It’s not impossible, but there were no confirmed sightings in the Gulf of St. Lawrence this season. Perhaps it was the thin tip of the lobe of a surface feeding minke whale, rolling onto its side and showing a portion of its black back and white belly? They can be deceptive!
With regard to the killer whale (also known as the orca) and its range, it is the most widespread cetacean in the world, though it seems to be scarce in the Northwest Atlantic. Even historically, in times of commercial whaling, very few killer whales were harvested in these waters. It nevertheless appears on the list of thirteen species of the St. Lawrence, even if killer whale visits to the Estuary and Gulf of St. Lawrence are rare and sporadic, with about twenty observations since the early 1980s.
It seems that the number of killer whales visiting the St. Lawrence has declined in the past sixty years; Vladykov (1944) supposedly reported several killer whales, up to a group of about forty individuals, which were regularly found in these waters in the spring and fall, attacking belugas notably. It is obvious that this species is much less abundant today: the largest group reported in eastern Canada in the last twenty years is 22 killer whales.
One group of killer whales was observed regularly between 1984 and 1997. This group, comprising four members, notably included the killer whale nicknamed “Jacknife”, easily recognizable by its dorsal fin with a peculiar notch. Jacknife, Jessie, Javelin and Junior became almost legendary at the Mingan Island Cetacean Study (MICS) after being seen attacking minke whales on eight different occasions. Then, between 1997 and 1999, Jacknife was seen alone, without the other members of its group. Most of these observations were made in the area between the Mingan district and Anticosti Island.
In the Estuary, the last sighting was in 2003: two killer whales were seen off Les Bergeronnes, an encounter which was also filmed by the team from the Group for Research and Education on Marine Mammals (GREMM). This was the first observation in the Estuary since 1982.
Other sporadic observations were made in the Mingan region in 2007: a young playful male was spotted by the MICS team near a group of white-sided dolphins as a blanket of fog was setting in. It lingered for more than 30 minutes, approaching the boat while showing its ventral side and slapping the water surface with its tail or swimming under the craft. It has not been seen since then. In 2009, a group of about a dozen killer whales was reported off the coast of Havre Saint-Pierre in the Gulf of St. Lawrence.
As can be seen, sightings of this whale species are extremely rare in the Estuary, but the chances of observing killer whales increase as one moves downriver along the Basse-Côte-Nord (Lower North Shore) and the Strait of Belle Isle. The MICS team claims to have observed this great sea dolphin every time they performed field work in the Blanc-Sablon area. Fishermen report them there regularly. Lastly, on July 4, 2015, photos were taken confirming the presence of three adult killer whales and one young between La Tabatière and Gros Mécatina in the Basse-Côte-Nord region near Newfoundland. One of the killer whales, which showed a clear notch in its dorsal fin, appears to be the same as one photographed by a whale cruise employee in Twillingate on the north coast of Newfoundland 10 years ago. For Atlantic Canada, a database and photo-ID bank includes at least 70 identified killer whales. This figure is probably attributable to the lack of quality photos and the few individuals with easily identifiable features.