Scientists have finally uncovered that the increasing phenomenon of beaked whales stranded on beaches are often times the direct result of naval mid-frequency active sonars being used to track submarines. Read on as Terence Koh investigates.
The phenomenon of whales and cetaceans beaching themselves in mass stranding events has frequently been explained by some scientists and media outlets as unexplained “suicidal” behaviour caused by some unknown misalignment of the whales’ “sonar” abilities underwater. In findings published by The Royal Society B entitled Advances in research on the impacts of anti-submarine sonar on beaked whales, it has finally been determined that most of the “atypical mass stranding events” of beaked whales are caused by naval mid-frequency active sonars deployed by ships and submarines. Deployed by the US Navy at 235 decibels underwater, these sonar waves can resonate around the whale’s ear causing tissues to tear. These sonar waves cause such intense fear and stress in beaked whales that they ascend to the surface too quickly and suffer decompression sickness, like scuba divers, eventually dying of “the bends”.
Typical vs Atypical Mass Stranding
Typical mass strandings of whales are defined as two or more cetaceans beach themselves while alive at approximately the same time and location. This could be due to sickness, disorientation, or being chased into shallow water by a predator.
A typical mass stranding of whales are defined as two or more whales are found washed up within a 6-day period no more than 74 kilometres apart  . These atypical mass strandings are most often associated with sound .
In the US Navy’s new draft environmental impact statement, it is stated that the sonar exercises planned for 2014 to 2018 may unintentionally “harm marine mammals 2.8 million times over five years.” This estimate includes two million incidents of “temporary hear loss” and 2,000 cases of permanent hearing loss. Without the ability to hear, there is no way for whales to navigate, communicate and find food – effectively handing them a death sentence.
According to the findings written by Y. Bernado de Quirós, A. Fernandez, R.W. Baird, R.L. Brownell, N. Aguilar de Soto, D.Allen, M. Arbelo, M. Arregui, A. Costidis, A. Fahlman, A. Frantzis, F.M.D.Gulland, M. Iñíguez, M. Johnson, A. Komnenou, H. Koopman, D. A. Pabst, W. D. Roe, E. Sierra, M. Tejedor and G. Schorr, before the 1960s, there were only about 15 reported cases of mass strandings of beaked whales worldwide and none of these were atypical mass stranding events. Using frequencies of 8KHz or higher, naval mid-frequency active sonars (MFAS) were developed in the 1950s to detect submarines in the oceans around the world. When these mid-frequency active sonars onboard naval vessels were shifted to frequency ranges of 4.5 to 5.5 KHz, atypical mass stranding events around the world increased as did the number of species affected . Between 1960 and 2004, there were 121 reported cases of atypical mass strandings of beaked whales .
The first case of Curvier’s beaked whales (Ziphius cavirostris) happened in Corsica, France, and was followed by beachings in Italy, the USA and the Bahamas during the 1960s . The causal relation of atypical beaked whales mass stranding events to naval exercises was first observed in the Canary Islands, Spain in the middle of the 1980s .
In September 2002, 14 beaked whales were stranded in the Canary Islands during a NATO naval exercise where mid-frequency active sonars were used. In 10 necropsies (animal autopsies) performed on the deceased whales, disseminated microvascular haemorrahages associated with widespread gas and fat emboli within blood vessels and vital organs were found – classic symptoms of decompression-like sickness . When a ban on mid-frequency active sonars around the Canary Islands was enacted in 2004, beaked whales mass stranding events in the area stopped.
In an experiment conducted at the Southern California Blight, blue whales (Balaenoptera musculus) were tagged to find out how they would respond behaviourally to mid-frequency active sonar. Even though the sound levels used in the experiments were far below that of most military systems, the blue whales in the experiment stopped feeding, increased their swimming speed in order to move away from the source of the sound .
Besides beaked whales, pygmy sperm whales (K. breviceps), pygmy killer whales (Feresa attenuata), dwarf sperm whales (Kogia sima), short-finned pilot whales (Globicephala macrorhynchus), pygmy sperm whales (K. breviceps), long-finned pilot whales (G. melas); and several dolphin species (Stenella attenuataand S. coeruleoalba) have also stranded due to naval exercises 
Besides mid-frequency active sonars, the proliferation of commercial ships on the oceans around the world also contribute to the noise pollution underwater. The amount of noise from commercial shipping activities cause cetaceans to stop feeding activities and swim away with long term exposures to noisy underwater environments leading to long term hearing loss as well.
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