The Atlantic menhaden is one of the most abundant species of finfish in estuarine and coastal Atlantic waters. The second most important species harvested in the United States in terms of quantity, it is factory processed for oil, protein meal and solubles, and is used as bait for commercial and recreational fishing. Menhaden are consumers of plankton and plant detritus, and, in turn, are fed upon by many predatory fish, mammals and birds.
The Atlantic menhaden is a member of the herring family, Clupiedae, but unlike shad and river herring, they spawn in the ocean and their young develop and grow in the less saline waters of estuaries during their first year. Menhaden are silvery in color with a distinct black shoulder spot behind their gill opening and a variable number of smaller spots on their sides. Like shad and herring, they possess a series of scutes along their belly. Their bodies are moderately compressed, their caudal fin is deeply forked, and their fins lack spines. Atlantic menhaden range from Nova Scotia, Canada to central Florida.
By convention, March 1st is considered the average birth date for the species. 1-year old menhaden are about 6 inches fork length and weigh 2-3 ounces, 3-year old menhaden are approx. 12 inches long and weigh over 0.5 lbs, and 6-year old menhaden can be approx. 14 inches or longer and weigh approximately 1 pound. Fish as old as age 8 were fairly common in the spawning population during the 1950s and early 1960s, but fish older than age 5 have been rare in recent years. An exceptionally large fish weighing 3lbs 6oz. was reportedly taken in August 1996 from the Chesapeake Bay. Sexual maturity begins as age-2 fish enter their third fall, prior to their third birth date.
Major spawning areas are from New Jersey to the Carolinas; spawning occurs primarily offshore (20-30 miles) during winter. Buoyant eggs hatch at sea, and larvae are carried into estuaries where they spend most of their first year of life. Young menhaden begin migrating to the ocean from Chesapeake Bay nursery grounds during the fall, however, significant numbers remain within the Chesapeake Bay over the winter months. Adult and juvenile menhaden form large, near surface schools, primarily in estuaries and ocean waters near shore, from early spring through early winter. By summer, menhaden schools stratify by size and age along the coast, with older and larger menhaden found farther north. During fall to early winter, menhaden of all sizes and ages migrate south with concentrations forming in the ocean off the North Carolina capes.
The menhaden fishery for reduction had its origins in New England during the early 1800s and spread south after the Civil War. The purse seine was introduced after the Civil War, allowing the fishery to expand. Coal-fired steamers gradually replaced sailing ships as carrier vessels in the late 1800s; diesel and gasoline engines gradually replaced steam engines following World War I.
Major innovation after World War II included use of spotter aircraft, radio communications, nylon nets, hydraulic power blocks, aluminum purse boats, fish pumps, and large carrier vessels (greater than 150 ft. long).
The number of vessels in fishery reduction declined from 150 in 1955 to 31 in 1993, while the number of plants declined from 23 in 1955 to 7 in 1993 (including two factory ships). During 1994-97, three plants operated with about 20 vessels. This decline in vessels and plants is offset by increased harvesting and processing efficiency.
Landings and fishing effort increased from 1940 through late 1950s, declined precipitously during the 1960s, and then improved significantly during the 1970s and early 1980s. Annual landings during 1990-1997 averaged 319,000 metric tons. Landings for 2000 only totaled 167,000 metric tons, the second lowest since the National Marine Fisheries Service began keeping records in 1940.
In 1996, about 36% of U.S. Atlantic coast commercial fisheries landings by weight were Atlantic menhaden. Landings of menhaden for bait by other fisheries (such as pound net and purse seine) are about 10% of the Atlantic menhaden catch.
In 2008, only one shore-side reduction plant operated on the U.S. Atlantic coast. This plant, utilizing about 10 fishing vessels, is located in Reedville, Virginia.
The overwhelming majority of menhaden landings (over 50% in recent years) come from the Virginia portion of the Chesapeake Bay. The remainder are caught in coastal waters from New Jersey to Virginia, mostly within 5 miles of the ocean shore. Maryland has prohibited purse seining in state waters (0-3 miles from the coast) and in the Chesapeake Bay since before the 1950′s.
Products and Uses
The purse seine fishery for reduction processes menhaden into fishmeal, fish oil, and fish solubles. Fishmeal is a valuable ingredient in poultry and livestock feeds because of its high protein content (at least 60%). The broiler (chicken) industry is currently the largest user of menhaden meal followed by the turkey, swine, pet food, and ruminant industries. The aquaculture industry has recently demonstrated an increased demand for fishmeal as well.
Menhaden oil has been used for many years as an edible oil in Europe. The oil is refined and used extensively in cooking oils and margarine. In 1989, the United States Food and Drug Administration (FDA) concluded that fully and partially hydrogenated menhaden oil is a safe ingredient for human consumption. In 1990, the FDA proposed an amendment based on an industry petition, to the standard of identity for margarine to permit the use of marine oils. It was approved in 1997 and could provide a significant new market for omega-3 rich menhaden oil.
Catches from the menhaden purse seine bait fishery are used by sport fisherman as chum and as cut or live bait for sportfishes such as bluefish, striped bass, weakfish, king mackerel, red drum, shark, and tuna.
The Chesapeake Bay is the most important nursery area for juvenile menhaden along the Atlantic coast; they utilize almost the entire Bay and its tributaries. Larvae are pelagic and spend approximately one month in waters over the continental shelf before entering the Bay and moving into lower salinity waters in estuarine tributaries where they metamorphose into juveniles. These juveniles, along with older year classes of Atlantic menhaden remain in the Bay until the fall when most migrate to ocean waters as far south as Cape Hatteras. The following spring menhaden return northward as far as New England waters, with large numbers entering coastal estuaries, particularly the Chesapeake Bay. Those menhaden remaining in the Chesapeake Bay during the winter-time are the major food source for resident and some migratory striped bass.
Atlantic menhaden are the most important and abundant large prey species in the Chesapeake Bay. During summer months, these fish swim in large schools and their silvery bodies can often be seen near the water’s surface. Juveniles primarily feed on zooplankton. Adults are mainly herbivores, but retain the ability to feed on zooplankton. Adults are very adaptable, as they feed on many species of plankton as well as suspended organic plant detritus. As prey and filter feeders, Atlantic menhaden are an ecologically critical fish species. They consume and redistribute a significant amount of energy (by turning plankton into menhaden flesh) within and between the Chesapeake Bay and other estuaries, and the coastal ocean. This is due, in part, to their tremendous numbers, individual growth rate, filter feeding capacity, and seasonal movements. An adult fish can filter up to a million gallons of water every 180 days. A robust Atlantic menhaden population has the potential to consume up to 25% of the Bay’s nitrogen (by plankton removal) in 1-year. Menhaden are an extremely important prey species for many predatory fish such as striped bass, bluefish, weakfish, and spanish mackerel. Because of their schooling behavior, they are also a favorite target for the common loon, herons, egrets, gulls, gannets, ospreys, and eagles. Some mammals, such as whales and dolphins, also feed on menhaden.
Menhaden recruitment to the Chesapeake Bay has been low since the early 1990′s. Recent studies indicate overfishing has been occurring for decades. Menhaden mortalities from disease and pollution occur throughout their range. These, and perhaps other factors, have decimated the Atlantic menhaden population.