"An invasion is under way that is undermining our nation's economy and endangering our most precious natural resources. The intruders are alien species - non-native plants and animals introduced into this country either intentionally or by accident. Attention to the problem of alien, or exotic species often centers on their costs to agriculture, ranching, forestry and industry. The price they exact from the nation's forests, grasslands, and waterways, however, is at least as great."
America's Least Wanted. The Nature Conservancy

Fortunately, it appears Alaska has been spared from extensive invasion by exotics. Alien or exotic species are considered to be any organism that enters an ecosystem beyond its historic range, whether it travels from another ecosystem within the region or state, or from an entirely different part of the world.

Often, aliens have positively contributed to the environment through agriculture, horticulture, landscaping and soil stabilization. But, sometimes, the alien species spread so quickly and rapidly, out competing indigenous species, due to a lack of natural predators or other controls. These invasive exotics can seriously and permanently impact an areas biodiversity and vitality. Disturbed sites are most vulnerable, but aggressive species can invade intact ecosystems. Long term risks include higher crop and livestock production costs, loss of native plants, degradation of wetlands and loss of wildlife habitat. Prevention should be emphasized, for removal is expensive and may be impossible.

The purchase of weed free products can help prevent the spread, as can minimizing vehicle traffic in the area. Items that may have come into contact with seeds should be thoroughly cleaned and inspected before leaving. If new species are spotted, several questions should be answered. What is it? Is it likely to spread? What are the options available for controlling it, and how effective are they?

Zebra mussel and green crab are among the most well-known invaders. Native to the Black and Caspian Seas, zebra mussels were first discovered in the Great Lakes in 1988. They have since spread throughout Eastern USA and Canada, along the Mississippi and other area waterways. By outcompeting zooplankton for phytoplankton, the foundation in any marine food web, they disrupt the food cycle. Although just thumbnail sized, by year 2002, USFWS expects they will have caused over $5 billion in damage. They clog intake valves on marine vessels, and water pipes in electrical utilities.

Another alien invader, the green crab, was first established in this country on the Eastern seaboard back in the 1800's. In 1989, it was found in San Francisco Bay, and has since spread throughout California into Oregon. It eats most everything in its path, depriving native species of food. With its voracious appetite, it threatens to disrupt coastal ecosystems , and harm fisheries. Just thumbnail sized, this destructive species is too small to eat, and has only negative economic impacts.

Closer to home, northern pike are seriously impacting aquatic species in the Mat-Su, Anchorage bowl area. Indigenous to Northern Alaska, pike has few, if any controls on population growth in Southern Alaska. It is a ravenous predator, devouring other fish and even waterfowl. It lives in lakes, and travels through river and stream networks, infecting other areas. Once pike has been introduced to an area, it soon eliminates other fish species. Sightings have occurred in the Kenai Peninsula and Southeast. In our next issue, we will look more closely at the impacts pike have on an ecosystem, and the methods people have used to try to control their spread.

Common weeds such as Canada thistle and even the all pervasive dandelion, are believed to be exotic species. For information more on weeds, contact the your local UAF Cooperative Extension office. The Anchorage office can be reached at (907) 279-5582. The BLM is also concerned with noxious weeds. Contact Paula Krebs by e-mail at pkrebs@ak.blm.gov . In addition, the Alaska Natural Heritage Program in association with NAFWS has begun tracking foreign species. For more information, call AKNHP at 257-2780.