Hawaiian-Emperor Seamounts ecosystems recovering after trawling, report finds

For decades the sunken islands northwest of Hawaii proved a popular draw for fishing and trawling, with crews dragging heavy nets across the fertile peaks. In the process, the nets scraped the real estate to devastating effect.

Many scientists gave up hope that these ecosystems would recover.

But now a team from Florida State and Texas A&M universities has found signs of hope. After years of federal protection, the area known as the Hawaiian-Emperor Seamounts is showing signs of resurgence, the scientists report.

“It’s been hypothesized that these areas, if they’ve been trawled, that there’s not much hope for them,” Florida State oceanographer Amy Baco-Taylor said in a news release earlier this month. “So, we explored these sites fully expecting to not find any sign of recovery. But we were surprised to find evidence that some species are starting to come back.”

Her findings appear in the journal Science Advances.

The realization that a trawled seamount can recover is a “game changer” in terms of fisheries management, Baco-Taylor and colleagues said.

“This is a good story of how long-term protection allows for recovery of vulnerable species,” she added.

The Hawaiian-Emperor chain is a largely submarine range that includes the Northwestern Hawaiian Islands.

In 1977 the United States claimed much of the region as a part of its 200-nautical-mile exclusive economic zone, which kept out foreign fleets. In 2006 then-President George W. Bush included the area as part of the Papahanaumokuakea Marine National Monument, further protecting it.

Baco-Taylor, doctoral student Nicole Morgan and Texas A&M associate professor Brendan Roark led four research cruises in 2014 and 2015. On visits to seven seamounts, they used an autonomous underwater vehicle and a research submersible to explore sites along the chain and take photographs some 1,000 to 2,000 feet down.

Among the 536,000 photos, they found not only trawl scars, but also baby corals and coral growing from fragments on nets left behind.

“We know the stuff growing on the net had to come after this practice stopped,” Morgan said.

They also found a few spots unscathed. These are crucial to further populating the seamounts, the researchers said.

How long that will take and whether the area will recover completely are uncertain. The team is still analyzing coral samples to determine their age and diversity.

The paper, Roark said, “bears directly on fishery management issues in the Northwest Hawaiian Islands and is timely relative to some changes the current administration is thinking about with respect to opening up marine monuments for more fishing.”