ON THE ST. CROIX RIVER - Possibly be-sieged by another aquatic critter that threatens untold destruction, the Department of Natural Resources on Monday and Tuesday dispatched fisheries crews here to set nets and send shock waves into the water in search of the latest targeted invasive species: the silver carp.
None was found.
The DNR announced last week special water tests conducted in June designed to detect traces of Asian carp indicated the possibility that silver carp -- the one whose Illinois River aerial acrobatics have won thousands of YouTube hits -- are in the St. Croix River.
Of 50 water samples checked approximately between Taylors Falls downstream a few miles to Franconia, 22 "environmental DNA" positives were returned, a rate high even by standards of the heavily infested Illinois.
The tests don't confirm the carp's presence, and the DNR's efforts at electrofishing and netting represent a first attempt to see if one or more silver carp can be put in hand.
In coming weeks, commercial fishermen under contract to the DNR also will string nets across the St. Croix.
"The commercial fishermen will probably have a better chance to catch one, if there's one in the river," said Jerry Johnson, DNR area fisheries supervisor for the east metro.
No silver carp have ever been caught in the St. Croix. A bighead carp -- one of three other unwanted fish of the Asian variety, along with the grass and black carp -- was netted by a commercial fisherman earlier this year in the St. Croix near Prescott, Wis.
Tuesday's effort was led by DNR large rivers fisheries specialist Joel Stiras. He's one of two agency workers who traveled to Illinois recently to watch fisheries experts corral silver carp using electrofishing and netting -- the same techniques employed on the St. Croix.
Two boats were used Tuesday. Stiras piloted one, an electro-shocking craft, as two helpers in the bow with long-handled nets retrieved and inspected stunned fish. Another three-man DNR crew set gill nets.
The nets had relatively large mesh sizes, 4, 5 and 6 inches, and Stiras and his crew attempted to steer fish toward them.
Asian carp reproduce rapidly and can quickly change a river's ecosystem, out-competing game fish for food and also putting water birds at risk.
DNR crews will return to the St. Croix daily at least through Friday.