Ministry for Primary Industries has cut the number of days its observers spend on snapper boats at a time when cameras in an electronic monitoring trial were failing.
Two years ago ministry fishery observers spent 511 days at sea. In 2015/16 that had been reduced to 210 days.
Video monitoring began in January this year but there were problems with new onboard cameras. About 80 percent failed for a number of months this year.
The ministry has been criticised this year over its failure to prosecute fish dumping.
Green Party primary production spokesperson Eugenie Sage said MPI was failing to monitor the East Coast snapper fishery, one of the most highly valued by recreational fishers and important commercially.
"MPI talks about the critical importance of observers for good fisheries management and here they are having dispensed with 60 percent of the observers."
MPI controversially awarded the electronic monitoring contract to Trident Systems - a company owned by the fishing industry.
It was recently revealed that 80 percent of Trident's cameras failed during their first few months.
Trident Systems chairman Jeremy Fleming recently said there had been problems with water getting into cables and condensation in the cameras.
"MPI have been as concerned as we have and they've worked with us to address the problems."
Mr Fleming said the cameras were now working at a "pretty satisfactory" level.
MPI's inshore fisheries manager Steve Halley said the ministry became aware in about April that Trident's cameras were not working properly.
"Camera monitoring is new technology and at the beginning of the significant expansion to electronic monitoring in this fleet there were some technical issues with the cameras but those have been resolved," Mr Halley said.
"So we are now monitoring 17 vessels with a high degree of confidence."
Greenpeace executive director Russell Norman said the reduced observer numbers combined with failing cameras meant there had been effectively no monitoring of the snapper fleet for months.
"When we roll out video monitoring it means that there won't be human observers, or far fewer human observers present.
"And that's why it's so critical that the video monitoring system has complete integrity and has the complete confidence of the people of New Zealand - which, of course, is why it can't be done by a company which is controlled by the fishing industry," Dr Norman said.