You need to do something! The law does not just speak to baiting but also hunting over it! An ECO can arrest you for hunting over that bait; whether you knew it was there or not (ie tell it to the judge). I see you having two options: 1) remove the lick so you are not at legal risk while hunting or 2) involve an ECO to catch the guy for both trespassing and baiting. A third option of trying to discuss with the trespasser puts you at risk if the ECOs are already after him/her.