An atv can only be operated on a highway if the municipality passes a bylaw allowing it. Then you have to have a plate ownership insurance drivers licence a helmet, and no passengers.
Here is the definition of a highway according to the highway traffic act: “highwayâ€, includes a common and public highway, street, avenue, parkway, driveway, square, place, bridge, viaduct or trestle, any part of which is intended for or used by the general public for the passage of vehicles and includes the area between the lateral property lines thereof; (“routeâ€)
Driving on the ice you would fall under the off road vehicles act and you need a helmet, ownership, and insurance.
There is nothing in the Off road vehicle act that says you are not allowed to have passengers.
Here's a link to the fines for the off road vehicles act. FINES