Forty Minnesota conservation officers descended on Lake of the Woods Thursday, executing search warrants after what the agency said was an investigation that documented “numerous’’ violations — most involving fishing — on the big border lake.

Among apparent targets of the investigation were fishing guides, as well as bear hunting guides.

In a press release, the DNR said it had documented the “illegal take transport and/or possession of over limits of walleyes’’ during its investigation. No charges have been filed yet, though they are expected, according to the DNR.

Interviews of suspected --  and what the DNR says are “documented’’ -- violators were conducted.

“A great deal of consideration was taken in the planning and execution of this operation,” said Col. Ken Soring, DNR enforcement division director. “Our goal was to perform our court-ordered duties as safe as possible and without any unnecessary delay or inconvenience for any businesses or the public.”

Soring said his officers’ investigation also revealed other fishing guides in the area followed the law.