Narwhals are amongst the most mysterious marine mammals known. Although the species has been known for centuries and has been exploited by humans, only little is known about their ecology. Especially the tusk has spurred human fantasy. Now, Canadian fisheries researchers were able to show by video footage for the very first time that narwhal bulls use their tusks for fishing.
The video footage, filmed by Fisheries and Oceans Canada (DFO) researchers by using an unmanned aerial vehicle (UAV), shows a large pod of narwhal bulls hunting a school of polar cod. The film clearly shows the whales shaking their heads and tusks and then hit the fish with a hard tap to stun and suck it in. “ With this observation, the field crew was able to see the narwhal approaching a school of Arctic cod and tracking the cod with the tusk which is a premolar coming out of their mouth. As the cod is positioned close to the tip of the tusk, the narwhale gave it a quick, hard tap that likely stun the fish. It was momentarily not moving and the narwhale was moving in and sucked in the prey,” says Steve Ferguson, senior researcher at the University of Manitoba and at DFO. Until now, this hunting behavior was unknown with narwhals and the theory was that narwhale use their tusks to help with the finding of fish.
Bob Hodgson from DFO explains: “From my perspective as a marine biologist, the use of drones is unique because it gives us a bird’s eye view that is close enough to the animals so it doesn’t disturb them at all. But at the same time, it gives us a close enough image to give us this kind of details of how the animals are feeding and how they are behaving. So it is a really new perspective.” The drone whad taken off from a coastal field camp and in the film, which also was published on Youtube, the behavior is hardly apparent. Only when analyzing the content frame by frame, the researchers discovered the behavior. “As soon as they saw the playback on the small screen, they knew something interesting was happening and definitely needed to be checked out further, “says Brandon Laforest, senior specialist for WWF Canada, who was on the field. The footage was taken by Adam Ravetch, a nature film specialist who had been there on behalf of WWF Canada which had partnered with the DFO for the expedition.
Narwhals belong to the toothed whales and are closely related with belugas. The tusk is the only completely formed tooth, the rest remains in the jaw bone as primordial remains. The prey of narwhals mainly consists of fish like halibut and polar cod. But calmar and other invertebrates had been found. Until now, it was assumed that the tusks only act as a secondary tracking device to find the prey and that the animals have a similar way of using echolocation like dolphins. Because tusks usually is a characteristic of the bulls and only 15% of the females form a small tusk. The findings now open the questions of how distinctive this feeding behavior is within males, what females and calves do which have no tusks and whether bulls are suing this behavior to cover their larger energy demands or whether the behavior led to a higher food intake and thus to a larger weight. Marianne Marcouox, narwhal expert at the DFO, says: “What is very exciting to me is the question what else they can do with their tusk.”
Source: Fisheries and Oceans Canada