Humpback Feeding Impacted by Ship Noise
Noise from ships impedes humpback whales from foraging for food, according to a study released this week.
Some shipping lanes overlap with the coastal migratory paths of whales, and earlier research has shown that the associated noise can interfere with the behavior of toothed whales, such as dolphins, killer whales and sperm whales. These animals emit sonar-like pings to locate prey and communicate.
However, little was known about how the constant, low-frequency noise emitted by ships affects baleen whales, such as blue, humpback, right and bowhead whales.
A team of scientists led by Hannah Blair of Syracuse University in New York attached non-intrusive sensors to 10 humpbacks in the western North Atlantic to find out.
Humpbacks have a wide array of foraging techniques used to consume a large number of small prey, including one maneuver scientists call the bottom side-roll. This enables the whales to eat sand lance, bottom-dwelling eel-like fish, by diving to the bottom, rolling on their side and scooping the up fish.
The study found that half of the whales, all of them adult females, failed to execute these important side-rolls in the presence of ship noise on at least one of their deep dives.
The humpbacks may have perceived the ships as a threat, and it is also possible that the prey reacted to the noise, scattering or digging more deeply into the sand.
Humpbacks have previously shown the capacity to adapt to increased ocean noise, but the researchers believe their study demonstrates that they are unable to completely adjust to this disturbance.