What do belugas do underwater?
Despite the considerable efforts that have already been deployed to study St. Lawrence belugas, researchers are still in the dark as to what these animals do once they leave the surface. Yet, it is beneath the surface—far from the inquisitive eyes of researchers—where they spend most of their time! To better orient strategies for the conservation of this resident population, it is essential that we gain a clearer understanding of how belugas use the St. Lawrence Estuary… in 3-D!
To go through the looking glass
Researchers place data recorders on the backs of belugas and track them using radio telemetry. The recorders are equipped with a microchip that gathers a wide range of data including water temperature, speed of movement, dive depth and dive duration. These data give researchers a three-dimensional impression of the animal’s movements
Thirty four tracking bouts—ranging in length from 42 minutes to 30 hours—were successfully carried out over the course of the four field seasons of this project (2001 to 2004). Analysis of preliminary data has allowed researchers to identify diverse beluga dive types and to associate them with various types of behaviour. For example, U-shaped dives where the animal carries out a series of ascending and descending movements several metres in amplitude while at depth—and where the swimming speed is relatively rapid—are associated with seeking and capturing prey. Another type of U-shaped dive—where the swimming speed at maximum depth approaches zero—is associated with resting. It should be noted that the target animal was also observed resting for long periods at the surface between these types of dives. Further tracking is projected in order to describe the behaviour repertoire of St. Lawrence belugas and their use of the Estuary more completely and with greater precision.
Fondation de la faune du Québec, Maurice-Lamontagne Institute (Fisheries and Oceans Canada), Saguenay-St. Lawrence Marine Park, Park Foundation and Interdepartmental Recovery Fund.