SHOW-ME STATE PLAYS HOST TO HANDFUL OF POTENTIALLY DANGEROUS INSURGENTS

JEFFERSON CITY--The Show-Me State is playing host to a handful of potentially dangerous insurgents who could wreak havoc on native Missourians.

Even more frightening, there are tens of thousands more of these unwanted emigrants waiting outside our borders. Any one of them could throw our system into chaos and cause serious economic losses.

Why not declare them personae non grata, ship them back where they came from and pass laws against further emigration? Officials with the Missouri Department of Conservation (MDC) say they wish it were that easy. These unwanted visitors aren't persons, they are exotic plants and animals. And the only law they obey is the law of the jungle.

Many exotics are masters of the ecological hostile takeover. An example is the zebra mussel. It hitched a ride from eastern Europe inside the ballast tanks of ocean-going cargo ships. From the St. Lawrence Seaway, it galloped rough-shod over native species in the Great Lakes. A short hop landed it in the upper Mississippi River, where it promises to clog electric and municipal water supply intakes, smother native mussels and generally disrupt the ecological balance of the Mississippi-Missouri river system.

Purple loosestrife is the plant equivalent of the zebra mussel. This attractive flowering plant was imported from Eurasia in the 19th century as an ornamental. But the import turned out to be an aggressive wanderer instead of a decorative wallflower. It jumped the garden fence and invaded wetlands, where it has crowded out native plants that are more beneficial to wildlife.

The common carp, native to Europe, was released into North American waters about 100 years ago, and has done remarkably well at the expense of more desirable native fish. In spite of this early lesson, silver carp, bighead carp and grass carp have been released or escaped into Missouri waters in recent years.

These more recently introduced exotics technically aren't members of the common carp family. The U.S. Fish and Wildlife Service once promoted introduction of the grass carp (also known as the white amur) into private waters. The idea was to control excessive aquatic vegetation. (Some of the plants were exotic imports, too.) Now fisheries biologists are concerned about its spread. The grass carp already is abundant in the Mississippi and Missouri rivers. It is good to eat, but competes with native fish species for space.

"As we see the damage done by exotics in other states, we're becoming increasingly aware of how important it is to limit the introduction of non-native species here," said Dan Zekor, chairman of MDC's recently formed Exotic Species Policy Committee. "We also face the problem of how to limit the spread and minimize problems created by exotics already in the state. It's a tall order, and we're having to write the book as we go."

Fortunately, Missouri doesn't have to write the book alone. Other states, particularly those east of the Mississippi River, have even more problems with exotics than Missouri does. Recognizing that the scope of the problem extends beyond state boundaries, several government agencies, private conservation organizations and other groups recently convened in Indianapolis, Ind. for the first-ever symposium on the impact and control of exotic species. Greg Gremaud, a natural history land specialist, represented MDC at the "Biological Pollution" symposium.

"I came away with some real practical information about what people are doing to combat some of the exotics we have here in Missouri," Gremaud said. "Some people are experimenting with biological controls. Others are working on more conventional controls, such as herbicides."

MDC Fisheries Division Chief Jim Fry said his division is particularly concerned about the effects of exotics because so many are aquatic. Imported tropical fish are not a significant concern in Missouri, because winter cold prevents their survival. But cold-tolerant exotics raised in the state have the potential for escaping into Missouri waters, with unknown ecological results.

Fry said MDC has very limited options for slowing the influx of exotics. It is difficult to enforce laws making it illegal to release exotics into the wild. A better approach, said Fry, is to regulate the species of fish that can be reared in Missouri hatcheries.

According to Fry, MDC has been working with commercial fish growers to develop a list of aquatic species that meet aquaculturists' needs without posing ecological threats. The resulting list includes 46 fish species and three species of crayfish. Beginning in 1992, those will be the only species that may kept outside of aquariums and other closed containers that discharge water into approved treatment systems.

Zekor said MDC hopes to develop a policy that will, as a minimum, guide the agency's use of exotic plants and animals.

"Eradication of existing exotics will be a difficult, costly and in some cases impossible," said Zekor. "However, with proper management and control, we may be able to minimize the damage done."