June 27, 2023 | Circular No. 11539

Dear Member,

The spring portion of the 2023 Cabot Strait Seasonal Voluntary Slowdown ends today. As outlined in past communications, Cabot Strait is an important migratory pathway for endangered and slow-swimming North Atlantic right whales when they migrate north into Canadian waters in the spring, and south out of Canadian waters in the fall. The seasonal voluntary slowdowns are designed to reduce risk of ships striking the whales during these periods, and take place in addition to Transport Canada’s mandatory measures for North Atlantic right whales in the Gulf of St. Lawrence.

We are pleased to share that the results available to date* show high participation by the shipping industry in this important slowdown. These results are based on an updated calculation method that TC adopted after we pointed out flaws in the previous system. The good news is that most vessels are slowing down, which decreases risks to these endangered whales. Congratulations on these results, and thank you for your continued efforts to protect these whales and make this voluntary slowdown a success.

Cabot Strait spring voluntary slowdown participation rates Weeks 1-8 in 2022 and 2023

*Figure shows the percentage of vessels participating in the 10-knot slowdown, including a 1-knot buffer. Results shown are through June 13, 2023

Looking Forward: North Atlantic right whales do not call (they do not make noise) when they travel through the strait and they are for the most part not visible as they swim underwater, so despite several new technologies being deployed to look for them in this area in the last few years, information on exactly how and when they use the strait is scarce. Nonetheless, a recent study shows that North Atlantic right whales do use Cabot Strait to some extent throughout the entire year. Based on this, we anticipate being active in the continued review of the Cabot Strait Voluntary Slowdown this fall via the Federation’s Environment Committee and Transport Canada’s North Atlantic Right Whale Advisory Group, which we co-chair. Please contact the undersigned if you are interested in providing input on this subject.


Miako Ushio

Manager, Enviornmental and Regulatory Affairs