MINNEAPOLIS (AP) - The Minnesota Department of Natural Resources says too many boaters are breaking state laws intended to make it harder for invasive species to spread in lakes and rivers. The DNR says it's ramping up enforcement this weekend as a result. DNR enforcement manager Capt. Greg Salo says conservation officers have issued 169 tickets and 375 warnings for violations of aquatic invasive species laws. Salo says officers have followed up with nearly 100 people after watercraft inspectors found their boats were unwitting carriers of zebra mussels. Salo says the violation rate at check stations is running at 26 percent, which he calls "way too high.'' He says the most common violation is people failing to pull their boat plug and keep it out while transporting their boats.