News
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.
Fire on Monroe Bravo is the latest book in the Jack Collier series by Fred Lockwood. Our story begins with our lead characters, Jack and Sandro, owners of Marine Salvage & Investigation Company, arriving on the Monroe Bravo Oil & Gas Platform in the North Sea. Having secured a contract for their vessel the MV Stavanger to act as support ship to the platform for TransGlobal Oil, our protagonists are on a celebratory visit.
However almost as soon as they arrive a series of explosions rock the platform, causing huge damage, loss of life and the very real danger of a massive human, ecological and financial disaster.
As the danger mounts for both our heroes and the surviving workers, Jack and Sandro will have to escape the inferno, all while trying to save the platform and the men still trapped unable to help themselves.
The disaster sets the scene for the unfolding story lines following the fate of the platform and our main characters, the police investigation into a suspected terrorist act and the actions of TransGlobal Oil as they attempt to navigate the pubic outcry and financial repercussions.
In his eighth book, Fire on Monroe Bravo, Fred Lockwood delivers an explosive thriller, with plenty of above and in-water drama, and our heroes fighting for survival, what more can you ask for?
We thoroughly recommend this read and look forward to the next in the series. For more information about his book series, you can check out the reviews of his previous books here on Scubaverse.
- Title: Fire On Monroe Bravo
- Author: Fred Lockwood
- ISBN: 979-8325324536
Available in a paperback version and for Kindle from Amazon and book stores.
In June we were incredibly fortunate to be invited to dive in Alonissos, a small Greek Island in the Sporades island chain located in the North Aegean Sea. While I have long been a big fan of the Greek Islands as a great holiday destination, I had not had the opportunity to do any diving on previous visits and Mike and I were extremely excited to see what Alonissos had to offer both above and below the surface!
The Sporades are easily accessible via the airport in Skiathos (the first island in the chain), which is served by Jet2 flights from all major UK airports from May through October. Numerous ferries and charter boats make island hopping from Skiathos Town a breeze. After an hour boat ride, the picturesque port of Patitiri was a wonderful introduction to Alonissos, where we were met by our gracious hosts Kostas of Albedo Travel and Dias of Alonissos Triton Dive Center. Mike and I were delighted to be staying at the Paradise Hotel, aptly named for its stunning views over the sea and great location for walking to the waterfront.
Alonissos is beautifully situated in the National Marine Park of Alonissos and the Northern Sporades, the largest marine protected area in Europe. The surrounding seas offer fabulous marine life, including incredibly rare species such as the Mediterranean monk seal. They boast deep walls covered in gorgonians and sponges, stunning topography with caverns, swimthroughs and pinnacles, and the first accessible ancient shipwreck from 500BC!
In locations where historical sites have been reported, the waters are largely restricted, but with collaboration between government, underwater archeologists and dive centres, incredible underwater museums are being created for a truly unique diving experience. Alonissos is home to the first of these, the Ancient Shipwreck of Peristera Accessible Underwater Archeological Site. The chance to dive into history (along with reports of healthy reef life and amazing underwater topography) meant Mike and I were keen to get in the water.
Our introduction to the diving around Alonissos was at the Agios Georgios Pinnacles, in the channel between Alonissos and Skopelos. This fantastic site was named “The Chimney,’ and proved to have a huge amount to see. We got to a decent depth here (over 25m), and marvelled at a colourful reef wall with a wonderful swim through whose rocky walls were absolutely covered with life. As well as brilliant topography there was no shortage of macro life here. We saw numerous nudibranchs, five different species in total. The second dive at Mourtias reef nearby was a shallower dive along a nice wall with lots of crevices. Several moray eels and grouper called this site home. We enjoyed looking in the crevices for lobster and smaller benthic life, such as cup corals and tunicates.
Our itinerary allowed us two dives a day with afternoons left to explore the island with our hire car and evenings to enjoy the famous Greek hospitality. This proved to be a lovely mix of in-water and land based diversions.
The next days diving to the Gorgonian Gardens and Triton’s Cave was to be even better! These two stunning sites are nothing short of fabulous. The Gorgonian Gardens was a deep wall near to the Agios Georgios islands. The ever-present currents in this deep channel meant that the sea life was amazing … the namesake Gorgonian sea fans dotted the wall at a depth of 30 to 50 meters, getting ever larger the deeper we went. Above 30m was by no means less beautiful, with sponges, corals, scorpionfish, moray eels and some rare and colourful nudibranchs.
The second shallower dive of the day was to Triton’s Cave or the Cavern of Skopelos, on the east side of that island. The spectacular rock formations had wild striations both above and below the water making a truly epic topography. The cavern entrance was at 14m, and big enough for a buddy pair, winding up to 6m and passing two beautiful windows out into the blue. Emerging from the cavern, the light at the shallower depths and the incredible rock formations made for a fantastic gentle swimming safety stop and we all surfaced by the boat with massive grins.
Check out our next blog :Alonissos: The complete diving destination (Part 2)” to hear about our amazing dive on the 2500 year old Peristera Wreck!
Thanks to:
Alonissos Triton Dive Center https://bestdivingingreece.com/
Albedo Travel https://alonissosholidays.com/activities/
Paradise Hotel https://paradise-hotel.gr/
Alonissos Municipality https://alonissos.gr/en/
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