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How ships can avoid being 'noisy neighbours' to whales and other marine mammals

Updated: Jul 1, 2023

Orcas are among the most spectacular mammals that make up the incredible diversity of marine life found in the coastal waters of British Columbia. Seeing an orca—or if you’re lucky, a pod of them—is awe-inspiring. Orca sightings are one of the gifts of living on the BC coast, and they remind us of the importance of protecting these magnificent animals and the rich marine environment they require to thrive.


Listen as an approaching diesel vessel as it passes by and drowns out the calls of an orca pod.

Recording courtesy of OrcaLab.


Although there have been many initiatives to protect the natural environment of marine mammals, in recent years, scientists have continued to discover more about orcas and the various factors affecting their behaviour. Alarmingly, these findings have revealed that one potential source of harm to marine mammals is often overlooked: underwater noise.


Whales, including orcas, have been shown to leave the area when underwater noise is present, which interrupts their foraging and socializing. By hightailing it out of a noisy area, they tend to spend less time at the surface. Orcas were even shown to experience a temporary loss of hearing of around 5 decibels after exposure to noise from fast boats 450m away. And crucially, underwater noise can also interfere with whale vocalizations, which they use to find food, “talk” to each other, and navigate their territories.


Many ships, including ferries, emit underwater noise both from their engines (whose airborne noise and vibrations can be induced into the hull), and propellers (during periods of cavitation, when an implosion of bubbles on the surface of the propeller blades can cause a “popping” or “cracking” sound). Noise from ships can radiate underwater for dozens of kilometers. The issue is particularly important in the Salish Sea, where busy marine operations share the waters with an active sea life.

Measuring Vessel Noise


How intense vessel noise is, both above and below the water, depends on several factors: the type of ship (size, design, load), where it is sailing, operational factors such as speed, conditions at the time of operation, and regularity of its navigation pattern. The noise field (typically measured in decibels by a hydrophone) varies by where the noise is carried—for example in coastal or offshore waters—and is not the same in all directions. While measuring vessel noise is not an exact science, steps are being taken on local, national and international levels to develop strategies for reducing marine noise: preventative technologies, policies, regulations and more. Reducing Noise Disruptions


The current prevailing strategies to mitigate the disruption of noise to marine mammals are reducing vessel speed and avoiding areas where whales are known to congregate.

Ensuring west coast whales have a noise-disruption-free environment is a multifaceted effort. The Protecting Whales and Dolphins Initiative, launched by WWF in 2020, is helping government, policymakers, and industry with methods to reduce acoustic threats to marine life. WWF is also working with Transport Canada and Quiet Oceans on this project. Additionally, the Canadian government is in the process of developing an Ocean Noise Strategy for Canada, part of the Oceans Protection Plan, which is expected to launch this year. WWF provided a variety of input on this initiative, such as setting thresholds based on biological limits and informed by Indigenous and local knowledge, incentivizing quieter propulsion technologies, and developing vessel-based and area-based noise targets.


Last August, the Canadian Ministry of Transport announced over $3.1 million allocated to 22 projects via Transport Canada’s Quiet Vessel Initiative to help reduce shipping impact, including workshops for best practices, developing a tool for the marine industry to implement quiet designs in newbuild vessels, and developing a real-time tool to track underwater noise and detection of marine mammals that would also alert nearby vessels.


One success story is the Vancouver Fraser Port Authority’s Enhancing Cetacean Habitat and Observation (ECHO) Program, launched in 2014 to study the acoustic disturbance on marine mammals. In 2021, over 80 shipping organizations voluntarily participated, resulting in approximately 50% noise reduction for at-risk whales. Last year, the ECHO Program’s initiative to reduce vessel noise covered approximately 80 nautical miles of the Salish Sea from June to November when the southern resident killer whale is known to be most present. The program also extended its inbound shipping lane slowdown to the main entry point to the Port of Vancouver, in addition to the slowdown measures outside of shipping lanes mandated by Transport Canada.

Further afield, the International Maritime Organization has also been working on voluntary guidelines for underwater radiated noise. The current draft guidelines provide ways to help shipowners develop their own underwater noise mitigation plans, as well as advice for ship designers and builders to reduce noise. Can All-Electric Vessels Reduce Noise?


All-electric ships are widely recognized for their abilities to avoid greenhouse gas emissions, but they may also offer significant benefits when it comes to reducing the noise threat to marine life. Although they still have the inevitable propeller noise, these vessels have quieter motors in place of diesel engines. Furthermore, ships with electric propulsion typically require a high degree of optimization, and this helps to ensure the ship’s propellers are operating at an optimal load, thereby reducing cavitation.


All-electric propulsion may not be readily achievable for larger vessels, but it is ideal for smaller vessels, especially those that travel on short, regular trips. As these technologies are relatively new, further research in this area is needed to better understand the specific noise opportunities and challenges associated with all-electric ferries. Where possible, all-electric vessels could go a long way toward reducing noise in areas that marine mammals frequent, providing the creatures both above and below the water with a quiet, comfortable environment.

Reducing underwater noise for whales, and all marine life, is a complex challenge that requires a multi-pronged approach from all stakeholders, including the public. Just like choosing to ride your bike instead of taking your car to work, you can choose to take an all-electric passenger-only ferry that provides an end-to-end travel journey that’s safe, reliable, and quiet, and supports the precious eco-systems and marine mammals of our waterways.

 

Do you support all-electric passenger-only ferry service into BC? Check out the findings from Greenline's Ferry Service Survey. The results are posted here, and regardless, let's stay in touch. Subscribe to our mailing list to keep up to date.





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