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Seen from Above: Dolphins Hitch a Free Ride from Migrating Gray Whale

June 28, 2013
In the photo below, a group of long-beaked common dolphins are hitching a free ride on the bow wave of a migrating gray whale. Taken near Catalina Island off the coast of Southern California, the photo was shot from about 600 feet by scientists with the Cetacean Health and Life History Program at NOAA's Southwest Fisheries Science Center.


Photo caption: A group of long-beaked common dolphins surf the bow wave of a migrating gray whale. This photo was shot by 
NOAA scientists off Southern California as they conducted their annual gray whale aerial survey. Credit: NOAA

Every year, almost the entire population of eastern North Pacific gray whales migrates from their feeding grounds in the Arctic down to their breeding and calving grounds off the coast of Baja California, Mexico. And most years, NOAA scientists survey and photograph the whales from the air. By analyzing the high-resolution photos, scientists can tell how well nourished the animals are, how many females are pregnant, and how many new calves are born.

One reason for doing this is to keep an eye on the health of the gray whale population. But in addition to that, the photographic study is an indirect way of monitoring the Arctic ecosystem.

The primary feeding grounds for the eastern north Pacific population of gray whales are in the Arctic. The rest of the year they fast or eat very little. So their physical condition during migration reflects conditions in their feeding grounds in the Arctic.

"We know the Arctic is changing, and changing pretty rapidly," said Wayne Perryman, a biologist with NOAA's Cetacean Health and Life History Program. "We want to know how this is impacting the gray whale population."

For example, many of the species that gray whales feed on are shifting northward as the Arctic warms. This means that gray whales have to migrate farther north to feed. For pregnant females, who by the time they arrive in the Arctic have been fasting for many months, this extra travel may be energetically taxing. One of the things that Perryman and his colleagues are studying is the relationship between the length of the migration and the rate of successful pregnancies.

"Gray whales integrate the impacts of climate change into their physical condition, then they swim right by our coast," said Perryman. "So we can actually do Arctic research right here from San Diego."

For dolphins, however, migrating whales mean only one thing. And that’s a free ride.

Photo caption: A very pregnant female gray whale. Aerial photos such as these allow scientists to monitor how healthy and
well-nourished the animals are, how many are pregnant, and how many successfully give birth. Credit: NOAA

How Do We Study Whales?

The aerial survey of gray whales is just one component of a comprehensive research program. NOAA scientists also survey the migrating whales from stations on land, and they collect DNA samples from the animals then do genetic analyses that reveal gray whale population structure. 

Together, these studies allow NOAA scientists and others to monitor and protect gray whale populations. Thanks in part to efforts like these, the eastern North Pacific population of gray whales was declared recovered under the Endangered Species Act in 1994. 

Gray whale populations in other parts of the world remain endangered, however, and all gray whales are protected under the Marine Mammal Protection Act. Learn more about gray whale research at NOAA’s Southwest Fisheries Science Center, and check out the Center’s Office of Protected Resources.

New Technology Gives Scientists New Perspective

NOAA scientists are at the forefront of using new technology, such as unmanned aerial vehicles, to study marine mammal populations. For instance, NOAA scientists are using aerial drones to Spy on Sperm Whales and also to get A Whole new Perspective on life in Antarctica.

Gray whales still sometimes surprise scientists with their unexpected migrations.