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Sonar Blamed for Mass Stranding of Melon-Headed Whales



Four years ago, about 100 melon-headed whales mysteriously entered a shallow lagoon system in northwest Madagascar and became stranded. Now scientists say the creatures’ demise was likely brought on by sonar used to map the ocean floor for ExxonMobil.

Previous research has suggested that sonar can be harmful to marine mammals. The underwater noise can mask the calls of dolphins and whales and scare them away from their feeding grounds. Naval exercises using sonar have been linked to a 2008 stranding of at least 60 dolphins along the coast of Cornwall, England.

But researchers say the new findings from Madagascar mark the first time a marine mammal mass stranding has been closely tied to high-frequency sonar mapping.

From May to June 2008, about 100 melon-headed whales (Peponocephala electra) swam into Madagascar’s shallow, tidal Loza Lagoon system, a highly unusually environment for the toothed whales, which usually stick to the open ocean.

An independent review panel made up of five scientists considered a wide range of possible explanations for the mass stranding, including disease, toxins, vessel strikes, storm conditions and unusual acoustic events.

The panel wrote in their newly published report that on May 29, 2008, a day before the first stranding occurred, a survey vessel contracted by ExxonMobil Exploration and Production (Northern Madagascar) had been using a high-power 12 kHz multi-beam echosounder system to map the ocean floor about 40 miles (65 kilometers) offshore. Multibeam sonars send out sound waves in a fan shape beneath a ship’s hull to produce a map of the seafloor.

The 12 kHz sonar emitted by the survey vessel is within the frequency of best hearing sensitivity for melon-headed whales, the panel wrote. But these sounds at the 120-decibel level would be well above the hearing threshold the whales.

The scientists concluded that the sonar mapping was the most “plausible and likely behavioral trigger for the animals initially entering the lagoon system.”

“Implications go well beyond the hydrocarbon industry, as these sonar systems are widely used aboard military and research vessels for generating more precise bathymetry (underwater mapping),” Howard Rosenbaum, director of the Ocean Giants program for the Wildlife Conservation Society, said in a statement.

“We now hope that these results will be used by industry, regulatory authorities, and others to minimize risks and to better protect marine life, especially marine mammal species that are particularly sensitive to increasing ocean noise from human activities,” Rosenbaum said.

ExxonMobil, meanwhile, disputed the findings.

“ExxonMobil believes the panel’s finding about the multi-beam echo sounder is unjustified due to the lack of certainty of information and observations recorded during the response efforts in 2008,” said Patrick McGinn, a spokesman for the company.


Roots Red Sea is the Travelers’ Choice



There is a remote spot on the coast of the Egyptian Eastern Desert that has been steadily developing an enviable reputation amongst the worlds diving community. It’s absolutely no surprise then that Roots Red Sea has just received TripAdvisors top award, Travelers Choice, the 10th year running it has been recognised with awards from TripAdvisor!

With a passing glance, many divers have dismissed a visit to this gem, its rustic appearance and remote location seemingly enough to deter further consideration. However, those that take a closer look have been rewarded with simply a totally unique experience with awesome diving, an unbelievable welcome and life long memories.

Winning an award once could be luck, every year for 10 years, there has to be a reason. Why not go to find out what it is?

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Miscellaneous Blogs

The BiG Scuba Podcast… with Nays Baghai



Gemma and Ian chat to Nays Baghai. Inspired by The Blue Planet as a child, Nays’ work as an underwater cinematographer and photographer has been showcased by numerous premier brands, including Rolex and Sony Alpha.  Nays was featured amongst the Top 30 finalists of the Australasian Top Emerging Photographers competition in the Portfolio and Animal categories. He is a PADI-certified Freediving Instructor and Master Scuba Diver, and can dive to 40m both with and without tanks.

Have a listen here:

Find out more:

Find more podcast episodes and information at the new  website and on most social platforms @thebigscuba 

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A luxurious dive resort in the heart of Lembeh Strait. Enjoy refined services while exploring the rich waters of Indonesia.

The resort is nestled around an ocean front deck and swimming-pool (with pool-bar) which is the perfect place to enjoy a sundowner cocktail at the end of a busy day of critter-diving.

All accommodation is full board and includes three sumptuous meals a day. Breakfast and lunch are buffet meals and in the evening dining is a la carte.

Book and stay before the end of June and benefit from no single supplements in all room types!

Booking deadline: Subject to availability – book and stay before end of June 2022

Call Diverse Travel on 01473 852002 or email

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