Just two years after fishery managers slashed menhaden harvests to prevent overfishing, a new review of the menhaden stock has concluded that the population of the small, oily fish has actually been in good shape in recent years, and hasn’t been overfished in decades.

This upbeat assessment, which was formally adopted by the Atlantic States Marine Fisheries Commission Feb. 3, has commercial fishermen hoping that the commission will grant them higher catch limits at its May meeting.

It presents a strikingly different picture of the menhaden stock than what was presented in the 2012 assessment, which had concluded that menhaden were suffering from overfishing, and abundance was near a historic low. Based on that information, the commission, which regulates catches along the East Coast, in December 2012 imposed a 20 percent coastwide harvest reduction.

The most recent assessment now paints an entirely different picture of the stock. It found that the coastwide menhaden biomass — an estimate of the weight of the entire population — was near or above the long-term average during much of the past decade. And, it found no evidence of overfishing since the 1950s.

Fishing industry representatives said the new assessment validates their objections to the 2012 cuts, and said it should boost the prospect for increased catch limits. The Menhaden Fisheries Coalition, an industry group, said “this new assessment reveals that the previous 2012 assessment was far too pessimistic and the subsequent cuts perhaps unnecessary.”

Conservation groups that have long pressed for more restrictive menhaden catch limits say it remains uncertain that enough menhaden are left uncaught to support rockfish and other predators. “There’s not a thing in the assessment that says we can take those fish back from striped bass and other predators,” said Ken Hinman, president of the conservation group Wild Oceans.

That illustrates one thing that hasn’t changed. Opinions remain sharply divided over how menhaden, which some have dubbed “the most important fish in the sea,” should be managed.

There is, nonetheless, agreement that the new assessment provides a much clearer picture of the menhaden stock. The assessment doesn’t mean the stock has dramatically changed since the 2012 assessment. Rather, new information and analysis has simply provided a dramatically different picture of the stock’s condition.

Whereas previous assessments had relied primarily on commercial fishing data, the new assessment made extensive use of new information provided by fishermen, states, federal agencies and organizations to help build a better picture of the stock.

Those data suggested better reproduction from regions where information was not available for previous assessments, and the presence of more larger and older fish — especially in areas farther north — than were previously thought to exist.

“This assessment was a back-to-the-drawing-board, consider-every-decision made,” said Amy Schueller of the National Marine Fisheries Service, who chaired the stock assessment panel. “So there are differences.”

As part of its review, the stock assessment panel also concluded that previous assessments had misinterpreted a decades-old study when they assumed most menhaden did not begin to reproduce until they were about 3 years old. Based on new information, the new assessment assumes that some portion of the fish begin to reach maturity when they are about 2 years old. That results in a larger abundance of reproductive-capable fish which, in turn, has the potential to produce more young.

The assessment also changed the assumptions about the age of fish caught in the fishery, based on surveys that suggested there were more older and larger fish in the population than previously thought.

The assessment got a thumbs-up from a peer review panel. “We were very, very impressed with the thoroughness and the comprehensiveness of the stock assessment,” said Michael Jones, a fisheries scientist with Michigan State University, who chaired the peer review panel. “Overall, bottom line, the panel offered a strong endorsement for both the findings and the methods of the assessment.”

But, conservation groups and some fishery managers say that, as in the past, the assessment is focused on the status of the menhaden stock, and whether harvests are staying within sustainable levels. Such “single species assessments,” they say, do not account for the ecological role of menhaden, which is an important food source for a wide range of predators. But exactly how many fish need to be left after the commercial catch to fulfill their ecological role is an illusive question. That question has made the menhaden debate one of the region’s most heated fishery issues since striped bass began rebounding in the Bay in the mid-1990s. Anglers have complained about rockfish that are skinny and in poor health, and have blamed the commercial fishery for catching too many menhaden.

Measured in pounds, menhaden make up, by far, the largest harvest in the Bay. They are harvested by a large “reduction” fishery based in Virginia, Omega Protein, which accounts for a little more than three-quarters of the coastwide harvest and turns it into a variety of products such as vitamin supplements and pet foods. The rest is caught by smaller operations along the coast that supply menhaden as bait for use in a variety of other fisheries.

The issue of how to manage fisheries so they meet both commercial and ecological roles is a larger debate playing out globally. Conservationists have sought to limit catches of forage species — such as menhaden, shad and herring — which are important food for other species.

The ASMFC has promised to adopt fishing targets that account for menhaden’s ecological role, but trying to identify the right number of menhaden to leave uncaught to benefit other species is a question that has eluded it for years.

“The challenge seems to be that these are largely policy questions, and we want a technical solution to a policy question,” said Robert Boyles, deputy director of marine resources with the South Carolina Department of Natural Resources, and chair of the ASMFC’s Menhaden Management Board.

At its February meeting, the menhaden board seemed divided over whether to use the assessment’s greatly improved outlook for menhaden to provide relief to fishermen, or as a stepping stone toward setting a new goal that accounts for menhaden’s ecological role in management decisions.

“I think it would be unfortunate for this commission to not make a commitment to increase the quotas for the 2015 fishing year across the board,” said Jeff Kaelin, who is in charge of government relations for New Jersey-based Lund’s Fisheries and is also a member of ASMFC’s Menhaden Advisory Committee. “We feel very strongly it is time to move ahead. It is a positive assessment. I see no reason why in May this board couldn’t come together…and at least provide an opportunity to make up what was taken away, as it turns out, without really any need relative with what we now know about the stock status.”

Many fishermen, especially small, bait operations were hard-hit by the cuts. Many states got what turned out to be significant cuts when quotas were set in 2012 because of a lack of historical data from bait fisheries to guide allocations. That, in turn, has also hurt other local fisheries that depended on the menhaden for bait.

But others worried about an abrupt change — some called it “regulatory whiplash” — in catch limits, especially when the question of how many menhaden should be left behind for ecological reasons remains unanswered.

“We just had a pretty rough go of this just a couple of years ago,” said Louis Daniel, director of the North Carolina Division of Marine Fisheries, who chaired the Menhaden Board when it adopted the catch limits. “I would hate to see us move forward too quickly on these results. We do need to move forward carefully, deliberately.”

Bill Goldsborough, a fisheries scientist with the Chesapeake Bay Foundation, and a member of the Menhaden Board, cautioned that while the stock assessment was generally good news, it also contained some issues of concern. Although the biomass is high, that appears to be driven in part by the findings that more old, large fish are found in the northern part of the menhaden’s range. Actual menhaden abundance — the number of individual fish — has been declining to low levels in recent years, the assessment showed.

“That is troubling from the standpoint of ecosystem services, the main one being menhaden’s role as prey for a lot of other species, because it is numbers of prey that are most important,” Goldsborough said. “So where we may have a lot of bigger, older fish farther north, we don’t have very high numbers of menhaden coastwide.”

For its May meeting, the board asked its scientific advisers to explore the impact that raising the catch limit would have on the overall stock status. It also asked them to explore new limits aimed at protecting ecological services provided by the menhaden stock, based on advice from the new stock assessment.

Some hope that, with the new stock assessment, there may be enough menhaden to accomplish both.