Michelle Workman, an EBMUD biologist, tags and measures a salmon carcass from the Mokelumne River. Workman does a weekly survey to measure the salmon cycle in the river. (Jennifer M. Howell/News-Sentinel)

Wild salmon of the Mokelumne: Saving a species

Salmon at risk — from dams to tiny mudsnails

When Bill Ferrero takes friends or clients fishing on the Mokelumne River he provides the wading boots, which he cleans in near-boiling water and bleach after each trip. He also keeps a second set of fishing gear stored for trips to other rivers.

This may seem odd to someone who hasn't spent much time on the Mokelumne River, but Ferrero takes these extra precautions to help stop the spread of a non-native snail living within the river.

About the size of a pencil eraser, the tiny New Zealand mudsnail could cause big problems for salmon and river ecology in general, according to biologists who study the river.

Invasive species, like the mudsnail, are only one of a number of threats facing salmon in California.

Destruction of spawning habitat, pollution from sediment and agriculture run-off, increased water demands from a growing population and development along riverbanks are all threatening the natural life cycle of salmon in the Mokelumne River and elsewhere.

Because the mudsnail feeds on the same types of aquatic insects needed by young salmon and other native creatures, their introduction to the river could create an imbalance in the food chain, especially because the population spreads quickly.

With no natural predators and the ability to reproduce asexually, just one snail in a water way could become 40 million within just one year, said Joe Merz, an East Bay Municipal Utilities District biologist studying the snails.

The species is spreading quickly from river to river by hitching rides with fisherman and recreational boaters who use the same clothing, boots and gear in more than one waterway, Merz said.

U.S. Fish and Wildlife have put up signs at many popular fishing sites in an effort to raise awareness and Merz tries to educate people he sees on the river often, which is why Ferrero has been boiling his boots after going in the river.

"With the amount of time I spend on the river, I feel it's my responsibility to be a steward of the river," Ferrero said. "If this is something that can ruin the nature balance of the river then we need to take steps to stop it from spreading."

Biologists studying other problems with the river are also looking to everyday citizens keep the salmon run and the river healthy, said J.D. Wikert, coordinator of the U.S. Fish and Wildlife's Anadromous Fish Restoration Program.

"We're working on a small scale to fix bits and pieces of the radical changes that have been made to the watersheds," Wikert said.

EBMUD biologist Jose Setka records the location of new salmon redds, or nests in the water of the Mokelumne River onto his GPS device. (Jennifer M. Howell/News-Sentinel)

A larger scale effort is being made to educate the public about how water usage and run-off can cause problems in the river.

He said household water usage diverts water from natural watersheds, changes water flow, increases the need for dams and closes off natural habitat areas for salmon.

Creating a buffer of native plants along the riverbank is one way Wikert said people can help restore the river. A natural buffer can reduce run-off from yard work and construction, create shade for wildlife, keep the river cool and provide nutrients for fish through leaf litter, Wikert said.

In 1999 the AFRP estimated it will cost $23 million to restore the ecosystem of the Mokelumne River, which includes maintaining the salmon population and doubling the average of yearly returns recorded from 1967 to 1991.

People should also be aware of what they are putting into the river. If it doesn't occur naturally, it shouldn't be there, he said. This includes invasive species, which only enter California waterways with the help of humans, either purposely or accidentally.

For people to continue enjoying the river some steps need to be taken to protect it, which means paying attention to posted signs, keeping the river clean and being respectful of the wildlife, according to Merz.

Ferrero boils his boots, but there are other ways to get rid of the mudsnails, Merz said. The U.S. Fish and Wildlife recommends using a bristled brush and Formula 409 to remove any visible snails, then freezing fishing gear, such as boots and nets, to get rid of any additional snails.

"It may not be convenient, but we need to be responsible," Merz said. "It's already here in the Mokelumne. Our job is to keep it from spreading."

Contact reporter Rebecca Adler at rebeccaa@lodinews.com.

First published: Wednesday, December 6, 2006