Out-of-Habitat Cetaceans

Every species of marine mammal has a range, or a geographic area in which the species can typically be found. An animal’s range corresponds to the area offering the environmental conditions the species requires to live and develop. When an individual animal is found outside this distribution, but still in a saltwater environment, it is considered out of range (article in French). In Quebec, a marine mammal is considered “out of habitat” when it is found in a freshwater environment, such as a river, including the St. Lawrence upstream of the eastern tip of Île d’Orléans.

Scientists struggle to explain why cetaceans end up outside their usual habitats, because these are mostly isolated and anecdotal events. However, Ocean Care’s report on out-of-habitat marine mammals suggests that these cases are increasing in number or at least in frequency.

Additionally, animals outside their usual habitat could be affected by climate change, declines in prey availability, habitat degradation, and even hunting.

These changes related to freshwater exposure could also predispose the animal to infections or ulcers, in addition to disrupting the levels of electrolytes, proteins or nutrients in its blood! This physical deterioration was noted in a young (between 7 and 14 years old) beluga that visited the Port of Montréal in 2012. However, these changes can be reversed if the animal returns to salt water.

Malnutrition and dehydration

A prolonged period in a freshwater environment also puts cetaceans at risk of malnutrition, as it is difficult for them to find their usual prey there, let alone in sufficient quantities. In fact, individuals that die in fresh water are often found with empty stomachs! In the absence of food, a cetacean that finds itself in fresh water can succumb to hunger or dehydration. Indeed, cetaceans mainly hydrate through their diet. Their prey provides them with the fresh water they need to survive.

While it manages these incidents, QMMERN raises public awareness to minimize disturbance of the marine mammal and issues navigational warnings to avoid disturbance or even a collision. By observing and monitoring the animal, the teams collect as much information as they can. In some cases, the animal leaves on its own; other times, it is found dead. In 2017, a beluga spotted in a New Brunswick river was even captured and airlifted to the St. Lawrence Estuary!

Whenever they receive a case of an out-of-range or out-of-habitat marine mammal, the QMMERN and its partners assess the animal’s situation and prepare response plans that take into account the status of the species, the animal’s state of health, its chances of survival, and human responsibility (anthropogenic causes involved).

The improvement of certain habitats and the return of marine species is certainly good news. However, humans residing close to the coast are not always accustomed to cohabiting with marine mammals. Raising awareness of the risks that our activities can have on these animals is a step in the right direction.