Increased shipping stressing out narwhals, say researchers

Study looks at blubber to measure the stress hormone cortisol

A narwhal swims in icy north Baffin waters. A new study of narwhal blubber from Eclipse Sound shows narwhals there produce increased amounts of a hormone linked to stress during times of increased shipping. (Photo by Kristin Westdal, courtesy of Oceans North)

By Jane George

Researchers have found evidence to suggest increased marine traffic is stressing out narwhals.

A new study, discussed on Tuesday, Dec. 8, at the ArcticNet science conference, has found the stress hormone cortisol increased in the marine mammals by 200 per cent after more vessels started visiting Eclipse Sound, near Pond Inlet, after 2006.

Eclipse Sound, located off north Baffin Island, is home to the world’s largest population of narwhals. It’s also where the Mary River iron mine project is located.

Sandra Black, lead researcher on the study, called cortisol an “early warning indicator” for how chronic stress affects narwhals.

Black is a zoo and wildlife veterinarian and clinical associate professor at the Faculty of Veterinary Medicine at the University of Calgary. She gave her talk during a session on shipping.

Cortisol is sometimes called the “fight-or-flight” hormone. It’s released by the adrenal glands.

It helps mammals deal with stressful situations, but it can also be harmful to health, affecting, among other things, the reproductive system.

The narwhal samples were supplied by the Mittimatalik Hunters and Trappers Organization and by James Simonee, a co-author of the study. The blubber spanned three periods – hunts that occurred between 2000 and 2006, before mine-related vessel traffic started; hunts during mine-related vessel traffic from 2013 to 2019; and then from an entrapment event in 2015.

Entrapment occurs when ice movement reduces the amount of places through which narwhals can come up for air. This can cause hundreds of them to crowd a single hole, where they run the risk of freezing.

While the 2015 entrapment event resulted in the highest levels of cortisol, Black called the 200 per cent increase after more vessels started visiting Eclipse Sound “significant.”

Increased boat traffic isn’t the only thing that stresses narwhals. Changing ice conditions, access to food, an increase in predation by killer whales and cumulative impacts from these sources likely all contribute, Black said.

This isn’t the first time researchers have used cortisol to gauge stress in whales. In 2018, they looked at beluga blubber sampled from the Beaufort region. That study didn’t find any significant sources of stress, and the data collected is considered baseline.

More presentations continue through Thursday at the ArcticNet conference, an annual science event that has gone virtual this year.

This year, 327 participants are joining the conference from northern communities, accounting for 22 per cent of the conference attendees.

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(5) Comments:

  1. Posted by Keep the Arctic Pristine on

    This is further evidence that international shipping needs to be limited and regulated. Other countries, such as Russia and China, have already decimated their own wildlife and they have no safety standards. It’s up to us to protect our waters.

  2. Posted by DGibson on

    There may be a positive correlation between increased cortisol in narwhals and marine traffic. However, there is not enough information here to show causation. The headline blames increased shipping, but Sandra Black, the lead researcher, states that there are other sources that contribute to stress in narwhals, so it may be a cumulative effect of many different factors.

  3. Posted by Orca Greed on

    Killer whales are probably more of a stress than ships , they’ve been going up more and more in the past few years

  4. Posted by Stop Atop on

    Please stop all mining and shipping in the East!

  5. Posted by Part time hunter on

    The Killer Whales are on the rise and killing and a lot of belugas and narwhals. The killer whales are no source of food to inuit of Canada. So, why doesn’t DFO do anything about the controlling of Killer Whale s’ which will continue to impact reduction of belugas and narwhals. The very species which they control to Inuit not to hunt them but they don’t mind killer whales doing all the damage. I say get rid of Killer Whales.

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