Tsunami debris can carry non-native plants and animals

Published on Wed, Apr 24, 2013 by Ian Ferguson

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Debris from the March 2011 tsunami in Japan is washing up on the shores of the Pacific Northwest, and experts say the biggest potential threat from the sea trash might be the stowaways onboard: foreign species of plants and animals that could be invasive.

A 185-ton floating dock washed up on a beach in Olympic National Park in January with nearly 90 species of barnacles, snails, algae and other sea life living on it. According to NOAA’s Response and Restoration blog, 30 – 50 of those species were native to Japan but not the United States. Responders scraped the organic materials off the hulk of metal and concrete and sprayed the dock with a diluted bleach solution to decontaminate it.

On March 22, an 18-foot skiff washed up in Long Beach, Washington with 5-inch fish living inside it. They were identified as striped beakfish (Oplegnathus fasciatus), which typically live in reefs off Japan. The fish survived the 5,000-mile journey across the Pacific Ocean in a small, submerged compartment onboard the boat. One of the fish was taken to an aquarium in Oregon and the other four were euthanized.

“We’re treating anything that’s non-native as potentially invasive,” said Washington State Department of Ecology (DOE) spokesman Curt Hart. “There’s always a risk they’ll become established and outcompete native species. We also don’t know if they might harbor microscopic bacteria or other things that could be harmful to the local environment.” 

With a $270 million statewide shellfish industry, the DOE and other agencies in the Washington State Marine Debris Task Force aren’t taking any chances with organisms found on potential tsunami debris.

“We’re euthanizing anything that’s non-native,” Hart said.

The March 2011 tsunami hit Japan following a magnitude 9.0 earthquake near the coast of the Oshika Peninsula. The wave reached heights of 133 feet and inundated 217 square miles of land, killing nearly 16,000 people and sweeping millions of tons of debris – houses, cars, docks, sailboats and countless other material – into the Pacific.

According to National Oceanic and Atmospheric Administration (NOAA), an estimated 70 percent of that debris sank near Japan. The remaining 30 percent floated away and dispersed across the Pacific Ocean, with the wind carrying some objects to the Pacific Northwest coast as early as winter 2011-2012. A map of floating debris sightings published on the NOAA website shows the highest concentration in an area between the Hawaiian Islands and the Pacific Northwest. Tsunami debris is expected to continue to arrive on Washington shores over the next couple of years, but Hart said little if any of it will make its way through the straight of Juan de Fuca and into Puget Sound.

“Everything we’ve found so far has really been concentrated on our outer coast,” he said. “That’s not to say there couldn’t be debris in the interior waterways, but the wind and water currents make that pretty unlikely.”

According to the state department of health, it’s also unlikely any of the tsunami debris is radioactive. Radiation experts have tested thousands of debris items and found no elevated levels of radiation.

Residents who spot marine debris on the coast are encouraged to call the Washington state marine debris reporting hotline at 855/WACOAST.