About 40 Islanders got a first look Wednesday at footage from an upcoming documentary about the Vineyard’s commercial fishery, which is struggling to stay profitable in an era of privatized permitting and industrial consolidation.

“It’s not completely dead. There’s a faint heartbeat,” said Wes Brighton, a Chilmark lobsterman and gillnetter who is making the movie with Vineyard filmmaker Jeremy Mayhew.

But Mr. Brighton told the audience at the Chilmark library that Island fishermen are at a severe disadvantage under federal regulations that favor larger businesses.

Commercial fishing licenses are now private property and like taxi medallions, they can be sold to the highest bidders. This gives the advantage to big fishing companies from New Bedford and Gloucester who can buy up multiple licenses and send out scores of boats, Mr. Brighton said.

In one clip from the documentary, tentatively titled The Changing Tide, longtime Chilmark fisherman Everett Poole warns that small operators are at risk of going out of business.

“It’s going to get tougher and tougher, the more the licenses are consolidated,” Mr. Poole tells the camera.

Other footage from the film is more upbeat, with arresting scenes of night fishing and belowdecks work. The clips screened Wednesday highlighted the vitality and diversity of the Vineyard fishery with shots of lobsters scuttling in traps, nets bulging with squid, shellfishermen bringing in their catch and a teenager heading out on his small boat, rod in hand.

The film crew, which includes Will Dintenfass, Dan Martino and Emily Vanderhoop, also sent cameras into the air for a drone’s-eye view of Menemsha and underwater to capture dolphins swimming alongside a fishing boat.

Mr. Mayhew and Mr. Brighton began working on the The Changing Tide after receiving a Vineyard Vision fellowship for the project in 2015. They are collaborating with the Martha’s Vineyard Museum and the Martha’s Vineyard Fishermen’s Preservation Trust, which presented Wednesday’s preview.

The full-length documentary, covering the Vineyard’s fishing history as well as its present and future challenges, is scheduled to be completed in August. On Wednesday, the filmmakers asked their audience to spread the word that they are still open to more interviews and are looking for historical images and footage.

Mr. Brighton, who is a member of the Fishermen’s Preservation Trust board, also made a pitch for donations to support the trust’s work in buying commercial fishing licenses to lease at a discount to Island fishermen.

A license can cost from $30,000 to millions of dollars for the right to bring in a particular catch, according to trust executive director Shelley Edmundson.

Chilmark selectman Warren Doty, who is also a board member of the trust, said a combination of donations, investments and low-income loans from environmental foundations have enabled the trust to purchase two licenses so far and a third, for lobster, is in the works.

The trust’s first license allows the taking of 32,000 pounds of sea scallops per year. The second had belonged to Island fisherman Luke Gurney, who died in 2016 after being swept overboard while setting conch pots off Nantucket. The trust bought the late Mr. Gurney’s conch, seabass and scup license from his family at market value, Mr. Doty said.

More information about the Martha’s Vineyard Preservation Trust, which also presents special events for the Vineyard community throughout the year, is online at mvfishermenspreservationtrust.org.