Five Indonesian nationals caught with 50kg of shark fin aboard their boat have pleaded guilty to illegal fishing offences in an Australian court.

In a joint statement, Australian Border Force and Australian Fisheries Management Authority said five Indonesian nationals were caught fishing illegally inside the Australian Territorial Sea approximately 294 km north-east of Darwin on July 7.

The vessel was seized, along with 50kg of shark fin, 80kg of bait fish and a substantial quantity of fishing equipment that was on board.

The men were detained and charged with offences against the Fisheries Management Act 1991, pleading guilty at Darwin Local Court on July 18.

Australian Fisheries Management Authority general manager Justin Bathurst said Australia’s waters were an attractive target for illegal fishing operators.

“Sharks are an important part of a healthy ecosystem, helping to control the balance of marine species and ensuring ecological stability. Removing sharks from the marine ecosystem threatens the health of our well-managed fisheries.”

Maritime Border Command rear admiral Brett Sonter agreed, saying “the combined efforts of MBC and partner agencies such as AFMA enables surveillance, patrol and response capabilities to combat illegal activity and threats to Australia’s border”.

Each of the accused fishers were released on AUD$1000 (NZD$1092) recognisance orders, on an undertaking to be of good behaviour for a period of three years.

They have since been removed from Australia and returned to Indonesia.