Vocal communication is a primary key to survival for many species, including the Arctic Ocean's bearded seals. According to the National Ocean and Atmospheric Administration (NOAA), bearded seals live throughout polar Arctic and sub-Arctic waters, and their distribution is closely tied to seasonal sea ice. In addition to their thick and sometimes curled white whiskers—which earned them the "bearded" name—this species is known for its unique and loud vocalizations. NOAA states that they can be heard for up to 12 miles, which is vital during breeding season as males try to locate and impress females with these calls.
Can bearded seals compete with increasing noise levels in the Arctic as decreased sea ice levels allow for more shipping traffic and other human activities? According to a new study from Cornell Lab of Ornithology's Center for Conservation Bioacoustics (CCB), bearded seals will not be able to compensate to be heard above surrounding noise levels. This study was published last month in Proceedings of the Royal Society: Biological Science.
In a quote to the Cornell Chronicle, Michelle Fournet, study lead and CCB postdoctoral researcher, said, "the goal was to determine if there was a 'noise threshold' beyond which seals either couldn't or wouldn't call any louder in order to be heard." She continued that once they established a threshold, they could determine and recommend a noise level limit to protect these seals from the excess human noise.
According to the Cornell Chronicle, the research team recorded and reviewed thousands of bearded seal calls from Arctic Alaska over two years. They measure the call and compared it to ambient noise conditions. The article reports that although bearded seals do vocalize louder to overcome ambient noise, there is an upper limit to their ability to do so. The study concluded that "as ambient noise conditions increase, the distance over which individuals can be detected goes down."
Fournet states that since the loudest calls are for reproductive reasons, the males are probably calling as loudly as they possibly can to be heard by females. Now that a threshold has been determined, she is hopeful that stakeholders in the regions where bearded seals live "can make responsible management choices moving forward."
The Cornell Chronicle also reports that Native communities in the Arctic depend on bearded seals for subsistence and cultural activities. If increasing noise levels threaten bearded seal survival in the Arctic, the communities are threatened as well. Fournet stated, "this work never would have happened without the insight and guidance of the Arctic communities."