A relatively small freshwater fish, the Nooksack dace takes its name from a river in Washington state, according to the DFO website. ((Mike Pearson/Fisheries and Oceans Canada))

The federal Department of Fisheries and Oceans will have to answer in court allegations that it has been defying endangered species legislation.

A Federal Court in B.C. has dismissed the department's effort to have a lawsuit by environmental groups tossed out.

The environmental groups allege that, contrary to the Species at Risk Act, the provincial and federal governments colluded in refusing to identify the habitat needed for the survival of the Nooksack dace, an endangered species of fish found in some Fraser Valley streams.

Lara Tessaro, a lawyer with Ecojustice, formerly the Sierra Legal Defence Fund, said her group filed the lawsuit against the fisheries department on behalf of Environmental Defence, Georgia Strait Alliance, the David Suzuki Foundation and the Wilderness Committee.

"The concern of many environmental groups in Canada is that there appears to be a very widespread practice of government refusing to identify critical habitat in recovery strategies," Tessaro said.

A recovery strategy is a recovery plan for an endangered species that sets out all the science related to a species, she said.

"An important part of that plan is the identification and mapping of that species' critical habitat, what a species needs to survive and recover," Tessaro said.

Tessaro said the current case is about the government's duty to identify critical habitat for the dace but has the potential to extend to other species.

"We are hoping to achieve at the end of the day a judicial ruling that DFO and other federal agencies can't rely on various excuses to stop identifying critical habitat," she said.

The lawsuit said specifically that the federal fisheries department failed to identify the critical habitat of the Nooksack dace in a recovery strategy released last year.

The department said it has now released a revised recovery strategy for the small fish.