New measures are expected to come into effect in 2012 and their success relies on the cooperation of boat captains and on understanding the complex dynamic between the various elements at play, such as the number of boats and whales, where each of them travel, the currents, the tides, the weather, human factors, and the economic imperatives of cargo ships.
The whales swim in high concentrations off the shores between Les Escoumins and Tadoussac, Qu., where they go to feed from a large marine cavity. Les Escoumins is where cargo ships arriving from the Atlantic Ocean approach the shoreline to let the seaway pilots come aboard and take control of the ship. Ships then transit the park, directly through the whale's main foraging grounds.
"There is little data on the number of collisions because pilots aren't always aware of colliding with a whale and because the carcasses sink," says Clment Chion, a PhD student who developed part of the model as part of his thesis. "But many quasi-collisions are reported and these accidents are a threat to the recovery of certain species. To reduce the risk, we can play on two factors: the speed of the cargo ships and their trajectory."
The speed limit in the marine park is 25 knots (46 km/h). At this speed, 100 percent of collisions are fatal. "Speed must be limited to 10 knots to reduce the mortality rate to below 35 percent," says Chion.
Another option is to impose a three-kilometer southbound detour to cargo ships so they avoid going along the north coast and through the park. However, this scenario would reduce the risk of collisions in the marine park while increasing the risk for belugas that swim in the center of the river and close to the south coast. The population of beluga whales is very fragile, as the pod
|Contact: William Raillant-Clark|
University of Montreal