Gov. Charlie Baker’s decision to scale back the state budget earlier this month has dealt a blow to key environmental and social service programs on the Vineyard, including shellfish propagation, addiction prevention and help for the homeless.

The cuts affecting the Vineyard are among $256 million in line item vetoes and $150 million in other spending reductions Governor Baker made to a $39 billion state budget for the 2017 fiscal year. The legislature could choose to override some or all of the vetoes before it adjourns for the summer on July 31.

The cuts include $175,000 for shellfish propagation on the Cape and Islands, $45,000 for homelessness prevention on the Vineyard, $100,000 for the Transportation Access Program administered by Martha’s Vineyard Community Services, and $15,000 for an addiction prevention program in Vineyard public schools.

While boosting spending to combat the opioid epidemic statewide, the governor trimmed funding for a wide range of program and services. Long-term state employees will pay more for health insurance under one such cut, which reduced state spending by $30 million. Other cuts include a $7.7 million reduction in funds for arts and culture, more than half the amount the Massachusetts Cultural Council had expected to receive. Programs administered by the Massachusetts Office of Tourism and Travel were also cut by almost $9 million.

In a message to legislators, Governor Baker said the cuts were made necessary by a projected shortfall in tax revenues. Capital gains tax revenues, the most volatile source of state funding, have been hurt by a flat financial market.

Meanwhile, this week intensive efforts were under way on the Vineyard to lobby the state legislature to override the vetoes and restore the funding.

Rick Karney, longtime executive director of the Martha’s Vineyard Shellfish Group, was busy in his Vineyard Haven hatchery Thursday afternoon — not tending baby shellfish but contacting supporters to write letters to their legislators about the funding cuts. The shellfish group’s annual operating budget is about $400,000. The $175,000 in state funding for shellfish propagation is split by thirds among the Cape and the two Islands.

“This money supplements our operating budget; it’s important and a big chunk of change for us,” Mr. Karney said, adding: “I was talking to the people on Nantucket, they’re all wound up. And all the towns on the Cape depend on that money to buy their seed shellfish.” He continued: “It makes a big difference. We do our bit of fundraising but if we get a cut like this we spend much more time fundraising and less time raising shellfish.”

Up in Boston, the Cape and Islands delegation was equally busy fielding a flurry of emails and phone calls and preparing for a marathon last two weeks in session.

“We’re going to be in session this Saturday and I may miss my first Possible Dreams auction [on the Vineyard] next weekend because we are going to be in session. A lot of it will be looking at veto overrides,” Rep. Timothy Madden told the Gazette Thursday afternoon. About the Vineyard cuts, he said: “I’m cautiously optimistic that we will be able to override those — this is not the first time we’ve bumped up against vetoes from the governor.” Mr. Madden will not seek reelection in November after four terms.

He has been involved with every one of the budget line items, often fighting for them.

He said the shellfish money cut was a blow. “It’s a small amount but these guys are so appreciative and it’s such an important part of the fabric of the Islands and the economy — can you imagine not going clamming and scalloping?” he said.

He also said before he leaves office, he hopes to have the shellfish money made a permanent part of the budget for next year. “People frown on earmarks, but I swear by them,” Mr. Madden said. “If you don’t do it, there’s no guarantee the money will trickle down to your district.”

One such earmark is the Transportation Access Program, which serves both Martha’s Vineyard and Nantucket. The program, championed by Mr. Madden and Sen. Dan Wolf, covers travel costs for patients and their families who have medical problems for which there is no treatment on the Islands, said Nell Coogan, director of operations and community relations for Martha’s Vineyard Community Services, which administers the program for both Islands. These include mental health, substance abuse, dental and eye services, she said.

The program received $75,000 in its first year, and served more than 300 people, including 160 on the Vineyard. The program has been administered by a part-time coordinator, Rose Murray, who also helped educate patients about other medical travel options. But most of the funds were used to pay ferry and bus fares and other transportation to Boston, Hyannis and elsewhere on the Cape where no options exist.

“It was enormously helpful to folks here,” said Ms. Coogan, who formerly served as the Vineyard legislative liaison. “We understand what the state is dealing with, but for the Islands this is really important. We saw how many people can’t get services here and need to travel.”

The money for the homeless program is administered through the Housing Assistance Corporation on the Cape and was put in place last year. It pays for a part-time staff person to work with people who are homeless and experiencing housing insecurity. Karen Tewhey, who has a long background in social work and advocacy, has been filling that role this year.

In a letter that went out last week, county manager Martina Thornton urged leaders in the House and Senate on Beacon Hill to vote to override the vetoes. “These budget lines . . . are vital for the Island community and economy,” she wrote on behalf of the Dukes County Commission. The letter was addressed to Senate president Stanley Rosenberg, House speaker Robert DeLeo and the chairmen of the Senate and House joint Committee on Ways and Means.

And a petition has gone up on change.org protesting the funding cuts.

“We are counting on the House to veto the Governor and support our community,” it says in part.

Jane Seagrave contributed reporting.