Blog Tags: Dolphin Strandings
The National Oceanic and Atmospheric Administration (NOAA) announced that a measles-like virus is responsible for hundreds of bottlenose dolphin strandings along the mid-Atlantic coast this summer.
Since early July, unusually high numbers of dead or dying bottlenose dolphins have washed ashore from New York to North Carolina. About 155 dolphins strand in the mid-Atlantic from January to late August during a normal year, but this year almost 500 dolphins washed ashore in the same time period. The sudden increase prompted NOAA to declare an Unusual Mortality Event for bottlenose dolphins.
In the last three months, more than 3,000 dolphins have washed ashore in Peru, most likely due to offshore oil exploration. Oil companies in the region often use sonar or acoustic soundings to detect oil beneath the floor of the sea, and dolphins and whales can be affected because of their sensitivity to sound.
Toothed whales, including dolphins and porpoises, have evolved to be able to echolocate. Instead of having two nostrils like other mammals and baleen whales, toothed whales have only one which is used as their blowhole. A whale emits squeaks and whistles from its blowhole, and the sounds bounce off objects in the water, providing an echo. The other nostril has developed into a fatty tissue known as the melon, which is used to receive and focus the returning echoes.
Hearing is considered to be whales’ most important sense, used not only for navigating but also for feeding, bonding with offspring, and finding mates. Noise pollution cause changes in calling behavior, but can also cause whales to change their diving habits which can result in “the bends,” when nitrogen bubbles get trapped in the body.
Sonar can be extremely loud (imagine the sound of 2,000 jet planes), with sound waves travelling hundreds of miles through the ocean. Noise levels this high can cause fatal injuries, similar to those seen in many strandings around the world. As the world’s oceans become noisier, they also become more dangerous for whales and dolphins.
- Photos: Oceana’s Dusky the Shark Visits Washington, D.C. to Raise Awareness for Dusky Sharks Posted Mon, November 17, 2014
- Ocean Roundup: Atlantic Bluefin Tuna Catch Quotas Raised, Kemp’s Ridley Turtles Stranding in High Numbers, and More Posted Wed, November 19, 2014
- Ocean Roundup: Seals Can Pick up Pings from Acoustic Tags on Fish, Climate Change Making Crabs “Sluggish,” and More Posted Fri, November 21, 2014
- Oceana’s New Report Highlights Uses, Benefits of Global Fishing Watch Technology Posted Mon, November 17, 2014
- Video: Humpback Whales Cause Quite the Surprise As They Hunt for Herring Posted Wed, November 19, 2014