BY: KEN DAVIS
AQUATIC BIOLOGIST

After a very successful morning in Putah landing eight rainbows, John and his brother remove their fishing gear and John faithfully places One Person, One Boot, One Snail his wading boots, complete with BB sized snails, in a water-proof boot bag. If he leaves Putah Creek within the hour, he can drive to the Upper Sacramento and fish the Cantera stretch before sunset. He calls ahead to book a room at the Tree House Best Western in Mt. Shasta. What a day! John can fish the morning hatch in Putah Creek then the October caddis hatch in the Upper Sacramento. Life is good! He makes it to the Upper Sac with plenty of time to don his gear and head for the river. In his haste, his laces weren’t properly tied and he felt some grit in one of his boots. Sitting on a rock next to the river, he removes his boot and washes off some of the grit (actually snails) into the river. The Upper Sacramento unwillingly receives a population of the New Zealand Mud Snails. Unfortunately, there is one live adult snail left in his boot for his short visit to the McCloud River the next day before he continues his journey home toward Portland. That’s enough. She’s ready to liberate 20-30 young live snails within days.

• What just occurred? The transferring of a few New Zealand Mud Snails into another waterway will result in thousands of mud snails hatching and thriving in these fisheries.
• Why the concern? Well, the mud snails consume the algae that are the basic food source for the mayfly. In turn the mayfly population diminishes dramatically and from there the trout population declines exponentially.

That same scenario could easily happen to a biologist like me who might not sterilize his invertebrate net between rivers or a kayaker who gets snails caught in her sandals and moves to other waters. For me, the thought of watching a river die is downright painful. Some might see a river as water, to the biologist, rivers are functioning communities that have a sound of their own. I’ve seen too many sterile streams such as Shoemaker, Dolly, and Spring creeks which all drain abandoned mines in Northern California. They’re yellow, and green, and orange and look like the surface of some distant planet. I was on the Upper Sacramento the day after the 1991 Cantera spill, covering the wreck for a magazine agency. Water hyacinth has been my enemy for several years as our team is working to keep it out of Lake Natoma and the lower American River. No more dead creeks please! Back to the New Zealand Mud snails and their non-snail-like march through the West. Some may say: “Hey, don’t panic: we don’t know what impact the snails will have on trout populations in California.” I say Phooey! We have a developing history of the snails in Montana, Wyoming, and Idaho. We know the following about the New Zealand Mud Snails:

• They are spreading rather rapidly from state to state.
• They appear to live very well in the very best fly fishing areas.
• In some areas of Montana snail populations reach 900,000 snails per sq. meter.
• They eliminate mayfly populations by eating algae normally taken by mayfly nymphs.
• They do not need males to reproduce.
• They can stay alive out of water, in moist situations for several weeks.
• They have no natural enemies in California
 

Now, you be the judge. Are we concerned about hurting the snails’ feelings by stating that they destructive and have the capacity to destroy a river forever: Just imagine your favorite river dominated by a growing population of mud snails and—starving trout.

Education
Because there is no effective and acceptable treatment to kill the snails once they are in a river we only have one choice left: education. Even then, conservation education is only effective when you have compliance and a targeted behavior change. Changing your own behavior is not easy and complicated by a multitude of factors such as traveling, fatigue, and the “it’snot-in-my-backyard” mentality. We dealt with all of those this year while on an invertebrate collecting trip to Montana and Wyoming. There are a multitude of potential treatments to kill NZMS on equipment but when you’re traveling between waterways, the treatments can become a pain. After a long day on the river, it’s easy to say, “I’m too tired to clean my equipment” and rationalize that there are no snails on your boots anyway.

The good news is that I’ve never witnessed such a dramatic change in behavior as with the discovery of NZMS in Putah Creek. I’ve talked to a guide who regularly fishes Putah who bought new gear for a trip to the McCloud and the Pit River. I get daily questions, responses, and suggestions to my website about the accepted way to treat equipment. The responses appear honest, show concern about protecting a resource we value, and seem doable. The response from California Trout and Granite Bay FlyCasters was immediate and highly supportive. No flip-flops or waffling, just get a poster completed and posted along Putah Creek.

Questions via email as posted on my website:

1. How do you think the snails go into Putah Creek? I believe that it is painfully obvious that the snails probably got here on the equipment of a fly caster. We have no proof, but lots of clues. Fly fishing magazines feature destination oriented articles such as “Fishing the Big Hole” and “Nymphing on the McCloud.” We take fly fishing road trips and fish a variety of waterways in a few days. The results of those multi-riverper-day trips can be catastrophic to the aquatic life we adore. Gary Flanagan, President of the Granite Bay FlyCasters; responded quickly after notification of the snails in Putah. He suggested, and I agree, that it is now prudent for all of us to clean our boots before leaving every river. In the near future, we need to develop and adopt a routine treatment for our equipment.

2. Is the effort hopeless? Will the snails relocate to other rivers? Dave Richards, the University of Montana researcher who is working on the snail problem, says “No! It is not hopeless.” The snails have one weakness; they do not have a dormant stage. And, they are susceptible to freezing. Although the snails seem to do very well in the best fly fishing waters, we simply don’t know what they’ll do in California. But I don’t think we should wait to find out. We have to educate ourselves, others, and change our behavior to slow or hopefully prevent the spread.

3. Do you think that putting up posters along the creek will help? After we posted the posters yesterday, I saw in three separate areas people that were reading the posters. Everyone we talked with was highly receptive to treating their equipment. They just wanted to know what to do. The U.S Fish & Wildlife Service has produced a business card size “Alert Card” that we can hand out to other fishermen. They are on order.

Treating your equipment

By far, the most important action we can take as individuals and as a group is effectively treating our equipment and sharing that knowledge with other fishers. We know that several treatments are highly effective; providing 100% kill if used properly. They include hot water, freezing, desiccation (dehydration), Realistically, my girlfriend won’t tolerate my boots in the freezer or in the bathtub, so here is what I suggest with the knowledge we have as of today. Hot water: We know that 120 degree water for one minute will kill the snails. It’s easier for me to throw my boots in a tub and pour hot tap water over them until covered and let them soak until the water cools. Our tap water reaches 130 degrees so I use that as my standard. Why pull the boots out after one minute (unless there is potentially damage  to the boots).

Freezing: Freezing your boots for four hours will kill the snails.

Desiccation: Allowing your boots to dry completely, especially in hot sun is highly effective.

Household bleach: A water bath with 10% household bleach will completely kill the snails in one hour.

What I do in reality: My equipment, including collection nets, boots and jars; are treated with a 10% bleach bath, then 130 degree tap water soak until the water cools. I then allow my stuff to dry when possible in the sun.

One interesting suggestion from the Oregon Department of Fish & Wildlife is the use of 409, a commercial cleaner available at grocery stores. They suggest you spray your equipment with 409 and allow it to dry in the sun for several hours. My own test this morning shows a significant snail kill when sprayed with 409. Remember to rinse off the 409 before getting back to fishing. the resource users. The response from the California Department of Fish & Game is wanting. The snail’s entry into California is rather predictable. California Department of Fish & Game and the U.S Fish & Wildlife Service have taken a pro-active stance and posted signs informing river users that they don’t want New Zealand mud snails in Alaska. What happened in California?
 

Ken Davis is an aquatic biologist/wildlife photojournalist who has been working with invasive species in crop lands and waterways for thirty years. He is currently working locally on a water hyacinth removal program in two Folsom creeks and Lake Natoma, a biomonitoring magazines. MacroWorld, featuring his nymph images will appear in the January 2004 issue of American Angler. He was working on an article for American Angler when he found the New Zealand Mud Snail population in Putah Creek.