A local preservation group has vowed to fight a decision to cull Barmah brumby numbers, saying it will not roll over.

Parks Victoria recently announced a plan to reduce the number of brumbies in Barmah National Park from 500 to 100 by 2023, with the long-term goal of total removal.

According to Parks Victoria the numbers must be reduced to protect floodplain marshes, control grazing and impacts and conserve flora and fauna species from the horses which ‘‘trample’’ the forest.

The plan outlines the preservation of Moira grass as a key reason for the cull, but Barmah Brumby Preservation Group president Murray Willaton said the grass was being killed off because of high unseasonal flows throughout summer, not the grazing by brumbies.

‘‘We’re absolutely devastated,’’ he said.

‘‘The reason for slaughtering all the horses is flawed ... We will not stand for our heritage being eradicated.’’

He believes the brumbies are simply victims of ‘‘mismanagement’’ of the forest as a result of high volumes of water being sent to South Australia and flooding the forest.

‘‘The whole Murray-Darling Basin Plan is a problem. The whole plan is flawed,’’ he said.

The group has spent recent months hand feeding the brumbies as the drought takes effect and the brumbies are unable to access some areas of the forest due to flooding from high flows.

The four-year strategic plan, Protection of floodplain marshes in Barmah National Park and Barmah Forest Ramsar site 2019-2023, has been released for public consultation, and Mr Willaton said his group was planning to ensure the public was engaged in the issue.

Under the plan, brumbies will only be trapped if appropriate rehoming facilities can be secured, otherwise they will be shot by professional shooters.

‘‘The impact of feral horses has been identified by both state and Commonwealth governments as impeding the effectiveness of environmental watering in recovering the extent and condition of Moira grass in the Barmah Forest,’’ the report states.

‘‘(However) there is a recognition of the need to minimise the impacts of unseasonal summer and autumn flooding.’’

Victorian Environment Minister Lily D’Ambrosio said the plan would protect the environment and cultural heritage of Barmah National Park.

Goulburn Broken Catchment Management Authority chief executive officer Chris Norman said the reduction in brumby numbers was critical to the long-term health of the wetlands.

‘‘The proposal to reduce the feral horse population down to around 100 animals by 2023 — and in the long-term, completely — will go a long way to reducing the impact of introduced animals on native wildlife and the landscape,’’ he said.

Although conceding they would prefer the horses were rehomed rather than shot, Goulburn Valley Environment Group president John Pettigrew said the situation in the forest was at ‘‘crisis point’’ and welcomed the total removal of the horses and other pest species.

■Victorians are encouraged to review the draft plan and provide their feedback by May 30 at: engage.vic.gov.au/barmah-strategic-action-plan