VANCOUVER, B.C. — The battle to ensure a safe haven for killer whales in Pacific Northwest waters resumes in federal court in Vancouver.

An environmental coalition says lawyers for the Department of Fisheries and Oceans will ask the court to toss out a lawsuit launched last fall by coalition members including Ecojustice and the David Suzuki Foundation.

According to the coalition, DFO will argue a regulation issued in February adequately protects the critical habitat of Northern and Southern resident killer whales in the Pacific Northwest.

But environmentalists want their full lawsuit heard because if it is successful, it will require Canada's Species At Risk Act be used to protect critical habitat of all endangered aquatic species.

They say the federal regulation issued two months ago only protects geophysical features of the whales' critical habitat but doesn't address threats to salmon populations, which are the orca's main food source.

Almost 300 endangered or threatened killer whales live off the B.C. coast but numbers of Southern resident orcas dropped 20 per cent between 1993 and 2003 before recovering slightly while the population of Northern resident whales has fallen about seven per cent in recent years.b