NEW ZEALAND MUD SNAIL
Additional information
Link to Federation of Fly Fishers, NZMS
web page, Click Here
Article from Covering the Drift, December 2005, page 8, Click
Here
Article from Oregon Flyfishers
Club, November 2005 newsletter, Click Here
Links to maps showing spread
of NZMS, Click Here
Download PDF copy of
full report CONTROLLING THE SPREAD OF NEW ZEALAND MUD SNAILS ON WADING
GEAR by California
Department
of Fish and Game, (779KB) Click
Here
FFF 2002 NZMS Angler
Warning, Click
Here
Return to Washington State Council,
FFF Main Page, Click Here
NEW ZEALAND MUD SNAIL
By Bob Bates
WSCFFF, VP Communication
 |
Copyright
by the Federation of Fly Fishers |
We, as anglers, need to be more aware and careful about this exotic intruder. It was first identified in the Idaho’s Snake River country in 1987. By 1997 it had spread through all major waters in Yellowstone National Park. Now it has spread, by anglers, to many states, and it is in waters that many of us fish: Snake R. near Lewiston, WA; Columbia R. near Portland, Madison R. and Missouri R in MT. When NZMS infest a stream they take food from native species. Also they are worthless as trout food since they pass through the gut without damage.
The FFF issued an Angler Warning in 2002 and has recently put a "Recommendation to Anglers" on its website:
Earlier studies indicated that the snails could be killed by cleaning thoroughly and drying the waders for several days. Or they could be frozen for 3 to 6 hours or more. These new recommendations come from a California study that tested various methods of killing the snails on waders and wading boots. Several chemicals will do the job, but the following is probably the most convenient for anglers.
1. Thoroughly brush gear with a stiff bristled brush to remove all snails. Be sure to brush boot treads, laces and other hiding places.
2. Mix Formula 409 Cleaner Degreaser/Disinfectant and equal parts water in a gear dry sack or other large, sturdy plastic container.
3. Place wading boots or wading gear in the gear dry sack and shake vigorously for 5 minutes, allowing the solution to cover all surfaces.
4. Allow to soak in solution for at least 5 minutes and your gear should be NZMS free.
Dangerous Hitchhikers
By Keith & Lisa Hansen,
Oregon Flyfishers Club, November 2005 Newsletter
Potamopyrgus antipodarum sounds somewhat elegant in Latin. Yet the New Zealand Mud Snail (NZMS) is an invasive thug that is rapidly spreading throughout the western U.S. The intruder has invaded 3 national parks, 10 western states, the Columbia-Snake drainage, and our beloved Deschutes. Recent studies have found that the snail had established itself in the Umpqua, lower Rogue, the Columbia Estuary, the Deschutes, and several Oregon lakes.
The spread of this exotic New Zealander has the potential of devastating habitat for macroinvertebrates (a.k.a. fish food) and seriously disrupting the ecology of western trout fisheries. NZMS reproduce asexually by cloning and can produce at up to 2 daughter snails every 24 hours. Thus, an entire river can be populated by a single clone. They prefer slower velocity waters with plentiful vegetation and can carpet stream bottoms, thereby crowding out resident aquatic invertebrates. They can close up in their shells and offer little nutritive value for trout. In fact, studies have shown that wild fish avoid eating NZMS and fish residing in high density snail territory are smaller than those in non-infested areas.
This southern hemisphere mollusk probably set shell in the U.S. in the mid-1980s through a shipment of rainbow trout destined for aquaculture. Research suggests the first spread of the snail to the Yellowstone Rivers likely occurred when the snails "hitchhiked" on the waders or boots of fishermen. They are tiny -- approximately 1/8 inch --and can cling to boats, trailers, fishing equipment, boots, and waders. They can be pulled up in boat ballast and may be spread by birds, livestock, fish and pets to other waters. The NZMS has evolved to survive tough conditions including desiccation and chemical exposure.
According to Portland State University’s David Santen1, you can help prevent the spread of NZMS by:
1. "Thoroughly inspecting and cleaning outdoor recreational gear, such as boots, nets, boats and trailers before leaving an area.
2. Remove any plants, mud, or other material that may be attached. Drain all water from your boat or other watercraft (livewell, cooling system, etc.).
3. Studies have also shown that NZMS can be killed by completely drying gear for 48 hours; freezing gear for at least 3 hours; or soaking gear in hot water (at least 120 degrees).
4. Gear also can be cleaned by soaking them in a 50-percent solution of Formula 409 and water for five minutes."
Other research studies have shown that soaking gear in 10% bleach solution for one hour or soaking in water at a constant 130 degrees is lethal to NZMS.
An easy method for treating your gear is to allow them to dry out completely in a low humidity environment. If your wading boots and waders have been very dry for days or weeks, the snails are dead.
Another word of caution: do not put plants, fish, or fish entrails in a body of water different from that which they originated.
Flyfishers need to take the NZMS seriously. We need to change our behaviors and increase our awareness to stop the spread of this dangerous hitchhiker.
Please reporting new sightings of NZMS to the Oregon Invasive Species Council hotline: 1-866-INVADER.
1David Santen. PSU Researchers Track New Zealand Mudsnail to Deschutes River. Portland State News October 24, 2005