Killer whales and other marine mammals likely hear sonar signals more than we’ve known.
That’s because commercially available sonar systems, which are designed to create signals beyond the range of hearing of such animals, also emit signals known to be within their hearing range, scientists have discovered.
The sound is likely very soft and audible only when the animals are within a few hundred meters of the source, say the authors of a new study. The signals would not cause any actual tissue damage, but it’s possible that they affect the behavior of some marine mammals, which rely heavily on sound to communicate, navigate, and find food.
The findings come from a team of researchers at the Department of Energy’s Pacific Northwest National Laboratory, working together with marine mammal expert Brandon Southall of Southall Environmental Associates. The findings were published April 15 in the journal PLOS ONE.
A team led by Zhiqun (Daniel) Deng, a chief scientist at PNNL, evaluated the signals from three commercially available sonar systems designed to transmit signals at 200 kilohertz. The impact of such systems on marine mammals is not typically analyzed because signals at 200 kilohertz can’t be heard by the animals.
The team found that while most of the energy is transmitted near the intended frequency of 200 kilohertz, some of the sound leaks out to lower frequencies within the hearing range of killer whales and other animals such as harbor porpoises, dolphins and beluga whales. The three systems studied produced signals as low as 90, 105 and 130 kilohertz.
At the levels measured, the sounds would be quieter than many other sounds in the ocean, including the sounds the animals themselves make, and they wouldn’t be heard at all by the animals beyond a few hundred meters.
“These signals are quiet, but they are audible to the animals, and they would be relatively novel since marine mammals don’t encounter many sounds in this range,” said Southall, who is the former director of the Ocean Acoustics Program of the National Oceanic and Atmospheric Administration.
“These sounds have the potential to affect animal behavior, even though the main frequency is above what they primarily hear. It may be that environmental assessments should include the effects of these systems. This may not be a major issue, but it deserves further exploration,” added Southall.
The new findings have their roots in a project to track marine mammals in Puget Sound, which was part of a broader effort to provide information on the environmental impact of a planned tidal energy project there near Seattle. Researchers had planned to use sonar to help locate killer whales, but some marine mammal experts had observed that the animals might actually be hearing the sonar. Those observations led to the study, which was funded by Depart of Energy’s Office of Energy Efficiency and Renewable Energy.
How do the sonar signals actually sound to marine mammals like killer whales? Since high-frequency sonar pings several times per second, it’s possible that it sounds like one continuous, high-pitched hum or ping.
“If you think of a keyboard on a piano, the ships would be hitting the low notes quite hard, the middle keys would be most of the sounds of the animals themselves, and the sonar systems we studied would be relatively quieter sounds in the top few octaves on the right of the keyboard,” said Southall.
The authors of the paper did not directly study the hearing capability of whales and other marine mammals. Instead, the study focused on the sounds produced by sonar systems, discovering that commercial sonar systems are emitting signals within the animals’ known hearing range. Deng and colleagues are currently considering ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals.
I absolutely love whales’ and all other marine life, and believe that further investigation is needed to ensure the safekeeping of these magnificent creatures. Studies should be made to determine the hearing capability of all sea animals so that they would not be desturbed in their habitat.
In an article titled “Sonar does affect whales, military report confirms” by Daniel Cressy it is stated that “Beaked whale species… appear to cease vocalizing and foraging for food in the area around active sonar transmissions”. According to the article “second and third-order affects could include starvation and then death, depending on the severity of the sonar’s initial affect on the whales”.
This might be called “noise pollution” and will make for further interesting research regarding ways to minimize risk of noise pollution or as the article stated “ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals .”
I think scientists should study about the hearing capability of whales and other marine animals, this will help to find the solutions on how to stop disturbing such animals especially those which rely heavily on sound to communicate, navigate, and find food.
It seems as people are now the disturbance of marine life. Whales and other marine animals are very important so we protect them.I believe this posts will encourage many scientist to study more about hearing range of many animals.
Sonar systems on broader spectrum, relates to super ultra sounds. It opens up a whole world to discover. On the field of marine biology, we can determine a lot of things, we can also determine distances, and classify a lot of marines animals…as we know marines animals have a very sensitive hearing, and can hear at very low frequencies. Sometimes sounds that we create can be disturbing to sea animals, and can be dangerous to there hearing tissue… Communication can also be difficult, if there is sounds at the same frequencies in the water… So we must be very carefull for ultra sounds that we create on the sea water… If we look at some land mamals, the elephant also communicates at very low frequencies, somlow that the human ear cant hear it… We use sonar for a lot of things, in the medical world we use sonar to classify, fetus growth, fractures and variable other things…Sonar is probably, the most common thing, that is very important to us……
The fact that marine mammals can hear these sonar signals is quite concerning. If it is in fact true, then this means that these mammals are being disturbed by the sounds emitted by sonar systems. This can pose to be a huge problem as we are disturbing these mammals in their natural habitat. Hunting and communication play a big role in these mammals’ lives, especially the killer whales who predominantly use sound and vibrations to survive. When these ways of communication are disrupted, the whales become confused and terrible things such as separation and even death may occur. The research into reducing the amount of signal leakage is extremely important because our marine life is suffering in the mean time. Hopefully they can find ways to reduce the signal leakage, thereby preventing the worsening of our seas and the mammals within it.
These marine aminals rely on their hearing to direct their whereabouts. If these ships or human-caused sounds give off these high frequencies, this can have a negative effect on our aquatic mamals. We can not ignore these mamals just for human expansions. We need to consider there exsistence. If we dont protect them then who will ?
I must agree with a previous comment whereby it was stated that human intervention into mother nature is rather excessive and concerning. In this article it is not very informative as to how the whales are affected by all these sonar signals. The disturbance of marine life with man made machinery is vast and the effects towards marine life have not been entirely taken into account. I feel methods must be taken to ensure the safety and health of marine life. For example forming marine area reserves and enforcing restrictions on the frequency and wavelengths on these sonar waves which affect the natural world.
The human intervention into the lives of nature and the wilderness is a concerning issue. Having technology that can possibly alter to behaviour of marine animals in the wild should be alerting and surelynsomeone should research this and find an alternative route. They were here long before us and we’re just guests on this planet. If these signals interfere with animals that rely heavily on ecolocation to navigate, communicate and hunt food… what are we doing to their natural primitive behaviour?
Sonar sounds do not just affect marine animals like whales it also irritates the hearing of polar bears in the northern pole. Sometimes these bears even kill people in the surrounding area out of their frustration.
This should be concerned. I also believe that marine life has disturbing by our new technology.
Technology should be the reason to the disturbance of marine or wildlife as whole humans should stop putting themselves first and look at the world around as and make it better both technologically and ecologically
its arguable , only when under water, that is were they are fluent.
This matter is very concerning. As a Scuba diver, I believe that our new technology should be developed in such a way so as to not disturb our marine life. I believe that scientists should make a genuine effort to develop technology that won’t have an effect on marine life as it will also influence the outcome of research by influencing the animal’s behaviour. Thus I agree with my peers in saying that we should do everything in our power to either lower the amount of sound waves that escape into the ocean or lower it to a lower frequency so it can’t be heard.
We can’t destroy these animals’ hearing, by using, like Demi Schoeman mentioned, human-caused sound waves. Scientists have to
consider ways to limit signal leakage to reduce the amount of sound from high-frequency sonar systems that would be audible to marine mammals.
Man’s affect on nature and its far reaching impacts can be seen in so many areas. This shows that this new information on how sonar may effect marine mammals must be taken seriously, as it could have impacts far beyond anything foreseeable. This phenomenon must be investigated, but in a safe and isolate manner so that it would not harm any wild marine mammals or their surrounding environment. It is also a great and new way to study the behaviourism of animals and how dependent these creatures are on their ability to communicate via sound.
I agree with Serlien.Whales are then very important animals to protect.Such matters must be researched to find if they might lead to extinction of marine animals.
wow
As mentioned in the article, whales and other marine mammals rely on their hearing for life’s most basic functions including communication, navigation and finding food. So when an extremely powerful human-caused sound such as ships emitting sonar fills their ears, the results may be devastating. Perhaps, this is because the human-caused sound waves drown out the noises that marine mammals rely on for their survival? Thus, research and extensive mitigation methods should be carried out to ensure the protection and existence of our marine mammals.
yes
I must agree with Manakana Kamogelo (u14027110). They should think about studying the hearing range of marine mammals and determine which frequencies would fall within their range and then tackle the issue of limiting signal leakage to fall outside their hearing range. It would probably be quite difficult to study the effect of the sonar on their behavior with these species because are they not naturally curious and would want to investigate this strange new sound? It would be quite an interesting study to execute.