The estimate released Thursday only represents animals counted in about half of walrus habitats in the Bering and Chukchi seas and does not account for animals that were in water rather than on ice.
The count was done by U.S. Fish and Wildlife Service in response to a court deadline requiring the agency to identify marine mammal stocks most affected by interactions with commercial fishing.
"We're still working on the final population estimate," said Suzann Speckman, a wildlife biologist with the agency.
A 1990 aerial survey estimated the walrus population at 201,039 in the region.
Pacific walruses are found mainly in the two seas off the west coast of Alaska in waters shared with Russia. Walruses occasionally move into the Beaufort Sea off northern Alaska and the East Siberian Sea on the Russian side.
Fish and Wildlife Service officials have been working since 2006 on a full walrus estimate with their Russian counterparts using thermal imaging. The latest target date for release of those numbers is January, Speckman said.
Brendan Cummings, a spokeseman for the Center for Biological Diversity, said the group was frustrated with the delay. The center has petitioned to list walruses as endangered because of the impact of global warming on Arctic sea ice.
In some ways, however, the number of remaining walruses is not important, he said.
"You don't need to know if there are 500 passenger or 1,000 passengers on the Titanic," he said. "When it hits an iceberg, they're all endangered."
Walruses dive from ice over the shallow outer continental shelf to feed on clams and other benthic creatures. Walruses cannot swim indefinitely, and females and young animals traditionally use ice as a moving diving platform to shift hunting areas.
Cummings said the changing conditions in the Arctic are being minimized by Fish and Wildlife Service in reports and decisions on oil and gas leasing.
"The management side of Fish and Wildlife has its head in the sand pretending everything is fine with these species when clearly it is not," he said.