Why does Sanriago wish he had never caught the fish?

Two hours later, a pair of shovel-nosed sharks arrives, and Santiago makes a noise likened to the sound a man might make as nails are driven through his hands. The sharks attack, and Santiago fights them with a knife that he had lashed to an oar as a makeshift weapon. He enjoyed killing the mako because it was a worthy opponent, a mighty and fearless predator, but he has nothing but disdain for the scavenging shovel-nosed sharks. The old man kills them both, but not before they take a good quarter of the marlin, including the best meat. Again, Santiago wishes that he hadn’t killed the marlin. He apologizes to the dead marlin for having gone out so far, saying it did neither of them any good.