Normally, fisheries management aims to set harvest limits at levels that sustain the population of a particular species.
In August, East Coast fishery managers are poised to grapple with a different question — determining how many fish not to catch in order to help other fish.
The species in question is menhaden, a small fish that has been the focal point of big fisheries debates for decades. Measured by collective weight, menhaden harvests are the largest of any species along the coast and in the Chesapeake Bay. Nonetheless, recent assessments have found its stock to be in good shape — “not overfished and overfishing is not occurring” in fisheries lingo.
But conservation groups have long contended that such analyses don’t account for menhaden’s role as a food source for everything from whales to birds — and especially for striped bass.
After years of work, the Atlantic States Marine Fisheries Commission, which manages migratory fish in state waters along the East Coast, is expected to take tentative steps toward recognizing that role by adopting its first-ever “ecological reference points” for menhaden at its August meeting. The reference points — or population goals — for menhaden would be based largely on what’s needed to support a restored stock of striped bass.
“Although the process has taken a long time … I think they are getting to a good place,” said Chris Moore, a fisheries scientist with the Chesapeake Bay Foundation. “Hopefully, the outcome is that we have a more robust stock of menhaden, and we have healthy and robust populations of those predators as well.”
In February, two reviews of the menhaden stock were presented to the commission’s Menhaden Management Board. One used the traditional single-species review focused only on the menhaden stock, and one accounted for its ecosystem role.
Both showed the overall menhaden population to be in good shape, but the one that accounted for menhaden’s role as a “forage” fish for other species suggested that its population should be managed more conservatively.
Computer modeling that contributed to the analysis indicated that the fish most sensitive to menhaden abundance is striped bass. If the striped bass were at their targeted population level — right now they are far below it — they would require more menhaden.
But presentations to the menhaden board also pointed out how complex this issue may become in future years. Most of the focus is on the link between menhaden and striped bass, which has the best data and where the connection seems strongest.
But other menhaden predators, such as bluefish and weakfish, are at low levels. If their populations rebounded, it’s conceivable they would need more menhaden as well.
On the other hand, spiny dogfish, another menhaden predator, is highly abundant right now. One commissioner mused that maybe harvests of the spiny dogfish — a mud shark — should be promoted to boost menhaden numbers.
That highlights the trade-offs fishery managers will face in the future as they embrace ecosystem management. It is impossible to manage all species — predators and prey — to have maximum populations at the same time, and managers will eventually, in effect, be placed in the role of determining winners and losers of their management actions.
“It is not like we can give you one magic answer,” acknowledged Katie Drew, the stock assessment team leader with the ASFMC. “You really have to start thinking about what do I want out of this fishery, what do I want for all of these predators?
“How do you evaluate those trade-offs between harvesting menhaden, which has socioeconomic benefits itself, versus leaving menhaden in the water which provide environmental and socioecomic benefits to other species?”
Any initial steps are not likely to have much impact on the Bay, where most of the menhaden harvest takes place and where battles have raged for decades over whether enough menhaden are being left uncaught.
Right now, the models only examine coastwide relationships between menhaden and other species because data — and modeling capabilities — are limited. But scientists say that both will improve over time, allowing consideration of more species and specific regions, like the Bay.
“This will be a big change for menhaden, obviously, on the coastwide level, but I don’t see it as a huge change for the Chesapeake Bay at this point,” Moore said.
Nor will making more menhaden more abundant by itself be a panacea for solving the problems of predators that are overfished like striped bass. More menhaden may be helpful, but striped bass catch restrictions are needed for its population to rebound, scientists said.
“You could set your menhaden at zero fishing, and your striped bass won’t come back,” said Matt Cieri of the Maine Department of Marine Resources, who chaired the commission’s ecosystem reference point workgroup.
If the commission sets reference points in August as expected, it would most likely consider how those goals would translate into harvest levels at its October meeting.
Menhaden are caught for bait used in other fisheries, as well as for use in products from fish oil to animal feed.
The size of any catch limit changes is unclear. The commission has set current menhaden harvest levels below “safe” levels in part out of concern for other stocks, so ecological reference points may not trigger significant additional reductions.
But, most seem to agree that the upcoming decision will signal the beginning of a new era of fisheries management along the East Coast.
“Ecosystem-based management is the future of fisheries management, including the menhaden fishery,” said Ben Landry of Omega Protein, which operates a menhaden fishing fleet operating out of Reedville, VA, and is the largest harvester of the fish in the Bay and along the coast.