And always they pitched camp after dark, eating their bit of fish, and crawling to sleep into the snow.

Buck was ravenous.

The pound and a half of sun-dried salmon, which was his ration for each day, seemed to go nowhere.

He never had enough, and suffered from perpetual hunger pangs.
Yet the other dogs, because they weighed less and were born to the life, received a pound only of the fish and managed to keep in good condition.
He swiftly lost the fastidiousness which had characterized his old life.
A dainty eater, he found that his mates, finishing first, robbed him of his unfinished ration.

There was no defending it.