Helena Joyce
Sonar, an acronym for sound navigation and ranging, is a system that uses sound waves to detect objects such as submarines, ships, and marine animals. While sonar is an effective tool for exploration and mapping the ocean, it has also been linked to harmful effects on marine life, particularly marine mammals such as whales. The intense noise generated by sonar systems can travel hundreds of miles underwater, disrupting the natural behaviours of these animals and even leading to injury and death. With increasing human activities in the ocean, including sonar testing and the rise in small-boat traffic, the issue of acoustic or sound pollution in the ocean has become a growing concern for environmentalists and marine biologists.
| Characteristics | Values |
|---|---|
| Sonar's impact on marine life | Marine biologists believe that the intensity of sonar noise is disturbing to whales, leading to their fatal rapid ascent. |
| Research has shown that beaked and blue whales are sensitive to mid-frequency active sonar and move rapidly away from the source, disrupting their feeding and causing mass strandings. | |
| Sonar has been linked to decompression sickness in whales. | |
| Sonar can interfere with the echolocation systems used by some marine animals for locating prey and predators, as well as for communication and navigation. | |
| Sonar can cause marine animals to flee affected areas. | |
| Sonar can be used to track whales. | |
| Sonar can be used to detect submarines and other marine objects. | |
| Sonar can be used to explore and map the ocean, including locating underwater hazards and mapping the seafloor. | |
| Types of sonar | Active sonar emits acoustic signals or pulses of sound, which can bounce off objects and return echoes. |
| Passive sonar detects incoming sound waves but does not emit its own signal. | |
| Mitigation measures | Locating navy exercises away from known feeding and calving grounds. |
| Tracking whales and shutting down operations when they are close. | |
| Gradually ramping up sound levels to give animals time to escape. | |
| Reducing long-term exposure by not repeatedly subjecting the same animals to high-amplitude sonar. | |
| Using "vibroseis" technology, which produces sounds over smaller areas and in a narrower frequency range. | |
| Employing strict regulations to govern the use of sonar. |
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What You'll Learn
Sonar's impact on whales
Sonar has a detrimental impact on the health and livelihood of marine animals, especially whales. The use of underwater sonar, with sound waves topping out at around 235 decibels, can lead to injury and even death. These sound waves can travel hundreds of miles underwater, retaining an intensity of 140 decibels as far as 300 miles from their source.
Whales are extremely sensitive to mid-frequency active sonar and move rapidly away from its source, disrupting their feeding and causing mass strandings. The impact of mid-frequency military sonar on a whale's hearing can be equivalent to that of a jet engine at takeoff on the ears of a human standing just three feet away. This intensity of noise is disturbing to whales, leading to their fatal rapid ascent and, in some cases, decompression sickness.
Research has shown that whales experience behavioural changes when exposed to sonar, with some swimming hundreds of miles and rapidly changing depth to escape the noise, sometimes leading to bleeding from the eyes and ears, and even beaching themselves. In one instance, 34 whales of three different species died after becoming stranded along North Carolina's Outer Banks during Navy sonar training nearby.
Environmental groups have been campaigning to ban the use of sonar technology in waters rich in marine wildlife, and while some success has been achieved in restricting its use in certain areas, the battle continues.
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Sonar's impact on dolphins
Sonar technology, which stands for "sound navigation and ranging", was first developed by the U.S. Navy to detect enemy submarines. Sonar systems generate slow-rolling sound waves, which can reach up to 235 decibels and can travel for hundreds of miles underwater. These sound waves can have a detrimental impact on dolphins and other marine life.
Dolphins rely on underwater sound to navigate, catch prey, and communicate. The loud noises created by sonar technology can interfere with these essential activities, causing stress and disorientation in dolphins. Research has shown that the use of sonar can lead to changes in the behaviour of dolphins, such as preventing normal feeding and separating family members. These disruptions can have significant impacts on the health and fitness of individual dolphins and potentially entire populations.
In addition, the intense noise from sonar can cause physical harm to dolphins. The impact of mid-frequency military sonar on a dolphin's hearing is comparable to a jet engine taking off very close to a human. This intense noise can lead to rapid ascent, which can result in fatal decompression sickness. While the precise relationship between sonar testing and decompression sickness in dolphins is still being studied, it is clear that sonar noise pollution significantly disrupts their lives.
The use of sonar by the Navy has been linked to strandings and deaths of dolphins and whales. In one instance, 34 whales of three different species died during Navy sonar training off the coast of North Carolina. While strandings may be the most visible impact of sonar, there may also be hidden consequences, such as sub-lethal injuries and stress responses. Environmental groups have campaigned to ban the use of sonar in waters rich in marine wildlife, and courts have found that the use of sonar by the Navy violates laws meant to protect marine mammals.
To mitigate the impact of sonar on dolphins and other marine life, measures such as locating navy exercises away from known feeding and calving grounds, gradually increasing sound levels, and reducing long-term exposure have been proposed. The use of alternative technologies, such as "vibroseis", which produces less noise and has a narrower frequency range, can also help reduce the harmful effects of sonar on dolphins.
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Sonar's impact on echolocation
Sonar refers to a technique that uses sound propagation to detect objects underwater. Military sonar systems, first developed to detect enemy submarines, can generate sound waves of up to 235 decibels, which can travel hundreds of miles underwater. These intense sound waves can have detrimental effects on marine wildlife, leading to behavioural changes and, in some cases, injury or death.
Echolocation, also known as bio sonar, is a biological sonar system used by several animal groups, including mammals and birds. Echolocating animals emit calls or sound waves and then listen for the echoes that bounce back from nearby objects. By analysing these echoes, they can determine the distance, size, and direction of objects, enabling navigation and prey detection.
The impact of sonar on echolocation can be understood through the concept of echo-to-noise ratio (ENR). In cluttered habitats with high noise levels, such as coastal areas, the ENR decreases, making it more challenging for animals to detect returning echoes. Human activities, including sonar use, contribute to this acoustic pollution, creating an infernal din in the oceans that disrupts marine life.
The powerful sound waves emitted by military sonar can interfere with the echolocation abilities of marine mammals, particularly whales. The intense noise may disturb whales, causing them to rapidly change depth or beach themselves to escape the sound. In some cases, this has led to fatal decompression sickness. Environmental groups advocate for restricting sonar testing, especially in areas rich in marine wildlife, to mitigate these harmful effects.
While sonar can negatively impact echolocation, it is important to note that echolocation itself is a form of biological sonar. The key distinction lies in the purpose and origin of the sound waves. Sonar refers specifically to sound navigation and ranging, often employed by humans for military or navigational purposes. Echolocation, on the other hand, is nature's built-in sonar system, utilised by animals for survival and navigation.
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Sonar's impact on whale migration
Sonar has a detrimental impact on whale migration. Research has shown that whales are sensitive to mid-frequency active sonar and move rapidly away from its source, disrupting their feeding and causing mass strandings. Whales have been observed to swim hundreds of miles and change depth rapidly, leading to bleeding from the eyes and ears, and even beaching themselves to escape sonar sounds. This has been observed during Navy sonar training, with 34 whales of three different species dying after becoming stranded along North Carolina's Outer Banks.
The impact of mid-frequency military sonar on a whale's hearing is comparable to a human standing three feet away from a jet engine during takeoff. While the precise relationship between sonar testing and acute decompression sickness in beaked whales is debated, human-caused noise pollution in the ocean is agreed to significantly disrupt marine life. Whales rely on sound to navigate, locate prey, and communicate, and the noise from ships, sonar, and seismic blasts can interfere with these essential activities.
Small-boat traffic near the shore contributes to higher-pitched sounds, with sonar from ships adding to this noise. The use of air guns and engine noise further contribute to the loudest human noises in the ocean. These noises can travel for hundreds of miles underwater, retaining an intensity of 140 decibels as far as 300 miles from their source.
To mitigate the impact of sonar on whale migration, some suggestions include locating navy exercises away from feeding and calving grounds, tracking whales, and gradually increasing sound levels to allow animals to escape. Environmental groups have lobbied the government to curtail testing during peacetime and implement proven methods to avoid harming whales, such as those suggested by the NRDC and IFAW.
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Sonar's impact on whale biology
Sonar has a detrimental impact on the health and livelihood of marine animals, particularly whales. The use of underwater sonar can lead to injury and even death. Sonar systems generate sound waves that can reach 235 decibels and can travel for hundreds of miles underwater, retaining an intensity of 140 decibels as far as 300 miles from the source. These sound waves are too much for some marine wildlife to bear.
Whales are extremely sensitive to mid-frequency active sonar and will move rapidly away from the source, disrupting their feeding and social behaviour. This can cause mass strandings, as seen in the case of around 50 short-beaked common dolphins in Cornwall, UK, in 2008. In another instance, 34 whales of three different species died after becoming stranded during Navy sonar training off the coast of North Carolina in 2005.
Sonar can also lead to behavioural changes in whales, such as rapid changes in depth, which can result in bleeding from the eyes and ears, and even beachings. The impact of mid-frequency military sonar on a whale's hearing is comparable to a jet engine taking off for a human standing three feet away. This intense noise is believed to cause distress in whales, potentially leading to their fatal rapid ascent and decompression sickness.
Environmental groups have been lobbying the government to curtail sonar testing or at least implement gradual sound level increases to give marine wildlife a chance to escape. Some suggest locating Navy exercises away from known feeding and calving grounds, tracking whales, and reducing long-term exposure by not repeatedly subjecting the same animals to high-amplitude sonar.
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Frequently asked questions
Sonar, short for sound navigation and ranging, is a system that uses sound waves to detect objects like submarines, ships, and marine animals. There are two types of sonar: active and passive. Active sonar emits sound waves and measures the strength of the returning signal, while passive sonar only detects incoming sound waves.
Pollution, including noise and physical pollution, can interfere with sonar by creating a noisy or unclear environment. Noise pollution from ships, engines, and sonar blasts can mask the sound waves used by sonar, making it difficult to detect objects or animals in the water. Physical pollution, such as sediments and industrial chemicals, can also cloud the water and affect the sense of smell of aquatic animals, further hindering the effectiveness of sonar.
Sonar, especially military sonar, can have detrimental effects on marine life. The intense sound waves produced by sonar can disturb and disorient marine animals, leading to rapid depth changes, bleeding from eyes and ears, and even beachings. Sonar has been implicated in causing behavioral changes and decompression sickness in whales, leading to strandings and deaths. Environmental groups are advocating for regulations and alternative technologies to reduce the impact of sonar on marine life.
