Traffic in beluga calving grounds (2015)
Added to the merchant ships crisscrossing the St. Lawrence beluga’s summer range are recreational and marine mammal-watching boats. This traffic has a number of observable impacts: risks of collision, noise pollution and disturbance of vital activities. Disturbance of females giving birth or caring for a newborn in the calving grounds is one of the hypotheses put forward to explain the rise in the number of newborn carcasses found in 2010 and 2012 as well the recent increased mortality of females following birth complications.
In order to document interactions between maritime activities and St. Lawrence belugas, diverse databases acquired from multiple sources (St. Lawrence pilots, Canadian Coast Guard, federal and provincial governments, research groups, recreational boaters, marina managers, etc.) were compiled for the 2003-2012 period. Data from the Observation Activities at Sea (AOM) project and from beluga visual surveys conducted by the GREMM and Fisheries and Oceans Canada (DFO) were also used.
What have we learned?
Although this information was not specifically intended to assess potential disturbance to females and newborns, an increase in tourism-related activities (excursions, recreational boating and kayaking) has been noted in the past decade in sectors highly frequented by adults and young, i.e. the Upper Estuary and the Saguenay. This increased traffic is all the more worrying in that it takes place mainly in July and August, in the heart of the calving grounds and season.
This disturbance may therefore lead to prolonged labour during calving, as observed in dairy cows, weakening the mother and the newborn and increasing the risk of complications. Disturbance may also cause separation of mothers from their young if they are already in a weak state.
Compiled data have also demonstrated peaks of pleasure boat traffic in the Tadoussac marina and peaks of interactions between belugas and watercraft in the Saguenay in 2010 and 2012, years in which the number of newborn mortalities was particularly high.
These results therefore suggest that human disturbance may have played a role in the rise in mortalities reported for these years.
Ménard, N. R. Michaud, C. Chion and S. Turgeon. 2013. Documentation of Maritime Traffic and Navigational Interactions with St. Lawrence Estuary Beluga (Delphinaterus leucas) in Calving Areas Between 2003 and 2012. DFO Can. Sci. Advis. Sec. Res. Doc. 2014/003. v + 25 p.