Officials say no genetic material from invasive bighead or silver carp has been detected in Michigan waters this year. The state Department of Natural Resources and the U.S. Fish and Wildlife Service are searching Michigan’s Great Lakes tributary rivers for Asian carp DNA. After this year’s work is completed, more than 7,000 water samples will have been collected since 2013. One sample from the Kalamazoo River tested positive in 2014, but officials say the source probably was a boat or angler from another water body. The DNR says it is waiting for results of a final round of sampling from the St. Joseph, Grand, Kalamazoo, Muskegon, Macatawa, Galien and Black rivers. But thus far, no samples this year have turned up signs of Asian carp.