Warming waters of the Arctic could pose a threat to Pacific right whales
As rising global temperatures push Arctic icecaps into retreat, large and small sea creatures and the commercial fishing boats that follow them are also migrating northward.
This mass migration toward the relatively narrow Bering Strait could lead to more ship collisions and gear entanglements for the extremely rare and critically endangered eastern population of North Pacific right whales, according to a researcher who recently completed her Ph.D. at Duke University's Marine Lab.
"There's a really wide, shallow shelf (sea floor) that extends about 500 kilometers in the whale's primary feeding ground north of the eastern Aleutian Islands off Alaska," said Dana Wright, who is the lead author on a study that appeared Oct. 4 online in Ecological Applications.
"Cold meltwater from the sea ice in spring combines with currents that move up on the shelf to aggregate the zooplankton the whales eat in this area," Wright said. For a filter-feeding whale, concentrated prey means more food with less effort, but all the other predators have the same idea.
"Ecosystem dynamics are changing," said Wright. Commercially valuable fish and some of the industrial-scale fishing fleets that follow them are moving north too. "Prey are responding to the changing climate, and species at the top of the food chain are too," Wright said.
Sightings of North Pacific right whales are exceedingly rare, but the animals are likely to have been moving north along with the zooplankton, according to Wright's modeling analysis of zooplankton and temperature data collected NOAA Fisheries' Alaska Fisheries Science Center.
Zooplankton, tiny sea animals at the base of the food web, are on the move in the arctic as the North Pole’s ice cap retreats. Predators, including humans and whales, will follow. Credit: NOAA
An artist’s conception of what a North Pacific Right Whale (Eubalaena_japonica) looks like. With only 30 estimated remaining animals in the eastern Pacific population, photos are hard to come by. Credit: NOAA