Illegal use of vehicles on Wonboyn Beach is causing consternation as well as concern for the critically endangered hooded plovers that roost there.
Mick Ripon from Clydebank in Victoria has fished Wonboyn for 42 years and said he feels "saddened ad angry" that other fishers flout the rules so openly, despite "many complaints to the authorities".
On a fishing trip just in the past fortnight he said he observed two recreational all-terrain vehicles (ATVs) parked at the water's edge near the entrance to Wonboyn Lake, which is part of Ben Boyd National Park south of Eden.
"I also noted two of the critically endangered hooded plovers nearby feeding on the abundance of sand hoppers in the area - one of the factors that also make this a good area for fishing, a pastime that does not require a vehicle to be driven along the beach," Mr Ripon said.
"Only a few weeks earlier an ATV was parked at the junction of North Wonboyn beach and Greencape well inside Ben Boyd National Park. These people also had an aggressive dog with them.
"We have witnessed, on many occasions over the years, the same few offenders, sometimes with dogs, well inside the national park.
"It is abundantly clear that vehicles and particularly dogs are not permitted in this area - NSW Parks also have a sign to that effect on the beach."
Mr Ripon said his primary concern was the protection of the hooded plover.
Hooded plovers make their nest on the sand within metres of the high tide mark and rely on camouflage for protection from predators.
However, as Mr Ripon pointed out, camouflage is no match for the scent detecting powers of dogs or the wheels of an illegally driven ATV.
"Vehicle use and particularly dogs are the biggest threat to this critically endangered bird," he said.
"I have been fishing this amazing area for 42 years and am saddened and angry that despite a whole range of laws that prohibit this activity, and many complaints to the authorities, this wanton environmental vandalism still persists on a frequent and regular basis.
"On Australia Day a few years ago we observed no less than seven vehicles driving in convoy along the North Wonboyn Beach towards Greencape, well inside the national park.
"It is time these people were held to account for their cavalier attitude towards the law, the environment and the authorities that manage these areas.
"They need to be made more aware of the impact their actions are having on the environment and vulnerable species, particularly the hooded plover."
A spokesperson for the Office of Environment and Heritage said NPWS Rangers have been conducting surveillance patrols at Wonboyn and investigations are continuing.
They said applicable fines could include $300 per instance of unauthorised vehicle access, and $300 for having charge of a dog in a national park.
"The critically endangered hooded plover breed in the dune areas of our beaches," the spokesperson said.
"They are highly sensitive to disturbance, which can cause the birds to abandon their eggs - 4WDs, ATVs and dogs seriously impact on the birds' ability to fledge the few chicks that they have.
"Such disturbances, as we're seeing at Wonboyn Beach, will see their numbers to continue to decline."
Anyone observing such activity at Wonboyn Beach, or in any national park is encouraged to report it to the NPWS Merimbula office on (02) 6495 5000.