The blue whale population on the West Coast is on the rise, according to researchers who photographed this one off Bodega Bay, Calif. (Gretchen Steiger/Cascadia Research)

Federal government lawyers are asking the Federal Court to toss out a legal attempt by a coalition of environmental groups to stop a U.S. research vessel from doing controversial seismic testing off the west coast of Vancouver Island.

The ongoing campaign resumed in Federal Court in Ottawa on Tuesday with an injunction application from the environmental law organization Ecojustice, which is representing several groups opposed to the research.

Columbia University researchers want to spend a month mapping the sub-surface of the sea floor where earthquake-causing tectonic plates diverge.

'We're seeking to turn this ship around, to uphold Canadian environmental laws and to prevent whale harassment in Canadian waters.'—Lara Tessaro, lawyer for Ecojustice

But Ecojustice says the ship's 36-gun towed seismic array would send 180-decibel blasts into the water every couple of minutes, which would create a noise as loud as an army artillery piece going off.

The proposed seismic tests would threaten endangered whales in the Endeavour Hydrothermal Vents — a protected Canadian marine area about 250 kilometres off the coast of British Columbia, according to Ecojustice.

Testing underway with 'mitigation measures'

The ship Marcus Langseth set sail from the northern Oregon coast on Saturday, said Kori Brus, communications director for Ecojustice.

But in court on Tuesday, lawyers for Foreign Affairs Minister Lawrence Cannon said Ottawa demanded and received various "mitigation measures" from Columbia University last week before granting permission for the research to begin.

The ship, which produces 3-D images of seabeds for geological research, has reduced the maximum sound level of seismic charges from 180 to 160 decibels.

It will also have a number of federally approved observers who will ensure no marine mammals such as whales are within 7.7 kilometres of the blasts.

The government argued the changes make the injunction application out of date and unreflective of what is actually taking place this week some 250 kilometres off Vancouver Island.

Harassing whales illegal

The Ecojustice lawsuit alleges that Canada's minister of foreign affairs cannot grant clearance to a foreign vessel that will harass marine mammals in violation of Canadian law.

"In Canada, it is illegal to disturb and harass whales and dolphins," said Ecojustice staff lawyer Lara Tessaro.

"The reason marine protected areas exist is to keep harmful activities from occurring in special areas that protect the animals living there, including endangered species like blue whales.

"We're seeking to turn this ship around, to uphold Canadian environmental laws and to prevent whale harassment in Canadian waters."

With files from The Canadian Press