Problems with the Unicorns of the Sea

Problems with the Unicorns of the Sea

By Adam Chappell

I read an article entitled “Heart monitors on wild narwhals reveal alarming responses to stress.”  I found it through the National Science Foundation’s page that was linked to on our course website.  You can find it here if you want to learn more: https://news.ucsc.edu/2017/12/narwhals.html This particular article was published on Dec. 7, 2017, and outlines some new findings about narwhals that have never been documented before.

The article describes how a team of scientists got permission in 2012 to work with native hunters to study narwhals.  These scientists would rescue narwhals caught in the hunters’ nets, and before releasing them, they would attach a heart-rate monitor to the narwhals that would stay attached for 1-3 days.  After that time, the device would float back to the surface of the water, where it would be collected, and the data could be studied. In previous years, these scientists were able to use these devices to get data and learn about “bottlenose dolphins, Weddell seals, and other species,” but this was the first time they were able to study deep-diving whales.  Melting sea ice in the arctic, where the narwhals stay, has allowed access to them that people haven’t had before.

One of the findings that the scientists were most alarmed by, was the narwhals inability to run from danger in a healthy way.  After being released from the nets, the narwhals dove deep and their heart rates dropped to 3-4 beats per minute. This, along with the strenuous exercise that it took to perform the deep dive, made the scientists worry that the animals were not getting enough oxygen in their brains, and they would be suffering from permanent damage.  During a typical dive, the creatures were found to be able to drop their heart rates to 10-20 beats per minute to conserve oxygen, (as opposed to the rate of 60 beats per minute at the surface). In this typical dive, the scientists determined that a narwal uses about 52 percent of its oxygen to complete the dive. In panic mode though, when it was fleeing after being caught from the net, they determined that the narwhal uses a whopping 97 percent of its oxygen store, “and often exceeded its aerobic dive limit (meaning depletion of oxygen stores in the muscles, lungs, and blood, followed by anaerobic metabolism).”  The article explained that the animal is unable to flee without causing permanent damage because it’s not usually how they deal with predators. “Their natural escape response to avoid killer whales and other threats typically involves moving slowly either to great depths or into shallow coastal areas beneath ice cover where killer whales can’t follow.” To make matters worse, the biggest threat to these narwhals and other similar animals isn’t just being caught in an occasional net or running away from a rare encounter with a boat. As mentioned in the first paragraph, melting sea ice means humans are able to get closer to these animals than ever before, and we are bringing our technology with us.  One of the scientists cautioned that, “unlike threats from predators like killer whales, noise from sonar or a seismic explosion is difficult to escape. Problems can start if the whales try to outrun it.” This suggests that narwhals, and probably other deep-diving animals, are causing themselves permanent damage trying to run away from us when we’re not even thinking about our proximity to them, or what kinds of sounds we’re putting in the ocean.

Narwhals are awesome and it’s great to think that we are able to be closer to them than humans ever have before.  Even the idea of attaching a fitbit-like device to them to track their activity is so beautifully simple that it makes me excited to think of where our studies will be able to go in the future.  But the fact that such bad news came from the first look at narwhals heart rates and physical activity is concerning. Since they are so secluded, I think it would be easy to make policies to protect them once people are educated about this problem.  Time will tell though.