New Evidence links Sonar to Whale and Dolphin Strandings
22nd Jul 2013
New research has been published that proves the use of sonar can have a major impact on marine mammals. The study demonstrates two species of whale responding to sonar, even at low levels.
When exposed to sonar waves, the Blue Whales in the study stopped feeding and swam away from the sound, some increasing their speed. The beaked whales in the study also stopped feeding, stopped fluking their tails out of the water and dived for longer. Spending less time feeding could be a risk to whale populations. Both species responded to sonar at less than the sound levels allowed by current regulations.
- photo courtesy of BDMLR
For a number of years there has been speculation that marine mammal beaching could be linked to the use of sonar by the military. In March 2000, just days after a US Military exercise in the Bahamas, 17 marine mammals were reported stranded in the area. Most were beaked whales. Some of the animals were rescued, but seven died on the beach.
Tests showed that the animals died from heatstroke after being stranded. While there was no evidence that the sonar itself killed the animals, it is believed they may have beached themselves as a result of military sonar and then died. As this report from Woods Hole Oceanographic Institution suggests, concern grew that military sonar had an impact on marine mammal behaviour.
Biologist Peter Tyack realised that the 2000 Bahamas incident was part of a pattern - there had been five other reported beaked whale strandings following the use of military sonar. Tyack, now based at the University of St Andrews, is a co-author of the new research. His work in helping develop a new way to tag whales was pivotal in allowing the new data to be collected.
In America, the US Navy has spent millions funding much of this research into sonar’s impact. However, it is also accused of planning new exercises with a predicted death toll of 1000 marine mammals and serious injuries for a further 5000 over the next five years. Actor Pierce Brosnan has joined a campaign started by Natural Resources Defence Council calling for a major rethink.
Closer to home, the Royal Navy were forced to move an exercise off Scotland earlier this year to minimise its impact on whales spotted nearby. Talking about these latest pieces of research, a Royal Navy spokesperson said:
"The Royal Navy already limits its use of sonar around whales. We are committed to taking all reasonable and practical measures to protect the environment and mitigate effects on marine mammals. This new research will be taken into account in the regular review of MoD active sonar mitigation procedures."
Modern technology has meant the military has become more dependent on the use of sonar in recent years. Stated simply, older submarines were noisier making them easier to detect with acoustic instruments. Although it’s highly unlikely that this new research will stop the use of military sonar completely, scientific research along with the data gathered by ORCA’s volunteers can play an important role in informing decisions about where the military plan exercises and so help safeguard marine mammals.
1. Help ORCA identify and protect whales and dolphins by volunteering on a marine mammal survey. This work helps locate habitats and migration paths and can inform other research
2. Learn what to do if marine mammals are beached. British Divers Marine Life Rescue run a marine mammal medic course. If you spot a marine mammal that has been stranded, note the exact location, tide and any injuries then call British Divers Marine Life Rescue on 01825 765545 during office hours or 07787 433412 out of hours.
3. Sign Pierce Brosnan’s petition to the US Secretary of Defence, Chuck Hagel:
4. Read more about the research on sonar and whale strandings. The two scientific papers mentioned in this article are available to read online:
Study on blue whales
Study on Cuvier’s beaked whales