Narwhals most vulnerable to increased shipping in Arctic

As ice melts, more ships will move through the habitat of Canada's tusked whale

There’s a surprising number of people who don’t believe in narwhals.

Not that a narwhal is a creature that can or can’t be believed in. But rather, somewhere along the way, the marine cetacean got lumped into the popular mind as a being on par with dragons, Bigfoot, or, unsurprisingly, unicorns (thanks in no small part to the giant tusk that shoots straight out of its forehead). But no matter how impossible the narwhal way may seem, it is very much real. And though remote, these not-so-mythical beasts are gaining visibility, and thus believability: namely, because they like to spend their summers smack-dab in the middle of the increasingly ice-free Northwest Passage.

In a new study published Tuesday in the Proceedings of  the National Academy of Sciences, researchers found that out of seven Arctic marine mammals, the narwhal is the most vulnerable to vessel traffic in the Arctic’s Northwest Passage and Northern Sea Route during the open water season. This is due to its high exposure and biological traits that make the narwhal sensitive to passing ships.

The polar bear, though often used as the poster child for climate change, was the least vulnerable as it spends much of the late summer on land.

Scientists hope that governments and industry can use this vulnerability assessment to better plan and implement regulations and protections for marine mammals.

Narwhals are a migratory animal that spend most of their time in the waters of the Eastern Arctic.

“At various points during the year, 90 per cent of the world’s narwhal can be found in Canadian waters,” says Brandon Laforest, senior Arctic specialist with World Wildlife Fund-Canada based in Iqaluit. “We have a really high responsibility for [them] in terms of proper management and conservation.”

Under the Committee on the Status of Endangered Wildlife in Canada, narwhals are identified as a species of special concern. That’s because, while their numbers are holding strong — between 80,000 and 100,000 worldwide — several red flags have been raised about their continued survival in the Arctic, given that narwhals have a fairly limited geographic extent and depend on sea ice for their life cycle.

September sea ice cover in the Arctic has retreated by 14 per cent per decade since 1979, lengthening the open-water season and increasing navigability for ships.

Previous studies have shown narwhals are also the most vulnerable to the effects of climate change, “and now, with this study, you see another … in that they’re highly exposed to future shipping threats and they’re also the most vulnerable to those threats,” says LaForest of the study.

When researchers broke all the mammal species down further, into 80 subpopulations, they found that the Eclipse Sound narwhal subpopulation was the most vulnerable to vessel traffic.

“At various points during the year, 90 per cent of the world’s narwhal can be found in Canadian waters.”  — Brandon Laforest, World Wildlife Fund-Canada

Donna Hauser, lead author of the study, explained that they looked at each population’s distribution in September, the height of the Arctic’s open water season, and overlaid that with the main sea routes. Narwhals, more often than not, had the greatest overlap.

Ships can affect marine mammals in a number of ways. First, there are direct strikes — most commonly seen with large whales, which are less manoeuvrable and slow to get out of the way. Then there are behavioral disturbances, which might alter how or where an animal feeds or moves. And lastly, there are acoustic disturbances, which can throw off an animal’s communication, navigation or feeding. Toothed whales, like narwhals, rely on sound to identify objects and obstacles.

With routine vessel transits expected by 2050 through the Northern Sea Route and Northwest Passage, it’s critical to understand exactly how this will impact species and which ones are most vulnerable.

“Armed with that information, we can start planning some precautionary measures for protection,” Hauser, says. This has been done in the lower latitudes, re-routing vessels and adjusting speeds to minimize exposure and acoustic disturbance.

A few years ago, the Arctic Council tasked nations to identify areas of ecological importance and assess measures that would minimize the effects of a growing Arctic shipping industry. This led to the International Maritime Organization adopting and implementing a new Polar Code in early 2017. But so far, it’s been difficult to exercise on the ground as there’s been limited data on Arctic species that would inform how best to minimize negative environmental impacts. Hauser hopes this study is a step toward changing that.

Last year, the Canadian government established a National Marine Conservation Area around Tallurutiup Imanga, or Lancaster Sound, at the eastern entrance of the Northwest Passage. Around 75 per cent of the world’s narwhals spend their summer in the sound. This 131,000-square-kilometre protected area will help protect them by allowing the government to place restrictions on the number of ships that can pass through, and their speeds.

“But it’s quite tricky,” notes Marianne Marcoux, a research scientist with the federal Department of Fisheries and Oceans. “Ships make noise and quicker ships make louder noises, but slower ships stay longer in an area,” increasing exposure and the risk that a strike could occur.

As waters become increasingly ice-free, and the open water season lasts longer, Hauser’s vulnerability index could change. Though polar bears were determined to be least vulnerable in September, that’s not say to there won’t eventually be strong vessel impacts in other seasons. Already, the open water season has increased between five and ten weeks, and spring break-up is coming sooner. Icebreakers, too, are pushing inward during the winter. What marine mammals will have the best chance of survival in this new Arctic remains to be seen.

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