Researchers estimated abundance of Pacific humpback whales (Megaptera novaeangliae) using photo-identification surveillance of identifiable adults.They found that the number of humpback whales in the region increased each year,and doubled from 2004 to 2011,resulting in a total of 137 whales in 2011.The survery was conducted year-round,but abundance was estimated only during the summer moths of July to September,when the migrating whale population is largest.