REDWOOD CITY — A pair of poachers was sentenced to jail time and fined more than $20,000 Wednesday for smuggling dozens of Dungeness crabs in hidden compartments on their boat off the coast off Half Moon Bay.

Oakland residents Minh Tran, 54, and Mai Tran, 52, were arrested Feb. 15 after authorities discovered 108 commercial-grade crabs aboard their boat — more than five times the legal limit, San Mateo County District Attorney Steve Wagstaffe said.

A warden from the Department of Fish and Wildlife approached the pair as they docked their 18-foot Boston Whaler speedboat at Pillar Point Harbor in Half Moon Bay, Wagstaffe said. The warden asked the couple if they had any luck fishing, and they replied they caught 20 Dungeness crabs — 10 per person, the maximum at the time.

Though the 20 crabs were in plain sight in an open ice chest, the warden decided to conduct an inspection as the couple finished loading the boat onto their trailer, the DA said. Inside the boat’s front anchor compartment under a rope, the warden found a canvas bag filled with 16 Dungeness crabs.

As the pair continued to deny having any more crabs on the boat, the warden went on to find 56 more hidden behind boat batteries in the driver console, authorities said. After noticing the fiberglass backing had been cut away from the driver and passenger seats, the warden found 16 more crabs between the two seat cushions.

In total, the warden discovered 108 commercial-grade Dungeness crabs. The nine-dozen crabs were returned to the sea.

The pair pleaded no contest Wednesday to exceeding the legal limit of crab and illegally possessing the crab for profit or personal gain, Wagstaffe said. A third charge for failing to display their catch to the warden was dropped.

Minh Tran, who had prior convictions for Fish and Game Code violations including unlawful possession of an animal and an undisclosed permit infraction, was sentenced to 10 days in county jail, three years probation and a fine of $20,580, Deputy District Attorney John Wilson said. Tran’s wife, who had no prior Fish and Game Code violations, was sentenced to five days in jail and two years probation.

As part of their sentence, the couple was also ordered to give up their boat to the Department of Fish and Wildlife. While the department usually sells forfeited boats at auction, Wagstaffe said the Trans’ boat will likely be destroyed because of its hidden compartments.

Follow Erin Ivie at Twitter.com/erin_ivie.