Supply Management is the name given to agricultural protectionism in Canada. It has made the news since some folks sought to use the inflated prices to their advantage by stealing some syrup (ok, a lake of syrup) and then sell nearby to make a killing. Sure, I wanted a Breaking Bad type story, but what we got was a story about protectionism.
Canada, a country that loves equality in theory and in rhetoric, has a system in place where the few gouge the many. Sure, agricultural protection exists in most places to varying degrees, but the systems in place in Canada seem especially bad. They are focused on maple (as we have seen), poultry and dairy, so that prices for milk, cheese, eggs and chicken are significantly elevated. Sucks to be poor or lower middle class in such a situation. But politicians here are just as chicken (yes, I went there) as those in the US who are afraid of the sugar industry.
By calling it supply management, the government does its best Orwell but is fooling fewer and fewer people these days. I doubt that it will change soon, but it is becoming increasingly clear that supply management is an obstacle to international trade negotiations as well as a burden that most of Canada must suffer to protect "small" farmers.
It is a lousy way to manage agriculture and the industry around it, but path dependence is a bitch. Changing this policy will mean upsetting powerful lobbies, so I don't expect significant change in the near future.