Guest Jim Papazoglov, who is also a Port Lincoln City Council councillor and a Ravendale board member, said the event began around 6.30pm and he noticed something happening around 6.45pm.

He said Fisheries confiscated the tuna because there was no "paper trail" although all seafood had been caught legally and donated honestly for the fundraiser.

"There was a good crowd and we all still had a pretty good meal with prawns, whiting and oysters."

Club president Mark Milton said the incident was an honest mistake and all paperwork was in place except for one product.

According to the PIRSA Fisheries website any person who for the purpose of trade or business processes or purchases or obtains fish must register as a fish processor.

It says fish processing includes scaling, gilling, gutting, filleting, freezing, chilling, packing or any other activity involved in preparing fish for sale.

More information about PIRSA Fisheries licensing is available at www.pir.sa.gov.au/fisheries

Fisheries officers were unavailable for comment before deadline.