A commercial fisherman from Northland has been fined $6000 for under-reporting his catch.
Tane Zanders' grey mullet catch was 931kg more than he reported, the Ministry of Primary Industries said.
The 45-year-old pleaded guilty to three charges under the Fisheries Act in Whangarei District Court last week.
The fines included $1500 for the release of the boat used in the offending, which was seized by the Crown.
Ministry for Primary Industries spokesman Stephen Rudsdale said the offending was disappointing.
"The commercial fishing pressure on grey mullet in New Zealand's upper North Island has increased recently with catches approaching or even exceeding the total allowable commercial catch.
"Under-reporting artificially inflates a fisher's catch entitlement, which not only provides financial gain for the fisher but impacts the sustainability of the fishery as well."
Rudsdale said the under-reporting was discovered when a fishery officer ran discrepancy reports on Zanders' catches.
"Mr Zanders was, on three separate occasions, directed to amend his monthly grey mullet harvest returns. He didn't make the amendments until the fishery officer finally directed him to attend an interview where the issue of anomalies was addressed.
"The returns he filed were 931kg less than the actual catch. That's pretty significant.
"Timely and accurate reporting is the cornerstone of the quota management system.
"Under-reporting puts an already stressed fishery at risk, and undermines MPI's ability to accurately assess the stock.
"In Mr Zanders' case, he risks being banned from fishing for three years if he re-offends."