Zebra Mussels

As some of you know I’m an underwater environmental and endangered species contractor. I work for many different State and Federal agencies across the country. My job is to determine bottom conditions before and after waterway work is done. Most of my work is done around bridges, dams, water outfalls and intakes. This has allowed me to closely follow the advancement of the Zebra Mussel.

What is a Zebra Mussel? The Zebra Mussel is a native of the Black and Caspian Seas in Eastern Europe. It stayed in the area till the early 1800′s. As shipping increased across Europe it spread and by the early 1900′s it was all the way to England and France.

The Zebra is a small animal, shaped somewhat like an almond shell, growing only to about 2 inches. It has zebra like stripe across its lengths and the shell color is brown with black stripes. It attaches to surfaces with a small thread called a Bissell thread.

Females release baby zebra into the water when the temperature reaches 54 degrees and continue to spawn throughout the year till the water temp falls below 54 degrees. One female may produce as many as 1 million eggs per year. They drift and swim around in the water for about 3 weeks, after which they start attaching to whatever is around. For the next 12 months they filter water and grow. They reach maturity at 12 months and live up to about 5 years. The mortality rate among the young can reach as high as 99 percent in bad areas. Even so, this still leaves 1000 zebras surviving in one year from just 2 female zebra mussels. The minimum reproduction in their lifetime is 5,000, the maximum reproduction can be as high as 450,000. The average is considered to be 200,000. Think about 200,000 almonds piled up, and remember after their first years spawn reaches 12 months, that minimum 1000 start to spawn. The problem is Huge!

Zebras were first discovered in the United States in 1986 in Lake Erie. By 1988 they were throughout the Great Lakes in extensive colonies of up to 40,000 per square meter. By 1991 they had reached Tennessee.

Zebras attach to any and everything in the water. Rocks, sticks, cans, bottles, boats, municipal water intakes and barges. Barges present the largest problem; while they are being loaded the zebras attach and colonize the hulls. Then as they move across our country’s waterways they are knocked off and continue to spawn, spreading them everywhere.

At the last Zebra Mussel Conference, they were reported to be throughout all the major rivers in the eastern half of the United Sates. These include Mississippi, Illinois, Ohio, Arkansas, Cumberland and Tennessee Rivers. The list goes on and on, but you get the idea.

In Tennessee, Kentucky Lake is the hardest hit. The crews that moved the navigational buoys and anchors reported findings of attached zebra colonies. In the summer of ’93 T.W.R.A. officers checked the lower unit of a houseboat on Old Hickory Lake and found a few zebras; the boat had just come from Kentucky Lake. When they de-watered the lock a Cheatham Dam they found 30,000 zebras. As you can see the problem is all over Tennessee.

What can we do as boaters to help??? First of all, we can and should always flush our lower units when we change lakes. Zebras get into the water intakes and cooling systems when they are young and can live in there for up to 1 week out of water. Next, spray off your boat and check the hull. Pull all grass and weeds off; this is another favorite spot for zebras to stow away. Live wells and minnow buckets also can have small zebras you can’t see on them.

Last year on a survey on the Illinois River, the zebras were a solid carpet, everything was completely covered. All the crawfish and native mussels had been smothered out. The ecosystem there has been changed forever.

Please, it’s time for us to do all we can to save our rivers and lakes from this fate. With a little work between lakes we can keep them out of places they aren’t now. The threat is real and can be devastating.

Hope you have a good month of fishing. June is a fine month on the water. Remember to wear your lifejacket, set the hook, and may the fish be with you.

Jim Duckworth

Ducktrail Diving and Guide Service