For anyone interested the Welland river west of Prince Charles is frozen and is being run by snowmobiles. I have no idea how thick or safe it is but I do see snowmobile tracks running west up the river.
Limits are per day. They are also your possession limit. So catch one. Go home and eat it. Go back tomorrow and catch another one.
Catch and release there is not really a limit. Catch as many as you can and release them.