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Narwhal Stories Tell a Difficult Story


Another disturbing sign that the researchers found in the ax was also the disclosure of whales. They looked at the stable isotope of carbon and nitrogen, the food residues of narwhals left in their legs. The air reveals much of the animal’s location – for example, whether it is in the ocean or near land. Nitrogen tells you how much trophic, or where you were eating. “Together, they give you ideas on the natural food of these species,” says Desforges.

Like mercury, Desforges is able to detect the effects of these changes over time. Prior to 1990, the whales ate “compassionate” animals associated with the frigid climate – Arctic cod and halibut. Then their diet began to move to more “pelagic,” or open sea animals, such as capelin, a member of the smelt family. “We’re not looking at the stomach of an animal or anything,” Desforges said. “But we argue that the ecological cycle is very similar to what we know of the Arctic sea ice, which since 1990 has begun to decline dramatically.”

As the ice level decreases, the narwhals change their diet. At the same time, mercury (Hg) levels have been rising.

Courtesy of Jean-Pierre Desforges

Several things can happen. As sea ice returns to the Arctic, the landscape may change, resulting in a decline between Arctic cod and halibut. In that case, narwhals would go hunting for freshwater fish. On the other hand, the amount of cod and halibut may not be less, but just moving north. Or perhaps because of the hot Arctic waters, many capelins live nearby, and narwhals are less likely to eat large amounts of food.

But if fish and fish, why is it important for narwhals to eat, as long as they get enough food? It seems that not all fish are alike. Desforges said: “Arctic species are healthier and more energy efficient. To survive the cold, fish need to carry fat, which means more calories they eat, such as narwhals. Desforges adds:” If they move fewer animals to the Arctic, it could have an impact on their intervention, “he adds.” Even so, it’s a big question we need to start asking ourselves. “

Modification of these foods — which may not be a problem for the narwhal — could be counterproductive to the amount of mercury, which but the problem of any animal. These two threats can be far more complex than those alone. “This is the hard part,” Desforges says. “We have information that shows that things are changing, but we don’t know how it affects whales here.”


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