Continue monitoring vessel speeds

Context and project description

In 2000, the maritime industry adopted a voluntary measure for reducing vessel speeds in four zones situated between Sorel and Montréal in order to reduce erosion on river banks caused by buffeting waves created by ships. Bank erosion is a complex phenomenon caused by many natural factors, including ice, gusts of wind, currents and water levels. But it is also partly attributable to human causes, notably waves created by the wakes of ships, which is called “wave action.” On page 57 of the first Sustainable Navigation Strategy for the St. Lawrence, we see that erosion chipped away more than 700,000 m3 of material from the banks of the Sorel-Montréal section from 1964 to 1983, meaning the banks are retreating at an average of 1.6 metres per year. Such erosion leads to many environmental consequences: destruction of habitat and an increase in water turbidity, to mention only a couple.

The directive for the voluntary slowing of vessels has been largely followed since its adoption. Moreover, since 2012, the compliance rate is approximately 98%. However, it remains necessary to maintain surveillance to ensure success and to document effectiveness. The SLAP project is to continue monitoring, starting with the previous phases.


An Automatic Identification System (AIS) has been installed on all ships that operate on the St. Lawrence River to track their speed in real time. A monthly report on vessel speed data is submitted to the Navigation Coordination Committee of SLAP, many of whose members are involved in the shipping industry. On a monthly basis, Transport Canada provides a report on the rate of compliance, and shipowner and pilot associations relay the information to their members.

This voluntary measure, which has been in place since 2000, is a great success. The mean rate of compliance has increased steadily over time and reached 98% in 2014 and 2015. This project will continue during the next phase of SLAP (2016–2021) with the aim of reducing shoreline erosion in areas where the measure is in effect.

Participating departments

Government of Canada

  • Transport Canada
  • Fisheries and Oceans Canada

 Government of Quebec

  • Ministère des Transports, de la Mobilité durable et de l'Électrification des transports