A draft minute from the state's chief wildlife management officer recommended eight areas of reserve land used traditionally over duck hunting season not be opened to protect duck populations.

It said the Tasmanian duck population was considered an important source of breeding stock to repopulate wetlands in mainland states.

It said other states had taken measures to better protect their duck populations and Tasmania should take a conservative approach to duck hunting in 2020.

Greens leader Cassy O'Connor said the government had a responsibility to rein in duck hunting following department advice that it was unsustainable.

"As a former government minister, I find it hard to believe that Mr Barnett did not see this advice," she said.

"If the minister hasn't seen this advice, it is deliberate and that's concerning."

Ms O'Connor said the department needed to release results from this year's waterfowl survey to prove numbers were sustainable.

BirdLife Tasmania convenor Eric Woehler said Tasmania was a refuge for mainland waterfowl escaping drought.

"It's utterly indefensible for the minister to ignore the advice from his department," he said.

"To shoot mainland birds while they are sheltering in Tasmania cannot be justified, and destroys any claims of sustainability by the Tasmanian Government."

Primary Industries Department secretary Tim Baker said the draft minute obtained under Freedom of Information laws was produced before survey results were compiled which showed no significant wild duck decline in 2020.

"The draft minute obtained by the media relating to wild duck hunting was not provided by my department to Minister Barnett," he said.

"The decision to allow access for wild duck hunting is not a decision made by the minister and instead is the responsibility of the Director of National Parks and Wildlife and Director General of Lands.

"Minister Barnett therefore had no involvement in the decision."

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