Alewives, one of the great harbingers of spring, have returned to Vineyard waters.

But there is a crucial difference this year: the state of Massachusetts has barred people from catching or possessing these anadramous fish, which return from the ocean to spawn in freshwater ponds.

The state has placed a three-year moratorium on the harvesting of alewives, also known as river herring. Connecticut has had a moratorium in place for years. Rhode Island fisheries managers will decide April 3 whether to do the same.

"People have to realize that even if they are putting herring in a lobster pot, they can be fined," said Derek Cimeno, shellfish constable from Tisbury.

Under the moratorium, all herring runs are closed to the public. The new state law prohibits possession of herring, even if the fish was caught in any way other than the traditional manner of scooping them out of a run with a net.

Fisheries regulators say alewives are so overfished that the fish are disappearing from the region. In some runs on the Cape, the herring already are gone.

Herring runs on Martha's Vineyard have not been so severely impacted, but the decline is clearly noticeable.

"I've watched the decline in just the last two years," said David Grunden, shellfish constable for Oak Bluffs.

The state moratorium, however, may come into conflict on the Vineyard with aboriginal rights held by the Wampanoag Tribe of Gay Head (Aquinnah) to harvest the fish.

Bret Stearns, natural resources director of the tribe, said tribal members do not believe the moratorium applies to them.

At 6 p.m. Thursday, the tribe will host a public meeting to discuss the commercial lease of the herring run for this season. The meeting is scheduled for the tribal administration building in Aquinnah.

Mr. Stearns said tribal members hold that they have a right to utilize herring as part of their sustenance rights. The question yet to be explored is whether a commercial season will be allowed. Brian (Chip) Vanderhoop has been leasing the herring run for the last three years.

State environmental police sergeant Pat Grady said he has not yet received a reading from the state on whether a member of the Wampanoag Tribe is violating the law if in possession of a herring. "That question has yet to be answered," the sergeant said.

Alewives spend most of their lives swimming in the open ocean. Each spring the adults return to the fresh water pond where they were born to spawn again.

Many species of fish feed on herring. The arrival of the osprey, the fish hawk, is known to coincide with the herring's arrival in the spring.

The Vineyard has four herring runs. The Aquinnah Wampanoag tribe manages a run in Aquinnah, a short distance from the Chilmark border. The run, considered the most healthy and productive on the Island, has been closed to the public for years and is accessible only to tribal members.

The Richard F. Madeiras herring run at the Head of Lagoon Pond, is managed jointly by the towns of Oak Bluffs and Vineyard Haven and was restored in the last 20 years. The run, off Barnes Road, is the most visible on the Island and also is also where the herring were first seen in the last few weeks.

A new herring run has been established at the head of Lake Tashmoo by the town of Tisbury and is already showing signs of working, though at a much smaller scale.

A fourth herring run in Edgartown, at Mattakessett and Katama, is in the process of being restarted. The re-establishment is being funded by the town with the help from federal funds.

Mr. Cimeno said efforts are underway to better protect the head of the Lagoon run against vandalism. Over the years, a hurricane fence covering the access pool has been broken into.

Police in both towns along with the state environmental police are going to keep an eye on the run, Mr. Cimeno said.

"We are going to enforce the herring regulations very strongly," Sergeant Grady said. "It is a valuable resource and there has been poaching in the past."

In recent years, Mr. Grunden said, he's seen a sharp decline in herring in the run.

"Six years ago there were a lot of herring in the run," Mr. Grunden said. "The limit per person was 25 fish. The run was open three days a week and it was not uncommon for someone to put his net in the run and pull out over 50 fish in just one net.

"Although the run used to be open three days a week and we curtailed the number of hours it is open, one person coming down to get fish was hard-pressed to get 12 fish," he said.

To many the disappearance of the herring in the state has nothing to do with herring runs. The fish disappearance has more to do with offshore fishing.

"I think it is absurd," said Chris Murphy, a Chilmark semi-retired commercial fisherman. "It is clear that the degradation of the herring is tied to the midwater trawlers working so far offshore you can't see them. This goes back years. Alfred Vanderhoop (of Aquinnah) pointed out to me at least 25 years ago that the herring was dropping precipitously because of those offshore boats."

Alewives are known to swim with their ocean cousin Atlantic herring. Both species of fish swim in tight schools and are easily targeted.

"When those fishing boat captains look at their fish finder, they don't see a difference between Atlantic herring and alewives," Mr. Murphy said. "When you tow and bring 100,000 pounds of alewives out of the water, they are gone. There are no herring in Massachusetts because they are caught offshore."

Mike Armstrong, a fisheries scientist for the state Division of Marine Fisheries, said the New England Fishery Management Council has moved to keep pair trawling boats away from the area to better protect the alewives.

Pair trawling is an aggressive way to catch fish. Two boats working together will wrap a fine mesh net around a school of fish.

Mr. Armstrong believes cormorants may also be responsible for the decline in herring.

Efforts to revitalize herring runs are not just about protecting the fish, they are about preserving habitat.

Rick Karney, director of the Martha's Vineyard Shellfish Group, was instrumental in revitalizing the herring run at the head of Lagoon Pond, did it as a measure to keep Lagoon Pond a healthy ecosystem. Herring feed on algae. Their presence in a pond helps the ecosystem.

Tom Osmers, West Tisbury's new shellfish constable, is taking steps to revitalize runs in his town, according to Mr. Karney.

Mr. Osmers is pursuing building a herring run in James Pond and reestablishing a herring fish ladder in Mill Brook and another in Tiasquam River. Mill Brook and the Tiasquam River feed into Tisbury Great Pond.

"Why should you care about herring? Because everything you want to eat depends on herring," said Mr. Karney. "If it weren't for herring there wouldn't be a lot of the other fish that we enjoy. Every time we lose a part of the food web, the whole system becomes unstable."