I've seen people fishing wacky rigged senkos in May before...on a well known bass lake...that got a call to the MNR. There is a local dam that is now policed often because of multiple calls to the MNR from various folks and repeated poaching...Trout & Salmon aren't really the target species there either.
If you don't feel comfortable confronting them take some non-suspicious pictures at least...might come in handy.
Whether or not you think the MNR will do anything or not, it should at least be reported....with a person description, vehicle, and license plate. You could call the local police I believe they can also press charges?. Even if it just gets them a visit or phone call....awareness does go a long way with some people. Some will never learn unfortunately but worth a shot.