 Blue whales are found in oceans around the world. Atlantic blue whales are listed as endangered in Canada under the Species at Risk Act. There are likely less than 250 mature animals. The number of Atlantic blue whales decreased in the 1800s because of whaling, but whaling in Canada came to an end in 1966. Today, blue whales still face many threats caused by humans. Blue whales include vessel strikes, pollution in the water from chemical spills, and getting tangled in fishing gear. The food sources for blue whales are also being affected by climate change. Blue whales live off the coast of eastern Canada, including the Gulf of St. Lawrence. They are found in these waters, especially during the summer months. The blue whale is the largest animal that has ever existed on Earth. The longest blue whale seen so far was 30 meters long. That's about the length of three school buses. Blue whales are usually found alone and often hundreds of kilometers apart. To communicate with each other over these long distances, they use sound. Sound can travel up to five times further through water than it can through air. Blue whales use loud, low-frequency songs and calls that are heard deep in the oceans from thousands of kilometers away. Some of their calls are louder than a space shuttle launch. Scientists can even use their songs to tell where they come from because their songs often vary from one region to another. Blue whales make sounds and calls to find food, to socialize, to attract a mate, and to navigate. Their calls can sound a lot like noisy human activities in the ocean. These include ship noises, sonar use for navigation, and sounds used in seismic surveys to find marine oil and gas sources. Noisy environments can change whale behaviors and activities. This includes making whale-to-whale communication harder. That can force blue whales to increase the number and volume of calls. It might also make them avoid noisy areas altogether. Today, all these new noises in the ocean mean that a blue whale call might be heard from only 200 kilometers away or even less. This is a big change compared to blue whale songs traveling up to 2,000 kilometers two centuries ago. Fisheries in oceans Canada as well as Transport Canada are helping to address ocean noise by funding research and additional work with partners throughout Canada, which will help blue whales communicate easier and help other marine animals that depend on quieter oceans to survive.