Because menhaden were essential to this natural bounty, they were a powerful hidden force in the colonization of North America. As Mark Kurlansky wrote in Cod: A Biography of the Fish That Changed the World, it was superabundant food fish that first drew Europeans—the Vikings, then the Basques, and later the British—to North American waters. Nineteenth-century scientists, partly drawing on the knowledge of generations of fishermen, concluded that menhaden, members of the same family as herring and shad, were essential to the diet of almost all Atlantic predatory fish, including bluefish, cod, haddock, halibut, mackerel, weakfish, striped bass, swordfish, king mackerel, and tuna, as well as many marine birds and mammals, including porpoises and toothed whales. As the ichthyologist G. Brown Goode put it in his monumental 1880 volume, A History of Menhaden, “It is not hard to surmise the menhaden’s place in nature; swarming our waters in countless myriads, swimming in closely-packed, unwieldy masses, helpless as flocks of sheep, close to the surface and at the mercy of any enemy, destitute of means of defense or offense, their mission is unmistakably to be eaten.” He wasn’t far from the truth when he proclaimed that anyone enjoying a meal of American Atlantic saltwater fish was eating “nothing but menhaden!”
But where did this enormous biomass of menhaden, so crucial to the food chain above it, come from? Just as all those saltwater fish are composed mainly of menhaden, all those billions of tons of menhaden are composed almost entirely of billions of tons of the tiny particles of vegetable matter known as phytoplankton. Eating is just as crucial an ecological mission for menhaden as being eaten.
Eons before humans arrived in North America, menhaden evolved along the low-lying Atlantic and Gulf coasts, where nutrients flood into estuaries, bays, and wetlands, stimulating the potentially overwhelming growth of phytoplankton. Although menhaden are the major herbivorous fish of these coasts, they don’t chomp on plants. They are filter feeders that live on phytoplankton, which most other aquatic animals are unable to eat. Dense schools of menhaden, sometimes numbering in the hundreds of thousands, pour through these waters, toothless mouths agape, slurping up plankton and detritus like a colossal submarine vacuum cleaner as wide as a city block and as deep as a train tunnel. Each adult fish can filter about four gallons of water a minute. Purging suspended particles that cause turbidity, this filter feeding clarifies the water, allowing sunlight to penetrate and encourage the growth of aquatic plants that release dissolved oxygen and harbor a host of fish and shellfish.
Much of the phytoplankton consumed by menhaden consists of algae. Excess nitrogen can make algae grow out of control, and that’s what happens when vast quantities of nitrogen flood into our inshore waters from runoff fed by paved surfaces, roofs, wastewater, overfertilized golf courses and suburban lawns, and industrial poultry and pig farms. This can generate devastating blooms of algae, such as red tide and brown tide, which cause massive fish kills, then sink in thick carpets to the bottom, where they smother plants and shellfish, suck dissolved oxygen from the water, and leave dead zones that expand year by year.
In the natural ecosystem, menhaden cleaned the upper layers while another great filter feeder, the oyster, cleaned the bottom. But as oysters have been driven to near extinction in many Atlantic bays and estuaries by overfishing and pollution, menhaden are left as the only remaining check on deadly phytoplankton explosions. Marine biologist Sara Gottlieb, author of a groundbreaking study on menhaden’s filtering capability, compares their role with the human liver’s: “Just as your body needs its liver to filter out toxins, ecosystems also need those natural filters.” Overfishing menhaden, she says, “is just like removing your liver.”
THE NARRAGANSET CALLED THE FISH munnawhatteaug, “that which manures,” soon corrupted to “menhaden” by the English colonists. The Abenaki of Maine called them pauhagen, their word for “fertilizer,” hence “pogy,” still a common name for the fish. This is the fish Squanto may have taught the Pilgrims to plant with their corn.
In the early 19th century, menhaden became an industrial-scale fertilizer for the coastal farmland of New England and the mid-Atlantic, with countless rotting fish spread out over many acres to prepare the land for crops. Groups of farmers often formed small companies—with jaunty names like Coots, Fish Hawks, Eagles, Pedoodles, and Water Witches—that owned the boats, huge nets, and draught horses necessary to catch and haul tens and even hundreds of thousands of fish at a time.