Whales Stressed Out By Ocean Noise
Ships’ propellers emit sound in the same frequency range that some whales use for communicating, and previous studies have shown the whales change their calling patterns in noisy places. Now, researchers have measured stress hormones in the faeces of the endangered North Atlantic right whale, and found they rose with the density of shipping.
Ocean noise has risen substantially in recent decades along with the growth in global shipping; one analysis showed that the north-eastern Pacific is 10-12dB louder now than in the 1960s. Past years have seen significant numbers of right whales hit by ships and entangled in fishing nets. It’s also possible that chronic stress may cause whales to struggle in breeding.