When the sharks mutilate the dead marlin hanging off the side of the skiff as Santiago struggles to sail home, the old man fights them off as if they were attacking him.
Only when the marlin's carcass has been entirely eaten away does Santiago give up, knowing he "was beaten now finally and without remedy" (119).
The old man exemplifies Hemingway's ideal of exhibiting "grace under pressure," as he refuses to submit to the overwhelming obstacles presented by the sea.
Santiago's attitude seems to be that although he is faced with tragedy -- as everyone is sooner or later in life -- he will not cease struggling.
Although the old man seemingly fails once the sharks steal his prize fish, they cannot take away the fact that Santiago -- the primary target for the jest and pity of other fishermen -- has done the unthinkable by staying with and catching a fish "bigger than he had ever heard of" (63).
According to the "Hemingway Code," based on principles of courage and endurance, the old man has actually triumphed in spite of his loss.
Notwithstanding, he bears all these obstacles without whining about it.
The author describes that Santiago felt the line painstakingly with his right hand and saw his other hand was bleeding ―shifting the heaviness of the line to the left shoulder, bowing deliberately he washed his hand in the sea and held it there, submerged, for over a moment observing the blood trail away and the relentless development of the water against his hand as the vessel moved.
Yet, throughout the test of endurance between man and fish the old man begins to recognize a bond between he and the marlin, repeatedly referring to it as his brother; he elaborates, "Now we are joined together and have been since noon. The old man and the fish are both mere inhabitants among the diverse tropical life residing in the Gulf Stream, bonded by the fact that they are at the mercy of the sea.
The fish, therefore, transforms from merely being Santiago's prey to serving as a metaphor reflecting the old man's emotional and physical state.