[env-trinity] Eureka Times Standard November 6 - Mud Snails

[Byron Leydecker]

Mud snail crops up in four more North Coast watersheds

Eureka Times Standard - 11/06/08

John Driscoll, staff writer

 

A prolific invasive snail has now been found in four coastal watersheds,
raising the possibility that it will infest a larger part of Humboldt County
in the near future. 

The New Zealand mud snail, first found locally in Big Lagoon in September,
has since been confirmed as present in Lake Earl, Tillas Slough off the
Smith River, in the lower Klamath River and in the Russian River east of
Hopland. 

 

Other watersheds infested with the invasive snail have been devastated by
their presence. It was first found in the Snake River in Idaho in the 1980s,
and now is present in 10 states. Without natural predators, the snails
consume algae and plant and animal debris, altering the food chain --
affecting protected salmon, steelhead and other species. 

 

While the state is launching an educational campaign to let boaters and
fishermen know how to prevent the spread of the tiny snail, it's clear it
will not be easy, if even possible. To date, there is no way to eradicate
the snail, either. 

 

"There's not a whole lot you can do once they get in there," said Fish and
Game district watershed biologist Michelle Gilroy. 

 

The snails can spread on the feet of wading birds, and can survive in the
digestive tracts of fish. To kill them on fishing waders and gear, the
California Department of Fish and Game recommends freezing the stuff for
eight hours; to scour them from boats, the agency recommends scrubbing them
off with hot water. 

 

The hope is to at least slow the spread of the New Zealand mud snail. Breck
McAlexander, a Fish and Game aquatic species coordinator said that the
snails, which thrive in fresh water, could have limitations in brackish
waters like lagoons and estuaries. If their introduction into a watershed is
reduced, it's conceivable that they might not take hold enough to produce a
viable population, he said. 

 

But even that is hopeful thinking. 

 

"The best strategy is to try to prevent their spread," McAlexander said,
"which may or may not be possible." 

 

On the American River, biologists have carefully monitored for the presence
of mud snails that can be transported by hatchery fish into their
destination lakes and streams. Fish and Game policy is to not allow fish
from infested hatcheries to be transported to bodies of water not yet
infested. 

 

Now, with the presence of mud snails not far from the Mad River Hatchery,
McAlexander said it is important to monitor that hatchery, too. 

 

So far, there have been no mud snails discovered there, and the Humboldt Bay
Municipal Water District is working to develop ways to prevent the spread of
the snails into the upper watershed, in Ruth Lake. 

 

Pikeminnow scare is quelled 

 

In the effort to keep invasive species in check, there is some good news. 

 

The dreaded pikeminnow -- which has voraciously consumed salmon on the Eel
River for years -- was believed to have worked its way into the Elk River,
which empties into Humboldt Bay. 

 

Biologists found a single pikeminnow in Martin Slough, a tributary to Elk
River, in August, and feared the worst. Along with other state and federal
agencies, the California Department of Fish and Game developed a sampling
strategy to detect whether any other pikeminnow were in the watershed. 

 

"The implications for restoration around Humboldt Bay with the introduction
of these invasive species is pretty frightening," said Fish and Game
district watershed biologist Michelle Gilroy. 

 

But after a number of attempts to find other pikeminnow, the stream turned
up clean. No pikeminnow. While the sampling will continue at least until
spring of 2009, biologists are reasonably certain that the fish's presence
was an isolated case. 

 

The question is how did it get there? Gilroy said that it seems most likely
the fish was planted in a nearby pond or in the slough itself. That's
illegal; Fish and Game requires a permit to stock fish in private ponds and
in no circumstance allows fish to be transported to other streams without
permission, Gilroy said. 

 

Gilroy said it's also possible the fish got there from the Eel River,
although pikeminnow aren't salt-water tolerant, and would have had to travel
miles to get into Elk River. 

 

Restorationist Mitch Farro with the Pacific Coast Fish, Wildlife and
Wetlands Restoration Association said that when the Eel River is running
strong, a current can push a stream of fresh water north from the mouth of
the river to Humboldt Bay. That could have allowed a pikeminnow to travel
into the bay and back into fresh water. 

 

"It's a possibility," Farro said. "It's also fairly likely that someone put
them there."

 

 

Byron Leydecker, JCT

Chair, Friends of Trinity River

PO Box 2327

Mill Valley, CA 94942-2327

415 383 4810

415 519 4810 cell

bwl3 at comcast.net

bleydecker at stanfordalumni.org (secondary)

http://fotr.org 

 <mailto:bwl3 at comcast.net>  

 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www2.dcn.org/pipermail/env-trinity/attachments/20081106/723f4798/attachment.html>