An independent scientific review panel has concluded that the mass stranding of approximately 100 melon-headed whales in the Loza Lagoon system in northwest Madagascar in 2008 was primarily triggered by acoustic stimuli, more specifically, a multi-beam echosounder system operated by a survey vessel contracted by ExxonMobil Exploration and Production (Northern Madagascar) Limited.
In response to the event and with assistance from the International Fund for Animal Welfare, the Wildlife Conservation Society led an international stranding team to help return live whales from the lagoon system to the open sea and to conduct necropsies on dead whales to determine the cause of death.
According to the final report issued Wednesday, this is the first known marine mammal mass stranding event of this nature to be closely associated with high-frequency mapping sonar systems. Based on these findings, there is cause for concern over the impact of noise on marine mammals as these high-frequency mapping sonar systems are used by various stakeholders including the hydrocarbon industry, military, and research vessels used by other industries.
The report concluded of the multi-beam echosounder systems: “The potential for behavioral responses and indirect injury or mortality from the use of similar MBES should be considered in future environmental assessments, operational planning and regulatory decisions.”
The Wildlife Conservation Society and the International Fund for Animal Welfare welcomed the report and praised all those involved in the process.
While aspects of the stranding remain unknown, the panel concluded that a multi-beam echosounder system, operated intermittently by a survey vessel moving down the shelf-break the day before the event was the most plausible and likely behavioral trigger for the animals initially entering the lagoon system.