New Zealand Mud Snail Alert
Boy, we're off to a great start for 2008. Not only do we have New Zealand Mud Snails
in the San Lorenzo River but also Zebra Mussels in San Justo Reservoir, San Benito
County. If you fish either of these waters, please take the time to review the links
below and take steps to clean your gear, boat, trailer, etc., so that these creatures
aren't transported to other waters by anglers. Thanks.
http://www.dfg.ca.gov/news/news07/07007.html
http://www.invasivespeciesinfo.gov/aquatics/zebramussel.html
The highly invasive New Zealand mud snail, which has spread explosively
throughout the Pacific Northwest, has been found in Alameda Creek. The non-native
mud snails were found in the flood control channel and in upper Niles Canyon in
November. Their presence could have impacts on resident rainbow trout and efforts
to restore steelhead to the creek.
New Zealand mud snails are invasive exotics that can occur in immense numbers,
typically tens to hundreds of thousands per square meter. They have spread widely
throughout the western U.S. since first detection in Idaho during the 1980s. They
occur in a variety of freshwater and estuarine habitats. They are known to occur at
several localities in California and within the nine Bay Area counties, they have been
found in the lower Napa River in 2004, in Solano County in 2006, and in Contra Costa
County (West Antioch Creek) this year. The Alameda Creek specimens represent
their first known occurrence in the southern Bay Area.
These tiny snails can live on sand, rocks, and mud and survive in fresh and brackish
water at many temperatures and in damp conditions out of water for weeks. They
destroy habitat, sometimes entirely coating surfaces with hundreds of thousands of
snails per square yard. They have the potential to alter stream insect populations and
impact the food web for native fish. The snails can pass through fish alive, and a
study found that trout fed New Zealand mud snails lost weight. See the Department of
Fish and Game's web site on the New Zealand mud snail.
No effective method of eradication has been found – our best hope is to prevent or
slow the spread.
Fishermen and biologists are suspected agents for dispersal as the snails can
hitchhike on wading gear, sampling nets, etc. Transportation by birds is also
probable. If you fish, hike, work in, or otherwise have contact with local creeks,
please get to know this pest and follow procedures for decontaminating your
equipment. You can download a flyer on how to decontaminate your equipment (be
patient - big PDF file).
The Alameda Creek fish rescues will be following strict protocols to prevent the
spread of mud snails - be prepared to follow these protocols if you volunteer for fish
rescue or participate in any activities in the creek.
If you suspect you have found New Zealand mud snails locally, please contact Arleen
Feng of the Alameda Countywide Clean Water Program, (510) 670-5575,
watersheds@acpwa.org.