What two things could John Thornton live off and how could he do this in the call of the wild?

In "The Call of the Wild," John Thornton could live off the gold he mines and the meat he hunts. By prospecting for gold in the Yukon, he could potentially gain wealth, while hunting and fishing in the wild would provide him with food to sustain himself and his sled dog, Buck. His skills and knowledge of the wilderness would enable him to survive and thrive in the harsh environment.