I don't know the law but the Charter Capt. would be the best guy to ask. Even if you can, he may not allow it.

Absolutely not. In Ontario waters it is illegal to have alcohol on board even if not consumed. That includes passengers. I've been stopped in candian waters a few times over the years fishing out there and every single time they checked my cooler for alcohol. The charter captain should and if he's a reputable one most likely he'll know the laws on canadian water