The possibility of seeing a bear or moose, trying to identify a brightly coloured bird, and listening to a cheeky squirrel's chirp all contribute to the connection with nature that a canoe trip develops faster than any other sort of travel. Naturally we don't want to get attacked by a bear, but humans are not the only ones in danger. The basic idea is to minimise all odours and smells as much as possible. Promptly clean up and burn any food spills. If you've been fishing and the lake is deep throw the remains into the water, not along shore.
Food fights are a definite no-no.
All food supplies should be plastic-wrapped, and these packages in turn should be in a food barrel or large, thick, plastic bag. Double packaging will not only keep the bears away but will also waterproof your food in the event of an upset. The clear bags used to package sand at some building supply stores are perfect. Pots and pans, with their residual food odours, should also be stored in a smellproof bag or barrel at night and when not in use. This rule needs to be emphasised when travelling with kids who generally like the idea of eating chips while sequestered in their sleeping bags.