Moving slowly in all the right places – killer whales and reduction of noise effects

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Moving slowly in all the right places – killer whales and reduction of noise effects

This summer a voluntary commercial vessel slowdown trial is planned to take place in the core summer habitat of Southern Resident killer whales. SMRU Consulting North America have played a significant role in the development and implementation of this exciting noise mitigation focused trial which is being led by Vancouver Fraser Port Authority’s ECHO Program. We have been chosen to monitor vessel source levels, underwater ambient noise levels and Southern Resident killer whale presence.

Infographic on the effects of noise on killer whales, courtesy of the ECHO Program. Click on the image for more information on the Vancouver Fraser Port Authority’s ECHO Program.

SMRU Consulting North America have been working to help answer killer whale-noise impact questions for the ECHO Program for 2 years. We have been crunching the numbers, using data on ambient noise, commercial vessel and whale watch boat sound source levels, and ship pilot data, to statistically model potential noise impact scenarios in Southern Resident killer whale habitat. In his role as ECHO’s Technical Advisor, Dom Tollit has been helping ECHO synthesize the information for industry, government, NGOs, First Nations and other stakeholders leading to broad support to reduce noise impacts on Southern Resident killer whales.

While changes to ship and propeller design hold enormous future promise in quieting the increasingly loud oceans, a long list of alternative and near future actions are being discussed. These include vessel slowdowns, route changes, convoys, as well as improved vessel maintenance, propeller modifications and changes in vessel operations.

The voluntary commercial vessel slowdown trial will take place in Haro Strait, a well-documented Southern Resident killer whale hot-spot off the west coast of San Juan Island. All vessels transiting Haro Strait will be asked to reduce their speed to 11 knots from averages of 18+ knots for container ships and 13+ knots for bulk carriers. This level of speed reductions may, in theory, reduce sound intensity levels by as much as 75% for container ships and 40% for bulk carriers.

During the trial period, SMRU Consulting will use hydrophones to monitor both vessel sound source levels at slower speeds, as well as total underwater noise levels and killer whale presence. We will also be working with JASCO Applied Sciences and running our bespoke computer model that quantifies relative impacts from changes in noise
exposure due to a slowdown on Southern Resident killer whales.

The planned location for the slow down trial in Haro Strait. Map courtesy of the ECHO Program.

This is a temporal and spatially explicit population model, developed by Ruth Joy and Jason Wood of SMRU Consulting that relates short-term changes in received level to behavioural impacts and masking of echolocation clicks. By running the model with data from the slow-down trial we will be able to simulate the benefits of slower ships to killer whales.

The trial will help us to better understand the relationship between reduced vessel speed and underwater noise, as well as potential benefits of this type of action to mitigate ship noise. The ECHO program team, in conjunction with industry experts, will be able to evaluate the potential benefits and implications of slowing vessels down to the shipping industry.

A vessel slowdown in Haro Strait has been frequently proposed as a candidate for noise mitigation action. This study is a major step forward in our understanding of the benefits and practicalities of such an action. It will provide robust field data to support scientific models and future decisions. We hope as many ships as possible will support the trial.

 

 

 

About the Author:

Frances is a Research Scientist at SMRU Consulting North America. Check out her bio under the "About Us" tab.

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