A comprehensive study led by Scott Baker, associate director of the Marine Science Institute at Hatfield Marine Science Center, has identified five distinct humpback populations in the North Pacific, providing a new landscape for Humpbacks under the Endangered Species Act (ESA). Humpback whales, with their songs and size, are iconic creatures of the Oregon coast, drawing visitors to bluffs every spring and fall to catch a glimpse as they pass by on their way to feeding or breeding grounds. However, until recently researchers didn’t know just how special the humpbacks of the North Pacific were.
Humpback whales were first listed under the ESA in 1966 after hunting practices reduced the worldwide population to an estimated 1,000 individuals. The International Union for the Conservation of Nature (IUCN) recently downgraded the status of the whales to “least concern” as numbers have swelled due to protections. In the case of the North Pacific, populations have rebounded to pre-hunting levels: more than 21,000 individuals. However, two populations in the Sea of Arabia and Oceania have been recognized as endangered by IUCN, and Baker added that one or more of the newly discovered populations may also be considered endangered by IUCN standards. This underscores the importance of management of these whales on the population level. According to Baker, these populations have their own history of exploitation and recovery, and these variables need to be considered when implementing management strategies.
The study, published in the journal Marine Ecology – Progress Series and supported by the National Fisheries and Wildlife Foundation, the Office of Naval Research, and the Marine Mammal endowment at OSU, identified the distinct populations by analyzing almost 2,200 tissue biopsy samples collected during a three-year study known as SPLASH (Structure of Populations, Levels of Abundance and Status of Humpbacks). Scientists analyzed maternally inherited mitochondrial DNA (mtDNA) and DNA profiles for differences between individuals from 10 different feeding regions and eight breeding sites. The level of difference between these DNA analyses indicates that these populations are genetically distinct from one another. These distinctions, according to Baker, are the result of cultural practices of the whale populations; migratory routes, feeding grounds, and breeding sites are passed down from mother to calf.
The five populations identified are Okinawa and the Philippines, Hawaii, Mexico, Central America, and one population of the Western Pacific with unknown breeding grounds.
By Kristen Daly