Pacific Underwater: If two ships pass in the night, does anybody hear? | Healthy Oceans | David Suzuki Foundation

By Kat Middleton, Western Region Science & Policy Intern

If you were to dunk your head into the cold coastal waters off British Columbia during the month of September, what do you think you would hear? Once your body gets used to the temperate ocean, you would begin to notice the sound of waves lapping on the shoreline beside you. Clicks and pops coming from the crabs scurrying amongst the eelgrass and bull kelp that sway in the tidal waters fill your ears. In the distance, you might hear the faint whistle of a pod of resident killer whales. You most likely will hear the sound of boat engines, the hum of cruise ships or ferries.

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For you, these sounds raise curiosity, but for animals in the ocean, the sense of hearing is like sense of sight for humans. Most of the ocean below several metres is too dark for animals to rely on sight, making sound an essential medium for marine creatures to communicate, sense what is around them, steer though their habitat, and locate food.

Toothed whales and dolphins rely on sound to find food and navigate the marine environment. They do so using echolocation — the ability to locate objects by sending sounds (usually clicks) that bounce off objects around them. This reflected sound is "seen" as an image in the animal's brain, much like sonar used for navigation. Marine mammals can also use sound to communicate between family members, large groups or pods. Baleen whales (such as humpback whales) have long distance, low frequency calls. The blue whale is both the largest and the loudest animal on earth. The vocalizations of this solitary animal are so loud — measured at 180 decibels, blue whales are substantially louder than a rock concert — that they can communicate across entire oceans spanning thousands of kilometres. These calls are at such low frequencies (14Hz) that we humans can't even hear it!

Unfortunately, whales, dolphins, and fish are having difficulties hearing each other these days over all the human-made noises in their underwater world. Aquatic noise in British Columbia comes from military sonar and boat traffic, including commercial, recreational, and shipping vessels as well as cruise ships and ferries. We're beginning to understand how these sounds harm marine creatures. For example, researchers have recently found that southern resident killer whales off Victoria make louder calls to compete with the buzz of boats around them.

Last year, I worked as a marine warden for Cetus Research & Conservation Society in Johnstone Strait, one of the highest vessel traffic areas in British Columbia. My job was to make sure boats in the area followed the Be Whale Wise guidelines when they approached whales, killer whales, dolphins and other marine animals. Boats are required to stay least 100m away from marine mammals to reduce noise pollution and minimize the risk of disturbing marine wildlife. Although these guidelines help, the volume and frequency of noise in critical habitats off British Columbia is extremely high and getting higher. The United States recently increased enforcement on vessel traffic around endangered southern resident killer whales in Washington to help reduce noise pollution and disturbance. Sadly, there is no enforcement on our side of the border this year, since the federal government cut funding for the Straitwatch program — run by Cetus Society along the B.C. coast for the last 10 years.

Another part of my job — and a challenging one — was to ensure boats did not enter the Robson Bight Michael Bigg Ecological Reserve. This killer whale sanctuary was established in 1982 to ensure boaters do not bother killer whales as they socialize and rub themselves on the beaches along the reserve. While working as a warden I witnessed first-hand how marine protected areas can effectively protect whales and other marine life from human disturbance and excessive noise.

If you are interested in what B.C.'s coastal waters sound like, go to the beach nearest you and stick your head underwater, or stay dry and listen online to one of dozens of hydrophones (underwater microphones) placed around the B.C.coast including OrcaSound , OrcaLive and the Pacific Wild websites.

September 13, 2013
http://www.davidsuzuki.org/blogs/healthy-oceans-blog/2013/09/if-you-were-to-dunk/

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