Article for September - October 2009
For Wildlife Watchers: Menhaden
by Rob Simbeck
photography by Phillip Jones
They are bony, oily, smelly and quick to spoil, but menhaden are among the most important fish on earth. They have made up a substantial portion of the total U.S. commercial catch for two centuries, and they remain vital both ecologically and in terms of human nutrition.
"Menhaden are unique," says Dr. Robert Latour, associate professor of Marine Science with the Virginia Institute of Marine Science at The College of William & Mary, "in that they fulfill multiple ecological functions as well as support a large industrial fishery."
They are, in essence, a gateway species, an important link up and down the food chain. Filter feeders, they sweep in schools through ocean waters, mouths agape, filtering and capturing tiny plankton that they turn into protein that passes up the food chain.
Atlantic menhaden - Brevoortia tyrannus
Description: 1 foot long, up to a pound. Silver, with brassy sides and dark bluish-green back. Large head, black spot behind gill opening, lines of smaller spots along flank.
Range and Habitat: Nova Scotia to Florida.
Reproduction: Spawning can take place anywhere along the East Coast but is concentrated in winter off the North and South Carolina coastlines.
Viewing Tips: Menhaden form large, compact schools. Watch for birds feeding on them. Smaller fish will be found in estuaries.
"They are a very important forage fish," says Dr. Mark Collins, senior marine scientist with the S.C. Department of Natural Resources. "Pretty much everything likes to eat menhaden"—a list that includes fish like mackerel, tuna, bluefish and striped bass, birds like gulls, terns and cormorants, and even porpoises and toothed whales.
Humans don't partake directly—in recreational and some commercial fishing, menhaden are used as bait—but that doesn’t keep us from utilizing their protein or their omega-3 fatty acids. They are ground and dried, becoming high-protein feed for pets and for dairy cattle, pigs and even farm-raised fish destined for human consumption. Menhaden oil, according to Ben Landry, director of public affairs at Omega Protein, the largest American commercial harvester of menhaden, is studied in Omega labs and kitchens as the company works to use the omega 3-rich oil in bread, butter and a host of other food products.
A member of the herring family, the Atlantic menhaden (a corruption of its Narragansett name) is related to the Gulf menhaden, common in the Gulf of Mexico, and to the finescale and yellowfin menhaden, found off Florida and in the Gulf. It can grow to a little more than a foot in length and a pound in weight. Rather thin with a large head, it is bright silver with yellowish fins and tail, yellow markings along the side and a lighter color beneath, with a series of black spots along the upper side.
Menhaden are prolific multipliers, with females laying anywhere from 35,000 to 350,000 eggs, depending on age, in open water. Birds and other fishes eat many of those, but many are washed toward shores and estuaries, where they hatch in two or three days. Young menhaden find shelter in river shoals and tidal creeks, filtering microscopic material from the water, including phytoplankton, zooplankton and plant detritus, and growing to about three inches long in their first year. As they get older, and their filtering mechanism becomes larger, they retain only larger food particles, which primarily include zooplankton.
From December through March, most spawning-age menhaden—those approaching three years of age—congregate offshore near and south of Cape Hatteras. Migration begins in the spring, with the population sorting itself by age and size as older, larger individuals travel farther north. Adults that remain in the south migrate toward northern Florida by fall.
In general, says Collins, South Carolina "doesn't get the big adult menhaden like up north," and the species has little commercial impact in the state, serving mainly as fish and crab bait.
Menhaden schools can be hundreds of feet long and scores of feet deep and were once an even more impressive resource. When Europeans first reached this continent's shores, they were astonished at the unspoiled bounty of coastal waters, and populations of menhaden were among the most impressive. There are tales of them filling bays and estuaries, where nutrients flowing from rivers and streams fed copious amounts of plankton.
Menhaden became the nation's main source of industrial oil in the 1850s, replacing increasingly scarce whale oil, and hundreds of ships fished for them along the Atlantic coast. Nearly 100 factories were set up to process oil, and fishing reached its peak in the 1950s, when schools a mile wide were still reported. Planes were used to spot schools, which would be surrounded by boats and netted.
In some years in the mid-'50s, as many as 1.6 billion pounds were brought to market, from as far as 50 miles out to sea, but by 1970 the catch had plunged by 80 percent. Economic factors, including alternate and foreign sources of oil and protein, and state government restrictions on some fishing in coastal waters, have further diminished the menhaden industry, and now Omega remains the major player, with its Atlantic operation concentrated in and around Chesapeake Bay. Including both its Atlantic and Gulf Coast operations, according to Landry, the firm operates about 40 fishing vessels, each with two purse seine net boats, and about 30 spotter aircraft, as well as four processing plants—one each in Virginia and Mississippi and two in Louisiana—producing both meal and oil.
The industry is the subject of debate on the effect its fishing has on menhaden sustainability, on predator species and on the ecology of the Chesapeake Bay and the Gulf of Mexico. The 2003 and 2006 stock assessments conducted by the Atlantic States Marine Fisheries Commission suggested the population along the Atlantic coast was not being overfished and was sustainable, according to Latour. He cited other studies, though, that show the number of newly hatched menhaden in the Chesapeake Bay, long considered a prime breeding ground, to be consistently low over the past 15 years. While he expresses concern over those numbers, he cites possible causes like a shift northward in spawning habitat or poor water quality in the Bay and says further study is essential.
Viewing menhaden in South Carolina can be a simple matter of watching the place where sky and sea meet in the spring as the water temperature hits 68 degrees or so and they come into shallow water in big schools.
"The key fishermen use in casting nets for menhaden is to watch the birds," says Collins. "The pelicans will dive on them." It's a window allowing the average wildlife watcher a glimpse of one of the earth's most important species, one that typifies both the oceans' fecundity and their relation to the earth’s growing human population.
Rob Simbeck is an award-winning free-lance writer living in Nashville, Tennessee.
© 2009 South Carolina Wildlife Magazine, September - October 2009 - www.scwildlife.com