Tracking Missouri's Exotics
Watery creatures are the most difficult of all to control. Exotic species can travel in the ballast tanks of ocean-going vessels or in the water sloshing around in an angler's bait bucket. Juvenile animals might attach to boat hulls or find a pocket of water in a trailer. People may be introducing exotics when they release fish that have grown too large for aquariums into the closest lake or stream.
Such accidental or inadvertent introductions have the most potential for harm. By the time biologists detect damage, the introduced species has been there long enough to become established. Once established, dealing with both the exotic and the resulting damage can be difficult and costly.
The zebra mussel is a good example of the economic damage an invader can cause. Most experts believe that the zebra mussel was introduced into U.S. waters through a ship's ballast water. Because they are new to U.S. waters, they have few or no natural enemies, and their numbers expand and increase quickly. A female can produce 30,000 to 40,000 eggs every year.
Since the arrival of zebra mussels into the Great Lakes in the mid 1980s, the species has spread rapidly. They currently inhabit most of the navigable waters in the Mississippi River Basin and recently were found in the Missouri and Meramec rivers. In many places, they have become so numerous they have clogged industrial, agricultural and municipal water intake pipes and caused some power plants to overheat. Similar problems will likely occur in Missouri.
In addition, zebra mussels could affect the fishing in Missouri. "If the zebra mussel continues to invade Missouri's waters, fishermen in the future will be asking, 'where have all the trophy fish gone?'" said mussel expert and Conservation Department research biologist Sue Bruenderman. "The more zebra mussels we have, the less food available for small fish. Less food means less growth and smaller fish in the long run."
People can help keep zebra mussels from spreading. The Conservation Department suggests washing your boat and trailer with hot water between trips to different bodies of water or, at the least, letting your boat dry out thoroughly for five days, which will kill zebra mussels that might be attached. If you collect your own bait from a lake or stream, make sure you return it to the same lake or stream. This will help prevent exotic species from spreading from one fishing hole to the