The 2008 survey to assess humpback whale populations throughout the North Pacific originally put the number of the animals at 20,000, but scientists at the National Marine Fisheries Service of the National Oceanographic and Atmospheric Administration say a refined statistical analysis indicates the population totals more than 21,000.
The figure is a significant improvement to the scant 1,400 humpback whales estimated in the North Pacific Ocean at the end of commercial whaling in 1966, a NOAA release said Tuesday.
"These improved numbers are encouraging, especially after we have reduced most of the biases inherent in any statistical model," Jay Barlow of NOAA's Southwest Fisheries Science Center in La Jolla, Calif., said.
The original survey involved NOAA scientists and researchers from the United States, Japan, Russia, Mexico, Canada, the Philippines, Costa Rica, Panama, Nicaragua and Guatemala.
It was the first systematic survey ever attempted to determine humpback whales' overall population, structure, and genetic makeup in the North Pacific, NOAA said.