What Conclusions Can be Drawn from the North Atlantic Right Whale Observations and Mortalities during the 2015 season?

A response from Véronique Lesage, Fisheries and Oceans Canada

First, a little bit of background… North Atlantic right whales were decimated by hunting and numbered just over 300 individuals a few decades ago. Following years of good recruitment, the population is now estimated at about 500 individuals.

Right whales migrate annually to the warmer waters of Florida and Georgia to breed, and come to our latitudes in the summer for intensive feeding. But about one third of the population surveyed in the breeding grounds cannot be located in the species’ known feeding areas (Bay of Fundy, Gulf of Maine, off the coasts of Nova Scotia and Cape Cod). It is suspected that the Gulf of St. Lawrence is a feeding area for the missing portion of this population, though observations are rare, usually in the order of a few individuals per year.

Since June 2015, the number of right whale sightings seems to be unusually high in the Gulf of St. Lawrence. But to properly interpret these results, we must first ensure that any potential bias that might arise through non-conventional or non-recurrent observation effort is eliminated. For example, on August 7 and 8, a team from NOAA, while conducting an aerial survey in the Gulf, was able to observe approximately 25 right whales some 35 nautical miles offshore from Miscou, New Brunswick. Unless these beasts are reported by more recurrent sources (fishermen, whale-watching industry, DFO patrols), these observations will be considered to be among the unusual efforts, as they are being conducted only this year and far from the coast. It is possible that right whales occupy this area annually, but that they go unnoticed simply because no one has ventured that far offshore. Nevertheless, even when unusual observation efforts are disregarded, the fact remains that the number of right whales observed this year in the Gulf (13 cases) is higher than the usual. Another cause for concern is the fact that 3 right whales have already been found dead this year in the Gulf of St. Lawrence, which exceeds the annual average of 2.6 individuals. This is not counting the carcasses which are found on the east coast of the United States.

Although we cannot rule out the possibility that this increase in observations in the Gulf is related to a growing population, there are indications that suggest that there are other factors at play. In recent years, significant fluctuations have been noted in the number of right whales observed in their traditional feeding grounds. This year for example, few right whales were observed in the Roseway Basin (approximately 30 nautical miles off the coast of Nova Scotia). Data collected by Fisheries and Oceans Canada and analyzed by one of its researchers, Stéphane Plourde, suggest a decline in recent years in the availability of right whales’ prey – copepods – on the Scotian Shelf and all other areas that this population normally frequents.

The fact that the animals are seeking food outside of their usual feeding areas is not necessarily good news.
Might the three deaths reported this year in the Gulf of St. Lawrence be a result of poor physical condition? According to preliminary data collected by NOAA and transmitted to researcher Moira Brown (New England Aquarium), the animals observed in the Gulf did not appear to be in a poor state. The question remains: what about the 95% of the population that has not been seen in the Gulf? And are we facing a trend that could grow worse with continuing changes and global warming?

Through various projects, researchers from Fisheries and Oceans Canada are working to shed light on the importance of the Gulf of St. Lawrence for the population of North Atlantic right whales. This work aims to identify areas frequented by right whales, characterize areas where their food sources are concentrated and identify their energy needs in order to better understand the current draw of the Gulf for this endangered species as well as probable trends in light of climate change.