The destruction of over 100 melon - guide whales , which stranded on the shores of a lagoon in northwesterly Madagascar in 2008 , were belike primarily trigger by a manikin of sonar being deployed by an ExxonMobil survey vessel , according to a scientific limited review board .
This is the first known nautical mammal mass stranding outcome to be intimately associated with what are be intimate as eminent - frequency chromosome mapping asdic system of rules ; but it is merely the latest in a long line of products of incidents in which industrial randomness in the ocean has been implicate in deaths and injuries to marine mammals , and specifically cetaceans .
One area of particular focus is theuse of active sonarby the United States and other navies . In 2004 , the Scientific Committee of the International Whaling Commission close that “ there is now compelling evidence implicating military sonar has a lineal impact on beak giant . ” In 2001 , the U.S. Navy acknowledged that its fighting echo sounder played a theatrical role in the stranding deaths of 14 beaked whales , two minke whales , and a dolphin in the Bahamas in 2000 . post-mortem of the beaked whales reveal that the animate being had suffered acoustic trauma result in bleed around the wit , in the inner ears , and in the acoustic adipose tissue locate in the straits that are involve in sound transmission .
Then there is theuse of air gunsto conduct seismic surveys for oil color and gas deposits in the sea seam . Because of business concern that the acute sounds from these tune guns can either cause physical scathe to cetaceans or stimulate them to flee , the U.S. Marine Mammal Protection Act requires visual observer to try out the domain for marine mammals for a flow of at least 30 minute . Assuming the coast is clear-cut , the survey must rage up slowly by firing first one seismic gunman and then others over a period of between 20 and 40 moment . However , if a hulk or other maritime mammal appears within an exclusion zona of 500 metre from the sum of the seismic raiment , the operation must shut down , and visual examination must resume for 30 minutes .
The presence of seismal survey vessels was initially considered a potential reason for the 2008 Madagascar incident , not least because melon - head whales are an open - sea species that had never before ( and have never since ) been recorded in the island ’s shallow tidal Loza Lagoon estuarine system ; it seemed reasonable to infer that something had start them into put down the area . expert with the International Fund for Animal Welfare and the Wildlife Conservation Societyattempted to rescue the whales , but with minimal succeeder , largely because of the large distance ( over 69 km/43 mil ) from the head where they were becoming stranded to the open ocean .
However , a vas using a dissimilar eccentric of surveying proficiency — a high - power 12 kHz , multi - beam echosounder system ( MBES ) — was , order the report , “ moving in a directed manner down the shelf - break the 24-hour interval before the event , to an sphere approx . 65 km offshore from the first acknowledge stranding location . The ISRP deemed this MBES enjoyment to be the most plausible and potential behavioral trigger for the animals ab initio get in the lagoon system . ”
Most tending has sharpen on the likely impacts of mid - frequency and low - frequency sound source , because of their bang-up generation through water ; it is possible , the ISRP note , that high-pitched - frequency sound like the MBES also touch on some cetaceans more than antecedently realized but that , under normal circumstances , those cetaceans drown forth . It was to the considerable misfortune of those melon - lead whales five year ago that they were in the improper position at the wrong time , and that when they change by reversal tail and fled , they swam into an inhospitable area from which there was no evasion .
“ implication go well beyond the hydrocarbon industry , as these sonar system are wide used aboard military and research vessels for bring forth more exact bathymetry ( submersed mathematical function ) , ” Howard Rosenbaum , director of the Ocean Giants programme for the Wildlife Conservation Society , tell in a statement . “ We now go for that these results will be used by manufacture , regulative authorities , and others to minimize risk and to well protect maritime life , specially marine mammal species that are in particular sore to increase ocean haphazardness from human activities . ”
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