What are the advantages for animals living in the polar region?

The advantage for living in the polar regions are that during the increasingly short "growing season" where temperatures are above about 3˚C, the high nutrient levels of polar seas means that extremely high densities of animals can be supported compared to hot climates where soils tend to be very old and infertile. These rich fisheries - though they are actually less rich where sea ice occurs for most of the year - allow for dense populations and much more rapid breeding that possible in hotter seas.