The Vancouver Fraser Port Authority is asking vessels coming through Haro Straight to slow down, in order to study how underwater noise affects orcas' ability to echolocate.

All piloted commercial vessels transiting between Discovery Island and Henry Island between August 7 and October 6 will be asked to reduce their speed to 11 knots.

The average speed for a vessel transiting through the area typically ranges from 18 knots for a cruise or container vessel and 13 knots for a tanker or bulk carrier.

Port authorities estimate the slowdown could cause delays of between 30 minutes to an hour to the total transit time between Boundary Pass and Brotchie Point.

Ship noise masks orca clicks

Carrie Brown, the director of environmental programs at the Vancouver Fraser Port Authority, said that previous research has indicated that underwater noise caused by fast moving ships can mask whales' echolocation clicks.

This interferes with their ability to hunt, navigate and communicate with each other.

"Southern resident killer whales are an endangered species on the South Coast. There's only 78 individuals, and underwater noise is one of the key threats to these whales," she said.

"As far as we know, this is the first [study] of its kind to focus on underwater noise for killer whales."

All piloted commercial vessels transiting Haro Strait are being asked to reduce their speed between Discovery Island at the southern end, and Henry Island at the northern end. (Port of Vancouver)

Promising participation rates

The program is voluntary — meaning that ships aren't legally forced to comply.

But Brown said that so far, all members of the Chamber of Shipping and the Ship Federation of Canada have agreed to participate.

"What's really unique and notable is the voluntary participation from the marine industry, it's a very significant undertaking for industry," she said.

Brown added that many ferries, recreational and whale watching vessels have also agreed to slow down.

The findings from the study will be released to the public in early 2018.

With files from Liam Britten