Quantcast

Invasion of the River Snatchers Cast of Many

July 23, 2008

By ERIK ROBINSON

Anglers line the north bank of the Columbia River below Bonneville Dam to fish for shad in June. A new scientific report recommends policymakers pay more attention to the harm caused to native plants and animals by invaders such as shad, an East Coast native that now forms the single largest mass of fish in the lower Columbia River.

Shad, native to the East Coast, were brought west in the 1870s.

Most Columbia River anglers have no reason to know the name Seth Green.

Yet today’s Columbia River fish population would be dramatically different were it not for Green’s decision in 1871 to hop a westbound train in Albany, N.Y.

An early fish culturist, Green was on a mission to seed the Sacramento River with juvenile shad native to the East Coast. Responding to a request from state fish commissioners in California, Green headed west on the newly completed transcontinental railroad.

His 12,000 traveling companions rode in four 8-gallon milk jugs.

After releasing the fish into the upriver reaches of the Sacramento River, Green had no way of knowing just how successful his experiment would be. These days, the modern progeny of Green’s traveling companions form the single largest mass of fish in the lower Columbia River after migrating up the West Coast.

“It’s emblematic of nonnative species that are now really abundant in the Columbia,” said Mark Sytsma, director of the Center of Lakes and Reservoirs at Portland State University. “The question you have to ask is ‘What’s the im pact of having this new species?’ You would imagine it’s going to have an impact on something.”

A new report by a panel of scientists agrees.

Whether they arrive by transcontinental railroad or in the ballast water of the world’s modern ships, eco-invaders are posing new threats to native plants and animals. A new report issued by the Independent Scientific Advisory Board recommends working hard to study and prevent these invaders from taking hold.

Sytsma, a longtime advocate for increased vigilance against eco- invaders, said millions of dollars are at stake.

The ISAB advises the four-state Northwest Power and Conservation Council, which each year earmarks about $140 million for fish and wildlife projects designed to offset the damage caused by federal hydroelectric dams. The money comes from electric rates paid to the Bonneville Power Administration.

“It’s a big step to have them acknowledge it and put it on the same level as habitat restoration,” Sytsma said. “The fish and wildlife money that the (council) distributes would be available for invasive species work.”

The scientists noted that a history of dam-building in the Columbia has generated energy, controlled floods and irrigated food crops. However, it has also created an environment th at’s ideal for creatures, such as American shad, that prefer warm, slow-moving water.

“Most of the free-flowing river habitats in the Snake and Columbia rivers have been converted into reservoir habitats,” according to the report. “The reservoirs have created hot spots of nonnative species.”

The report concluded invaders are bad for local populations by eating them directly or, just as bad, breeding with them. Scientists worry that interbreeding erodes tried-and-true genetic charac teristics that have allowed native species to evolve and survive over thousands of years. They also take their food; alter the river’s food web; and transmit new kinds of disease and parasites.

Prevention crucial

One of the authors said preventing new introductions is crucial, especially as scientists are only beginning to understand the effects of a vast array of nonnative plants and animals.

“Prevention will be a key,” said Thomas Poe, a retired federal fisheries scientist who lives in W hite Salmon. “We have a lot of gaps in knowle dge, even with what’s going on with competition. It’s pretty complex, and we don’t have much information at all.”

The Columbia basin is home to 119 native plants and animals that have dwindled nearly to the point of extinction, the report stated.

Over the past 10 years, a new invertebrate species h as been discovered about every five months in the lower Columbia River.

In the case of the American shad, experience shows that even the best intentions can bear unintended consequences. The shad population barely registered in the Columbia River until the late 1950s and early 1960s. That’s when dam managers cut notches in fish ladders to ease the ability of chinook salmon to pass Bonneville and other federal dams.

The improvement helped chinook, but scientists say it also proved to be a boon for shad drawn to the slackwater reservoirs above Bonneville.

“Once those ladders were modified, then shad just took off,” Poe said. “They’ve done amazingly well.”

Originally published by ERIK ROBINSON Columbian staff writer.

(c) 2008 Columbian. Provided by ProQuest Information and Learning. All rights Reserved.




comments powered by Disqus