Brevoortia tyrannusBunker(Also: Menhadem)

Last updated:

Geographic Range

Brevoortia tyrannus, commonly called the Atlantic Menhaden, can be found anywhere in the western Atlantic, Nova Scotia, Canada and southward to Indian River, Florida, USA. Menhaden are also common in all salinities of the Chesapeake Bay.

Habitat

For the most part menhadens can be found at a depth of up to -20m. This puts them in the palagic, brakish, marine area of the Atlantic Ocean. In this habitat predators of the menhadens consist of such aquatic animals as sharks, rays, and bony fish. Also, parasites like isopods, copepods, cestodes, and trematodes are found on the menhadens.

Physical Description

Brevoortia tyrannus can be described as a silvery in color. However, the sides of it differ from the silver color and range closer to a brassy color. Menhadens have dark bluish green backs. They are usually characterized by a small, irregularly placed scales on their backs, above their anal fins. They are also characterized by a black spot that is usually behind their gill openings. Following this larger black spot are approximately six lines of smaller spots. They have inner and outer finrays and a pelvic fin with rounded hind margins.

  • Average mass
    1283 g
    45.22 oz

Reproduction

Spawning for menhadens occurs all year long. However, productive spawning has been noted to occur from March to May and again between September and October. Estuaries are usually the safest salt water havens within menhadens habitat so their nurseries occur there. Breeding can be limited by high water temperatures.

Behavior

Menhadens can be found inshore. However, when cold temperatures approach they can be found at deeper levels in the water. They can be found swarming together in what are known as "schools". Their schools are usually large in size, including juveniles and mature adults. Menhadens are usually found in the bays and inlets, but in the early fall migration occurs. They remain in their migration habitat, usually North Carolina, until March and early April. Then they return to their bays. At times the young remain in the bays, while the older menhadens go north. Menhadens are known to reach maturity at 2.1 years old. Their life span is about 8.4 years.

Communication and Perception

Food Habits

Menhadens feed by filtering. They consume from the primary trophic levels, including phytoplankton and zooplankton. Their main food source also includes detritus(dead organic matter found in the water, usually settled on the bottom), plants/detritus and animals. Menhadens' food consumption is usually 31.40 times their body weight per year.

Economic Importance for Humans: Positive

Menhadens are considered highly commercial fish for the United States. They are used in the production of such things as: oil, fertilizer and fishmeal. They can also be found marketed for consumption, either fresh, smoked, salted, or canned. This species was realized recently to have a very significant value as an alternative for whale oil. They are also used for lubricants and as fuel for lamps. Since these fish have begun to be used as an alternative oil, they are being used for making soaps and paints. Virginia, North Carolina and the Gulf are major ports for the menhaden. There are more menhaden brought onto US land each year than any other fish. Their input ranges from 300,000 to 400,000 metric tons per year.

Economic Importance for Humans: Negative

Menhadens by themselves are considered a harmless species. However, when large numbers of these fish come in contact with the dinoflagellate Pfiesteria piscicida, many health risks become readily exposed to humans. Pfiesteria changes into a toxic encysted stage when it inhibits the menhadens. This causes health risks ranging from epidermal problems to central nervous system problems.

Conservation Status

Menhaden are not threatened in or around the United States. They do not appear in the IUCN red list, which means that their species is safe from extinction as of now. Examples of regulations and status of menhaden can be found at NOAA (1999).

Contributors

Sandi Carney (author), Western Maryland College, Randall L. Morrison (editor), Western Maryland College.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

tactile

uses touch to communicate

References

Agbayani, E. June 1, 1999. "Key Facts on Brevoortia tyrannus Atlantic menhaden" (On-line). Accessed May 7, 2001 at http://www.fishbase.org/PopDyn/KeyfactsSummary_1.cfm?ID=1592&genusname=Brevoortia&speciesname=tyrannus&vstockcode=1785&fc=43.

Agbayani, E. April 23, 2001. "Species Summary for Brevoortia tyrannus Atlantic menhaden" (On-line). Accessed May 7, 2001 at http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Brevoortia&speciesname=tyrannus.

Anderson, H. February 2000. "A History of Menhaden Fishing" (On-line). Accessed May 7, 2001 at http://www.mdsg.umd.edu/MarineNotes/Jan-Feb00/side3.html.

Bellas, J. April 29, 1999. "Pfiesteria in the Chesapeake Bay and its Estuaries" (On-line). Accessed May 7, 2001 at http://www.ems.psu.edu/info/explore/PFIEST.html.

NOAA Chesapeake Bay Office, 1999. "Fisheries of Chesapeake Bay: Species information -- Atlantic menhaden" (On-line). Accessed 10 December 2001 at http://noaa.chesapeakebay.net/spc/menhaden.htm.

Orner, D. n/a. "Species Information Atlantic menhaden Brevoortia tyrannus" (On-line). Accessed May 7, 2001 at http://noaa.chesapeakebay.net/spc/menhaden.htm#description.