What is the most important fish in the sea?
The answer is—surprise!—menhaden.
If you’re scratching your head over that one, you’re not alone. Like a character actor whose name you can’t recall, menhaden provides critical support to the ocean’s stars. Whales, tuna, cod and striped bass are among the headliners that nosh on the nutritious morsels.
But the species also plays a meaty, if unheralded, role on land.
By weight, it’s the largest catch pulled from the Atlantic Ocean. It’s earned at least $300 million in revenues this year for the reduction industry, which turns the fish into animal feed, fertilizer and food supplements.
And it’s at the heart of a debate that is roiling conservationists who want to protect the species and fisheries that want to profit from it.
Trying to sort it out is the Atlantic States Marine Fisheries Commission, which manages two dozen species groups living within 3 miles of the U.S. coast from Maine to Florida.
“Our big question is how many fish are out there and how many can we take without driving the population to collapse?” said Katie Drew, a senior stock assessment scientist with the marine commission.
Mature menhaden weigh about a pound each and are commonly known as pogy or bunker.
Until recently, there was no coastwide fishing limit on the fish, but in 2013, worried about overfishing, the marine commission implemented a quota of 170,800 metric tons a year, or 20% less than the preceding three-year average.
It was short-lived.
Last year, the commission raised the quota by 10%. Next year, it will increase it by another 6.5%, to 200,000 metric tons, or about 441 million pounds. And it’s likely to review the figure again as it grapples with how to best manage this important fish.
Before setting a quota, the marine commission evaluates the fish population, which is easier said than done. Experts at the Pew Charitable Trusts compare it to counting trees—except it’s midnight, the trees are moving, and they’re eating each other.
In its assessments of menhaden, the commission examines the size of the commercial catch and conducts two types of independent surveys. One focuses on fish that are less than a year old to get an idea of how many have been born. The other focuses on fish that are one or more years old to get a sense of how many offspring they might produce the coming year.
To collect the survey data, researchers go to the fish’s nursery grounds, capture the juveniles and count them. Individual sites are sampled multiple times at the same time each year and with the same gear to help ensure the tallies are comparable. The older fish are sampled using similar protocols.
To illustrate how the data are used to discern information about the population, Dr. Drew said to imagine a survey that yields a sample of 100 menhaden. Fishermen then net 2,000 pounds of the fish, and a subsequent survey yields only 50 menhaden.
“So, the fishery took out 2,000 pounds, and the population declined by 50%,” Dr. Drew said. “Fish do not just die from fishing, but we can get a handle on that by looking at how long they live, the expected longevity, or how big they are.”
With this information, the commission can begin to think about limits.
Like most fish, menhaden are managed as a single species without regard to the predators that rely on them for food, and from that perspective, they do not appear to be overfished. But an alternative, multispecies approach would also estimate the effect of menhaden fishing on other species.
A multispecies model could account for a few important predators, like striped bass, or it could include everything from plankton to whales.
“Menhaden play a really critical role in transferring energy from the lowest end of the food chain to the largest predators,” said Joseph Gordon, Mid-Atlantic Ocean conservation manager for the Pew Charitable Trusts, explaining the appeal of the approach. “Hundreds of thousands of relatively small fish with their mouths agape are just churning through large blooms of plankton. And everywhere they go, they are chased by predators.”
The marine commission is in the process of building a multispecies model and is soliciting public comments about how to manage menhaden.
“It’s easy to say more menhaden in the ocean mean more striped bass, but how much more?” Dr. Drew said, noting some of the issues. “Is it fair for the menhaden industry to take a hit so the population of striped bass goes up?”
If the commission adopts a multispecies approach, it will be a first.
“No one in the world has managed a whole species for predators,” said Aaron Kornbluth,an environmental scientist with The Pew Charitable Trusts.
And in this spotlight, the humble menhaden might, at last, get the star treatment it deserves.