The Most Important Fish......

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The Most Important Fish in the Sea
You've never heard of them, but your life may depend on them
By H. Bruce Franklin
Photography by Tom Tavee
Menhaden make up approximately 40 percent of the catch of commercial fisheries in the United States. But some ecologists estimate that the menhaden population declined by more than 50 percent in the last decade.
First you see the birds— gulls, terns, cormorants, and ospreys wheeling overhead, then swooping down into a wide expanse of water dimpled as though by large raindrops. Silvery flashes and splashes erupt from thousands of small herringlike fish called menhaden. More birds arrive, and the air rings with shrill cries. The birds alert nearby anglers that a massive school of menhaden is under attack by bluefish.

The razor-toothed blues tear at the menhaden like piranhas in a killing frenzy, gorging themselves, some killing even when they are too full to eat, some vomiting so they can kill and eat again. Beneath the blues, weakfish begin to circle, snaring the detritus of the carnage. Farther below, giant striped bass gobble chunks that get by the weakfish. From time to time a bass muscles its way up through the blues to take in whole menhaden. On the seafloor, scavenging crabs feast on leftovers.

The school of menhaden survives and swims on, its losses dwarfed in plenitude. But a greater danger than bluefish lurks nearby. The birds have attracted a spotter-plane pilot who works for Omega Protein, a $100 million fishing corporation devoted entirely to catching menhaden. As the pilot approaches, he sees the school as a neatly defined silver-purple mass the size of a football field and perhaps 100 feet deep. He radios to a nearby 170-foot-long factory ship, whose crew maneuvers close enough to launch two 40-foot-long boats. The pilot directs the boats' crews as they deploy a purse seine, a gigantic net. Before long, the two boats have trapped the entire school. As the fish strike the net, they thrash frantically, making a wall of white froth that marks the net's circumference. The factory ship pulls alongside, pumps the fish into its refrigerated hold, and heads off to unload them at an Omega plant in Virginia.

Not one of these fish is destined for a supermarket, canning factory, or restaurant. Menhaden are oily and foul and packed with tiny bones. No one eats them. Yet they are the most important fish caught along the Atlantic and Gulf coasts, exceeding the tonnage of all other species combined. These kibble of the sea fetch only about 10 cents a pound at the dock, but they can be ground up, dried, and formed into another kind of kibble for land animals, a high-protein feed for chickens, pigs, and cattle. Pop some barbecued wings into your mouth, and at least part of what you're eating was once menhaden.

Humans eat menhaden in other forms too. Menhaden are a key dietary component for a wide variety of fish, including bass, mackerel, cod, bonito, swordfish, bluefish, and tuna. The 19th-century ichthyologist G. Brown Goode exaggerated only slightly when declaring that people who dine on Atlantic saltwater fish are eating "nothing but menhaden."

And that is one problem with the intensive fishing of menhaden, which has escalated in recent decades. This vital biolink in a food chain that extends from tiny plankton to the dinner tables of many Americans appears to be threatened. The population of menhaden has been so depleted in estuaries and bays up and down the Eastern Seaboard that even marine biologists who look kindly on commercial fishing are alarmed. "Menhaden are an incredibly important link for the entire Atlantic coast," says Jim Uphoff, the stock assessment coordinator for the Fisheries Service of the Maryland Department of Natural Resources. "And you have a crashing menhaden population with the potential to cause a major ecosystem problem." Menhaden have an even more important role that extends beyond the food chain: They are filter feeders that consume phytoplankton, thus controlling the growth of algae in coastal waters. As the population of menhaden declines, algal blooms have proliferated, transforming some inshore waters into dead zones.
A school of menhaden is captured in Chesapeake Bay. Directed by a spotter pilot, boats deploy a giant purse seine (above), close up the net (1), and dump the catch in the hold of a factory ship (2). The fish are destined for a nearby Omega Protein processing plant (3).

To grasp how ubiquitous menhaden once were, you can read the journals of explorer John Smith. In 1607, he sailed across the Chesapeake Bay through a mass of menhaden he described as "lying so thick with their heads above the water, as for want of nets (our barge driving amongst them) we attempted to catch them with a frying pan." Colossal schools of menhaden, often more than a mile in diameter, were once common along the entire Atlantic and Gulf coasts of the United States. Since World War II, however, fishermen using spotter planes and purse seines appear to have dramatically decreased both the population and the range of menhaden.

Bryan Taplin, an environmental scientist in the Atlantic Ecology Division of the Environmental Protection Agency (EPA), has witnessed the destruction of all the large schools of menhaden by purse seiners in Rhode Island's Narragansett Bay. During the last two decades he has also studied changes in the diet of striped bass in the bay by analyzing the carbon isotope signature of their scales. What he has discovered is a steady shift away from fat-rich menhaden to invertebrates that provide considerably lower nutritional value. That has been accompanied by a loss of muscle and a decrease in the weight-to-length ratio of striped bass. The bass that remain in Narragansett Bay, says Taplin, are "long skinny stripers" that have been forced to shift their diet because "the menhaden population has crashed to an all-time low."
SMALL FRY: During their first year, menhaden seek shelter in shallow river shoals and tidal creeks and can grow to about 3 inches in length.

NEW LIFE: During spawning season, a female may produce 40,000 to 360,000 eggs, most of which are eaten by fish or seabirds. Survivors hatch as transparent larvae after 2 or 3 days.
Photograph courtesy of National Marine Fishery Services, Beaufort, NC.
"You have to scratch your head and wonder— since we set quotas for bluefin and tuna— why we don't set quotas for this crucial part of the oceanic food chain," says Taplin. "Not to regulate a fishery that's so important is to ask for trouble. I wonder whether we are about to see something go wrong unlike anything we have ever seen."

Signs of what could go wrong are already obvious in the Chesapeake Bay, the tidal estuary that once produced more seafood per acre than any body of water on Earth. "There's nothing in Chesapeake Bay that can take the place of menhaden," says Uphoff of the Maryland Fisheries Service. "Menhaden are king." Jim Price is a fifth-generation Chesapeake Bay fisherman. For 10 years he captained a charter boat specializing in light-tackle fishing for striped bass, also called rockfish by bay anglers. One day in the fall of 1997, Price caught a rockfish so diseased he still becomes upset when he talks about it. "I'd never seen anything like that in my entire life," he says, wringing his powerful, deeply tanned hands. "It was covered with red sores. It was so sickening it really took something out of me."

Price deposited several sick rockfish at the Cooperative Oxford Laboratory in nearby Oxford, Maryland, and then began his own independent study. When he cut some open, he was shocked. "I've been looking in the stomachs of rockfish for 40 years," he says, "but I couldn't believe what I saw— nothing, absolutely nothing. Not only was there no food, but there was no fat. Everything was shrunk up and small."

An Oxford lab pathologist speculated that the fish might have been "decoupled from their source of food," but Price was incredulous. "I thought to myself, with all the food here in the Chesapeake, that's a stupid idea. Then I got to thinking. In years past, at that time of year I would find their stomachs full of menhaden, sometimes a half-dozen whole fish."

Price hypothesized that malnutrition, caused by the decline in the menhaden population, made the rockfish vulnerable to disease. Since then, his hypothesis has been confirmed by research. Half the rockfish in the Chesapeake are diseased, with either bacterial infections or lesions associated with Pfiesteria, a toxic form of phytoplankton known as the cell from hell. But that is only one symptom of the depletion of menhaden.

Dense schools of menhaden swimming with their mouths open slurp up enormous quantities of plankton and detritus like gargantuan vacuum cleaners. In the Chesapeake and other coastal waterways, the filtering clarifies water by purging suspended particles that cause turbidity, allowing sunlight to penetrate to greater depths. That encourages the growth of plants that release dissolved oxygen as they photosynthesize. The plants also harbor fish and shellfish.

Far more important, the menhaden's filter feeding limits the spread of devastating algal blooms. Runoff from many sources— farms, detergent-laden wastewater, overfertilized golf courses, and suburban lawns— floods nitrogen and phosphorus into coastal waters. Nitrogen and phosphorus in turn stimulate the growth of algal blooms that block sunlight and kill fish. The blooms eventually sink in thick carpets to the sea bottom, where they suck dissolved oxygen from the water and leave dead zones. Menhaden, by consuming nutrient-rich phytoplankton and then either swimming out to sea in seasonal migrations or being consumed by fish, birds, and marine mammals, remove a significant percentage of the excess nitrogen and phosphorus that cause algal overgrowth.
The Food Chain
Menhaden are a critical link in the coastal marine food chain, turning tremendous quantities of plankton into biomass for a wide variety of predatory forage fish, seabirds, and marine mammals.
Graphic by Matt Zang
Nature had developed a marvelous method for keeping bays and estuaries clear, clean, balanced, and healthy: Oysters, the other great filter feeders, removed plankton in lower water layers, and menhaden removed it from upper layers. As oysters have been driven to near extinction along parts of the Atlantic coast, menhaden have become increasingly important as filters.