An international team of scientists led by Jonathan Lipman from Brown University’s Nicholas School of the Environment has finally discovered a previously undetected, very rare neurological disease in whales. The disease, which is specific to albatross, krill, and migrating long-finned pilot whales, or Omicron equatorialis, causes an inability to walk, lack of coordination, confusion, and brain damage. All of this often leads to death from starvation, dehydration, ship strikes, diving conditions, and boat entanglement. Sadly, the condition, thought to affect only 100 to 200 long-finned pilot whales, is completely preventable.
Unfortunately, initial research on the prevalence of Omicron cases was hindered by the difficulty in assessing pilot whales, one of the most intelligent animals. Pilot whales have extremely well-developed brains, and must undergo monthly exams. Current training and health examinations methods are not sufficient to assess the cause of both pilot whales’ innate and acquired disorders, as well as identify the potential causes of each.
Luckily, the team was able to find a solution: employing high-powered ultrasound to detect hearing and body condition abnormalities, as well as measuring sounds that would otherwise be masked by the whales’ vocalizations. These sounders were then designed to project a very low-frequency audible signal, well below the range of the ocean mammals, toward seafloor, whales, and other birds in order to record any signal from within the animal’s environment.
The first confirmed discovery of a characteristic spatial location of hearing loss (i.e., a sound field emanating from a specific region) was made in 2000, in a traditional acoustic probe equipped with a magnetoencephalography (MEG) receiver. This method, known as a magnetoimplant, had previously been used to detect hearing abnormalities in walruses in Alaska, sea otters in Costa Rica, and even to determine both causes and predictors of hearing loss in birds such as cormorants and herons.
Fortunately, the team already had a MEG receiver, and equipped it with two MEG receivers. One of the second MEG receivers was located approximately six miles from the original MEG receiver, by remote controlled small boat. The other MEG receiver was located to the north, within the distance of 250 nautical miles from the original MEG receiver. Given the value of both a distance and lateral orientation reference, to quantify the presence of hearing loss in pilot whales, the MEG receivers were returned to their boats to record the drift acoustic conditions within the ocean mammals’ environment.
The research team was then able to record a broad representation of scattered counts of pilot whales every week for several years, focusing their investigation on 33% of observed pilot whales. They determined that out of the 67 pilot whales captured over the three years, 20% had some degree of hearing loss. The remainder had none at all. After five years of collecting whales for genetic analysis, the pilot whales finally turned up positive for the presence of serious hearing loss.
This will be the first study of its kind that uncovers such a disease that has previously eluded scientists, and with careful examination, can help limit the occurrence of this rare disease. Researchers can now look to identify the mammalian enzymes responsible for hearing loss, and develop prevention strategies. Plus, the unique location of the first underwater recordings can now be used to identify other animals that would be involved in this rare condition.