Concerned that overfishing is destroying the ability of menhaden to reproduce, the commission that manages the Atlantic coast fishery voted Wednesday to sharply reduce the catch of the fish.

Tiny, oily menhaden are called the ocean’s most important fish by environmentalists because they provide food for essential fish such as striped bass and for birds such as osprey, bald eagles and brown pelicans. Without menhaden, environmentalists say, the Atlantic Ocean and Chesapeake Bay ecosystems would come crashing down.

At a meeting in Boston, the Atlantic States Marine Fisheries Commission voted 14 to 3 to cut the amount of menhaden that can be harvested annually from 183,000 metric tons to 174,000 metric tons. The commission must now draft and vote on a plan to implement the new rule, which is likely to become effective in May 2013, spokeswoman Tina Berger said.

A single company, Omega Protein Corp., took 160,000 metric tons of menhaden — 80 percent of about 450 million fish harvested last year — off the coast of Virginia, the only state that permits industrial fishing of menhaden. The company crushes the fish into meal to feed livestock and farmed fish around the world.

Bait fishermen, who mostly sell to sport fishers, caught the rest.

Ben Landry, Omega Protein’s spokesman, said the commission’s decision could lead to job cuts at the company processing plant in Reedville, Va., where 250 people work. “It’s too early to say,” Landry said.

In the run-up to the vote, the 45-member commission received more than 91,000 letters, the vast majority of which urged members to drastically reduce the catch. States from Maine to Florida each have three representatives, only one of whom can vote.

The commission wants to ensure that at least 15 percent of adult menhaden are left to spawn in the ocean and its tributaries after the yearly harvest. But the commission is pushing to have 30 percent of the adult population left to spawn. That would nearly quadruple the current threshold of 8 percent.

Landry said the commission could have set the threshold at 20 percent and waited to see whether menhaden stocks would rebound, rather “than immediately go to 30 percent.”

Menhaden stocks are in steep decline: 50 years ago, about 90 billion were a year old or less, according to commission estimates. Twenty-five years ago, there were 70 billion. Now only 18 billion menhaden that age remain.

“Certainly there was concern about the population,” Berger said, explaining the commission’s vote. “They have an obligation to stop overfishing.”

Peter Baker, an official with the Pew Environment Group, watched the meeting at the downtown Langham Hotel. “We think they did the right thing,” said Baker, director of the group’s Northeast Fishery Program. “We supported a 40 percent target. We did that knowing it was unlikely.”

Bill Goldsborough, fisheries director for the Chesapeake Bay Foundation, which had called for the exact reduction that was approved, said the commission “found a result that was responsible and reasonable.”

Goldsborough said the diets of striped bass (also known as rockfish) and osprey have suffered for want of menhaden. He said the commission’s management of the fishery kept the menhaden’s population artificially low.

Omega Protein argued that the population was adversely affected by poor water quality and other environmental factors, a finding that the commission supported, Berger said.

But overharvesting made matters worse, she said. The commission reduced the harvest to improve the chances of a favorable spawn in years to come.

In an essay for the Richmond Times-Dispatch, Bryan Watts, director of the Center for Conservation Biology at the College of William & Mary and Virginia Commonwealth University, said the reduced menhaden population hit osprey hard.

“More than 70 percent of the fish delivered to nests were menhaden” in the 1980s, Watts wrote. By 2006, menhaden accounted for less than 27 percent.

“It’s not much of an exaggeration to call it the most important fish in the sea,” Goldsborough said. “It’s an essential link in the food chain.”