There is no question that humans have drastically changed the way wildlife worldwide interacts and behaves. One of these areas that has seen a lot of negative change is marine life with the growth in commercial shipping and infrastructure.
Recently, Dutch researchers have discovered that harbor porpoises lose their appetite and flee after hearing noise from ships. This is the first time that scientist have recorded changed behavior from Denmark’s porpoises due to shipping practices.
Denmark’s is one of the world’s most trafficked waterways in the world and the finding that porpoises quit feeding and flee the area after hearing the noise from ships is a concern.
Sounds caused by humans from shipping, oil and gas development, naval sonar training, tourism, fishing, construction can negatively impact marine life that are very sensitive to noises. Noise pollution has reportedly killed hundreds of dolphins and whales at a time. For some species that are endangered, such as the Pacific Bryde whale, the noise pollution puts them at an even higher risk.
The findings were published in the journal Proceedings of the Royal Society B and researchers are unsure of the potential damage being cause to the marine animals outside of behavioral change.
“Our measurements show that the porpoises do respond to heavy ship noise,” said co-author Peter Teglberg of Madsen of Aarhus University. “It is still too early to say, though, what this means to the well-being of the porpoises, their production of offspring and, in the long term, their survival.”
The team of researchers collaborated with Danish fisherman to tag the animals, who occasionally accidentally catch porpoises in their nets. The electronic tags recorded sounds from the seven porpoises that were tagged, as well as the noise from ships to see when the animals feed and at what depth they stay.
“When the ship noise exceeds a certain level, the porpoises stop feeding,” according to senior researcher Jonas Teilmann in a statement. “At very high sound levels the animals dive to the bottom and move fastly along this, and they cease emitting the bio-sonar clicking sounds that they use when searching for food.”
Harbor porpoises are found in temperate waters around the world and typically stay near the surface to feed. The porpoises have been found to surface about every 25 minutes but they can dive to depths of more than 655 feet.