A mass stranding of 100 melon headed whales
(Peponocephala electra) in a Madagascar mangrove lagoon was caused by sonar mapping conducted by Exxon-Mobil. That is the conclusion of an independent scientific review panel which studied the 2008 event. Wildlife Conservation Society with assistance from the International Fund for Animal Welfare sent in a stranding team to the Loza Lagoon in northwest Madagascar to return live whales to the sea and perform necropsies on dead whales. The
review panel concluded, "the potential for behavioral responses [fleeing] and indirect injury or mortality from echosounder systems should be considered in future environmental assessments, operational planning and regulatory decisions." The United States Navy, when confronted with objections to sonar operations from environmentalists, often responds with a claim there is no scientific evidence of a link between strandings of marine mammals and sonar use. Not any more,
buddy.
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| credits: T. Collins/WCS |
The Loza even was unusual because despite its remote location, it was scientifically documented within days of its occurrence. The species is a deep water variety and had never been previously known to be present in the shallow tidal estuary. The melon heads entered the bay on May 30, 2008 after an initial triggering event. Seventy-five died over the following weeks. The triggering event was most plausibly the use of echo sounding equipment by a survey ship very close to the stranding event. The 12kHz multi-beam echo sounder equipment was known to be operating in the mammal's hearing range of 10-100 kHz. Dr. Howard Rosenbaum of WCS said, the review "adds to the mounting body of evidence of the potential impacts of anthropogenic noise on marine mammals. Implications go well beyond the hydrocarbon industry, as these systems are used aboard military and research vessels for generating more precise bathymetry."
