Other Physical Features: bilateral symmetry
Based on studies in:
South Africa, Southwest coast (Marine)
This list may not be complete but is based on published studies.
Known prey organisms
Based on studies in:
South Africa, Southwest coast (Marine)
This list may not be complete but is based on published studies.
Life History and Behavior
Perception Channels: tactile ; chemical
Molecular Biology and Genetics
Statistics of barcoding coverage
Specimens with Sequences:2337
Specimens with Barcodes:1653
Species With Barcodes:130
Tresus is a genus of saltwater clams, marine bivalve mollusks in the family Mactridae. Many of them are known under the common name the horse clam or as species of gaper clam. They are similar to geoducks.
Species within the genus Tresus include:
- Tresus allomyax (Coan & Scott, 2000) – strange gaper
- Tresus capax (Gould, 1850) – fat gaper
- Tresus keenae (Kuroda & Habe, 1950) – mirugai clam
- Tresus nuttallii (Conrad, 1837) – Pacific gaper
- Tresus pajaroanus (Conrad, 1857) – lost gaper
These species' habitat is the lower intertidal zones on out to waters as deep as 50–60 feet (13–15 m). They prefer sand, mud, and gravel substrates, normally burying themselves 12–16 inches (30–41 cm), so they are much easier to dig than geoducks. Their preferred substrates are also preferred by butter and littleneck clams, so horse clams are often taken incidentally in commercial harvesting.
Tresus clams often have a relationship with small commensal pea crabs, often a mating pair, which enter through the large siphon and live within the mantle cavity of the horse clam. The crabs are easily seen and in no way affect the clam as food. The meat is good and makes excellent chowder. They tend to be ignored by sport diggers in Washington but not in Oregon.
Notes and references
- Tresus Gray, 1853. Retrieved through: World Register of Marine Species on 30 September 2008.
- Beach watchers
Clupeidae (Latin: "sardine") is the fish family of the herrings, shads, sardines, hilsa, and menhadens. They include many of the most important food fishes in the world, and are also commonly caught for production of fish oil and fish meal. Many members of the family have a body protected with shiny cycloid scales (very smooth and uniform scales), a single dorsal fin, with a fusiform body built for quick evasive swimming and pursuit of prey composed of small planktonic animals. Due to their small size, and placement in the lower trophic level of many marine food webs, the levels of methylmercury they bioaccumulate are very low, reducing the risk of mercury poisoning when consumed.
Description and biology
Clupeids are mostly marine forage fish, although a few species are found in fresh water. No species has scales on the head, and some are entirely scaleless. The lateral line is short or absent, and the teeth are unusually small where they are present at all. Clupeids typically feed on plankton, and range from 2 to 75 cm (0.8 to 30 in.) in length. The family arguably also contains the "Sundasalangidae", a paedomorphic taxon first thought to be distinct salmoniform family but then found to be deeply nested in Clupeidae. In the fossil record clupeids date back to the early Paleogene.
Clupeids spawn huge numbers of eggs (up to 200,000 in some species) near the surface of the water. After hatching, the larvae live among the plankton until they develop a swim bladder and transform into adults. These eggs and fry are not protected or tended to by parents. The adults typically live in large shoals, seeking protection from piscivorous predators such as birds, sharks and other predatory fish, tooth whales, marine mammals and jellyfish. They also form bait balls.
Commercially important species of Clupeidae include for instance the Atlantic menhaden (Brevoortia tyrannus), the Atlantic and Baltic herrings (Clupea harengus), the Pacific herring (C. pallasii) and the sardine (Sardina pilchardus).
- Froese, Rainer, and Daniel Pauly, eds. (2014). "Clupeidae" in FishBase. December 2014 version.
- Nelson, Gareth (1998). Paxton, J.R. & Eschmeyer, W.N., ed. Encyclopedia of Fishes. San Diego: Academic Press. pp. 91–92. ISBN 0-12-547665-5.
- Froese, Rainer, and Daniel Pauly, eds. (2014). "Clupeidae" in FishBase. August 2014 version.
|This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. (October 2010)|
Recent taxonomic work using DNA comparisons have organized the North American menhadens into large-scaled (Gulf and Atlantic menhaden) and small-scaled (Finescale and Yellowfin menhaden) designations.
The menhaden consist of two genera and seven species
- Genus Brevoortia T. N. Gill, 1861
- Brevoortia aurea (Spix & Agassiz, 1829) (Brazilian menhaden)
- Brevoortia gunteri Hildebrand, 1948 (Finescale menhaden)
- Brevoortia patronus Goode, 1878 (Gulf menhaden)
- Brevoortia pectinata (Jenyns, 1842) (Argentine menhaden)
- Brevoortia smithi Hildebrand, 1941 (Yellowfin menhaden)
- Brevoortia tyrannus (Latrobe, 1802) (Atlantic menhaden)
- Genus Ethmidium W. F. Thompson, 1916
Gulf menhaden and Atlantic menhaden are small oily-fleshed fish, bright silver and characterized by a series of smaller spots behind the main, Humeral spot. They tend to have larger scales than Yellowfin menhaden and Finescale menhaden. Menhaden are flat, have soft flesh, and a deeply forked tail. In addition, Yellowfin menhaden tail rays are a bright yellow in contrast to those of the Atlantic menhaden. Menhaden's maximum length is 15 inches with a varied weight range.
- Finescale menhaden from the Yucatán to Louisiana.
- Yellowfin menhaden from Louisiana to Virginia.
- Gulf menhaden range from the Yucatán Peninsula, Mexico to Tampa Bay, Florida.
- Atlantic menhaden ranges from Jupiter Inlet, Florida, to Nova Scotia. Atlantic menhaden seasonally migrate along the coast. In June mature adults are typically in the northern portion of the coastline with sub-adults and juveniles located in the southern portion.
- The various species of menhaden occur anywhere from estuarine waters outwards to the continental shelf. Menhaden grow in less saline waters of estuaries and can be found in bays, lagoons,as well as river mouths. Adults appear to prefer water temperatures near 18 °C.
Atlantic menhaden can spawn year round in inshore waters off the Atlantic coast, with the highest spawning rates near North Carolina in the late fall. The eggs hatch in the open ocean and the larvae drift to sheltered estuaries via ocean currents. The young spend a year developing in these estuaries before returning to the open ocean. At this early stage, they are commonly known as “peanut bunker”. The Atlantic menhaden usually do not become sexually mature until the end of their second year, after which they reproduce until death. A young, sexually mature female can produce roughly 38,000 eggs, while a fully mature female can produce upwards of 362,000.
Eggs are buoyant and hatch within 2 to 3 days depending on the temperature. The larvae will spend 1 to 3 months in waters over the continental shelf. The Chesapeake Bay is a popular nursery for juvenile menhaden. Larval fish will enter the Bay in late winter and early summer. The larval fish will move into lower salinity waters in estuarine tributaries while juvenile and immature fish remain in the Bay until the fall.
Menhaden are omnivorous filter feeders, feeding by straining food particles from water. They travel in large, slow moving, and tightly packed schools with open mouths. Filter feeders typically take into their open mouths "materials in the same proportions as they occur in ambient waters". Menhaden primarily eat phytoplankton (microscopic plants); although, since they are omnivorous, they take in a small portion of zooplankton (microscopic animals). Even though most other related fish (in the family Clupeidae) eat zooplankton, "Menhaden primarily consume phytoplankton, that is, algae and other drifting bits of vegetable matter. The ecological significance of this difference can hardly be overstated."
According to James Kirkley of the Virginia Institute of Marine Science (VIMS), there are two established commercial fisheries for menhaden. The first is known as a reduction fishery. According to the Omega Protein Corporation, this fishery's output produces omega-3 oils for human consumption, and for aquaculture, swine, and other livestock feeds. The second is known as a bait fishery, which harvests menhaden for the use of both commercial and recreational fishermen. Commercial fishermen, especially crabbers in the Chesapeake Bay area, use menhaden to bait their traps or hooks. The recreational fisherman use ground menhaden chum as a fish attractant, and whole fish as bait. The total harvest is approximately 500 million animals per year. Atlantic menhaden are harvested using purse seines.
Menhaden were prized in America for their delicate but rich flavors in the mid 18th century. Mark Catesby (1682–1749), an English naturalist, wrote of the menhaden as an "exellent Sweet Fish, and so excessive fat that butter is never used in frying or any other preparation of them....[menhaden were] much esteemed by the Inhabitants for their delicacy." Colonel William Byrd II, the founder of Richmond, Virginia, commended menhaden as food fit for a gourmet writing of the menhaden as a "small, but splendid fish when it is baked." Over a century later George Brown Goode (1851–1896) praised the menhaden for its flavor, saying it is "superior in flavor to most of the common shore-fishes," and notes that menhaden sold at a "price nearly as high as that of striped bass, the favorite fish in Washington."
Presently, menhaden are an important input for fishmeal and fish oil, with both of these "reduction" products being used as feed for livestock and aquaculture, such as salmon. Fish oil made from menhaden is also used as a dietary supplement, and as a raw material for products such as lipstick. Atlantic menhaden are an important link between plankton and upper level predators. Because of their filter feeding abilities, "menhaden consume and redistribute a significant amount of energy within and between Chesapeake Bay and other estuaries, and the coastal ocean." Because they play this role, and their abundance, menhaden are an invaluable prey species for many predatory fish, such as striped bass, bluefish, mackerel, flounder, tuna, Drum (fish), and sharks. They are also a very important food source for many birds, including egrets, ospreys, seagulls, northern gannets, pelicans, and herons.
Two companies harvest menhaden in the United States:
- Omega Protein Inc., Houston, Texas, with operations in Virginia, Louisiana, Mississippi, and Alabama which takes 90% of the national total; and
- Daybrook Fisheries, Empire, Louisiana.
According to the Atlantic States Marine Fisheries Commission, the overall Atlantic coast stock of menhaden is robust as of 2006. However, according to Paul Greenberg, who has called for a ban on fishing menhaden in US federal waters and the Chesapeake bay, the continued harvesting of menhaden (especially by Omega Proteins) is having detrimental effects on the population, which in turn is affecting populations of fish that feed on menhaden and especially on water quality:
The muddy brown color of the Long Island Sound and the growing dead zones in the Chesapeake Bay are the direct result of inadequate water filtration — a job that was once carried out by menhaden. An adult menhaden can rid four to six gallons of water of algae in a minute. Imagine then the water-cleaning capacity of the half-billion menhaden we "reduce" into oil every year.
There is increasing concern, especially from recreational fisherman and conservationists, that the Chesapeake Bay’s population is declining significantly. The Chesapeake Bay’s major menhaden fishery is located in the southern (Virginia) portion. According to the Chesapeake Bay Program:
- "Chesapeake-specific population estimates for menhaden are not currently produced; estimates are only made for the entire Atlantic coast stock, which appears to be healthy. Still, scientists are concerned about what appears to be a low abundance of menhaden in the Bay, which is one of the fish's key nursery areas.
- Fisheries-independent data from seine surveys in Maryland and Virginia through 2004 suggested that menhaden recruitment—the number of juveniles that grow to a “catchable” size—was possibly declining in the Bay. Coast-wide recruitment is considered to be at median historic levels.
- The exact causes of the decline in recruitment remain unknown. While additional scientific knowledge is necessary to understand the variability of menhaden recruitment, scientists have cited several possible contributing factors, including:
- - Heavy fishing on the adult menhaden stock.
- - Possible increases in mortality by predators.
- - Changing environmental conditions, such as climate change or poor water quality, in menhaden nursery areas."
Menhaden have been called 'the most important fish in the sea'. H. Bruce Franklin’s most recent book, The Most Important Fish in the Sea: Menhaden and America is an interdisciplinary study of the role of menhaden in American environmental, economic, social, political, and cultural history from the seventeenth into the twenty-first centuries.
- ^ Anderson, Joel (2007). "Systematics of the North American menhadens: molecular evolutionary reconstructions in the genus Brevoortia (Clupeiformes: Clupeidae)". Fishery Bulletin 105 (3): 368–378. http://fishbull.noaa.gov/1053/anderson.pdf. Retrieved 10 February 2011.
- ^ "引越し完全マニュアル" (in Japanese). Archived from the original on 30 January 2009. http://web.archive.org/web/20090130035507/http://menhaden.org/
- ^ GSMFC 2002
- ^ a b Franklin, H. Bruce (2007). The Most Important Fish in the Sea: Menhaden and America. Island Press. ISBN 978-1-59726-507-2. OCLC 74569179. http://www.mostimportantfish.org/.
- ^ a b Based on data sourced from the relevant FAO Species Fact Sheets
- ^ Omega Protein (home page). Omega Protein. http://www.omegaproteininc.com
- ^ a b c d Greenberg, Paul (15 December 2009). "A Fish Oil Story". The New York Times. http://www.nytimes.com/2009/12/16/opinion/16greenberg.html. Retrieved 10 February 2011.
archive via Archive.org not available due to login requirement; login not required to view content via provided link.
- ^ http://www.dnr.state.md.us
- ^ Atlantic Menhaden Technical Committee (26 September 2006). 2006 Stock Assessment Report for Atlantic Menhaden. Atlantic States Marine Fisheries Commission. Archived from the original on 27 September 2011. http://www.webcitation.org/621Wo9Pqv. Retrieved 13 June 2010
- ^ "Chesapeake Bay Program (homepage)". http://www.chesapeakebay.net
- ^ http://andromeda.rutgers.edu/~hbf/menhaden.htm
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one of a series on
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- Saving Striped Bass by Managing Menhaden | KeepAmericaFishing™
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