To what extent can The Old Man and the Sea be considered an epic struggle of man against nature ?

In Hemingway's novella The Old Man and the Sea, the old fisherman Santiago battles for his life after being taken out to sea by a massive marlin that he had intended to catch. The entire work serves as a seminal example of the man-against-nature conflict, for it is the marlin and the sea itself that the man struggles against in order to survive. After nearly catching the marlin, the old man is taken far out to sea, where he finds himself in grave danger of drowning, starving, and freezing. Santiago experiences no conflict with other men, nor with himself. It is the sea—and nature itself—that Santiago must fight against in order to survive.
In one passage, the novella reads:

He looked across the sea and knew how alone he was now. But he could see the prisms in the deep dark water and the line stretching ahead and the strange undulation of the calm. The clouds were building up now for the trade wind and he looked ahead and saw a flight of wild ducks etching themselves against the sky over the water, then blurring, then etching again and he knew no man was ever alone on the sea.

Santiago is made to feel alone amongst the sea and its inhabitants until he notices the ducks. Eventually, Santiago spears the marlin, killing it. When he begins to head home toward the shore, sharks are attracted to the marlin's fresh blood and begin attacking the boat. This serves as another battle that Santiago must fight against nature, for the sharks, some of the sea's natural inhabitants, exist as a part of nature itself. After killing several of the sharks, Santiago arrives ashore safely, having conquered and persevered over nature.