In its annual report, the Game Management Authority said shooting at the Koorangie State Game Reserve also began well before the opening of the season and more than 1000 hunted birds were not collected by hunters.

The GMA’s responsible hunting guidelines tell hunters to take only what they can use and shoot only when the quarry can be retrieved.

Hunters were permitted to take a maximum of 10 ducks per day.

“Hunter behaviour at Koorangie was unacceptable,” GMA chairman Brian Hines said in the foreword to the GMA’s 2016-17 annual report.

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A GMA spokesperson said the non-game species hunted at Koorangie State Game Reserve in were freckled duck, Eurasion coot, blue-billed duck and hoary-headed grebe.

“This is the first time that the GMA has been made aware of or attended incidents where this extent of illegal behaviour has occurred,” the spokesperson said.

The spokesperson told the Bendigo Advertiser the agency had provided the minister with advice on measures to improve hunter behaviour and compliance, and ensure hunting was conducted safely and in a sustainable manner, as part of a review into managing duck hunting in the opening weekend of the season.

A video filmed by the Coalition Against Duck Hunting on March 19 – the day after the season opened – and released to the ABC’s 7.30 program showed piles of dead ducks buried at Koorangie.

The reserve was closed to duck hunting from March 25 after a survey identified significant numbers of freckled and blue-billed ducks, threatened species off-limits to hunters.

At that time, the GMA revealed at least 75 freckled ducks and 22 blue-billed ducks had been illegally killed at Koorangie in the opening weekend of the hunting season.

Duck hunters in Victoria must hold a valid game licence with permission to hunt duck; to obtain this permission, a hunter must pass a waterfowl identification test.

The GMA spokesperson said hunters and the broader community were encouraged to report suspected illegal behaviour at www.gma.vic.gov.au.