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Coastal cacophony deafening to seals

When seals speak, Jack Terhune listens.

The University of New Brunswick Saint John biology professor has travelled as far afield as the Antarctic to figure out exactly how the aquatic mammals communicate, and, once he’s cracked that code, how noise from human activity is interfering with that.

“Its not simply if there’s noise, you’ll have death and destruction,” he says.

“Just the amplitude of the noise may drive them out of the way and cause them to occupy a less optimal habitat.”

Terhune and other researchers worldwide are increasingly concerned about the effect of noise from offshore wind farms, increased Arctic shipping and seaside construction projects.

He says that it is possible the noise from those activities could be interfering with some seal species’ ability to communicate effectively and, thus, to attract mates. In other cases, it may simply drive seals away into other parts of the sea that may have less optimal conditions.

Terhune says the consequences of drowning out seal calls could be far-reaching.

“Whenever top-level predators have a population change either up or down, that tends to have impacts that ripple through the eco-system, and that can impact on other species, but also the commercial fisheries,” he warns.

“But the total impact on the population is extremely difficult to measure. We don’t even know how many seals there are in the Bay of Fundy.”

Depending on the species, seal calls range from low whistles to loud shouts, often made underwater for up to a minute, and Terhune says some are louder than a human yelling in open air.

The millions of seals in Atlantic Canadian waters, with Newfoundland harp seals alone numbering between 5.5 and 6.5 million, rely on that communication to socialize and attract mates. Some seal calls can be heard as far as 30 kilometres away, and each seal call is distinctive enough that individual seals can he heard clearly even in large groups, a phenomenon Terhune calls the “cocktail party” effect.

Terhune will be taking his research to a conference on the effect of underwater noise on sea life in Nyborg, Denmark, from Monday to next Friday. Aside from other scientists, there will also be representatives from industry and shipping.

Dr. Arthur Popper, one of the conference’s organizers and an expert in underwater noise from the University of Maryland, says the presence of the non-scientific representatives is key to having the gathering produce real-world effects.

“Were hoping that by putting them in the position where they’re hearing science from the scientists, we’ll be educating them in what they should be regulating, how they’re producing the sounds, what they can do to mitigate (them),” he said.

Denmark has some of the world’s largest off-shore wind farms, whose gear boxes produce a continuous, low-frequency sound.

But Sara MacIntyre, a spokesman for wind power firm NaiKun, which is developing a 1,750 megawatt offshore wind farm off the coast of British Columbia, says facilities such as these already undergo complicated environmental impact assessments that take noise pollution into account.

She says Danish research into the subject debunks theories that the windmills hurt sea life.

“Obviously, we don’t want to have any foregone conclusions, but judging from past experiences, its been negligible with respect to impact on marine life,” she said.

New Brunswick is considering wind power in a bid to increase the proportion of renewable energy the province uses, but a spokesperson for NB Power says it currently has no plans for offshore facilities.

By Daniel Martins


9 August 2007