New Zealand Mud Snail

Cleaning Protocol

August 8, 2005

Stop the Spread of New Zealand Mud Snails in California

In North America the New Zealand Mud Snail (Potamopyrgus antipodarum, NZMS) was first discovered in the middle Snake River, Idaho in the mid-1980s and has rapidly spread throughout the western U.S.  It is a parthenogenetic (clonal) livebearer with a high reproductive potential.  There is much concern about the impacts that NZMS may have on native species, fisheries and aquatic ecosystems in the western U.S.  Its rapid spread into new systems is considered to be primarily human caused.

In California there are now six locations known to be infested with NZMS, although most of California has not been surveyed for NZMS.

Western North American populations of NZMS reach maturity at 1/10 of an inch in shell length, and only grow to 1/4 inch long.  Due to this small size they can be easily overlooked in the folds of waders, boot laces, in crevices of gear and other areas even by an attentive observer.  In addition, NZMS have a specialized plate-like operculum that allows them to seal their shell and prevent drying out.  This operculum allows NZMS to survive for long periods of time out of water (20 days or more), when on damp media similar to wet waders or boots.  Their small size and resistance to drying makes it likely that anyone who wades in NZMS infested waters will spread them to new areas if they do not take adequate precautions. 

Since NZMS reproduce asexually, it only takes one snail to start a new population when introduced into a wide range of tolerable habitats. 

NZMS have never been eradicated from any stream.  Remember, if NZMS are introduced to a stream, it is likely that they will remain in that stream indefinitely.  Don't spread NZMS to your favorite fishing spot!

Several methods have been demonstrated to be effective in removing or killing NZMS on wading gear and boots without damaging the gear.
 

Don't let your wading equipment spread NZMS to your favorite fishing spot!

There are many ways to avoid spreading NZMS that will not significantly damage wading gear

1.   Avoid sites that are known to contain populations of NZMS. 

Surveys have found live NZMS in damp leaf litter as far as 26 feet from a stream edge.  Even hiking near infested waters can spread NZMS.  Contact the CDFG for an updated list of infested waterways at (916) 445-3417, or check their website: www.dfg.ca.gov/fishing/html/Administration/MudSnail/MSLocList.asp

2.   Dedicate an extra set of gear to any NZMS positive area.

Dedicated gear should only be used in areas with populations of NZMS.  If you travel to other areas, the dedicated set of gear should be treated with one of the methods below.  Be sure to store the dedicated gear away from contact with any other gear used elsewhere.

3.   Dry gear in direct sun for as long as possible on a hot, dry day, or for a few hours on a very hot day. 

To eliminate NZMS, dry gear at 84-86ºF for at least 24 hours, or dry gear at 104ºF for at least 2 hours.   Larger NZMSs generally survive longer than small ones.  When using this drying method, it is important to thoroughly brush gear with a stiff bristled brush prior to drying in the sun to remove all larger NZMS.   

4.   Clean gear with brush and Formula 409 Cleaner Degreaser/Disinfectant, diluted 50% with water.

• After leaving water containing NZMS thoroughly brush gear with a stiff bristled brush to remove all snails.  Be sure to brush boot treads, laces and other hiding places. 

• Mix Formula 409 Cleaner Degreaser/Disinfectant and equal parts water in a gear dry sack or other large, sturdy plastic container.

• Place wading boots or wading gear in the gear dry sack and shake vigorously, allowing the solution of 409 and water to cover all surfaces that touched the infected water.

• Allow to sit for 5 minutes and rinse with tap water.

• An alternative to this treatment method is #5 below.

5.   Clean gear with brush and copper sulfate solution (1 gal. of water to 3/4 tsp.  copper sulfate pentahydrate) 

• After leaving water containing NZMS, thoroughly brush gear with a stiff bristled brush to remove all snails.  Be sure to  brush boot treads, laces and other hiding places, such as under laces, boot tongue, under the instep inserts, etc.)

• Mix 3/4 teaspoon copper sulfate pentahydrate (such as Triangle Brand Copper Sulfate Instant Powder) to 1 gallon of water and shake vigorously to dissolve.

• Soak gear in the solution, as in treatment #4 OR

• Thoroughly spray all parts of gear that were in contact with the infested waters with the copper solution.

• Allow to sit for 5 minutes and rinse with tap water.

 *Only dispose of chemical solutions in a system that will be treated, such as a household drain that is treated by a City’s waste water system