Climate change could push bowhead whales to cross paths with shipping traffic

Researchers used more than a decade of acoustic data to monitor bowhead whale movements between wintering grounds in the Bering Sea and summer feeding grounds in the Chukchi and Beaufort Seas. Based on acoustic data, whales departed the summer feeding grounds about six weeks later in 2022 than in 2008.

Some also spend the winter in the Chukchi Sea to the north, where commercial traffic in particular is increasing. This means they can stay longer in shipping lanes, which become busy as the sea ice shrinks.

“Such change isn’t necessarily a bad thing for whales, but any time we see more overlap with whaling and shipping traffic, we have to think about it,” said marine scientist Angela Szczeworka of Oregon State University’s Marine Mammal Institute. should be concerned.” led the study. “There will be winners and losers, but only time will tell.”

The study was published in Geophysical Research Letterswhich publishes high-impact, short-format reports with immediate implications spanning all Earth and space sciences.

A wheel on the move

Historically, the population of bowhead whales studied by Szczeworka spent their winters in the Bering Sea. In April, they move north through the Chukchi Sea and into the Beaufort Sea off the coasts of Canada and Alaska, west to the Russian Chukotka Peninsula, and finally back south in mid-November. will go During the 2008-2009 International Polar Year, researchers deployed an underwater microphone called a hydrophone on the Chukchi Plateau for the first time and were surprised to hear the sounds of bowhead whales in late spring and summer, which they had previously thought was not possible. The migration routes were further north.

Traditional knowledge among local Arctic communities has suggested that whale migration patterns have been changing in recent years, and data from a handful of satellite-tagged whales has reflected this. As temperatures warm the waters and sea ice extent shrinks, the entire Arctic ecosystem is forced to change, from tiny plankton and krill to whales. Scientists wonder if climate change is behind changes in bowhead whale migration patterns, but they need more information about whale migration patterns over time to know for sure. can be done

Szczecorka and his colleagues had previously monitored bowhead whale movements through the Bering Strait using data from hydrophones. They used hydrophones to monitor bowhead whales in the western Beaufort Sea and Chukchi Plateau from 2008 to 2022.

“Boyhead whales are extremely vocal,” Szczeworka said. “The males sing about twenty-four times from fall to spring, so you know when they’re there.”

Recordings show that whales shifted the timing of their winter departure from the western Beaufort Sea 45 days later in 2022 than in 2008. They also spend more time in the Chukchi Sea in the summer, and some seem to stop migrating back altogether. Bearings c as they normally would.

The study suggests that some of these changes are due to increased food availability in the Chukchi Sea as a result of warmer waters and shrinking sea ice. But scientists will need to do more research to know for sure.

“The changes we’re seeing in migration patterns raise a lot of questions,” Szczeworka said. “How many whales are going into the Chukchi Sea in the summer? What are they eating? Do the same ones come back every year? We’re basically learning how whales are responding to a changing climate. “

There is also concern that local harvests of bowhead whales may be affected. Bowhead whales may abandon parts of their historic range, and some tribes do not have access to this traditional food and cultural resource. Szczeworka said tribal involvement in whale management is important.

Climate change and shipwrecks

Spending more time north, where commercial shipping traffic is increasing as sea ice extent recedes, could put whales at increased risk of dangerous collisions with ships.

“With this general northward shift with increased ships and shipping, the risk of a ship attack will likely increase,” Szczeworka said. Shipping in the West Chukchi Sea has increased by about 13 percent since 2009. However, there has not yet been an increase in bowhead vessel strikes “that we know of,” he asserted. Vessel strikes can only be confirmed during harvest. Other whales may die and wash ashore.

But Szesciorka sees opportunity.

“Right now, the Arctic is like the Wild West,” he said. “As sea ice continues to decline, shipping, especially large commercial ships that go much faster than small fishing boats, is only going to increase. It’s better to start thinking about this sooner rather than later.” Let’s go so that we can prevent problems instead of trying to answer them. For them.” One solution, he said, would be to establish speed limits in the bowhead whale’s seasonal habitat, reducing the risk of ship collisions and noise pollution.

The seasonal movement of bowhead whales is changing rapidly, along with other rapid changes in the Arctic. But that’s not necessarily a bad thing. Szczeworka said the wheels can be fast enough to keep up with the changes.

“We’ve seen these changes in migration patterns in just nine years,” he said. “For a species that can live to be 200, that’s pretty tough. It shows that they can adapt to their changing environment right now. But will there ever be a point where they can’t adapt anymore?” Will we be able to? We’ll have to wait.”