An Auckland man and woman have just avoided prison sentences for selling and planning to sell hundreds of crayfish pilfered from Hawke's Bay's Māhia coastline.

Appearing before Judge Penelope Ginnen in Papakura District Court on Monday, they admitted seven joint charges, including one of selling 277 spiny red crayfish online.

They were also convicted in relation to the possession of 222 crayfish in a vehicle in which they were randomly stopped by a lone police officer near Kotemaori, between Wairoa and Napier, on July 28, 2020. The court ordered the forfeiture of that vehicle.

Before the court were 24-year-olds Kim Te Ohorere Ormond-Daniel and Edmond Taena Angell, who were each sentenced to five months' community detention and 140 hours' community work.

The maximum penalty available on the most serious charges is five years imprisonment or fines of up to $250,000.

The Ministry for Primary Industries (MPI) says it's illegal to sell recreationally-caught seafood, and the daily catch limit for crayfish on the Hawke's Bay coast is six per person.

MPI regional manager fisheries compliance Tyrone Robinson said that when officers stopped the vehicle they noticed the inside smelled strongly of seafood and called in fishery officers, who inspected the vehicle, finding four bins of crayfish - including 193 spiny red, of which 34 were undersize.

They also found 29 undersize pack horse crayfish, two crayfish carrying eggs and one with a broken pleural spine, he said.

Further inquiries exposed uncovered evidence of past online black-market sales of 277 additional crayfish by the pair.

"One of the defendants admitted they had done this run before - taking crayfish from Māhia, and our investigation," Robinson said. "We're grateful to the police for alerting us to this offending. During our inquiries the pair admitted they had come down to Māhia to pick up crayfish to sell in Auckland through online Facebook chat groups for between $20 and $80 a crayfish.

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"Māhia crayfish are under pressure and when MPI finds evidence of people taking more than their share, we will hold them to account," he said. "This kind of offending affects the sustainability of this taonga species which needs to be looked after for current and future generations."

"We expect this sentence sends a strong message of deterrence to others who might be tempted to sell recreationally-caught crayfish on the black market - you will be prosecuted."

In August last year MPI announced a series of searches in an operation in response poaching and black market sales of rock lobster in the Māhia-Wairoa area in recent years.

Multiple search warrants had been executed at properties of people believed to be involved, but while no arrests were made at the time an officer said it was "likely that some of these people will appear before the courts".

About 80 fishery officers searched eight homes in the Māhia, Wairoa, Whakatāne and Kawerau areas, and at some properties were supported by police officers.

MPI does not believe the couple's offending was linked to the major operation.

MPI encourages people to report suspected illegal fishing activity through the ministry's 0800 4 POACHER number (0800 47 62 24).