Revival plan shields fish to aid coral

Establishing a network of no-take protected coastal zones, restrictions on lay gillnets and a ban on commercial fishing of parrotfish are among the actions being considered to help Hawaii’s coral reefs fend off the lethal effects of ocean warming and climate change.

State officials discussed the progress of a coral bleaching recovery plan Thursday during a news conference at the Heeia-Kea Small Boat Harbor in Kaneohe.

The plan, expected to be finished in a couple of months, comes in the wake of severe coral bleaching events in Hawaii in 2014 and 2015 and the potential for more impacts this year.

As part of the effort, teams from the state Division of Aquatic Resources have been investigating how scientists and managers from around the world promote coral recovery and are discussing how those efforts could work here.

Bleaching occurs when corals are stressed by changes in the environment, especially a rise in temperature. The coral ejects the symbiotic algae living in its tissue, causing the tissue to weaken and fade to white. Without the algae the coral loses its primary source of food and is left to starve.

If high temperatures continue, corals can die.

“It’s a very, very serious problem. It’s happening all over the world at different times of year and in different intensities,” said Ruth Gates, director and researcher at the University of Hawaii’s Institute of Marine Biology.

Gates said the severe 1998 El Nino weather event caused between 15 and 18 percent of the world’s coral to die. And last year was arguably worse, she said, with the loss of a third of the corals in the northern Great Barrier Reef and 90 percent of the corals around Christmas Island.

“When the figures (about last year) start trickling in, it’s going to be a devastating global impact,” she said.

In Hawaii, Kaneohe Bay endured up to 80 percent bleaching in 2014, officials said. In 2015 West Hawaii saw up to 50 percent mortality, while Maui experienced 20 to 30 percent loss, including at popular snorkeling spots like Olowalu and Molokini. Kaneohe Bay fared better in 2015 with a 97 percent recovery rate.

As for this year, Brian Neilson, state aquatic invasive species biologist, said National Oceanic and Atmospheric Administration models indicate that bleaching in Hawaii won’t be as severe as last year.

And so far, he said, there have been no reports of major bleaching around the state. But the peak of the season isn’t until October.

“So we’ll have to wait and see,” Neilson said. “We will continue to monitor.”

Bruce Anderson, Division of Aquatic Resources administrator, said that while it’s possible Hawaii will escape severe bleaching this year, there will be future events as the oceans continue to warm.

The challenge for scientists and aquatic managers, he said, is to not only find a way to lessen the impacts of bleaching, but to try to help the reefs recover.

To address this, state aquatic biologists surveyed more than 80 coral experts and scientists and reviewed the scientific literature, described as a synthesis of more than 200 articles, officials said.

Last month a workshop attended by 44 Hawaii scientists and managers reviewed the body of information and began identifying management recommendations for four priority locations that saw the most severe temperature stresses during the 2014 and 2015 bleaching events: West Hawaii, West Maui, Kaneohe Bay and North Kauai.

Among the actions recommended was to establish “a network of permanent, fully protected, no-take marine protected areas,” officials said.

The aim, they said, is to help corals recover from bleaching by eliminating additional environmental and human-caused stresses, including too much fishing.

“The challenge is to set up a network that is effective and that is not going overboard,” Anderson said.

Gov. David Ige told the World Conservation Congress last week that he wants the state to “effectively manage” 30 percent of its near-shore waters by 2030, and Anderson said he would expect to strive for that level of protection.

The scientists and managers also recommended steps to reduce pollution and especially nutrient-filled muddy runoff that can smother corals and spread toxic substances across the aquatic landscape.

“It’s not a problem you can go after very easily,” Anderson said. “It takes millions of dollars to set up artificial wetlands and try to deal with those issues.”

But there are actions that can be taken. Sewage discharge was seriously harming the corals in Kaneohe Bay at one time, “but we diverted the sewage 2 miles offshore, and most of the bay recovered,” he said.

Another recommendation was the protection of reef herbivores, or algae-eating fish and invertebrates. Herbivores, such as the parrotfish, remove algae that can choke a coral reef in the throes of bleaching.

Parrotfish are the biggest herbivores on Hawaii’s reefs, and they eat a lot of algae. And unlike most fish that just graze, the parrotfish bites and gouges the coral, too, opening up spaces for new coral polyps to grow.

Anderson said he would expect to limit the parrotfish that spear-fishers take and to ban commercial fishing of the species altogether.

“Right now there are no limits most places,” he said.

Also under consideration, he said, are regulations on fishing gear, specifically lay gillnets that usually kill every fish that swims into them.

“It’s something we could easily do in the near future to try to preserve and protect the herbivores that are so important to our reefs,” Anderson said.

Gates said these measure are more important now than ever as the climate changes. The coral reefs, she said, are like a canary in a coal mine when it comes to global warming.

The International Society for Reef Studies has declared that the majority of the world’s reefs will be massively degraded by 2050 if nothing is done to respond to climate change.

“It’s critical that we take heed,” Gates said.