Scientists have increased the estimate on the number of humpback whales in the North Pacific by more than 1,000.

Conducting a statistical analysis of an earlier study, the researchers now say the number of humpbacks exceeds 21,000 — up from 20,000.

"These improved numbers are encouraging," said Jay Barlow, a marine mammal biologist at the Southwest Fisheries Science Center in La Jolla, Calif., part of the National Oceanic and Atmospheric Administration. "We feel the numbers may even be larger since there have been across-the-board increases in known population areas and unknown areas have probably seen the same increases."

The earlier number was based on a preliminary look at data in a 2008 study called SPLASH, for Structure of Populations, Levels of Abundance and Status of Humpbacks.

The SPLASH research was a three-year project begun in 2004 involving NOAA scientists and hundreds of other researchers from the United States and nine foreign nations.

Researchers were able to quantify the humpback whales by photographing and cataloging more than 18,000 pictures of the animal’s tail, or fluke, because the pigmentation patterns on the fluke act like a fingerprint and are unique to each animal.

The researchers estimate that there were only 1,400 humpbacks in the North Pacific when commercial whaling ended in 1966.

The study is published in the October edition of the journal Marine Mammal Science.