Dolphin Strandings Linked to Widespread Sonar Use

A new study by a team of marine researchers from marine facilities around the U.S. has positively linked live dolphin strandings to naval sonar sources. A live dolphin stranding is also called a beaching, because the dolphin will voluntarily push themselves onto the beach. This eventually causes them to die for a lack of water.

Record number of dolphin beachings

A record number of dolphins have been beaching themselves around the world in recent years. Hundreds of dolphins strand themselves each year.  For example, in 2012, during just January and February, over 175 dolphins stranded themselves in Cape Cod, Mass., and over two hundred dolphin strandings were discovered on the beaches of Peru.

Marine researchers have been investigating the possible causes. While some consider natural environmental issues like enclosed bays, or tough currents, the record numbers this year indicates other causes. Scientists have ranged in their hypotheses.

Possible causes narrowed down

The warming ocean waters is one cause researchers have taken seriously. Ocean temperatures have risen over one degree Farenheit in the past decade, and even warmer currents have been found in a number of ocean habitats.

Pollution in the water is also high on the list, as the amount of degrading plastics, nitrogen runoff from chemical fertilizers, oil spills and other pollutants have been alarmingly increasing in the oceans worldwide. Many of these pollutants accumulate up the food chain, poisoning the larger sea mammals like dolphins gradually

The increasing use of sonar by military submarines and warships, especially during naval exercises, by far has gained the most credibility, and recent research confirms this thesis. Because both dolphins and whales have extensive sonar capability, and their sensitivity to sonar is so strong, research has connected their beachings to U.S. Naval exercises. This led to a 2008 Supreme Court battle between environmental groups and the U.S. Navy. The Court ruled that the Navy had to begin developing other tools that would not harm whales and other marine life.

Scientists study stranded dolphins

Researchers from Massachusetts’ Woods Hole Oceanographic Institution, Texas A&M University-Corpus Christi, the Marine Mammal Rescue and Research facility, the International Fund for Animal Welfare, and the Chicago Zoological Society have recently conducted a study of 22 self-stranded (beached) dolphins. They found that the kidneys of 21 of the 22 stranded dolphins contained gas bubbles. The bubble content was identical to the gas bubbles found among the tissues of whales and dolphins that have been found stranded during naval exercises.

The connection between the tissue bubbles and the beachings appears to be related to their need to decompress as they surface and dive. Should their decompression system not be working properly, they need to find an avenue for decompression. Beaching themselves appears to be an attempt to achieve such a decompression.

The researchers also tested wild dolphins not stranded, and found no such bubbles in their tissues. They also found that following a beaching, dolphins appear to tolerate the bubbles and some improve after returning to the sea. At least until faced with the next military naval exercise.

International studies by marine scientists

In 2011, an international team of marine scientists supported by the U.S. Office of Naval Research conducted a whale behavior study published in the scientific journal PLoS ONE. The study showed that mid-frequency sonar waves in the range of 140-160 dB significantly altered whale activity. This mid-range frequency, also used by naval warships, helicopters and submarines, caused whales to react negatively. The researchers concluded that the whales are sensitive to these sonar devices.

Dolphins and whales use similar sonar sensory organs. Dolphins use sonar to communicate, navigate their positions, and understand the positions of their prey and other dolphins.

We might compare being in the ocean surrounded by sustained military sonar to being in close proximity to loud public sirens, such as those used for tsunamis and airplane bombing warnings. The intensity of these sirens after only a few minutes would drive any person as far away from the siren sound as possible.

In humans, our tympanic membranes and middles ears are also connected to our sense of balance and our body’s atmospheric pressure compression. This is why are ears pop when we climb to high altitudes or dive into deep water. Whale and dolphin sonar senses are also connected to their decompression facilities.

Another 2011 study from The Netherlands found that porpoises were sensitive to the helicopter long range active sonar (HELRAS) system. They found that the mammals were sensitive to amplitudes of 76 dB of HELRAS sonar arrays.

Previous studies have confirmed that whale beachings increased in regions and during times when there was an increase in Naval exercises.

The beachings of dolphins in Chiclayo, Peru occurred side by side with anchovy beachings. Researchers at the Peruvian Sea Institute are now assuming that whatever beached the anchovies also forced the dolphin beachings, indicating some kind of environmental pollutant. The connection with the anchovies has yet to be determined, but sonar has not been eliminated.

Whether it is chemical pollutants or sonar pollutants, humanity is increasingly interfering with the lives of those creatures that live around us. What is the real cause? The cause is humanity’s lack of respect for nature and the intelligence of our environment. Humanity’s assumption that we can conquer and control nature without responsibility, boundary or sensitivity is what is destroying the very environment we need to survive, and those beautiful creatures that share our environment.

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