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Another Non-Native Species Found in West Marin’s Creeks

Forest Knolls, CA – The recent discovery of a nine inch long non-native spiny softshell turtle in Marin’s Lagunitas Creek Watershed has caused environmental groups and state agencies to warn of the potential harmful impact on native species, especially coho salmon and steelhead trout. This recent discovery adds to a growing list of alien species ranging from channel catfish to bullfrogs to large mouth bass. Groups are calling on the public to not release non-native species, such as unwanted exotic pets, into the wild and remind them that such releases are illegal

The spiny softshell turtle was discovered by veteran Salmon Protection and Watershed Network (SPAWN) naturalist David Ford during a routine spawning salmon survey in a creek in the Lagunitas Watershed’s San Geronimo Valley. “I saw a tiny snout sticking out from the sediment on the creek bottom so I dug down and to my surprise pulled up this turtle.” said Ford of his discovery this winter.

“The discovery of this turtle highlights another serious risk that threatens the survival of local endangered species,” said Reuven Walder, SPAWN’s Watershed Biologist. “We implore people not to introduce such species into the wild. The impacts can be catastrophic – potentially contributing to the loss of our wild salmon.”

“Spiny softshell turtles are fish predators and this turtle may have been feeding on juvenile salmon and steelhead. Furthermore, the introduction of non-natives into our streams always runs the risk of introducing new diseases that could impact a multitude of native species,” said Todd Steiner, director of SPAWN.

Furthermore, female turtles have the ability to store sperm for years, and thus a single female introduced into a stream has the possibility of eventually laying eggs and inadvertently starting a growing colony of exotic turtles, and possibly out-competing the native western pond turtle.

Researchers are not exactly sure where this turtle originated from. However, these turtles can be found in Bay Area pet stores as well as ethnic food markets where they are often kept in unsanitary conditions that breed disease.

This is not the first non-native species discovered in the watershed in recent years. SPAWN crews regularly discover large mouth bass and bluegill during their fish rescue efforts nearly each summer. Other researchers have confirmed these sightings along with several other species including channel catfish, golden shiner, carp and bullfrogs.

It is unknown how the introduction of this species can affect native salmon populations or whether there are others roaming the waters there. Since the Lagunitas Watershed is considered to have one of the strongest runs of coho in California, the presence of another invader is disturbing to environmental organizations especially since native salmon populations in the Lagunitas Watershed have suffered a 90% decline in recent years due to loss of habitat and water, pollution and over-development.

Fears of other non-native invaders loom over the Lagunitas Watershed. The discovery of the invasive New Zealand Mud Snail (NZMS) last October in Putah Creek in Davis, CA and other creeks and rivers in California signals that more problems may be on their way.

While the full impact of the NZMS is not known, researchers believe that the very small snail with the potential of extraordinary population densities – up to approximately a million snails per square meter – will likely replace the native aquatic invertebrates communities and offer almost no value to feeding trout and salmon populations.

California Department of Fish and Game (CDFG) fishery biologist, Bill Cox, is concerned about the turtle discovery as well and the potential of other invaders like the NZMS reaching these waters. “It is illegal and punishable by law to introduce such species into the wild.” said Cox. “We ask people to not jeopardize the fragile balance of watersheds like this one.”

While researchers hope that the discovery of the turtle was an isolated incident, organizations like SPAWN and agencies such as CDFG are on the lookout for people who might knowingly or unknowingly introduce such species. They encourage people to find out how they can help by contacting local watershed groups to learn about the detrimental effects of species invasions. You can find out more about non-native species introductions and organizations that will accept unwanted pets by going to http://www.spawnusa.org.

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