Background: Zebra mussels (Dreissena polymorpha) originated
in the lakes of southern Russia and spread around the world in the bilge water or ballast water of large ships. They
first appeared near Lake Erie in 1986 and quickly spread to all the Great Lakes. They are small freshwater mussel about
the size of a thumbnail, D shaped and striped. They are filter feeders cleaning the water they are in. They have a razor
sharp edge (known to cut through fishing line and bare feet) and they reproduce very rapidly(100,000 offspring or more per
year).
They were found in Lake of the Ozarks in 2006 and as of Sept 2011 are also in Pomme
De Terre, Bull Shoals, and Lake Taneycomo. They are suspected to be in Truman Lake
but it is not verified. They are also in the Mississippi River and part of the Meramec River and Osage River.
All other lakes appear safe for now. Once introduced, they cannot be stopped.
Negative impact:
Initially it appears that their impact may be positive because the water clarity improves; however, this is not true
due to the many negatives they bring to a lake. First, they filter algae and plankton out of the water. Given how rapidly
they reproduce, they can severely reduce both in the lake. Plankton and algae create the base of the food pyramid, so as they
disappear, the food chain becomes much smaller and game fish, such as bass, are reduced in size and number. Newly hatched
fish eat plankton directly. Older larger fish eat insects, fish fry, and other organisms that live off of plankton. In addition,
zebra mussels occupy shallow water covering pea gravel and rock previously used by game fish to spawn. This loss of nesting
sites again may decreases the fish population in the lake over time. Zebra mussels on pea gravel can now be seen in
the Lake of the Ozarks when they drop the water level.
In the Great Lakes some fish species like salmon have been reduced
dramatically. It is too early to predict how severe the loss of game fish in Missouri will be. Hopefully
it will not be as bad as in northern states. Lakes in Missouri are different from lakes farther north. However, zebra mussels also attach to docks, boats, and other
structures kept in a lake for periods of time causing great damage. They can attach to your boat in as little as a day.
How do they spread: They reproduce in the spring and the fall and their offspring are microscopic
larva that are invisible to the naked eye and can float in the water for up to three months. They are easily picked
up in live wells and bilge water. They can spread as juveniles and adults by attaching to plants, boat hulls, props, anchors
or boat trailers. They can live out of water for several days. They can live in your bilge or live well much longer.
Prevention:
The steps to help prevent the spread of zebra mussels are simple:
- Drain
water from bilge, boat, motor, bait wells and live wells
- Remove weeds from the trailer, motor, or anywhere they may
become tangled
- Dispose of live bait in the trash, not in the water
- Wash the boat and trailer with hot (104o
F) water or let it dry in the sun for five days before going to a different water body.
- One site also suggests that
if you have been to a known infested lake that you wash your boat including live-wells and your trailer at a car wash using
hot soap and water and then rinsing thoroughly. Washing the deck of the boat will help clean the bilge area.
- Inspecting
the trailer for unwanted guests is a good idea.
