"heavy shorefast ice has been shown to be associated with devastating declines in pup production for nearshore-breeding ringed seals...polar bear numbers have also crashed dramatically during heavy ice years"

Hudson Bay Ringed Seal Populations Declined Significantly Due to Heavy Ice in the 1990s

In summary, heavy shorefast ice has been shown to be associated with devastating declines in pup production for nearshore-breeding ringed seals in two regions of the Arctic (western Hudson Bay and the Beaufort Sea). These heavy ice conditions are known to have occurred during each decade between the 1970s and the 1990s. Because female polar bears that den close to shore are dependent on nearshore-breeding ringed seals to successfully rear their cubs, polar bear numbers have also crashed dramatically during heavy ice years, although so far this has only been documented in the Beaufort Sea.