It isn't necessary to analyze or find motifs in the story. In the end its a very simple story of a man who just wants to catch a fish after a long dry spell. 
 The old man differentiates his mind from himself as he talks when he is at the sea. He berates himself - his body and his mind, finds association with a fish that he chases deep into the sea and makes friends with a sad bird that's as lonely as him. 
 Its a heartwarming read where you root for the old man. He isn't disappointed when he loses the fish. His pride comes from catching the fish and way to prove to himself that he is a fisherman first. 
 When he returns to island, he is at peace.