Hear This: Ship Noise Stresses Whales

Quiet oceans make for calmer right whales, new research suggests. When fewer ships sail the Bay of Fundy, the big baleen whales are less stressed — as evidenced by hormone levels in their poop.

This stress could be one reason the North Atlantic population of right whales, which spend part of their lives in the Bay of Fundy off the East Coast, is having such a hard time reproducing. If the sounds chronically stress them, they could be more prone to disease and it could possibly interfere with their ability to reproduce, the researchers say.

"We know that whales have responded to underwater noise by changing their vocalization, but we didn't know if they responded with physical changes as well," study researcher Rosalind Rolland, of the New England Aquarium in Boston, told LiveScience. "What this study has shown is that they are having a measurable physiological stress response to the noise in their environment."

Calling all whales

Right whales use their calls to communicate across long distances. They use low frequencies because they carry farther, but these are similar to the frequencies made by ocean-going ships. Previous studies have shown that noise levels can impact the whales' behaviors, including where they swim and how they vocalize. It's like trying to talk at a party — often a lot of noise will make you either speak louder or, in the worst cases, wait until later to make your point. What the researchers didn't know is how noise may be impacting the whales physically.

The researchers analyzed noise recordings from September 2001, in areas of the Bay of Fundy where the whales generally reside; they then compared them with samples of whale poop collected by researchers in 2001 through 2005. They were looking for evidence that decreased ship traffic after the tragic events of 9/11 lowered the whales' stress hormone levels.

In the two days before 9/11, nine ships passed through the Bay, but in the two days after, only three ships passed through. This led to a significant decrease in low-frequency noise in the Bay and a drop in the intensity of the noise, they found. This coincided with a drop in stress-hormone levels in the whales' fecal samples: Compared with before Sept. 11, hormone levels were significantly lower after Sept. 11 … only in 2001.

Read on:  http://www.livescience.com/18367-ship-noise-stresses-whales.html