A commercial fishing boat is among four boats seized during a crackdown on black market fishing operations in Hawke's Bay.
Fisheries officers raided 22 properties in Napier, Hastings and Mahia on Wednesday, saying 31 people were suspected of being involved in illegally selling 1.8 tonnes of paua (shell on) and 600 crayfish.
One commercial fishing vessel, three recreational vessels, one tractor and 11 other vehicles were connected with black market catch and sales.
The Ministry for Primary Industry's Dean Baigent says it has been aware of black market operations in Hawke's Bay for years, but it was difficult to target.
Operation River began collecting information in March last year, and an undercover officer became involved in the black market, he said.
"The officer uncovered illegal trading of paua and crayfish which had been gathered by recreational fishers, some of whom disguised their activities through the use of customary authorisations."
Customary authorisations are issued by local tangata kaitiaki/tiaki but must not be used for financial benefit, he said.
Illegally selling recreational fishing catch can attract a maximum penalty of five years' jail and/or a $250,000 fine.