A Stonington lobster hatchery is in full production for its second year of raising young lobsters for seeding in the Penobscot Bay area and plans to expand its research project to include rearing older lobsters as well.

Working with local fishermen, the Zone C Lobster Hatchery staff released an estimated 10,000 to 12,000 2-week-old lobsters at two sites off Vinalhaven on Sunday. That comes after the release of about 17,000 young lobsters at two locations late in June.

“The many modifications we have made in the hatchery this year, learning from last year, appear to be really paying off,” said hatchery director Ted Ames. “Last year, we released 40,000 lobster; this year, we will release around 25,000 [to] 30,000 from just the first run.”

The survival rate in the hatchery is very high this year as well, Ames said.

Depending on how many egg-bearing female lobsters with ripe eggs the hatchery can acquire, the rearing process could continue into October, Ames said Saturday. That could yield two more runs of young lobsters with the potential of releasing a total of 100,000 more Stage IV lobsters, he said.

The purpose of the hatchery project is not to create a “put and take” fishery, Ames said. The goal is to provide young lobsters for traditionally good lobster fisheries that for whatever reason have become depleted.

“The idea is to place lobsters in good locations to rebuild the populations that have disappeared,” he said.

The hatchery is working with Dr. Rick Wahle at the Bigelow Laboratory for Ocean Studies in West Boothbay Harbor to determine whether raising lobsters in a hatchery is a viable way to restock those areas, he said.

The initial hatchery effort has been to raise lobster larvae from eggs to Stage IV, which takes about two weeks. At that point, they are about a half-inch long and are just beginning to look like lobsters.

In the wild, they normally would float in the water column, where they are easy prey. At Stage IV, they begin to settle to the bottom, where they seek out rocky areas where they can find shelter and continue to develop.

Last year, the hatchery released about 40,000 Stage IV lobsters but had difficulty tracking them. The hatchery staff and collaborating scientists from the Bigelow lab conducted suction sampling at three research sites which determined that the Stage IV lobsters are much more mobile than expected, too mobile to track reliably.

“Stage IVs are what we call superswimmers,” Ames said. “While they touch down, they just don’t settle on the bottom.”

That made it difficult for researchers to document the survival rate of the hatchery-reared lobsters, one of the goals of the project, prompting them to consider raising older lobsters.

So this year, in addition to raising the Stage IV, the hatchery staff also plans to raise Stage V lobsters, which will require keeping them in the hatchery for up to five weeks.

“The reason we’re doing this is that Stage Vs are more likely than Stage IVs to settle immediately on the ocean bottom, where we can find them and track their survival to adulthood,” Ames said. “This is a critical step for the work we are doing to determine whether hatcheries can successfully enhance the fishery.”

Ames and hatchery manager Rich Crowley plan to raise the lobsters from Stage IV to Stage V in the ocean and are constructing specially designed containers in which they will live.

“We’re still in construction mode and will be for another week or so,” he said. “Growing Stage Vs is very labor-intensive. Nobody does it. We’re hoping to grow enough to give Rick Wahle the number of true benthic dwellers he needs for his experiments.” “Benthic” refers to animals and plants living at the bottom of the ocean.

Once constructed, the containers will provide a “novel system” for feeding and caring for the growing lobsters, Ames said. The containers will be stacked in bottomless barrels and moored. There, the young lobsters will feed on marine growth inside the compartments as well as on food washed though the trays by the tide.

Although Ames said it would take 8,000 to 10,000 Stage Vs to make a substantial signal for Wahle to track, the hatchery probably will raise 2,500 to 5,000 this year.

“If we can release even the 2,500, that would provide a credible and detectable number,” he said. “It would be good to get the 5,000 if we can get the drums made and if they work.”

The hatchery is working with the MDI Biological Laboratory in Salisbury Cove, which conducts DNA analysis on the juvenile lobsters that researchers track. According to Ames, DNA from the lobsters tracked by divers are sent to the lab to ensure that they are tracking the lobsters raised and released at the hatchery.

Penobscot East Resource Center, a community-based fisheries organization formed to support local fishing communities in the region, is raising funds that will allow Wahle from the Bigelow lab and volunteer fishermen to conduct dive surveys on the release sites to track the Stage V lobsters.

BANGOR DAILY NEWS PHOTO BY KEVIN BENNETT

Stage IV lobsters are seen in a petri dish at the hatchery.