What are the most effective noise abatement strategies for marine mammals?

1 What is noise abatement?

Noise abatement is the process of reducing or eliminating unwanted noise from a source or a receiver. It can involve modifying the source of the noise, such as using quieter technologies, changing the operational practices, or applying noise-reducing devices. It can also involve altering the propagation of the noise, such as using barriers, curtains, or bubbles to deflect or absorb the sound waves. Finally, it can involve protecting the receiver of the noise, such as creating exclusion zones, implementing seasonal or spatial restrictions, or using acoustic deterrents or warning signals.

2 Why is noise abatement important for marine mammals?

Noise abatement is important for marine mammals because noise pollution can have serious and long-term effects on their health and well-being. Noise pollution can interfere with their acoustic signals, masking their ability to hear and communicate with each other. It can also induce stress, behavioral changes, hearing loss, and physical injuries, such as hemorrhages, embolisms, and strandings. Moreover, noise pollution can disrupt their habitat use, migration patterns, feeding habits, and reproductive success, potentially affecting their population dynamics and conservation status.

3 What are the benefits of noise abatement for marine mammals?

Noise abatement can have multiple benefits for marine mammals, both at the individual and the population level. By reducing the noise exposure, noise abatement can improve their acoustic performance, allowing them to detect and respond to important sounds, such as prey, predators, mates, and conspecifics. It can also enhance their physiological condition, preventing or minimizing the negative effects of noise-induced stress, hearing impairment, and tissue damage. Furthermore, noise abatement can support their ecological function, enabling them to maintain or restore their natural distribution, movement, and behavior.

4 What are the challenges of noise abatement for marine mammals?

Noise abatement for marine mammals is not without challenges, as there are many factors that can influence its effectiveness and feasibility. Some of these factors are related to the characteristics of the noise source, such as its frequency, intensity, duration, and variability. Others are related to the environmental conditions, such as the water depth, temperature, salinity, and topography. And others are related to the biological features of the marine mammals, such as their species, population, age, sex, and acoustic sensitivity. Therefore, noise abatement strategies need to be tailored to the specific context and objectives of each situation.

5 What are some examples of noise abatement for marine mammals?

There are many examples of noise abatement for marine mammals, depending on the type and purpose of the noise-generating activity. For instance, some of the noise abatement measures that have been implemented or proposed for shipping include using low-noise propellers, hull designs, and engines, reducing the speed and traffic density, and avoiding or minimizing the use of noisy activities, such as bow thrusters, anchors, and icebreakers. For seismic surveys, some of the noise abatement measures include using alternative sound sources, such as marine vibroseis or air guns with low-frequency or directional beams, applying ramp-up procedures, and conducting passive acoustic monitoring. For military sonar, some of the noise abatement measures include limiting the output power and duty cycle, modifying the frequency and waveform, and implementing mitigation zones and shutdown protocols. And for offshore construction, some of the noise abatement measures include using pile driving with noise-reducing casings, cushions, or hammers, employing alternative methods, such as drilling or vibropiling, and deploying acoustic barriers, such as bubble curtains or cofferdams.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?