After receiving an unprecedented amount of correspondence ­— and a fair share of verbal testimony as well — the Martha’s Vineyard Commission closed a public hearing on the construction of two undersea cables that would connect the nation’s largest offshore wind farm to mainland Massachusetts.

“We really appreciate all the written testimony we’ve received,” said Richard Toole, chairman of the public hearing, at the meeting Thursday. “I don’t think I’ve ever seen so many letters about a subject submitted to the commission before. It’s great you’re all paying attention, and all concerned about this.”

As of Thursday afternoon, the commission had received 87 letters relating to the project. According to executive director Adam Turner, 39 of those letters opposed the project, with the vast majority of those coming from people off-Island. He said about 90 per cent of the project’s supporters were Island residents.

Vineyard Wind, a New Bedford-based energy partnership between Avangrid Renewables and the Danish company Copenhagen Infrastructure Partners, plans to build an 800 watt, 84-turbine wind farm 14 miles south of Wasque Point. Although most of the project is planned for federal waters, the commission has jurisdiction over a portion of two undersea cables that would run approximately one mile off the Eastern shore of Chappaquiddick.

The commission is reviewing that part of the project as a development of regional impact (DRI).

Helen Parker discussed the negative economic and environmental impacts of industrial wind farms.

Noah Asimow

Helen Parker discussed the negative economic and environmental impacts of industrial wind farms.

Noah Asimow

In February, after listening to testimony from the project’s supporters, Mr. Toole abruptly closed the public hearing engaging in a heated exchange with an opponent of the project, Helen Parker. The hearing was continued to this Thursday, when it seemed tempers had cooled. Mr. Toole apologized for the hearing last month and briefly outlined a new set of rules for testimony, including a five-minute time limit for speakers.

“After the last hearing, I apologize,” Mr. Toole said. “I think that didn’t go over very well, I’m sorry.”

On Thursday, Oak Bluffs eighth-grader Jocelyn Baliunas led off the testimony by reading a letter she and two of her classmates had penned in support of the project. Jocelyn said that despite concerns about the installation of the cable, she felt Vineyard Wind had come up with an effective plan to minimize the effects on wildlife. She also noted that four undersea cables already run from the Vineyard to the Cape.

“As you can see, the Vineyard Wind project will be beneficial to this Island with jobs and clean energy for hundreds and thousands of homes,” Jocelyn read. “The world is changing and we need to change with it by taking a step toward clean and renewable energy.”

All told, the Oak Bluffs eighth-graders submitted nine letters in support of the project.

Others who spoke in favor of the project included Islanders Tom Saldini, Jonah Maidoff, Allen Straylor, Tom Hodgson and Christine Gault. All echoed Jocelyn’s sentiments about the minimal environmental impacts of the cables relative to their importance for providing renewable energy.

“I completely agree with the previous speaker in every aspect of what she said,” Mr. Saldini told commissioners. “That was easy.”

Middle school teachers and recent landowners, Zoe Turcotte and Timothy Penicaud, also spoke in favor of the project.

“We have a house on Chappaquiddick, specifically bordering Wasque reservation, and our view right now is incredible,” Ms. Turcotte told commissioners. “We understand that will be where the cables will be put, and I just want to say we can’t wait.”

“It can definitely be in our backyard,” Mr. Penicaud added.

Allen Straylor, who is a scientist and member of the Edgartown energy committee, said worries about the cable’s magnetic field were unfounded.

“I’ve been teaching magnetic theory for years,” Mr. Straylor said. “The actual measurements of the magnetic fields of undersea cables are about 100 times smaller than the measurements of the earth’s magnetic field itself, which in turn is about 100 times smaller than a refrigerator magnet. So there should be very little danger to marine life.”

The project’s other vocal supporters, including John Packer and Peter Cabana, said their knowledge of previous cable installations and energy industry in and around the Island made them confident these cables were worth the minimal risk. Mr. Packer brought a cross-section of a six-inch undersea cable to show commissioners. The proposed Vineyard Wind project would include two cables, both 10 inches in diameter.

“The reason the lights are on is that we have a cable,” Mr. Packer said.

Others cautioned commissioners about the unknown effects of a 220-megawatt undersea cable.

John Keene, a Chilmark resident and president of the Fishermen’s Preservation Trust, submitted a 2015 Bureau of Ocean Management report that discussed the potential dangers of undersea cables to migratory marine species, like squid, haddock, mackerel, herring and whales. Mr. Keene said Vineyard Wind’s proposed cables had 40 times the electric carrying capacity of the ones already in Vineyard waters.

“The impacts are magnified,” Mr. Keene said. “In Denmark, for instance, when the cables were turned on, the cod and haddock scattered, and the catch rate decreased almost 70 per cent...It almost acts like a wall they won’t cross.”

Aquinnah resident Megan Ottens-Sargent warned commissioners about the potential for a “spider web” of undersea cables if the current wind leaseholding companies don’t work together in the future.

“I’m really asking us all to pause,” Ms Ottens-Sargent said. “I’m hoping you all look diligently at all the correspondence you get.”

Vocal wind energy critic Helen Parker also spoke at the hearing, discussing the negative economic and environmental impacts of industrial wind farms. She argued that wind was the exact opposite of energy conservation because it led to greater fossil fuel usage as energy resources became more plentiful.

“What I believe is that for 40 years we have been following the wind emperor and we don’t have a clue, as a world, as a nation, as a community, what is involved,” Mr. Parker said.

Representatives from Vineyard Wind, present at the hearing, addressed the concerns of critics and commissioners, saying that a more recent BOEM study concluded that the cables did not hamper the movement of two species — lobster and skate ­— believed to be the most sensitive to electromagnetic fields.

In response to other questions from commissioners about a cable off Block Island, they said that BOEM requires a decommissioning fund for the cable and that they would have a constant monitoring process to check if the cable became unburied. Vineyard Wind plans to bury the cable five to eight feet beneath the sea floor.

Commissioners then closed the public hearing, leaving the written record open until March 28. No date has been set for deliberation or the post-public hearing review.