Does seismic blasting harm marine life?

By Robert C. Jones Jr.

Does seismic blasting harm marine life?

By Robert C. Jones Jr.
UM experts weigh in on the effects of air gun blasting during oil and gas exploration in the Atlantic Ocean.

When the Trump administration late last November authorized the use of seismic airgun blasting to locate untapped oil and gas reserves deep underneath the Atlantic Ocean along the Eastern Seaboard, environmental groups expressed outrage, saying that such ear-piercing surveys would harm marine life. 

The administration’s action, which reverses an Obama-era policy against the use of seismic surveys, is “shortsighted and dangerous,” Diane Hoskins, campaign director of Oceana, said in a statement. “Seismic air gun blasting can harm everything from tiny zooplankton and fish to dolphins and whales.” 

Although the National Marine Fisheries Service said it expects no marine life will be harmed by the surveys, some scientists disagree, saying that the blasts could affect the mating, communicating, and feeding patterns of marine mammals.

“Marine mammals use sound to communicate, navigate, and hunt for prey,” said Jill Richardson, program director and senior lecturer in the Department of Marine Ecosystems and Society at the University of Miami Rosenstiel School of Marine and Atmospheric Science. “Evolutionarily, they capitalized on the effective propagation of sound underwater, but this also makes them very susceptible to noise pollution. Airgun noise can be so pervasive, spatially and temporally, that it can be debilitating.” 

Changes in diving and surfacing patterns, displacement from important feeding habitats, disorientation, stress, and either temporary or permanent shifts in hearing thresholds are some of the known impacts to marine mammals, according to Richardson. “And since sound is so important to their survival, the fact that they may not be able to hear each other is extremely concerning and may lead to impacts at the population level,” she said. “Imagine trying to raise a baby or communicate with friends while navigating in a concert hall where the band, essentially, never stops.” 

This is how seismic surveys work: Oil and natural gas deposits deep in the ocean seabed cause the geological stratified layers above to bulge instead of lying flat. Sound pulses from airguns reflect off the bottom layers and are received on a long line of towed hydrophone receivers behind a ship. By measuring the travel times to each receiver, the depth of the layers of the sub-bottom can be reconstructed, allowing geologists to “see” the bulges and know where they need to drill for oil. 

According to Richardson, the sounds generated by airguns can travel more than 4,000 kilometers from the source. “We are only starting to understand the impact of stress on marine mammal health, but it likely contributes to immune function disruption,” she said. “This, when layered on top of the menagerie of other emergent threats, such as exposure to contaminants and biotoxins and the loss of habitat, can lead to devastating effects on marine mammals.” 

The critically endangered North Atlantic right whale is particularly at risk, said Richardson. 

But Harry DeFerrari, a professor emeritus of ocean sciences at the Rosenstiel School, said there is a general misconception that because seismic surveys are allowed, oil companies can blast away with impunity. “Nothing could be further from the truth,” he said. 

“It is my opinion that current practice and regulations in place have already eliminated effects on marine life,” said DeFerrari, who developed and taught the graduate course Applied Acoustics and Marine Mammals, served on two National Research Council Committees that resulted in the publication of two books on the effects of low frequency sound on marine mammals, and is currently a paid consultant for Exxon Mobile. 

“Before any seismic survey is approved, an environmental impact statement is required,” he said. “What I have seen of these studies, they are as detailed and conscientious as any scientific research program. They use the latest methods in ocean acoustics measurement and modeling methods and hundreds of observers to determine whale activities in the planned survey areas. Sensitive areas such as feeding grounds and well-populated areas are avoided. Observations continue during the surveys and are canceled if whales are present. Environmental impact is taken very seriously by both the enforcing government agency and the oil companies.” 

DeFerrari further noted that there is agreement among government regulators that seismic surveys do not have any effect at all on marine life, citing a recent statement from the U.S. National Academy of Sciences’ National Research Council that reads: “No scientific studies have conclusively demonstrated a link between exposure to sound and adverse effects on a marine mammal population.” 

Five companies have been awarded “incidental take” permits by the National Marine Fisheries Service to survey the Atlantic Ocean seabed for oil. The only thing standing in their way are final geological permits from the Bureau of Ocean Energy Management and a lawsuit filed by a coalition of environmental groups seeking to stop the surveying. 

That lawsuit, filed in a federal court in Charleston, South Carolina, in early December, claims that seismic mapping violates the Marine Mammal Protection Act and other federal laws that protect marine mammals. Just before the new year, nine state attorneys general joined the lawsuit. 

“While the administration continues to place the interests of the fossil fuel industry ahead of our precious natural resources, attorneys general up and down the Atlantic coast will continue to fight these and other efforts to open waters off our shores to drilling for oil and gas,” Maryland Attorney General Brian E. Frosh said in a statement. 

Whether or not the lawsuit will be successful is difficult to predict, said Natalie Barefoot, associate director of the Environmental Justice Clinic at the University of Miami’s School of Law. “From the legal perspective, the environmental coalition will have to prove to the court that the decisions the National Marine Fisheries Service made were arbitrary, capricious, an abuse of discretion, or otherwise not in accordance with the law,” said Barefoot. “That is quite a hurdle to jump, yet the coalition provides some compelling examples in the complaint.” 

Barefoot noted, for example, that in issuing the incidental harassment authorizations under the Marine Mammal Protection Act, the National Marine Fisheries Service determined that each of the five applicants could individually take—this means harass, hunt, capture or kill—one-third or more of the total species of marine mammals without having a “negligible impact” on each marine mammal species or stock. “The National Marine Fisheries Service made this decision without any consideration of whether or not the species is endangered, nor did [it] take into account the aggregate effects of the seismic air gun activities,” said Barefoot. 

Environmental groups fear that the seismic surveys are part of the Trump administration’s plans to bring offshore drilling to the Atlantic for the first time in 50 years. 

“The extent to which a ruling in favor of the environmental coalition would hamper the Trump administration’s plans depends on the findings of the court,” said Barefoot. “The court could find that the National Marine Fisheries Service violated all three laws—The Marine Mammal Protection Act, the Endangered Species Act, and the National Environmental Policy Act—or just one or two of the three. In each instance NMFS will have work to do to reconsider the decisions it made to bring them in line with the court’s opinion and the law. Regardless, a win will certainly postpone seismic activity for a period of time.”