Menhaden

The Atlantic menhaden (Brevoortia tyrannus) is a bony, oily fish that is of commercial importance for oil, fish meal, and fertilizer products. It belongs to the family Cludeidae. It is a major protein component in commercial feed fed to cultured fishes. Livestock and poultry feed may also contain menhaden meal. The production of paints, soaps, and certain lubricants may use the menhaden oil. It is not consumed by humans because it has a lot of bones and its oily nature gives off an unpleasant odor when cooked. It is a particularly important fishery from Massachusetts to the Carolinas. It resembles the herring in appearance except for several features. The menhaden is deeper in the body, being more elliptical from a lateral view. It has a large head and lacks teeth. It also has a distinctive black spot posterior to the gill covers with more spots of irregular shapes and sizes along the ventral halves of the flanks. It has silvery sides with a back that can have a blue, brown, or green hue to it. Menhaden are harvested almost exclusively by the purse seine net. Purse seine fishing depends almost completely on the sighting of schools of menhaden at the surface, from aircraft or large vessels. The schooling behavior is an outstanding characteristic of this species, from larval to adult stages.

The menhaden is distinct in its feeding habits in that it is one of few fish that can feed on planktonic organisms. While it is rather common for juvenile fishes to feed on plankton, most fishes use feed higher up the food chain. The menhaden has very fine gill rakers that filter out phy-toplankton such as diatoms as well as planktonic crustaceans.

The menhaden is euryhaline. The Atlantic menhaden is mainly an ocean fish that schools off coastal waters of the Atlantic, although it has been reported in fresh water as well. It is distributed from the Gulf of St. Lawrence to southern Florida. Freshwater populations have been reported in the St. John River, New Brunswick, Canada.

The Atlantic menhaden can live up to 12 yr, although specimens over seven yr old are rare. While a few mature at 1 yr of age, 80% are sexually mature at 2 yr of age, and all are sexually mature by the time they are 3 yr old. The body size at 3 yr is approximately 25 cm. Reproduction of the menhaden is similar to the herring. They spawn at sea or in large bays, throughout their distribution. They may also be able to spawn in the St. John River, where they are found year-round. The spawning period for Maine to Massachusetts, its northern distribution, occurs between May and October. Populations south of that area spawn during the other half of the year. The male and female broadcast eggs and sperm into the water where fertilization occurs. The fertilized eggs measure about 1.3-1.9 cm in diameter. Fecundity of females measuring 20-35 cm were 38,000631,000. The eggs are spherical and bouyant, the latter being due to the presence of an oil globule in the yolk. The young are approximately 2.4-4.5 mm in length at hatching.

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