Using archaeological, biochemical and ecological techniques, researchers have found evidence of vast changes in reproductive behavior among northern fur seal populations over the past 1,500 years.

While today, the breeding colony of northern fur seals is on the Pribilof Islands in the Bering Sea, researchers found that seal populations once had major breeding colonies at temperate Californian and Pacific Northwestern latitudes, as well as in the eastern Aleutian Islands and bone findings suggest that they played a large part in marine ecosystems within those regions.

UC Santa Cruz graduate student Seth Newsom said that such findings are vital, as commercial harvesting decimated fur seals, along with multiple other species, before scientists could study them firsthand.

“”In a lot of cases, what we consider natural for a species may not have been its natural state prior to human disturbance,”” Newsom said.

The arrival of Russian and European fur traders corresponds with the disappearance of northern fur seals in some temperate regions. In central and northern California, however, seal populations were devastated long before human contact. Scientists link the cause of this mysterious disappearance to climate change or a combination of natural factors.

“”We think now of sea lions, harbor seals and elephant seals as the natural inhabitants of the California coast,”” said professor of Earth and planetary sciences at UC Santa Cruz Paul Koch. “”But how did … the ecosystem work in the past when fur seals were more abundant? I suspect California was really different when these animals were here in the past.””

Researchers are beginning to incorporate genetic studies in their investigation, by analyzing DNA in ancient fur seal bones to reconstruct the genetic diversity of prehistoric seal populations.