Environmental groups have filed a lawsuit in federal court against the Department of Fisheries alleging it has failed to legally protect the critical habitat of killer whales.

Six organizations -- the David Suzuki Foundation, Greenpeace, Western Canada Wilderness Committee, Raincoast Conservation Society, Environmental Defence, and the International Fund for Animal Welfare -- hope the lawsuit will force the government to take concrete measures to protect the habitat of B.C.'s most iconic marine mammals, which are threatened by increased boat and tanker traffic, toxic contamination, and acoustic impacts from military sonar tests, seismic testing and dredging.

"B.C.'s endangered species deserve better," said Gwen Barlee, policy director of the Wilderness Commitee in a release.

"DFO's decision not to protect critical habitat of resident killer whales is symptomatic of the federal government's widespread failure to implement the Species at Risk Act."

Lara Tessaro, staff lawyer at Ecojustice, said the lawsuit is unprecedented in Canada and is only being used as a last resort after an unsuccessful two-year battle between concerned scientists and the federal government about the need to apply the Species at Risk Act to whales' habitat.

There are 87 southern resident killer whales and 240 northern resident killer whales left in B.C. waters.

They are also threatened with extinction by declining salmon stocks.

Some whales off the coast of southern Vancouver Island have been losing blubber, said scientists -- a clear sign they are having difficulty finding food due to extremely low supplies of chinook and other salmon stocks.