.”

* Colleen Uechi can be reached at cuechi@mauinews.com.

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