Scientists use new acoustic tools to study sounds made or heard by marine creatures

Reports indicate that scientists are using new acoustic tools to study sounds made or heard by marine mammals and fish.

Over the past decade, researchers have developed a variety of reliable real-time and archival instruments to study sounds made or heard by marine mammals and fish.

These new sensors are now being used in research, management, and conservation projects around the world, with some very important practical results.

Among them is improved monitoring of endangered North Atlantic right whales in an effort to reduce ship strikes, a leading cause of their deaths.

"The tools available to both acquire and analyze passive acoustic data have undergone a revolutionary change over the last ten years, and have substantially increased our ability to collect acoustic information and use it as a functional management tool," said Sofie Van Parijs, lead author and a bioacoustician at NOAA's Northeast Fisheries Science Center laboratory in Woods Hole, Massachusetts.

"These tools have significantly improved monitoring of North Atlantic right whales and enhanced the efficacy of managing ship traffic to reduce ship strikes of whales through much of the western North Atlantic off the US East Coast," she added.

Van Parijs and her colleagues focus on two types of acoustic sensors, real-time and archival. 

Real-time sensors are mounted on surface buoys, usually anchored or cabled to the ocean bottom, or deployed as arrays towed from a surface vessel.

Archival sensors are affixed on bottom-moored buoys equipped with hydrophones to continuously record ocean sounds for long periods of time, often up to three months, before the sensors are temporarily recovered and their batteries refreshed. Some archiving sensors can be mounted of individual animals.

"Marine animals live their lives and communicate acoustically across different time and space scales and use sound for different reasons," said Van Parijs.

"We need to use the right tool in the right place for the right need. There is no 'one size fits all' when it comes to using technology in the ocean," she added.

The use of passive acoustic monitoring is increasing as improved reliability and lower hardware and software costs provide researchers with a set of tools that can answer a broad range of scientific questions. This information can, in turn, be used in conservation management and mitigation efforts.