Again, just conjecture here:
I don't know if a market hunter is professional in that he gets paid for the time he spends hunting, or just that he hunts and is then paid for what he is able to bring back and sell "to the market.''
I also don't know if the term market hunter expresses one's level of expertise, or simply one's intent in selling the goods on the market.
My guess is that to be a successful market hunter, one must also be highly skilled.
I would wait for others who have a better grasp of the subject to provide you with a more detailed answer.
Given the sentence, however, it is clear that a market hunter does sell what he catches/kills to restaurants.