The combination of natural sounds generated by marine animals, wind, underwater earthquakes, and waves creates the submarine soundscape in the Earth's oceans. Deep-sea creatures have become accustomed to Arctic underwater acoustic environments.
During the past decades, the Arctic region has been extensively explored, which caused man-made sounds. Some sources of human noise include commercial shipping, oil and gas extraction, local skiffs, and research vessels. These noises were found to cause a nuisance to marine organisms such as the unicorn-horned whales called narwhals.
Unicorns of the Sea
Narwhals (Monodon monoceros) are toothed whales only found in the Arctic. They are one of the two species in the "white whales" family, the other being the beluga. Also known as the unicorns of the sea, narwhals are known for the long tusks protruding from their heads.
Only male narwhals possess ivory, spiralized teeth that make up the tusk which can grow up to 9.8 feet. Despite this, narwhals differ from the other species of the toothed whale family because they do not have teeth in their mouths.
This whale species can weigh up to 4,200 pounds and grow as long as 17 feet. They are usually found in herds of 15 to 20, although groups of several thousand have already been seen. The longest-lived narwhals were assumed to be between 105 and 125 years old. Unlike some migratory whale species, narwhals thrive in the Arctic waters of Greenland, Canada, Russia, and Norway, where they look for food in deep waters near the ice edge.
Altered Underwater Soundscape
Every summer season, each narwhal returns to the same small fjord where it was born to hunt for squid, fish, and shrimp. As human activities in the Arctic waters increase, conservationists, scientists, and Inuit communities express concern about the effect of development and ship traffic on whales. In Greenland, many Inuit communities depend on narwhals as their culturally significant food source.
In 2011, the government of Greenland started to release new permits for offshore oil exploration in the area. Ecologist Outi Tervo from the Greenland Institute of Natural Resources decided to examine the effect of such development and its noise pollution on the behavior of narwhals.
Boats exploring the Arctic sea floor drag instruments called airguns, which blow air below the vessels to locate the presence of cavities that may hold oil and gas. The pulses generated from these blasts are considered the loudest sound humans release in the ocean.
Tervo and her colleagues collaborated with the local hunters to help them catch narwhals and install tracking devices to determine their reaction to the boat noises from oil development. The narwhal's location is noted via GPS through these tracking tags, and their other behaviors, such as diving depth and swimming speed, are also monitored.
After fastening the tags to the narwhals, the researchers simulated some of the noise from the oil expedition using a Danish patrol vessel. The vessel roamed the sea and fired airguns at set intervals, after which the researchers monitored the narwhal's reaction. It was found that as soon as the noise reached the whales, the narwhals halted their deep dives and stopped their clicking sound in locating food underwater.
Understanding how the whales react to such noises can provide new insights to conservationists in protecting the animals in the Arctic region. The researchers hope that their study results will prompt government authorities to develop management plans for conducting human activities in the Arctic.
RELATED ARTICLE : Are Unicorns Real? Narwhal Sold to European Markets Are Allegedly Horns of These Creatures
Check out more news and information on Narwhal in Science Times.
