PORTLAND — Dozens of lobster fishermen on three Casco Bay islands kept their boats tied up in port Monday as prices for their catch dropped to the same low levels that prompted a four-day lobstermen’s “strike” a year ago, an industry consultant said.

The action by fishermen from Chebeague, Long and Cliff islands came as Massachusetts lobstermen continued a work stoppage and gave away lobsters rather than sell them for depressed prices.

The Maine protest appeared limited to the three islands in the Portland area, but Alan R. Caron, a consultant to Maine lobstermen, said it could spread quickly to other areas.

“This started the same way last year, with a spontaneous flareup in one area,” Caron said. “By this time (Tuesday), we ought to know where it will go.”

“I don’t know where it will go, but it will happen quickly,” he added.

The three islands have large lobstering communities, and Caron estimated that 100 to 150 fishermen were involved in the protest.

Last summer’s work stoppage began in Portland after the “boat price” paid to fishermen dropped as low as $1.75 a pound for softshell lobsters, about $1 a pound less than they were getting the year before.

The price had been hovering around $2 a pound this summer but dropped to $1.85 on Saturday, according to fishermen and dealers, who said an abundance of lobsters and a drop in tourism linked to a sluggish economy were responsible for the slump in prices.

“Right now, the catch is pretty good, and there’s nobody around to eat them,” said Peter L. McAleney, manager of New Meadows Lobster in Portland. “It’s a good time for the consumer to buy lobster.”

Prices around the region range from $1.50 in eastern Maine to $2 in Boston, according to McAleney.

As of mid-afternoon, there was no indication that the protest was spreading beyond Portland.

“I haven’t heard a thing yet,” said Marshall Murphy, spokesman for the state Department of Marine Resources.

As a result of last year’s tie-up, lobstermen formed a committee to gather and distribute marketing information. They also spearheaded a successful campaign to introduce the sale of lobsters at the display auction of the Portland Fish Exchange.