SANDWICH — More than 4,000 immature oysters were stolen from Mill Creek near the Sandwich Boardwalk, according to David DeConto, the town’s natural resources director.

Officials discovered the missing batch on Aug. 9 when they went to check the floating cages containing the oysters in the aquaculture farm in the creek. The town has been cultivating the shellfish, which take between two and three years to mature, as part of its aquaculture program.

The town’s been growing roughly 100,000 oysters each year. At the start of their lives, they’re roughly about the size of a pencil eraser, DeConto said.

The theft struck officials as odd because none of the oysters were of legal size, and therefore not able to be sold.

“We’re scratching our heads a little bit,” DeConto said Monday. “If somebody thought they were going to have a picnic — there’s actually not enough meat in the shell to eat.”

DeConto said the stolen shellfish ranged in size from about 1½ to 2½ inches. According to state shellfishing regulations, aquaculture-raised oysters may be harvested and sold at a minimum size of 2½ inches.

Additionally, the oysters were taken from water that is unsafe for harvesting due to high levels of fecal coliform bacteria, DeConto said. Every year, there are seasonal closures associated with the bacteria content caused by animal waste and runoff from septic systems, he said.

The Massachusetts Environmental Police are handling the investigation into the theft. Representatives from the agency did not immediately return a message seeking comment Monday.

Last January, the town held its first oyster harvest for licensed shellfishermen. The event was a testament to the success of the fledgling aquaculture program, which has been underway for nearly a decade, according to Town Manager George “Bud” Dunham, who said he learned about the theft last week.

The town has been working for years to meet quality standards appropriate for the cultivation of shellfish, Dunham said. The waters had been unsuitable for the project for nearly three decades, he said.

There may not be a harvest this year because of the theft, which has prompted officials to put up lights and cameras to help monitor activity in the creek.

DeConto said he isn’t sure how much the theft costs the town, which is the only entity permitted to conduct the aquaculture farming.

“It’s not the money so much as the time and effort,” he said.