To clarify:
You don't need a license to sell roe.
Yes it's illegal to sell roe from fish that have been caught. There is a legal way to sell roe and it requires no license..only requires that the eggs be sourced from a legal (aquaculture) source.
If your roe vendor has you questioning their source, ask them where they purchase their roe. There aren't as many aquaculture sources in Ontario as you would think.
They have machines that separate eggs that will hatch from eggs that won't. The eggs that won't hatch, are sold in bulk to roe vendors. Various curing methods are used to bring back colour and desired firmness to the eggs.
If someone is selling roe on Kijiji, they aren't necessarily breaking any laws. But it wouldn't be far fetched to think that some of these 5 hen per outing guys are indeed illegally selling their harvest.