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DFG News Release: For Immediate Release
December 16, 2003
Discovery of Invasive New Zealand Mud Snail Forces Temporary Closure of Putah Creek
Contacts: Ed Pert, Chief, DFG Inland Fisheries Division, (916) 445-3616; Patrick Foy, DFG Information Officer, (916) 358-2938; Steve Martarano, DFG Office of Public Affairs, (916) 654-5866
The late-October discovery of non-native New Zealand Mud Snails (NZMS) in Putah Creek has prompted the Fish and Game Commission to close the creek for 120 days to fishing. The closure, which has the support of the Department of Fish and Game (DFG) and various fly-fishing clubs, will be temporary while affected agencies determine the extent of the infestation and the appropriate course of action. Closing the creek to angling will help prevent the unintentional spread of NZMS from Putah Creek to other waters.
The emergency closure, unanimously adopted during a special Fish and Game Commission meeting on Tuesday, will be effective in approximately 10 days, pending approval by the Office of Administrative Law.
The regulation closed Putah Creek from Monticello Dam downstream to, and including, Lake Solano in Yolo County. This reach of Putah Creek is a popular winter trout fishery. The action was necessary to delineate the reaches of Putah Creek where the snail has invaded, and evaluate options to control or eradicate the snail. Currently, no method of eradication has been successfully applied to large, open river systems. The most important control method typically used is to educate anglers who fish in infested waters to completely clean their equipment before moving to a new stream. Anglers can avoid contact with the snails altogether by staying out of infested waters where NZMS are present, restricting their fishing to the banks.
NZMS is a very small snail with the potential of extraordinary population densities – up to approximately a million snails per square meter. Populations in New Zealand are kept in check naturally by native parasites. In North America, however, native stream communities can be drastically altered because there are no natural predators or parasites of the snail and the populations have flourished where they have been introduced. Several streams throughout the west have been affected by the snail, including famous trout streams such as the Madison and Snake. The Owens River and Hot Creek in the eastern Sierra are the only other locations in California where the snail is presently known to occur. NZMS are believed to be spread within North America, primarily by anglers who fish an infested area, then leave the area without cleaning their waders and other fishing gear. The snails get stuck to the waders – often in debris and mud – and can survive for weeks in the moist conditions until the angler visits a new stream. NZMS are parthenogenic, which means that they are able to start a new population with one snail.
NZMS colonies disrupt the base of the food chain by consuming algae in the stream and competing with native bottom-dwelling invertebrates. A population crash of invertebrates (small aquatic insects) can follow the introduction of NZMS, which reduces fish forage. With a decrease in food availability, the fish populations can crash as well.
December 16, 2003
Discovery of Invasive New Zealand Mud Snail Forces Temporary Closure of Putah Creek
Contacts: Ed Pert, Chief, DFG Inland Fisheries Division, (916) 445-3616; Patrick Foy, DFG Information Officer, (916) 358-2938; Steve Martarano, DFG Office of Public Affairs, (916) 654-5866
The late-October discovery of non-native New Zealand Mud Snails (NZMS) in Putah Creek has prompted the Fish and Game Commission to close the creek for 120 days to fishing. The closure, which has the support of the Department of Fish and Game (DFG) and various fly-fishing clubs, will be temporary while affected agencies determine the extent of the infestation and the appropriate course of action. Closing the creek to angling will help prevent the unintentional spread of NZMS from Putah Creek to other waters.
The emergency closure, unanimously adopted during a special Fish and Game Commission meeting on Tuesday, will be effective in approximately 10 days, pending approval by the Office of Administrative Law.
The regulation closed Putah Creek from Monticello Dam downstream to, and including, Lake Solano in Yolo County. This reach of Putah Creek is a popular winter trout fishery. The action was necessary to delineate the reaches of Putah Creek where the snail has invaded, and evaluate options to control or eradicate the snail. Currently, no method of eradication has been successfully applied to large, open river systems. The most important control method typically used is to educate anglers who fish in infested waters to completely clean their equipment before moving to a new stream. Anglers can avoid contact with the snails altogether by staying out of infested waters where NZMS are present, restricting their fishing to the banks.
NZMS is a very small snail with the potential of extraordinary population densities – up to approximately a million snails per square meter. Populations in New Zealand are kept in check naturally by native parasites. In North America, however, native stream communities can be drastically altered because there are no natural predators or parasites of the snail and the populations have flourished where they have been introduced. Several streams throughout the west have been affected by the snail, including famous trout streams such as the Madison and Snake. The Owens River and Hot Creek in the eastern Sierra are the only other locations in California where the snail is presently known to occur. NZMS are believed to be spread within North America, primarily by anglers who fish an infested area, then leave the area without cleaning their waders and other fishing gear. The snails get stuck to the waders – often in debris and mud – and can survive for weeks in the moist conditions until the angler visits a new stream. NZMS are parthenogenic, which means that they are able to start a new population with one snail.
NZMS colonies disrupt the base of the food chain by consuming algae in the stream and competing with native bottom-dwelling invertebrates. A population crash of invertebrates (small aquatic insects) can follow the introduction of NZMS, which reduces fish forage. With a decrease in food availability, the fish populations can crash as well.
