What do fin whales do during the day? And at night?

It is essential that we have a better understanding of how fin whales, occupy their time in order to ensure their harmonious co-existence with the whale watching industry. What is important for them?

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  • Mother and calf fin whales
  • Photo credit: © GREMM

To go through the looking glass

Scientists followed a total of 25 fin whales with the help of VHF transmitters. They studied the movements of these animals in three dimensions and followed them day and night.

In short

Tracking fin whales allowed us to define three types of activity: deep dives, intermediate dives and shallow dives. Deep dives appear to be linked to feeding; intermediate dives to exploration. Shallow dives could be tied to either surface feeding or resting. Fin whales generally feed during the day, especially at high tide, while at night they remain near the surface. Behaviour varies depending on their location.

Project collaborators:

Robert Michaud, Janie Giard, GREMM

Partners

The Saguenay-St. Lawrence Marine Park, Parks Canada, Department of Fisheries and Oceans Canada, ministère de l’Environnement et de la Faune du Québec and Croisière AML Cruises.


I want to know more

The days and nights of the fin whale

Translated from the document “Résumés des projets de recherche scientifique” produced by the Saguenay—St. Lawrence Marine Park and WWF Canada, 1998

A whale’s life is closely tied to its need to breathe. The frequency and duration of its appearances on the water’s surface are often the only information we have to allow us to study their behaviour. But how do these aquatic giants behave underwater?

Tracking whales by telemetry

Tracking whales by telemetry (tele:: from a distance, metry:: to measure) will allow us to partially answer this question. Using VHF transmitters GREMM researchers have succeeded in tracking fin whales in the St. Lawrence Estuary to a depth of 150 metres. When the fin whale is underwater, the transmitter, attached to the animal’s back with a suction cup, records depth every five seconds. When the fin whale resurfaces, the transmitter produces a summary of the animal’s last dive. Using a computer onboard our boat, we can see that Jimmy — the fin whale we have been “tailing” since this morning — has just swum 120 metres in a matter of seconds, from the bottom of the Laurentian Channel to the water’s surface. At last, we have gone “through the looking glass” and can now follow the whales into their universe.

Between 1994 and 1996, in collaboration with the Saguenay–St. Lawrence Marine Park and the Maurice Lamontagne Institute, we gathered data, for close to 400 hours, on the underwater behaviour of 25 fin whales. We studied some 2500 dives and displacements over a distance of more than 1000 kilometres between Les Escoumins and Tadoussac.

Busy days

This long period of deep diving was usually preceded by a shorter period of exploration during which the animals made a series of V-shaped dives. During these dives, they were most likely looking for fairly dense schools of prey. Fin whales rarely dove at night. We have still not been able to determine whether they use this time to rest or if they feed near the water’s surface where many organisms, such as copepod, krill and even capelin, feed at night.

In collaboration with François Saucier and Yvan Simard, researchers at the Maurice Lamontagne Institute, we are now trying to gain a better understanding of the complex relationships that exist between the extraordinary dynamic of water masses, the concentration of prey and the activities of fin whales. For instance, we have observed that the tide has a significant impact on the fin whale’s activities during the day, but not at night.

The life of a fin whale is, therefore, not only conditioned by its constant comings and goings between the ocean’s surface and depths, but also by the days and nights and the rhythm of the Estuary’s tides.


Scientific papers

Michaud, R. et J. Giard. 1997. Les rorquals communs et les activités d’observation en mer dans l’estuaire maritime du Saint-Laurent entre 1994 et 1996 : 1. Étude de l’utilisation du territoire et évaluation de l’exposition aux activités d’observation à l’aide de la télémétrie VHF. Rapport final. GREMM, Tadoussac, Québec. 45 pp + cartes.

Michaud, R. et J. Giard. 1999. Les rorquals communs et les activités d’observation en mer dans l’estuaire maritime du Saint-Laurent entre 1994 et 1996 : 2. Évaluation de l’impact des activités d’observation en mer sur le comportement des rorquals communs. Rapport final. GREMM, Tadoussac, Québec. 24 pp.