Herring have arrived in Vineyard waters, and this is particularly good news for a fish in trouble. Years ago local fishermen used to count the herring by the barrel; today they are counted only by the handful.

This is the fourth spring Massachusetts anglers have been prohibited from catching these fish. The state moratorium is a hardline effort to protect the fish from further decline. An initial three-year moratorium was renewed; it is to last another two years.

River herring, also called alewives, are anadromous fish. They live in saltwater but as adults, every spring they return to their birthplace, a freshwater pond, to spawn.

Anadromous fish are especially vulnerable to changes in habitat and fishing effort, fisheries managers report. They include alewives and blueback herring. They are near the bottom of the food chain; just about every fish, and even whales and birds, feed on them. Herring are essential to the ecosystem for another reason: they feed on algae. Like shellfish, they contribute to the health of waterways by feeding on phytoplankton.

Herring runs are man-made structures that assist the fish as they make their pilgrimage upstream from saltwater to the freshwater ponds. There are several herring runs on Martha’s Vineyard and more than 75 in Massachusetts.

The Island’s oldest continuously functioning herring run is on tribal land in Aquinnah. It runs from Squibnocket Pond to Menemsha Pond. Another ancient run is at Mattakessett in Edgartown. A herring run at the head of Lagoon Pond and a smaller one at the head of Lake Tashmoo are in operation, too.

Derek Cimeno, shellfish constable for Tisbury, oversees the herring run at Lagoon Pond, and he is partly responsible for the building of a new run at Lake Tashmoo six years ago. He makes nightly visits to the runs to see how they are doing.

A week ago Tuesday, Mr. Cimeno said he and his nine-year-old son, Anthony, made a visit to the Lagoon Pond herring run with the hope they’d spot the first of the fish, just as some Islanders are anxious to hear the first pinkletink or see the first osprey.

“When we got out of the car, my son said, ‘I smell fish,’” Mr. Cimeno reported. The two went down and looked in the swirling, bubbling water in the run. “We saw at least a dozen. My flashlight spooked them,” Mr. Cimeno said.

Last year was slightly better for the herring than the year before, Mr. Cimeno said, so there is reason for optimism. He said the worst was over three years ago, coinciding with the state’s moratorium, when only a small number of herring came into the run. Only a few years before, there were plenty of herring in the run. “The dramatic drop was quick, in only a few years,” Mr. Cimeno said.

The Aquinnah run has a history that goes back before recorded time. Bret Stearns, natural resource director for the Wampanoag Tribe of Gay Head (Aquinnah), said the drop in herring returning to this run was dramatic, too. Mr. Stearns said the tribe is aggressive about overseeing the run and making sure it is in good order. Even before the moratorium, the tribe regulated access to the run and set limits for the tribal fishermen who harvested the run.

To protect what fish swim the run, the tribe has put up lines and streamers that go over a pool; these keep the fish safe from cormorants as they move upstream to Squibnocket.

Cormorants and osprey are aggressive avian predators that feed on all small fish. Osprey are indigenous to the Vineyard and cormorants are not. In the history of herring, cormorants are a fairly new predator.

For the tribe, Mr. Stearns said, “There is an extreme level of concern. I was up at the herring run the other night. I haven’t seen one yet. I do believe they are here. When an osprey is resting on the perch, I believe the herring are here.”

Tom Osmers, shellfish constable for West Tisbury, has spent time over the past two years attending to a small fish ladder at Mill Pond in West Tisbury. Mr. Osmers hopes it is helping the herring restoration effort on a small scale. Last year the Town of West Tisbury received the authority from the state to manage herring. Other towns with herring runs already have that authority.

Paul Bagnall, shellfish constable for Edgartown, said there have been steps through the years to enhance the Mattakesett herring run. Herring Creek Farm at Katama gets its name from an era when herring were a far more important resource. The manmade creek runs along Atlantic Drive from Katama Bay to Crackatuxet Pond. More than a century ago, that run was a major contributor to the economy of the town. A hundred years ago town residents built temporary tents down near the run to harvest hundreds of barrels of herring in the spring for shipment off-Island. In those days before plastic, herring scales were used in the manufacturing of artificial pearls. They were called Priscilla Pearls.

Fish swimming in the herring creek off Atlantic Drive at Mattakesett seek to reach Crackatuxet Pond, which a century ago was one of Edgartown Great Pond’s coves.

Edgartown Great Pond was kept fresh and not opened to the sea in those days when herring was a prized resource.

Edgartown Great Pond still offers freshwater sources for returning herring, but they gain access only when the pond is opened to the sea.

Mr. Bagnall said an opening is planned for April 15 if the weather and seas cooperate. An opening earlier in February lasted but a few days.

On the first year of the moratorium, Mr. Bagnall and a group of volunteers helped to stock Crackatuxet with adult herring from Lagoon Pond, hoping that they will imprint the young with the site, so they will return to the same spot as adults. The intent was to jump-start the pond as a herring fish destination. He believes the effort was successful, though it is still too early to tell.

Edgartown has a number of inactive runs. Mr. Bagnall has his eye on a stream that runs from Lily Pond down to Trapp’s Pond. The creek crosses through Sheriff’s Meadow Foundation’s Caroline Tuthill Preserve, near the Triangle, and runs under the Oak Bluffs to Edgartown Beach Road.

Adam Moore, executive director of Sheriff’s Meadow, said yesterday he is reviewing the possibility of restoring the run. “It would be a great project for us,” he said. The creek goes under the road and through private property to the pond. On Wednesday afternoon, the stream wasn’t moving. Mr. Moore said any effort to restore the run would be a collaborative effort involving the town and state.

Rick Karney, the director of the Martha’s Vineyard Shellfish Group, led the effort to build the herring run at the head of Lagoon Pond, which is considered the Vineyard’s signature herring run. It is accessible to the public and was built with the help of Oak Bluffs and Tisbury officials. Called the Richard F. Madeiras Herring Run, it was named after an Oak Bluffs shellfish constable who also shared the vision. It took Mr. Karney at least 10 years to pool all the help to get the run built.

The problem with the status of herring isn’t just land-based. There is an even greater concern that the herring are being overfished, either deliberately or as a bycatch in federal waters, more than three miles offshore.

Joe Costa is the executive director of the Buzzards Bay Coalition, an environmental group working on protecting habitat and the environment. Mr. Costa said his group has spent a lot of money on anadromous runs in the Buzzards Bay area. “The confounding factor is what is happening in the offshore fishery. Commercial fishing has so altered the offshore stocks it has been difficult for us to restore stocks even though we are working on runs. Herring are an important resource, and this problem has to be addressed.”

The Herring Alliance, an advocacy organization which focuses more on Atlantic herring in the open ocean, has been fighting to protect forage fish in the waters of the Gulf of Maine and surrounding areas. It is widely known that river herring and Atlantic herring make up huge schools of fish.

The alliance’s Nancy Civetta, said her organization, which is made up of other conservation organizations, is seeking to make sure that the herring are protected not just for future harvest, but are protected because of their importance in the ecosystem. The organization has run a campaign to stop large fishing boats from harvesting bait fish in the Gulf of Maine with fine mesh nets.

Mike Armstrong, a state fisheries official charged with overseeing the anadromous fish in the state for the Division of Marine Fisheries, said the moratorium appears to be working. He said offshore fishing in federal waters is not the cause of the decline, though it may be a contributor.

This week fisheries managers charged with overseeing shad and river herring are meeting in Baltimore to look over data about the state of these fisheries.

Kate Taylor, a coordinator for the Atlantic States Marine Fisheries Commission, said the problem of herring recruitment is being examined as far north as Maine and down into the Carolinas.

“There is concern, and we are trying to use the data we have,” Miss Taylor said, adding: “The commission is working with agencies to help restore water systems that are blocking the herring from spawning.” She said this includes dams and fouled streams.

But the attention shifts back out to federal waters where the large fishing boats may be targeting mackerel, Atlantic herring and coming up with the far more troubled alewives in their nets.

“We are working within our jurisdiction, which is state waters, but we are also working with our counterparts, the National Marine Fisheries Service and councils which oversee the federal waters,” Miss Taylor said.

Two weeks ago the board of directors of the National Fish and Wildlife Foundation agreed to make the recovery of river herring a focal initiative. The foundation is interested in helping organizations move to protect river herring. They plan to raise and spend tens of millions of dollars over the next 10 years on the effort. Last year the organization spent $70 million on conservation on marine and landbased conservation projects in all 50 states and outside the country.

Anthony Chatwin, director of marine and coastal conservation with the foundation, said applications will be juried.