Prominent scientists and environmental groups are urging the federal Liberals to hurry up and repair what they see as damage to fisheries done by the previous government.

"We request that previous habitat protections be immediately reinstated in the Fisheries Act," says a letter signed by 47 individuals and organizations.

The signatories run from the World Wildlife Fund to the B.C. Federation of Fly Fishers and include researchers such as David Schindler from the University of Alberta, whose work revealed some of the earliest evidence that the oilsands were releasing contaminants.

"The time to start is quickly," said signatory John Smol, an ecologist at Queen's University in Kingston, Ont.

"Delay in the environment costs us dearly. Nature is very slow to pardon mistakes."

Repeal sought of Tory law

The letter asks Federal Fisheries Minister Hunter Tootoo to repeal changes made under the Harper Conservatives in a controversial 2012 omnibus bill. Those changes removed prohibitions against the harmful alteration, damage or destruction of any fishery. Attention was instead focused on commercial fisheries.

Nature is very slow to pardon mistakes. - John Smol

"One of the biggest factors that affect fish abundance is habitat," said Smol. "We have to restore habitat protection."

Smol pointed out the changes came as fisheries began to face threats, including climate change, invasive species and new contaminants.

"If anything, we have to strengthen the act. Instead, it was weakened."

Protecting commercially valuable fish without protecting the habitat for all fish just doesn't work, said Linda Nowlan of the West Coast Environmental Law Centre.

"I don't think we humans are capable of picking which parts of nature need protection. You need to look at the ecosystem as a whole."

Mandate letter ordered changes

Tootoo has been instructed by Prime Minister Justin Trudeau to restore the protections.

Prominent Alberta researcher David Schindler is among those lobbying the Liberal government in Ottawa to repeal legislative changes made in 2012. (CBC)

"Work with the minister of transport to review the previous government's changes to the Fisheries and Navigable Waters Protection Acts, restore lost protections and incorporate modern safeguards," says Tootoo's mandate letter from Trudeau.

After he gets done with that, Tootoo can move on to reforming the 150-year-old act to put science at its heart and with a view to the future, Smol suggested.

"We want long-term thinking. We don't want typical mandate thinking of four years."

An amended act should limit the discretion of politicians to override scientific evidence and enshrine cautions that ensure future generations enjoy the same fisheries as Canadians do today, said Nowlan.

"They need to make their decisions in accordance with modern environmental law principles."

Thursday's letter is the latest open letter from scientists hoping to influence government policy. Two such letters this month — one criticizing studies into liquefied natural gas exports in British Columbia and another discouraging investment in fossil fuel infrastructure — have already been sent to the federal Liberals.

Scientists are hoping the new government will listen more closely to their warnings than did the previous administration, Smol said.

"We're seeing the muzzling of scientists being changed. We have issues that we think need looking at and we think we have a government that will pay some attention to it."