Regional fishery managers have taken the first step toward limiting the Bay’s commercial catch of menhaden, a small, oily fish that plays a big role in the Chesapeake’s ecology and supports hundreds of Virginia fishing jobs.

At the same time, the Atlantic States Marine Fisheries Commission called for stepped-up research to determine why menhaden abundance, a key food for the Bay’s booming striped bass population, has been declining for more than a decade.

Once largely unknown to most people, menhaden have emerged as one of the region’s most heated fishery management issues as recreational fishermen contend that the Virginia-based commercial fishery is taking too many out of the Bay, depriving striped bass and other predators of food.

Besides being an important food for other fish, menhaden are one of the most important filter feeders in the Bay. Schools graze on algae, often eating undesirable types of phytoplankton that other fish won’t touch.

Measured by weight, menhaden have been the Bay’s largest catch for decades. But scientists say it is unclear that the industry is to blame for the low numbers of small menhaden found in the Bay, noting that other factors, such as climate, may be limiting production or that the Chesapeake’s increased abundance of hungry striped bass may be taking too large a bite out of the population.

The commission, which is responsible for managing migratory fish along the East Coast, in February proposed capping the total Bay menhaden catch at 110,400 metric tons—the average Bay catch during the past five years—during 2006 and 2007 while scientists step up research.

The commission will review options for implementing the cap, as well as other management alternatives, at its May meeting. If approved, the measure would then be released for public comment. Final action could take place at the commission’s August meeting.

Proponents described the action as “precautionary,” saying it keeps the catch from increasing until scientists can determine the true status of menhaden in the Bay.

“We have had too many experiences where we waited too long to take action,” Pete Jensen, associate deputy secretary of the Maryland Department of Natural Resources, told the commission. He said delaying action may only magnify the severity of the management efforts ultimately required.

Larry Simns, president of the Maryland Watermans Association and a state representative on the commission, said he had agonized over whether to support restrictions on other commercial fishermen, but supported the measure because it maintains catches at recent levels.

“There doesn’t seem to be any economic impact that is going to affect the fishermen at this time,” he said, adding that “we need to really press the scientists to get the information that we need.”

Critics countered there is no scientific basis for such an action, noting that ASMFC’s own stock assessment considers the coastwide menhaden population to be healthy.

Jack Travelstead, director of fisheries for the Virginia Marine Resources Commission, told the commission it was doing little more than “picking a number out of the hat” in proposing a catch limit and suggested that more weight was being placed on public opinion than the commission’s own technical advisers.

Omega Protein, the company that operates the Reedville-based menhaden fleet, has indicated it has no plans to increase its menhaden catch in the Bay. But investors may view a cap as the first step toward closing the Bay fishery altogether, as has happened in most other East Coast states, said Toby Gascon, Omega’s director of governmental affairs. “That hurts us as a company,” he said. “This industry has been forced over the years to compromise itself into a box, and that box is basically Virginia and the Chesapeake Bay. We have compromised all that we can. We have nowhere else to go.”

Right now, only North Carolina, Virginia and federal waters more than three miles off the coast remain open to menhaden fishing along the East Coast. Gascon said action to restrict fishing in the Chesapeake should include measures that reopen other areas, allowing fishing pressure to be spread out.

Menhaden have been used for decades in animal feed, but recently the Omega-3 fatty acids found in the fish oil have found popularity as a diet supplement believed to have certain human health benefits.

Coastwide menhaden landings have decreased over the past decade, but the percentage of the catch coming from the Bay has increased over what it was decades ago as other states closed their waters to menhaden boats.

That has caused some to suggest that the Chesapeake may be suffering from “localized depletion” of menhaden, even as ASMFC’s surveys indicate the overall menhaden stock is healthy.

Many fishermen have blamed the reduced abundance of menhaden for thin striped bass increasingly found in the Chesapeake, often with little or no body fat. Some contend the weakened fish are more susceptible to mycobacteria infections, a chronic wasting disease which infects more than half of the rockfish in the Chesapeake.

Such concerns have spurred sports fishing groups and environmental organizations to wage an aggressive campaign to limit the catch.

While the number of small fish, which are the primary food source for striped bass and other predators has declined, many scientists, including those on the ASMFC’s Menhaden Technical Committee, said it’s unclear whether the Bay’s total menhaden abundance has actually declined.

Schools of larger fish, which are the primary target of the fishery, freely move in and out during the year. And although their analysis of the overall stock health is conducted coastwide, the scientists say great weight is given to the Chesapeake.

“The Bay is sort of like a breadbasket for menhaden,” said Joe Smith, a scientist with the National Marine Fisheries Service. “We put a lot of weight on it in developing our indices.”

The commission’s final vote was 12 in favor of the proposal to cap the fishery, and three—Virginia, Massachusetts and the Potomac River Fisheries Commission—opposed. The National Marine Fisheries Service abstained, as it does on all allocation votes.

— The Associated Press contributed to this report