Last month, the International Whaling Commission released a report that, for the very first time, established a firm connection between a sonar mapping tool used for offshore oil and gas exploration and the deaths of marine animals.
In 2008, about 100 “melon-headed whales” stranded in a shallow lagoon in northwestern Madagascar. Despite their name, melon-headed whales are actually a type of dolphin, found in deep oceans near the equator. They’re similar in size to a bottlenose dolphin, with dark grey coloring and a large, rounded head. At least 75 dolphins—three-quarters of those stuck in the lagoon—eventually died from dehydration, starvation, and sun exposure in the shallow waters.
Local officials, conservation organizations, and oil and gas exploration companies launched a rescue effort immediately after the stranding. As they tried to save the survivors, they also collected data and samples from dead dolphins to figure out why these dolphins would swim into shallow water, which is a deadly place for deep-water species.
After examining all the evidence, an international science review panel concluded that nearby oil and gas exploration by ExxonMobil was the most plausible trigger for the melon-headed whales to swim into the lagoon, where many ultimately perished. Before the mass death, an ExxonMobil contractor used a sonar-like device called a multi-beam echosounder to map the ocean floor near the lagoon. The device sends out acoustic blasts and uses the rebounding sound waves to create a map. The noises generated by the echosounders—like those from seismic testing—were incredibly disruptive to the dolphins. Like other cetaceans, dolphins use sound, in the form of echolocation, to find food and communicate with each other. The study concluded that the nearly-continuous wall of sound created by the echosounders covered a large area and drove these animals into the dangerous lagoon, resulting in many of their deaths.
ExxonMobil and other critics are attacking the study, claiming that it’s impossible to know for sure if their offshore acoustic activities really triggered the stranding. But the study is based on good science, and the reviewers systematically ruled out other possible triggers. Dolphins are living creatures, and we can’t put them in a lab and blast them with sound waves to see if it causes distress or injury. The panel’s comprehensive review is the closest we can come to understanding the dire consequences that human-made underwater sounds can have on marine life, and the results are solid.
There are increasing claims from around the world of marine animals dying or changing their behavior dramatically following the search for offshore oil and gas, but few of these incidents are ever comprehensively studied. By refusing to consider sound science like this report, oil companies might underestimate their acoustic impacts and needlessly jeopardize marine life across our oceans.
Oceana is currently fighting to keep similar noise-generating devices, called seismic airguns, out of U.S. waters. The government estimates that using seismic airguns on the East Coast would directly injure at least 138,500 marine mammals and would cause 13.5 million disturbances to their behavior, much like the disturbance that lead to the deaths of these melon-headed whales.
Please join our efforts to require the U.S. government to use good science before deciding whether to permit a massive expansion of geophysical activities off our coasts to search for oil and gas. We need to be sure that we won’t see a repeat of what happened to these dolphins in Madagascar in U.S. waters.
For the oceans
Chief Executive Officer
- Sea Turtles Can Get the Bends after Capture in Fishing Gear, Says New Study Posted Tue, November 25, 2014
- Ocean Roundup: North Atlantic Right Whales Calving in Southeast, New Shark Repellent Tested in South Africa, and More Posted Thu, November 20, 2014
- Ocean Roundup: Dolphins Use Whistles as Names, Conservationists Call for Removal of Queensland Shark Nets, and More Posted Mon, November 24, 2014
- Creature Feature: Ocean Sunfish Posted Thu, November 20, 2014
- Oceana in Chile Submits Recommendations for Lowering Common Hake Catch Quotas Posted Mon, November 24, 2014