Will new guidance reduce hearing loss in whales and dolphins?

A new controversy is beginning to rumble over the potential injury to marine mammals from sounds transmitted in the water.

Transient killer whales Photo: Kitsap Sun
Transient killer whales // Photo: Kitsap Sun

The National Marine Fisheries Service, also called NOAA Fisheries, is moving closer to finalizing new “technical guidance” for assessing temporary and permanent hearing loss in whales and dolphins caused by human activities — including Navy sonar, seismic explorations and underwater explosions. The guidance will be used for approving “take” permits under the Marine Mammal Protection Act and Endangered Species Act.

Meanwhile, in another development, Navy officials have acknowledged that Navy personnel made a mistake by using sonar in Puget Sound without getting approval through the chain of command. I’ll describe the circumstances of that event in a moment.

Proposed noise guidance

The new “Draft Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing” is a major revision from guidance in effect since the late 1990s. The document is currently going through its third public comment period since the end of 2013, having been updated and reviewed by three expert panels.

The new guidance is focused on hearing loss rather than how the behavior of marine mammals might change in the presence of loud noise. Since foraging and social activity are essential among whales and dolphins, further guidance is expected to assess how animals may be affected in other ways by noise.

The new guidance does not include mitigation measures for minimizing the effects of sound. In some cases, the new information may lead to additional protections for the animals, but in other cases protections may be reduced, according to information from NOAA Fisheries.

Currently, regulators use a single noise threshold for cetaceans (whales and dolphins) and a single threshold for pinnipeds (seals and sea lions). They do not account for the different hearing abilities within the two groups or how different types of sound may be experienced.

The new acoustic threshold levels divide sounds into two groups: 1) impulsive sounds lasting less than a second, such as from airguns and impact pile drivers, and 2) non-impulsive sounds, in which the sound pressure rises and declines more gradually, such as from sonar and vibratory pile drivers. Measures account for both peak sound pressure and cumulative sound exposure.

Marine mammals also are divided into groups based on their general range of hearing. There are the low-frequency cetaceans, including the large baleen whales; the mid-frequency cetaceans, including the dolphins; and the high-frequency cetaceans, including the porpoises.

The pinnipeds are divided into two groups. The eared seals, including sea lions, have a somewhat wider hearing range than true seals, including harbor seals.

After years of covering the effects of sonar and other noise, I’m just beginning to understand the complexity of how sound is measured and the mathematics used to calculate levels at various locations. At the same time, the guidelines are growing more complex — as they should to model the real world. New thresholds account for the duration of sound exposure as well as the intensity, and they somewhat customize the thresholds to the animals affected. For additional information, see NOAA’ Fisheries webpage on the guidance.

Despite incorporating new studies into the guidelines, some acoustics experts are finding serious problems with the methods used to arrive at the new thresholds, according to Michael Jasny of the Natural Resources Defense Council. The NRDC, an environmental group, has a long history of battling NOAA Fisheries and the Navy over sound exposures for marine mammals.

“This is an extremely technical subject,” Michael said, noting that he relies on experts who have provided comments on the methodology. “By and large, NMFS has drunk the Navy’s Kool-Aid with the exception of low-frequency effects, even though the Navy’s science has been sharply criticized.”

The statistical analyses leading to the guidelines are so flawed that they call into question how they could be used to protect marine mammals, Michael said, pointing to a paper by Andrew J. Wright of George Mason University.

“These are high stakes we are talking about,” Michael said. “We are talking about damaging the hearing of endangered species that depend on their hearing to survive.”

The effects of sound on behavior, which are not described in the new guidelines, may be just as important, he said, since too much noise can impede an animal’s ability to catch prey or undertake social behavior that contribute to the perpetuation of the species. NOAA Fisheries needs to move forward to raise the level of protection, not just for injury related to hearing but for other effects, he said. One can review a series of related studies on NOAA Fisheries’ website.

“If these guidelines are not improved, at least to address fundamental statistical errors, then it is easy to imagine that they might be legally challenged — and they would deserve to be,” Michael told me.

Sonar in Puget Sound

As for the Navy’s mistake with sonar, the story goes back to Jan. 13 of this year, when acoustics expert Scott Veirs of Beam Reach Marine Science picked up the sound of sonar on hydrophones in the San Juan Islands. About the same time, Ken Balcomb of the Center for Whale Research was observing transient killer whales to the south in Haro Strait.

At first, Scott believed the sonar may have been coming from the Canadian Navy ship HMCS Ottawa, but Canadian officials were quick to deny it. His suspicions shifted to the U.S. Navy. He was disturbed by that prospect since the Navy stopped using sonar during training exercises in Puget Sound shortly after the USS Shoup incident in 2003. For a reminder of that incident, check my story in the Kitsap Sun, March 17, 2005.

USS Shoup, a Navy destroyer based in Everett. U.S. Navy photo
USS Shoup, a Navy destroyer based in Everett. // U.S. Navy photo

Later, the requirement for approval from the Pacific Fleet command became an enforceable regulation when it was added to the letter of authorization (PDF 3.4 mb) issued by NOAA Fisheries. The letter allows the Navy a specific “take” of marine mammals during testing and training operations.

Within days of this year’s sonar incident, Scott learned from observers that two Navy ships had traveled through Haro Strait about the time that sonar was heard on a nearby hydrophone. Navy Region Northwest confirmed the presence of Navy vessels.

Later, Scott received an email from Lt. Julianne Holland, deputy public affairs officer for the Navy’s Third Fleet. She confirmed that a Navy ship used sonar for about 10 minutes at the time of Scott’s recording. The ship was identified as a guided missile destroyer — the same type as the Shoup — but its name has never been revealed.

“The Navy vessel followed the process to check on the requirements for this type of use in this location, but a technical error occurred which resulted in the unit not being made aware of the requirement to request permission,” according to Lt. Holland’s email to Scott. “The exercise was very brief in duration, lasting less than 10 minutes, and the Navy has taken steps to correct the procedures to ensure this doesn’t occur again at this, or any other, location.”

Because no marine mammals appeared to be injured, the story kind of faded away until I recently contacted Lt. Holland to tie up some loose ends. She ignored my questions about whether disciplinary actions had been taken against any Navy personnel. “The Navy has taken appropriate action to address the issue, including reissuance of specific guidance on the use of sonar in the Pacific Northwest.” The memo was sent to “all units in the Northwest.”

After I reopened the discussion, Scott did some acoustic calculations based on figures and graphs he found in a Navy report on the Shoup incident. He located published estimates of the source levels and concluded, based on NOAA’s old thresholds, that marine mammals within 10 kilometers (6.2 miles) would experience noise levels likely to change their behavior (level B harassment).

Based on the data available, Scott could not conclude whether the transient killer whales in Haro Strait were within that range, but he said it was encouraging that Ken Balcomb did not notice any changes in their behavior. It was also helpful that the sonar was used for a relatively short time.

“It was a little nerve racking to hear the Navy was making mistakes,” Scott said, “but we can give them a pat on the back for doing the exercise during the day” when lookouts on the ship at least have a chance to spot the animals.

2 thoughts on “Will new guidance reduce hearing loss in whales and dolphins?

  1. Chris, Thank you so much for keeping us informed about this subject. I finished War of the Whales by Joshua Horwitz last month, and am so sad and horrified at the harm the US Navy is inflicting on our mammals in the sea. Many others contribute to this noise level, but the secretive nature of the Navy…and that they don’t seem to learn, is very disturbing. Thanks again!

    1. I appreciate the support. I thought it was important to get the Navy incident out in the media, even though it comes late and any effects from the sonar appear to be minimal.

      As for the new technical guidance on sound, it is a complicated issue but one that will affect both marine mammals and many types of human operations that create underwater noise. On a personal note, I’m trying to increase my understanding about the nature of sound, including the mathematical formulas needed to describe how sound travels through water.

Leave a Reply

Your email address will not be published. Required fields are marked *

Before you post, please complete the prompt below.

Please enter the word MILK here: