The North Water by Ian McGuire is a modern novel in the tradition of historical realism, set in the high arctic. It is a violent, masculine novel with a clear debt to the work of Cormac McCarthy which deals in themes of physical and mental isolation and the unforgiving cruelty of nature.
(minor spoilers follow)
Most of the plot revolves around interactions between the crew of a whaling ship. Polar bears, however, appear at various pivotal moments of the story. The crew kill one and capture its cub, hoping to sell it to a zoo. Paragraphs are expended describing the bear's captivity aboard the ship, how the novel's protagonist, Sumner, takes pity on it and how it eventually escapes.
Later, another bear becomes crucial to the survival of the crew. And the final chapter ends on an encounter with a bear captive in a zoo - it is implied, although not confirmed, that this may be the bear that was captured earlier in the novel.
Given that the bears appear at such important points, including the otherwise uneventful final chapter, it seems clear they are there to serve some symbolic purpose. What is it, especially as regards the captured cub aboard the ship?