The man, 68, was fined $1000 for hunting a freckled duck and ordered to pay costs of $5000 in the Horsham County Court last week.

The case was initially heard in the Horsham Magistrate's Court on October 18, 2013.

The man was found guilty of hunting the freckled duck and pleaded guilty to possessing and using toxic lead shot.

The man appealed against the findings, which were upheld by the County Court.

The court heard the man shot at the freckled duck at about 7.30am on March 17 at Natimuk Lake on the opening weekend of the 2013 Victorian duck hunting season.

Authorised officers observed the man shooting at the duck.

He was subsequently interviewed and his firearm and ammunition seized.

Ammunition tests revealed the man was using lead shot, which is prohibited for duck hunting.

Game Management Authority chief executive Greg Hyams said hunters must clearly identify their target before shooting.

"The illegal shooting of threatened species can put pressure on populations. Hunters must be sure of their target before they pull the trigger, and if you are not sure, don't shoot," he said.

Mr Hyams said the man's use of lead shot was of equal concern.

"Lead shot has been prohibited for use in all duck hunting since 2002," he said.

"Affordable non-toxic alternatives are readily available and there is no reason for any hunter to use lead shot in contravention of the regulations.

"Hunters are a generally law-abiding group, but there are some who choose to do the wrong thing.

"The Game Management Authority is working closely with hunting organisations and industry to maintain the highest standards of behaviour in the field through the Respect: Hunt Responsibly initiative."

Mr Hyams encouraged hunters to report any illegal hunting to the authorities by calling 136 186.

"Illegal hunting damages the reputation of hunting and can put people and wildlife at risk," he said.

"I strongly encourage hunters and the broader public to report any suspected illegal activity they see to ensure hunting is conducted safely and responsibly."

He said people could visit www.gma.vic.gov.au for more information about game hunting in Victoria.