Eating Like A Whale

Dr. Carin Ashjian of the Woods Hole Oceanographic Institution and a team will head out to the oceanic shelf near Barrow, AK., in mid-August for the second field season in a two-year study on the zooplankton that nourishes migrating bowhead whales each year.

WHOI researcher Phil Alatalo motors out to the Annika Marie, a small research vessel chartered for the zooplankton study led by Carin Ashjian. This picture courtesy of Wood's Hole Image of the Day.

Hoping to understand the dynamics and oceanographic characteristics that provide a copius buffet of nutrient-rich organisms on the shelf near Barrow, the team also intends to gather enough information to understand the potential impact of climate change on the feeding environment. Specifically, they are interested in investigating the impact of melting sea ice and variability in Pacific water.

Steve Okkenen from the University of Alaska, Fairbanks, and Phil Alatalo from Woods Hole Oceanographic Institution deploy the Acrobat, an instrument towed by the boat to measure water temperature, salinity, and fluorescence. Source: Woods Hole Oceanographic Institute.

Reached at her office, Ashjian was remarkably low-key for one about to embark on field work that will put her in the presence of whales, freezing ocean, and millions of tiny creatures (zooplankton), which have been called some of the most ecologically important aquatic species. Rather, she cautioned that her work was still in the data-gathering phase.

Bowhead whales feed on zooplankton, especially copepods and euphausiids or krill. To feed efficiently, baleen whales such as the bowhead whale and the Northern Atlantic Right whale must feed in locations where their zooplankton prey are found in abundance.

Barrow hunters prepare to bring in a whale. Results from the research may help scientists predict how climate change may affect the Arctic shelf ecosystem--and may in turn impact subsistence whaling by Inuit living in the area. Source: Winter reflections blog

The shelf near Barrow is a critical feeding area for whales, and it is also a complex ecosystem whose oceanographic and atmospheric conditions impact the composition, distribution, and availability of plankton prey. To better understand the dynamics, the team will deploy three moorings in August to collect information on water currents and temperature, mammal sounds (whale vocalizations, for example), and the quantity of zooplanton present. They also will analyze ice cover via satellite imagery and analyze the gut contents of whales harvested during spring and summer hunts.

“We don’t really look at whales in the sense that someone who studies whale behavior does,” said Dr. Ashjian. “We’re really looking for the plankton.”