Mark Spalding from The Ocean Foundation sent us an article in Science Daily this week which discusses the findings of Susan Parks and colleagues regarding how North American Right whales are increasing their vocalization levels to overcome the background noise of shipping traffic.
Parks, along with Mark Johnson, Peter Tyack, and Douglas Nowacek were monitoring the “upcalls” with acoustic suction-cup tags placed on the whales. The upcalls are also called “contact calls” because they have been associated with social contact. Parks et. al. found evidence that the whales increased the amplitude of these calls when they were in louder settings in a manner that we humans also elevate our voice to be heard in loud environments.
I am currently working with Tom Reuterdahl and David Goldstein modeling ambient noise levels in the ocean prior to industrialized whaling. Historic whaling records, maritime accounts, and modern DNA research indicate that hundreds of thousands to millions of large whales once inhabited the sea. Given that all of these whales could produce some fairly loud noises, the pre-19th Century Ocean may have been a really loud place.
Estimates of current whale populations indicate that some whales are at or below 5% of their pre-whaling populations. The difference being of course that with so many other whales in the sea before whaling they didn’t need to ‘shout’ to reach one another. Now with only 300 Right whales remaining it is pretty important that they stay in touch.
Unfortunately with growing ocean noise from shipping, communication systems, sonars, airgun surveys, and other industrial activities, the growth rate of background noise is outpacing the increase in whale populations. And while they are ‘adapting,’ there is an upper limit to how loud these whales can shout.