Bring home the fish, but leave the mussels

Jul 11, 2014

Zebra mussels are very small.

The spread of Zebra mussels in Texas lakes has caused for new regulations that all fishermen/boaters should be aware of. Beginning July 1, boaters must drain all water from their boat and on-board receptacles before leaving or approaching  a body of fresh water anywhere in Texas.

The new Texas Parks and Wildlife Department regulation is designed to help combat the further spread of zebra mussels and other invasive species. It applies to all types and sizes of boats whether powered or not: personal watercraft, sailboats, kayaks/canoes, or any other vessel used on public waters.

The regulation requires the draining of livewells, bilges, motors, and any other receptacles or water-intake systems coming into contact with public waters.

Live fish, including personally caught live bait, cannot be transported from the water body where the fish were caught in or aboard a vessel in water from the water body where the fish were caught. Personally caught live bait can be used in the water body where it was caught.

Anglers are allowed to transport and use commercially purchased live bait if they have a receipt that identifies the source of the bait. Any live bait purchased from a location on or adjacent to a public water body that is transported in water from that water body can only be used as bait on that same water body.

Anglers participating in a fishing tournament confined to one water body may transport live fish in water from that single water body to an identified off-site weigh-in location, but all water must be drained and properly disposed of before leaving that location. Anglers are required to possess documentation provided by tournament organizers that identify them as participants in the tournament.

Movement from one access point to another on the same lake during the same day does not require draining, and there is an exception for governmental activities and emergencies. Marine sanitary systems are not covered by these regulations.

What does it look like?

Mussels are also called 'bivalves'. This means they have two shells or valves (a right valve and a left valve). The zebra mussel gets its name because of the dark, striped pattern on each valve. Usually the shell is a light color (tan, beige) with the zig-zag stripes. However, some are almost completely all brown and the stripes are not pronounced. Even more rare are those nearly all light colored with little striping.

Where are they from?

Zebra mussels are native to freshwater rivers and lakes in Eastern Europe and western Asia. In 1769, Pallas first described populations of this species from the Caspian Sea and Ural River in Russia.

When were they first found in the United States?

Zebra mussels were first discovered in Lake St. Clair in 1988. Lake St. Clair is located east of Detroit, Michigan between Lake Huron and Lake Erie.

Where are they?

Zebra mussel spread rapidly throughout the Great Lakes region and in the large navigable rivers of the eastern Mississippi drainage including the Mississippi, Tennessee, Cumberland, Ohio, Arkansas, and Illinois rivers. They can also be found in the Hudson River on the Atlantic Slope. Barge traffic in these large rivers helped to disperse zebra mussel their first few years here. Since then, dispersal has been mostly into small lakes within the Great lakes region. Currently, there are more than two hundred and thirty lakes that have zebra mussels. Much of this recent dispersal can probably be attributed to recreational activities such as boating and fishing.

How did they get here?

It is generally agreed upon by scientists that zebra mussels entered the Great Lakes from ballast water dumping by large ocean-going vessels from Europe. Ballast water is used to keep ships stable in the water. The amount of water carried is dependent on the amount of cargo on board. A ship will carry large amounts of ballast water when there is no cargo and will dump it in port as cargo is loaded.

What do they eat?

They are primarily algae feeders. They feed by filtering the water through a siphon, up to a liter per day. This is why they like the insides of pipes so well, there is a constant supply of water and food flowing by them.

What impact are they having on the ecosystem?

One of the most well documented impacts is on our native mussels. Zebra mussels are anchoring themselves by the thousands to native mussels making it impossible for the native mussel to function. As many as 10,000 zebra mussels have attached to a single native mussel. Our natives have all but disappeared in Lake St. Clair and the western basin of Lake Erie. Zebra mussels also are filtering the Great Lakes at an amazing rate, making the lake very clear. Most people assume that this increased visibility in the water must mean the water is "cleaner." Not true. All they have done is filter out all the algae which normally would be food for native microscopic organisms.

What's unusual about the species?

• Once they are drawn into a pipe filled with water, they can grow and clog the pipe until the water stops flowing. 
• Females can lay over one million eggs in a spawning season. 
• They attach themselves to a usually hard surface and are difficult to remove. This is a common trait of mussels that live in marine (saltwater) ecosystems, but not of freshwater mussels. 
• They can withstand short periods (several days) out of the water if conditions are moist and humid. 
• They have a saltwater relative, the dark false mussel (Mytilopsis leucophaeata), which is native to our Atlantic coast. This relative looks very much like the zebra mussel and is often mistaken for it. Should you find what appears to be a zebra mussel in saltwater, it is probably the dark false mussel. 

• Zebra mussel larvae (called veligers) are microscopic in size and are undetectable by the human eye. They can be unknowingly transported in boat live wells and bait buckets or anything that carries small amounts of water.