Do the whale-watching boats disturb whales?

In the St. Lawrence Estuary, nearly 50 whale-watching boats transport over 300 000 tourists onto the Estuary every year to encounter whales. Fin whales, blue whales, humpback whales and minke whales are the main target species of this industry. Do whale-watching boats disturb whales?

Rorqual bleu

  • Telemetry survey of a blue whale
  • Photo credit : © GREMM

To go through the looking glass

Between 1994 and 1996, researchers tracked a total of 25 fin whales with the help of VHF transmitters. They studied the movements of these animals in three dimensions and compared their behaviour patterns in relation to the number of boats present. In 2002 they began the same project on a species newly classified on the endangered species list: the blue whale. To date, six blue whales have been tracked using radio transmitters.

In short

The fact that fin whales alter their diving behaviour in the presence of a large number of boats could have a negative impact on their ability to feed. The results of this study reveal the necessity of reducing concentrations of boats on whale-watching sites. This recommendation was used to elaborate the Marine Activities Regulations, in force in the Saguenay–St. Lawrence Marine Park as of 2002. The analysis of blue whale radio-tracking bouts is underway. Further tracking will be carried out in coming field seasons.

Project collaborators

Robert Michaud, Janie Giard, GREMM and Véronique Lesage, Maurice-Lamontagne Institute (Fisheries and Oceans Canada)


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 Croisières AML Cruises.

I want to know more

Do the whale-watching boats disturb whales…

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

The question “Do the whale watching boats disturb the whales?” is not new. Nor is it unique to the situation that prevails in the St. Lawrence Estuary. We have been able to shed some light on this question by studying the activities of fin whales that were tracked using VHF transmitters.

Given that an animal’s reaction to a stimulus will vary depending on what it is doing, observations used to analyze the effect of the presence of boats must be made at a specific time of day and in an area where there is little variability in the animal’s activity. Data collected during the day at the head of the Laurentian Channel at high tide (between two hours before and three hours after high tide) fit these criteria. This data totals 36 hours during which the majority of the animals were engaged in deep-diving activities. The types of behaviour that were noted included: group size, distance covered at the surface between two dives and diving behaviour or, more specifically, dive time, duration of breathing sequences at the surface and duration of bottom excursions. Exposure was measured by the number of boats present around the whales in increments of 0, 1, 2 to 5, 6 to 9 and 10 or more boats.

Less time to feed?

The presence of boats could greatly reduce the feeding efficiency of fin whales. Of all the behaviour studied, diving is likely to consume the most energy. As it turns out, in the presence of a large number of boats, fin whales do, in fact, dive for shorter periods of time. Hence, they devote less time to bottom excursions where they are probably herding schools of prey before engulfing them. This change in behaviour could therefore reduce the time usually dedicated to capturing prey.

Too many boats?

Exposure of fin whales to whale watching activities in the St. Lawrence Estuary is particularly intense and sustained. In addition, several fin whales that stay in the Estuary do so for several weeks, if not months, at a time and return every summer. Consequently, even if the reduction of feeding efficiency as suggested by the aforementioned analysis is slight, the cumulative effects could have serious repercussions on the ability of these animals to store up the energy reserves that they need.

Data analysis did not allow us to identify a critical level above which fin whales started to alter their diving behaviour. By contrast, the intensity of measured reactions was shown to be proportional to the intensity of exposure to boats. This research, which was carried out in collaboration with the Saguenay÷St. Lawrence Marine Park and the Maurice Lamontagne Institute constitutes one of the first evaluations of disturbance to go beyond the simple observation of immediate reactions of the animal at the surface. The results of this study clearly indicate the importance of reducing and controlling the number of boats on the observation sites and confirms the urgency of adopting a new management plan for the whale watching industry in the St. Lawrence Estuary.

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.