A Ministry of Fisheries observer on a Korean fishing trawler says she felt intimidated by the officers on the boat, who are accused of illegally dumping fish worth up to $NZ1.3 million.

Chong Pil Yun, Wongeun Kang, Juncheol Lee, Minsu Park and Tae Won Jo are wanted to face a variety of charges including the dumping of fish, making false and misleading statements and hindering a fisheries observer following the alleged dumping of the fish from the Oyang 75 commercial fishing vessel last year.

But the five men are working overseas and haven't returned for the hearing at Christchurch District Court, which means the hearing is likely to become a formal proof hearing rather than lead to a trial.

The accused can be sentenced in their absence if the judge decides the charges are proved.

Fisheries observer Elizabeth Dyer told the court on Wednesday the Korean officers responded negatively when she tried to tell them how to use a system for counting discarded fish.

When she saw fish being discarded and started pulling them off the conveyor belt she and the crew nearby were yelled at by the vessel's factory manager, Christchurch Court News reports.

Ms Dyer said the crew continued to discard fish because they were frequently yelled at.

She stopped telling the officers they were doing something illegal because she didn't want to antagonise them.