Acoustic bleaching—there’s an expression you don’t hear every day. Whales operate in a world of sound; it is their primary sense. Blue whales make sounds that can be heard thousands of miles away, or at least they used to be able to. Humanity is not just filling our oceans with trash, we are filling our oceans with sound. From commercial shipping, seismic exploration and military testing, the oceans are no longer the silent world that Jacques Cousteau once talked about.
The RV Odyssey just returned to port after a collaborative expedition with the Scripps Whale Acoustic Lab. Expedition leader and former Voyage of the Odyssey crewmember, Josh Jones, was retrieving acoustic recording devices from the ocean floor in the Gulf of Mexico–switching out the batteries and hard drives and re-deploying them.
The Whale Acoustic Lab has developed autonomous acoustic recording devices in a number of different configurations for various marine environments to monitor marine mammals and study ambient ocean noise over long periods. These devices are commonly referred to as HARPs (High-Frequency Acoustic Recording Packages). The Whale Acoustic Lab has been deploying these HARPS around the world so we can better understand the undersea world of sound.
So what is acoustic bleaching? Here is a human analogy: imagine if two or three times a day the world around you went brilliant white, so white that you could not see or do anything. Or imagine if every 5 minutes the world went brilliant white for one minute. Think about how complicated that would make our lives. Acoustic bleaching is the expression we use when whales cannot hear what is going on around them or communicate with each other because their hearing is being overwhelmed by a loud sound source. Studying this issue is going to be more relevant to us as the East Coast has just been opened up for oil exploration.
-Iain Kerr, CEO Ocean Alliance