Thousands of feral animals, including 4,750 pigs, have been eradicated in a targeted aerial shoot in the western Riverina region of New South Wales.

Local Land Services, which coordinated the cull, estimated that the feral pig population in the western Riverina could swell to two million within five years if uncontrolled.

Aerial surveys over three years found numbers as high as 170 pigs per square kilometre.

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LLS biosecurity and emergency services manager Michael Leane said the aerial shoot, which covered 750,000 hectares, killed up to 70 per cent of the pig population.

"This knockdown was required to reduce the pig population long term," Mr Leane said.

"We made a big effort to get these figures by surveying the area, so we knew how many we needed to take out of the landscape."

Mr Leane said feral pigs were a huge pest for both productive agricultural land and the environment because they spread weeds and disease.

"With it being dry they are concentrating on the waterways and fouling up the waterways," he said.

"They are also predators for native species and also at lambing time."

The cull, which took place across 30 private properties, national parks and the Nimmie-Caira wetlands, eradicated 5,644 pests including feral pigs, cats, goats, foxes and deer.

These are some of 4750 feral pigs that were culled in the NSW western Riverina. ( Photo: Local Land Services )

Landholders overwhelmed

The cull was implemented after NSW Farmers Association reported to LLS that feral pig numbers were beyond the control of landholders, requiring a coordinated approach to manage the pest.

The Western Riverina Pig Project, a joint initiative by Riverina, Murray and Western Local Land Services, was developed to reduce numbers and enable landholders to manage pest problems in the future.

The $200,000 cost of the shoot was footed by the 2018 Pest and Weed Drought Funding Program recommended in the Australian Government Agricultural Competitiveness White Paper.

Other control measures also being used by LLS, landholders and community groups include baiting and trapping.

Locating pigs in the western Riverina during the aerial cull. ( Photo: Local Land Services )

Drought prime time to cull feral animals

The aerial shoot was conducted over the last six weeks with dry conditions proving ideal.

"There's not many silver linings to drought conditions, but it's an ideal window to achieve significant knockdowns when it comes to pest control," Mr Leane said.

"When you cull so many pigs in such a short period of time, it really amazing that the land is carrying those numbers with the production as well."

Mr Leane said despite shooting more than 4500 pigs, numbers were actually lower than when the region was surveyed last year.

"Pig numbers have dropped significantly due to the drought, so this recent cull means we can put a bigger dent in the pig population," he said.

Mobs comprised of as many as 40 pigs were located during the aerial shoot, with many of the animals in poor condition due to thirst and hunger.

"If there's water, there's pretty much pigs," Mr Leane said.

"They were chasing food so it was probably a good time to shoot."

Feral pigs were located in mobs of up to 40. ( Photo: Local Land Services )

Deer, cat and goat numbers a surprise

There were also 539 deer, more than 50 feral cats, 100 foxes and 200 goats eradicated during the cull.

Mr Leane said despite fears that deer numbers could reach 'plague proportions' in NSW, it was surprising to find so many in that part of the Riverina.

"As with everywhere in the state, deer are a huge emerging issue in the pest world," Mr Leane said.

"The western region is not where you think you would find deer, you probably think of it more in the forested areas, but they are in the west in big numbers also."

Keeping numbers under control

LLS will now develop maps for landholders to show them where pigs were located and shot.

"We need to continue with the monitoring, we can't just rest on our laurels now that we have killed these pigs, we will now push the trapping and baiting programs," Mr Leane said.

"We will also have more traps built for the landholders that have participated in the shoot to keep the pig control going," he said.

LLS will also work with the Nari Nari Tribal Council in training staff to manage pests, particularly feral pigs, on the 80,000 hectare Nimmie-Caira wetlands near Hay.