NSW Fisheries officers mounted a 4am search of dozens of commercial fishing boats after a critically endangered shark was found washed up at Evans Head with its fins sliced off late last month.
The 125kg grey nurse shark, which is protected in NSW waters, later died.
A Department of Primary Industries (DPI) investigation has found the 2.67m shark had been healthy before five of its fins were removed.
Ballina Fishermen's Co-Op general manager Phil Hilliard said commercial fishermen were "very agitated" whenever illegal fishing activity was detected because they copped the brunt of it.
"They (fisheries officers) checked dozens of boats," Mr Hilliard said.
"They came in late because they were delayed by inspectors going through everything."
He said it was highly unlikely that a commercial fisherman was involved as they risked instantly losing their licence and their livelihoods.
But he said amateurs could wait months to face court and then often only get "a slap on the wrist".
Mr Hilliard said it was also well known that the area between Coffs Harbour and Tweed Heads was heavily policed by fisheries compliance officers.
"They wouldn't risk it," he said.
He said there were few black market operators in the region but they caused big problems for commercial fishermen.
A DPI spokesman confirmed Ballina fisheries officers had interviewed fishers and inspected boats and premises.
"The DPI will initiate prosecution action if an offender can be identified and sufficient evidence found to bring them before the courts," the spokesman said.
Despite growing worldwide condemnation of the shark finning trade, shark fin soup is still considered a delicacy in some cultures and restaurants.
Federal residents Tristan Bayer and Mia Forrest from the Fin-Free environmental group are campaigning to shut down the entire shark fin trade in Australia.
"Australia exports a conservatively estimated 230 tonnes a year to the booming Asian shark fin trade, which is decimating our local shark populations," Ms Forrest said.
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