view of a gray whale near the ice edge with mud plume from
bottom feeding. Photo credit: Vicki Beaver, NOAA Fisheries.
NMFS Permit No. 14245. Funded by the Bureau of Ocean Energy
Management (IA Contract No. M11PG00033).
Gray whales do things differently.
Gray whales look different, swim farther, and fight more fiercely
than other whales.
They owe their distinctive mottled look to a coat of crustaceans
that can weigh up to 400 pounds. Their swim from Alaska to Baja
and back may be the longest annual migration of any mammal. And
they were named devilfish by whalers who watched them
charge and smash boats to defend themselves and their calves.
But perhaps what sets gray whales apart most is their eating
habits. Gray whales are the only baleen whales that feed primarily
on the bottom of the ocean.
Other baleen whales strain plankton from the water column. A
gray whale dives to the bottom, turns on its side, scoops the top
inches of sediment into its mouth, and strains small animals from
it, especially amphipods, small shrimp-like creatures that are the
favorite food of gray whales in the Arctic. A telltale plume of
mud shows where a gray whale fed on the bottom.
Thats what gray whales usually do. But scientists have
learned that with gray whales, you cant count on usual. Most
migrate, but some dont. And most gray whales bottom feed,
but if there is better eating in the water column, they will feed
It may be this flexible, opportunistic approach to life that
has kept the species swimming through multiple warming and cooling
phases during their 2.5 million years on the planet.
Thats why marine mammal scientist Amelia Brower is keeping
an eye on them.
Climate change is real and its happening fast. The
Arctic is the area of the world that is changing fastest. Comparing
where gray whales are and how they behave over time may provide
insight into how the ecosystem is changing, says Brower. Gray
whales may be important sentinels of ecosystem changes to come.
A Moveable Feast
Climate warming affects high latitudes faster and more dramatically
than the rest of the earth. Melting away the sea ice cover exposes
more ocean area and alters the entire ecosystem.
One way that sea ice affects the ecosystem is through its influence
on the spring bloom of phytoplankton, microscopic algae that are
the base of the ocean food web.
Loss of sea ice changes the ecosystem from the bottom up.
In cold years ice cover remains until late spring. Sea ice and
meltwater stabilize the water column, creating a clear, nutrient-rich
surface layer, which, combined with increasing light, sets the stage
for an intense phytoplankton bloom that follows the retreating ice
edge. Zooplankton are not yet ready to graze, so most of the phytoplankton
sinks to the bottom, where it is eaten by bottom-dwelling creatures,
In warm years, sea ice melts early in the spring, before there
is enough light to fuel an intense phytoplankton bloom. Melting
ice exposes the surface of the ocean to winds that mix the water
layers, disrupting the stratification that keeps nutrients and phytoplankton
in the light zone. The bloom is less productive and happens later,
when hungry zooplankton are present and ready to eat; most of the
phytoplankton are grazed before they sink to the bottom, leaving
little for the bottom-dwelling amphipods.
If it gets warm enough for this to happen in the Arctic, gray
whales may shift their banquet from the bottom to feed on zooplankton
in the water column, or they may move elsewhere to find other food.
So Brower is watching them. As part of the Aerial Surveys of
Arctic Marine Mammals project, she and her team fly over the northeastern
Chukchi Sea to see where gray whales are, where they are bottom-feeding,
and how they behave. She records when they breach, dive, feed, flipper
slap, log play, mate, mill, rest, roll, spy hop, swim, tail slap,
thrash, or blow under water. She compares this data with information
on amphipod distributions.
The most exciting thing about this research is being in
the airplane. The sea ice is beautiful, I get to see the animals,
and Im working in the area of the world that is changing the
If gray whales can change with it, it bodes well for their futureand
may help us to better understand ours.
Because as Brower says, Everything is connected. All the
ecosystems around the globe. What happens in the Arctic will affect
the rest of the world.
Joint Institute for the Study of the Atmosphere and Ocean
The Joint Institute for the Study of the Atmosphere & Ocean
in the College of the Environment at the University of Washington
is among the largest and oldest of NOAAs Cooperative Institutes.
In collaboration with NOAA and university researchers, JISAO scientists
are at the forefront of basic and applied investigations on such
critical issues as climate change and its impacts on humans and
ecosystems, ocean acidification, fisheries assessments and tsunami
modeling and forecasting.