Underwater cacophony is latest threat to belugas
Scientists have begun a major study to find out whether
beluga whales in the St. Lawrence River are suffering
from noise levels that can be so high, the mammals must
repeat themselves to be heard.
Federal scientists are mapping the sound levels experienced
by the animals, fearing the constant din of whale-watching
boats and commercial freighters might cause permanent
Belugas have been nicknamed canaries of the sea because
of their frequent vocalization. Experts say even partial
deafness could be catastrophic as hearing is their primary
sense in a murky world.
The St. Lawrence estuary is home to a dwindling population
of about 500 of the animals, decimated by whaling in the
past and more recently by pollution spewed by surrounding
Previous research has shown that when boats pass nearby,
the belugas behave much like people in a bar with loud
music, said Véronique Lesage, a Department of Fisheries
and Oceans scientist.
"They start to repeat themselves, and then yell and then
move to higher frequencies to avoid the band where the
noise is louder," she said.
"And, at some point, they just shut up and say, 'Let's
talk later,' I guess."
The St. Lawrence's beluga population was declared endangered
in 1983. Some of the chemical waste in the river has been
eliminated, but the effects of contamination are still
being found, with many belugas suffering cancerous tumours
and impairment of their immune and reproductive systems.
Research begun in the early 1990s points to another possible
hazard. Tests using underwater microphones suggest noise
in parts of the belugas' St. Lawrence habitat is loud
enough that it would cause temporary or permanent damage
to hearing in a human, concluded Peter Scheifele, a researcher
from the University of Connecticut.
Mr. Scheifele said beluga ears are sufficiently similar
to those of people to apply the same noise safety standards.
The Fisheries and Oceans study now seeks to determine
more definitively whether the whales are facing perilously
high levels of sound.
The goal is to attach instruments, including a hydrophone
(a waterproof microphone) on the backs of belugas with
suction cups fired from crossbows. The instruments would
track the movements of the whales, the sounds they make
and hear, and their response to the noise around them,
Ms. Lesage said.
Technical difficulties have delayed that part of the
experiments until next year at the earliest but, in the
meantime, researchers have begun mapping exactly where
the whales live and swim in the estuary. That information
will be matched with data on the noise underwater to determine
indirectly where belugas encounter loud noise, said Robert
Michaud, scientific director of the independent Group
for Research and Education on Marine Mammals, which is
taking part in the federal study.
"If you live in a three-dimensional world where sound
is the first means of communication, being deaf at some
specific frequency could be catastrophic," he said.
"Essentially, they are sensing their world through sounds."
The many whale-watching boats that ply the mouth of the
St. Lawrence could be the main culprits. Ms. Lesage said
their low-frequency motors tend to produce sound in the
range used by the whales to communicate.
As well, the belugas' summer range overlaps a major shipping
lane for freighters entering the Great Lakes from the
Ms. Lesage said new regulations might be necessary, but
the research will not be completed for about three years.
Whale-watching boats already have to stay 400 metres
away from belugas.
Critics of whale-watching tours off of Vancouver Island
have also raised concerns about noise pollution there.