How non-migrating grey whales survived the ice age

London, Oct 18 (ANI): A new study attempts to shed light on how non-migrating grey whales survived the last ice age.

Grey whales feed on the seafloor at depths of up to 50 metres, and rely heavily on the shallow regions in Alaska's Bering Sea for food.

But when Nick Pyenson of the Smithsonian Institution in Washington DC modelled Pacific feeding grounds during peak glaciation, he found that very little of the north Pacific was shallow enough for feeding: sea levels were up to 120 metres lower than today and the Bering Sea was a land bridge, reports New Scientist.

Northern feeding grounds might have supported only a few hundred whales. Yet genetic studies show no sign of a bottleneck at the time.

Pyenson thinks the whales shifted to open-water feeding to survive. Support for this idea comes from a small group of open-water feeders found living year-round in the Pacific Northwest.

He said that after the ice age the non-migratory whales would have been easy targets for early whalers, so the migratory population has come to dominate.

Pyenson talked about the findings at the Society for Vertebrate Paleontology meeting. (ANI)