Most anglers have heard the term Invasive Species and recognize some of the infamous aquatic nuisance names of Whirling Disease, New Zealand Mud Snails, Didymo and Zebra Mussels. But anglers need to be aware that one of our most challenging and complex environmental issues impacting our fisheries worldwide is the continued spread and danger from both plant and aquatic Invasive Species.
The dramatic impact that state, local and federal agencies are seeing as a result of these invasives is the reduction of game fish populations, fouling pristine waters, ruining recreational equipment and making lakes and rivers unusable for all our aquatic recreation users therefore impacting our economy. Additionally, these harmful species are dramatically increasing operating costs of everyday things we all take for granted -drinking water, reducing property values and reducing native species populations and are ultimately degrading ecosystems.
Fantastic waters like the Yellowstone, Deschutes, Madison, Great Lakes along with many rivers across the country from California to Vermont are some of the aquatic systems that are experiencing negative impacts from invasive species such as New Zealand Mudsnails, Whirling Disease, Didymo and Zebra Mussels.
The frightening thing is these invasive species are angler spread through their gear and boats, and can very well end up impacting your local waters. We all must act to assure the sustainability of our fishing resource and your future business. Whether you are an outfitter, dealer, angler or boater, there are simple things to can do to educate the angler and have them take simple steps to readily stop the transmission of invasive species.
These simple steps one can take to prevent the spread of these invasive species:
1. Remove all dirt, plants and other materials from your gear or boat before you leave a body of water.
2. Thoroughly rinse your gear or boat with clean water.
3. Thoroughly dry your gear. Consider keeping two sets of wading boots, and alternate their use between drying.
4. Never transport plants, animals or water from one body of water to another.
5. Never dispose of bait, fish or fish parts in any body of water.
6. Find out what invasives are in the waters you fish and recreate in.
7. Report illegal activities.
WHAT ELSE CAN YOU DO
If you are a manufacturer, outfitter or dealer, take a leadership position and join the Stop Aquatic Hitchhikers Program. It is free, takes only a few minutes and will provide you and your customers continual information. www.protectyourwaters.net.
- Add Invasive Species information and actions to your company website and blog.
- Involve your local fishing groups and grassroots organizations in this effort.
- Put up signs in your store and have your guides educate their clients about this threat.
- Place a stock tank or receptacle at your store so customers and guided trips can soak their gear while obtaining flies, tippets and licenses.
- If you are a manufacturer, add informational insert cards in waders and shoes to provide the warning and action steps to address these threats.
Commonly Spread Invasive Threats by Trout Anglers…
New Zealand Mudsnail
This aquatic invasive species was first discovered in the U.S. in the Snake River in Idaho. It was thought to have been introduced in the water with live game fish. Since that time, it has now spread to 10 different Western states, 3 National Parks and Lake Ontario, primarily by anglers through their wading gear, river users and through ballast water in ships coming from Europe.
The mudsnails can reproduce asexually and very rapidly. In the U.S., there are no natural predators or parasites to control them like they have in their home country. Because of their rapid reproduction, they can take over streams very quickly. They compete with native snails and insects for food. This leads to sharp declines in native snail and insect populations. Fish populations then suffer because the native snails and water insects are the main food source for fish. When a fish tries to feed on New Zealand mudsnails, the mudsnail provides as little as 2 percent of the nutritional value of native snails and insects.
These mudsnails are impressively resilient. A snail can live for 24 hours out of water. They can survive 50 days on a damp surface like the felt on a wading shoe, giving them ample time to be transferred to another body of water. They can even survive passing through the digestive tract of a fish.
The snail can grow up to a 1/4 inch (6 mm) with 1/8 inch (3 mm) being the size at which they begin to reproduce. They take 6 to 9 months to reach sexual maturity. They can reproduce every 3 months with 20-120 offspring. For instance, in under a decade, snail densities have gone from undetectable levels to 10,000 to 500,000 snails per square meter in streambeds in Yellowstone National Park.
What can you do to prevent the spread of New Zealand mudsnails? Each time you leave the water:
1. Remove any mud, plants fish or animals before transporting equipment.
2. Eliminate all water from equipment used.
3. Clean and dry anything that came in contact with water. If you can, allow equipment to dry for 5 days before using.
4. Do not release or put plants, fish or animals into another body of water
Didymo – Rock Snot
Lurking in your favorite fishing stream is the latest menace to our fisheries: rock Snot. Formally called Didymosphenia geminata, or didymo, this aquatic invasive species is threatening streams across the United States. The first time I saw what many cells of this algae could do to a stream in a wildlife agency video, my jaw dropped. Thick carpets covered all the boulders, and chunks and strands of algae tissue were floating downstream. This can’t be good for all the macro invertebrates that rely on the rocks for habitat, I thought immediately and also not good for the fish that rely on them for food.
This single-celled organism is gaining attention in rivers around the world. Didymo has been documented in many places across North America historically; only recently it has been expanding its range and increasing in density. Didymo is a versatile alga. It’s found at temperatures between 32 degrees and 80 degrees F, and can grow in slow moving, shallow waters as well as waters with greater depth and swift currents. The nutrients in the water also determine where you will find didymo. The puzzling thing about didymo is it doesn’t act like most algae; it blooms in waters with very low levels of nutrients. Most algae blooms, like red tide for example, bloom with excessive amounts of fertilizers and high nutrients. Other locations across North America have experienced excessive algal growth, but not of the same magnitude as locations in New Zealand. Places in North America that have experienced blooms of didymo include the South Fork of the American River, California; Kootenai River, Montana; Rapid Creek, South Dakota; White River, Arkansas; Deer River, Alberta, Canada; and numerous rivers on Vancouver Island, British Columbia, Canada.
Whirling Disease is a metazoan parasite that penetrates the head and spinal cartilage of fingerling trout, where it multiplies rapidly, putting pressure on the organ of equilibrium. This causes the fish to swim erratically (whirl), and have difficulty feeding and avoiding predators. In severe infections, the disease causes high mortality rates in young-of-the-year fish. Those that survive until the cartilage hardens to bone can live a normal life span, but are marred by skeletal deformities. Fish can reproduce without passing on the parasite to their offspring.
This minute organism, native to the Eurasian continent, was introduced into North America in the late 1950’s. Thus far, the severe damage has been to the wild rainbow trout populations, although many other salmonid species can become infected.
Regardless of species, when an infected fish dies, many thousands to millions of parasite spores are released in the water. This spore can withstand freezing and desiccation, and survive in a stream for 20-30 years. It then must be ingested by its alternate host, a tiny and common worm called the Tubifex, where the spore will take on the form that once again will infect trout. This parasite will continue to spread to drainages through birds, animals and humans.