Narwhal (Monodon monceros)

Whale Portraits: Vol. 17, Issue 15, written by Camille Bégin Marchand

The narwhal has been identified again this year on several occasions. It does not have a code, as it is the first of its kind to have been photo-identified in the Estuary. The narwhal is distinguished by its dark speckled colouration that contrasts with the almost uniform white colouring of the belugas with which it is found. Another difference compared to belugas is its “tusk”, which is in fact a clearly visible left incisor. Still relatively short, this tooth does not often emerge out of the water. The size of the tooth indicates that it is probably a juvenile. Research assistants employed by GREMM compared photos of both flanks of the individual observed this year with photos taken the previous two years. As the narwhal’s colouration evolves from year to year, it is generally the notches in its dorsal ridge that make it possible to identify it. In the case of this individual, the spots near the neck and around the ridge were still present and confirmed that this is indeed the same narwhal observed since 2016. For the time being, we have not yet determined whether or not the narwhal is being seen with the same belugas each year or at every sighting.

The narwhal and the beluga are the only two species that belong to the family Monodontidae, a suborder of toothed whales. The narwhal has just one tooth that grows in a spiral and can measure up to 300 cm in adult males. This diagnostic tooth is found in males and occasionally in females. At the Marine Mammal Interpretation Centre, visitors can observe and touch a narwhal tooth measuring 176 cm long and weighing nearly 7 kg. Narwhals and their beluga cousins share a few characteristic traits. These two species live in the Arctic and subarctic regions and have a circumpolar distribution, i.e. all around the North Pole. They are characterized by the lack of dorsal fin on their back; instead, they have a dorsal ridge, which may be an adaptation to life in cold water. In fact, the dorsal fin in cetaceans, which is devoid of blubber, is known to be used to evacuate heat. In Monodontidae species, the dorsal ridge is believed to be used notably to break the ice in order to reach the surface.

Highly social and gregarious animals, belugas and narwhals are most often seen in groups. To date, no beluga-narwhal hybrid has ever been confirmed. In the late 1980s, a skull discovered in western Greenland belonging to a toothed whale raised hypotheses in the community, but no definitive conclusion could be drawn.

 


Whale Portraits: Vol. 16, Issue 10, written by Audrey Tawel-Thibert

For this issue, we push the boundaries of the typical Whale Portraits content on the occasion of the confirmed presence of a special visitor: the stray narwhal spotted last summer is back in the Marine Park! It was by complete chance that the animal was photographed last August 20 off Pointe-Noire. Our research assistant had taken a few shots of a herd of about six belugas passing by, and he was examining his photos when his colleague on board also noticed an animal that stood out with its dark, speckled mantle. The doubts were quickly dispelled: it was indeed a narwhal!

Narwhal photo-ID projects are rare. In an Arctic study, researchers Marianne Marcoux (Fisheries and Oceans Canada) and Marie Auger-Méthé (Dalhousie University) relied on notches in the animals’ dorsal crests to differentiate them, as colour patterns in narwhals evolve over the years – unlike blue whales for example, whose speckled mosaics are permanent.

Narwhal, August 20, 2017. © GREMM

Getting back to our exceptional visitor, we had to scrutinize its pigmentation pattern to validate that it was the same individual as the one documented last year: the distinctive marks around the animal’s head and neck were used as a reference, as they have remained unchanged over the past year. “We do not have a catalogue of narwhals, despite the fact that they are abundant in Canada (150,000). Furthermore, narwhals do not exhibit much genetic diversity, so it is not possible to use genetics to determine where this narwhal comes from,” says Marcoux.

“It will take other series of photographs to ensure monitoring of the animal over the long-term”, adds GREMM Scientific Director Robert Michaud. It should be noted that, although it might be tempting to go take a peek at our special guest, the latter seems to have been adopted by a group of belugas. This means that no breach of regulations can be justified by the presence of the narwhal. The minimum distance of 400 m between boats and belugas – even if accompanied by the narwhal – remains in force. Thank you for helping to protect this endangered population!