Fishing industry bosses claim turtles are being “killed and turfed overboard” and the ocean floor “stripped of all sorts of creatures” by illegal foreign fishers in waters off Western Australia’s Kimberley coast.

The WA Fishing Industry Council raised the concerns on behalf of commercial fishers, after the Australian Border Force announced it had detained its largest cohort of foreign fishers in more than a decade.

A multi-agency operation apprehended 30 illegal fishers in waters within the Kimberley Marine Park, and uncovered three illegal fishing boats, more than one tonne of trepang and 600 kilograms of salt used to preserve the highly sought after sea cucumbers.

The vessels have been destroyed and the detained Indonesian fishers transported to Yongah Hill Immigration Detention Centre, north-east of Perth.

The Australian Fisheries Management Authority (AFMA) would not confirm whether charges had been laid or whether the group had been removed from Australia.

WA Fishing Industry Council CEO Darryl Hockey said while the recent operation was a good start, illegal fishing activity remained a bigger problem.

He claimed hundreds of boats were entering WA waters every month.

“The fishermen are really quite indiscriminate,” he said.

Mr Hockey said not only were illegal foreign fishers hauling in trepang, he had received reports demersal fish and turtles were also being caught.

“They’re peeling all the shells off the reef, they’re spearing every fish they find, they’re catching every shark they can catch.”

He said illegal fishers were camping on islands off the Kimberley coast, with one Australian fisher chased.

“We’ve had first hand reports from one of the fishermen who actually went on the island and was chased off by a couple of them [illegal fishers],” he said.

Mr Hockey acknowledged the remoteness of the region was difficult to police.

WA Fisheries Minister Don Punch said while he was not surprised by the number of detainees apprehended in the marine park, he was confident in the federal government’s response.

“Blitzes have a role to play,” Mr Punch said.

“We don’t just do an operation and see the end of it. This is really about an ongoing effort. But occasionally serious blitzes do drive home a pretty significant message to the fishing vessel fleet, that they’re at risk”.

Shadow Federal Fisheries Minister Jonathan Duniam said the Kimberley Marine Park operation could be the “tip of the iceberg”.

“I’m concerned about what we don’t know and how many people are still out there conducting these illegal operations,” he said.

Mr Duniam said he welcomed any investment in protecting Australian’s marine environment and borders.