Fisheries Minister Phil Heatley has applauded the results of an operation targeting illegal commercial fishing after two companies pleaded guilty yesterday to breaking quota rules and misreporting a $2.4 million catch.

New Zealand company Aurora Fisheries and Japanese company Kanai Fishing, along with four Japanese nationals, pleaded guilty in Wellington District Court to 54 charges under the Fisheries Act 1996 of making false returns.

The breaches were some of the worst New Zealand's quota management regime had seen, a Ministry of Fisheries spokesperson said. They will be sentenced later this year.