Cetacean sonar: How ocean traffic is affecting orcas.

Photo: Miles Ritter, flickr creative commons

Photo: Miles Ritter, flickr creative commons

Imagine trying to have a conversation on a construction site. According to Oceans Initiative, this is the effect that chronic background noise from ships have on orcas and other cetaceans.

When we hear about orcas being endangered, most of us think of ship propellers and the damage they might do if an animal got too close. There are many harmful human impacts we have on whales, dolphins and their environments, but ocean noise is a significant problem many have overlooked.

Living in the murky darkness of the ocean is not conducive to seeing, so the livelihood of these animals is based on sound. At mealtimes, they listen for their fish, rather than looking or smelling for it like a land predator.

Orcas rely on the personal sonar they have evolved, called echolocation. They send out sound beams, with the vibration sending a signal back to the orca. If a salmon swims through an orca’s beam, the orca can find it and hunt for it.

Similarly, orcas also communicate with each other through sound. These sounds are the foundation behind an orca’s way of life. Talking to each other allows orcas to navigate, stay together and locate and warn each other about predators. Different orca families even have distinct sounds, and it’s how orcas find their special someone and mate.

Orcas are constantly communicating with each other - often over long distances that can span many miles.

The ocean has a natural acoustic background that cetaceans are used to and is ample for orca communication. Add noise pollution from ships, and you cut off the ability of orcas to detect the signals their lives depend upon. Ships may not seem that loud to us, but prove to be unbearable to orcas while under water.

Imagine being deaf, trying to find your family, and hunting for dinner while an unidentifiable source of bright lights flashes unpredictably in your eyes and prevents you from seeing. You might get lost or separated from your family. Something or someone you cannot see might attack you and you certainly wouldn’t be able to hunt down your dinner if you could not see it swim away. This comparison might give you an idea of the plight of the orca and just how much noise can harm these mammals as well as other cetaceans.

As part of a recent study, Cornell University put underwater microphones along the Pacific coast. They found that ship noise was strongest in areas important to the southern resident orcas, which inhabit the Strait of Georgia and Puget Sound, near Vancouver and Seattle. These industrial areas are likely to become even more developed, while much more development has already been proposed at other locations along B.C.’s coast.

Very loud, sudden noises can also cause permanent hearing damage to cetaceans. Even worse, in many locations around the globe, extremely loud sonar has caused multiple whale species to end up stranded on beaches. A particularly bad event was when four whale species ended up stranded in the Bahamas in 2000 after U.S. Navy sonar testing. These whales were found to have suffered deadly bleeding around the brain and ears. One species practically disappeared from the region. Scientists think the loud sonar causes whales to panic and “change their dive patterns in a way their bodies cannot handle”, which causes them to change depth too fast and leads to the deadly bleeding.

Unfortunately, our economy is incredibly dependent on shipping. From natural gas to all those gadgets that say “Made in China” on the bottom, most things come to us by ship.

The solution is complex and unclear. One possibility is to design ships with quiet engines, which would have a reduced impact on marine life.

In the meantime, we can slow boats down in areas occupied by whales and dolphins and respect guidelines and keep our distance from them. We can buy local whenever possible, to reduce the amount of products that need to be shipped to us through whale habitat. We could even set aside acoustic sanctuaries for cetaceans that would be free of chronic noise.