Register-Guard: Invader species trigger state alert

Invader species trigger state alert

By Scott Maben
The Register-Guard

April 7, 2005

The dreaded zebra mussel has yet to penetrate Oregon.

But look in the hills of Southwestern Oregon and you'll find feral swine, a hairy hybrid with tusks and a big appetite. And in Lane County, giant hogweed and gypsy moths have landed.

Each is on the state's most-unwanted list, an annual compendium of the 100 "most dangerous species threatening to invade the state," according to the Oregon Department of Agriculture.

Others that made the cut this year have names that make them sound downright sinister: dead man's fingers, toxic cyanobacteria, Paterson's curse and imported fire ant.

Some of the plants, insects, fish, microorganisms and other invaders have established a toehold in parts of the state, prompting efforts to eradicate them or slow their spread. Others have not shown up, and officials want to keep it that way.

Yellow floating heart

"We have parts of the state we know are infested and other parts that aren't, and we'd like to keep the clean parts protected as long as we can," said Dan Hilburn, who heads the Agriculture Department's plant division and is on the state Invasive Species Council, which issues the annual list.

The agency is trying to draw more attention to the growing problem of invasive species, which crowd out native plants and animals and can dramatically alter ecosystems.

Although more exotic species show up each year, Oregon still has a fairly pristine natural environment compared to other states, Hilburn said.

"If you look at our forests and our rivers and the marine environment, it's pretty healthy in most cases," he said. "It's the way it was, and we're lucky that way." In the eastern United States, forests, lakes and rivers have been vastly transformed, he said.

"Yes, we have (invasives) here, but the worst 100 list contains some really scary ones that we don't have. So we have a lot to protect," Hilburn said.

One of the greatest threats is the zebra mussel, which infests the Great Lakes, the Mississippi, Hudson and Ohio rivers, and other Eastern waterways. The freshwater molluscs cover boats and dams and clog underwater pipes, and they change the ecology of a lake or river by devouring food needed by native organisms.

"It's one we're very worried about because they can hitchhike on boat trailers," Hilburn said. "It's a potentially nasty one for us."

Western Oregon could see a rise in feral swine populations in the next few years. The unwelcome visitor already is established in Southwestern Oregon and easily could spread north, Hilburn said.

"They could definitely live on the west side without any trouble," he said. "This is well within their range."

A mix of wild boar and escaped pig, feral swine are wily, nocturnal beasts that can grow to several hundred pounds. They root for food, tearing up native habitat, gardens, golf courses and agricultural fields.

"Some hunters like them, but the benefit from hunting is faroutweighed by the damage to native plants and ecosystems," Hilburn said.

California now has hundreds of thousands of them, but the Oregon population is still small, probably fewer than 1,000, he said.

"Lane County, I think, needs to be aware of them," he said. "They are difficult to control."

Hilburn also flagged gypsy moth and giant hogweed as threats to the county.

The moth, a voracious tree eater in its caterpillar stage, reappeared in Eugene's south hills in 2003, 20 years after a major outbreak in the same area. Both times the state responded by spraying a biological insecticide.

Agriculture officials believe they again have rid Lane County of gypsy moth, but the insect crops up somewhere in Oregon almost every year. This year, Clackamas County has an outbreak.

Another invader that officials are trying to control locally is giant hogweed, a fast-growing plant that can reach heights of 15 feet and favors wetlands and stream banks. It's also hostile to humans. The plant's sap can cause burns and large, scarring blisters.

A member of the parsley or carrot family, giant hogweed was found near Oakridge in 2001 and has spread to 66 known sites, mostly in the Willamette Valley. Some people, unaware of the plant's rogue status, grow them in their gardens and exchange the seeds, Hilburn said.

Feral swine, giant hogweed and gypsy moth, as well as Japanese beetle and mitten crab, appear on the list each year because they have not established permanent populations.

But it's too late to combat the spread of other invasive species, so officials don't bother listing them. They include infamous invaders such as Himalayan blackberry and Scotch broom.

The New Zealand mud snail dropped off the list last year after it had spread into the Snake and Columbia rivers. It's too late to eradicate it, the state decided.

Hilburn emphasized that the list targets invasives that still can be beaten back.

"We want to focus people's attention on the things that aren't here," he said.

Officials ask that anyone who spots an invasive plant or animal call a hot line, (866) INVADER, so that experts may investigate. The hot line usually receives several dozen calls a month from people who see something they don't think belongs.

NEW THREATS

Three species make their first appearance on this year's list of the top 100 worst invasive species threatening Oregon:

Phytophthora kernovii: A more virulent cousin of the microorganism that causes sudden oak death. It has not been found in Oregon to date.

Yellow floating heart: An aquatic weed that forms a mat of lily padlike leaves in still bodies of water. It curtails boating and swimming when dense. It was discovered last year in a Beaverton city park.

Sea squirt: An aquatic invertebrate that coats the bottoms of pilings and other underwater objects with a slimy gel that crowds out other marine organisms. It appeared last year in Puget Sound but hasn't arrived in Oregon.