On Thin Ice

A harp seal pup less than two days old lies in slushy ice in Canada's Gulf of St. Lawrence as its mother keeps a wary eye on the photographer from the water. Due largely to a 1987 ban on hunting pups like this one, the harp seal population in the northwest Atlantic has surged to an estimated 5.2 million, about three times the number in the early 1970s. But a new challenge has emerged. Female harp seals need a platform of solid ice for whelping, and pups need it to live on until they've fattened up enough to retain heat in frigid waters. During a recent string of warm winters, many seals struggled to stay afloat on thin ice.