Silver carp, Hypophthalmichthys molitrix, are native to eastern Asia and are commonly found in northeastern China and Siberia. They have also been introduced to other areas of the world, and are now considered invasive to North America. Silver carp have been reported in 16 states in the United States and are well established in the Mississippi River Basin. ("Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005; Luna and Baily, 2010)
Silver carp live in freshwater in temperate (6 to 28 °C) to subtropical climates. They are commonly found in impoundments or backwaters of large slow flowing rivers or large lakes. Silver carp are benthopelagic, but they often swim near the surface of the water and are well known for breaching the surface. They can tolerate brackish waters (up to 12 ppt) as well as low dissolved oxygen content (3 mg/l). ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Hypophthalmichthys molitrix - Silver Carp", 2007; Luna and Baily, 2010)
Silver carp are olive green in color on their dorsal side and silver on the ventral side. They have a deep, laterally compressed body and a large head. Their eyes are located near the ventral side, which makes them easily distinguishable from other carp. Both dorsal and anal fins are present, but an adipose fin is lacking. They have 1 to 3 dorsal spines, 1 to 3 anal spines, 6 to 7 soft dorsal rays, and 10 to 14 sot anal rays. The lateral line is approximately 80 to 130 scales in length. They have numerous thin gill rakers (100 or more). Silver carp are also characterized by a smooth ventral keel on the abdomen that runs from the anus to the gill membrane. Silver carp vary considerably in size; most are relatively small (10 to 30 cm), but some can grow as much as 1 m in length and weigh in excess of 60 pounds (27 kg). ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Hypophthalmichthys molitrix - Silver Carp", 2007; "Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005; Luna and Baily, 2010)
Eggs of silver carp reach maturity when they are about 3.2 to 4.7 mm in size. Young enter the larval stage about 68 hours after hatching. During the larval stage, fry are vulnerable and inefficient feeders. After about 5 months, fry have grown to a size of 8 to 12 cm in body length and have become more efficient feeders. Silver carp reach maturity at 4 to 6 years of age, at which point they are capable of reproduction. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005)
Silver carp generally reproduce during the spring or summer. Reproduction is primarily cued by increased water temperature. Like other species of carp, silver carp participate in broadcast spawning. During spawning, a female releases eggs and males fertilize them within the water column. A single female can carry as many as 2 million eggs. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005)
Spawning of silver carp takes place upstream and generally occurs in spring or summer. Optimal water temperatures for spawning range from 22 to 28 °C. Females release eggs in the water column, where they are then fertilized by many males. Fertilized eggs float downstream to floodplain zones where they absorb water and eventually settle to hatch. Silver carp reach sexual maturity at 4 to 6 years of age. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010)
Silver carp do not demonstrate parental investment in their offspring. After eggs are released into and fertilized in the water column, silver carp leave the area and do not return. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010)
With substantial food sources and few natural predators, silver carp can grow quite large and can live many years. Silver carp may live as long as 20 years in the wild, and may be capable of living longer. ("Hypophthalmichthys molitrix - Silver Carp", 2007)
Silver carp fry generally travel in schools to reduce predation. They are typically more active during the day. Silver carp are also able to jump out of the water. It is believed that during feeding, debris and other irritants clog their gills, and they jump in an effort to remove blockages. They may also exhibit this behavior as a means to escape during a disturbance (usually caused by a boat). ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Hypophthalmichthys molitrix - Silver Carp", 2007)
Little information is available regarding the home range of silver carp.
Like many other fish, silver carp use their lateral line system to detect motions and vibrations. As filter feeders, however, they do not rely as heavily on their lateral line system as do predatory fish. Silver carp also utilize their senses of sight and smell. Reproduction is often cued by increases in water temperature as well as olfactory cues. (Luna and Baily, 2010)
Silver carp are filter feeders, feeding primarily on phytoplankton. Using specialized gill rakers covered with a thick matrix of calcified substances, silver carp are able to filter out the very smallest organisms (ranging in size from 8 to 100 micrometers). However, only a small part of their diet consists of zooplankton and detritus. Silver carp may also eat small arthropods and algea. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; Cremer and Smitherman, 1980)
Adult silver carp do not have any natural predators. However, fry are subject to predation from other fish and possibly birds. ("Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005)
Silver carp are considered invasive in North America. They were initially introduced into the United States in the 1970’s to control plankton blooms but have subsequently spread into 16 states after escaping from aquaculture centers. Silver carp can adapt to many different environments and can grow very quickly. They can consume 2 to 3 times their body weight in plankton each day. In controlled experiments, silver carp gained 2.7 g/day when fed a large diet. Because of their large size and voracious appetite, silver carp are able to out-compete many other species of fish. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010; "Silver Carp Hypophthalmichthys molitrix (Valenciennes 1844)", 2005; Cremer and Smitherman, 1980)
Silver carp are becoming increasing popular sources of food. They are also commonly used to clear algal blooms. Harvesting of silver carp increased from 1.9 million tons in 1993 to 4.1 million tons in 2003. Because silver carp do not require supplementary feed like other species of farm grown fish, they have become popular worldwide. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010)
The lasting effects of silver carp as invasive spices on local ecosystems remains to be seen. ("Hypophthalmichthys molitrix - Silver Carp", 2007)
Due to their rapid growth rate and worldwide popularity, silver carp are not considered threatened. They are often sold for human consumption and are also used for cleaning waters of algael blooms. ("Fisheries and Aquaculture Department : Hypophthalmichthys molitrix", 2010)
Filip Ancevski (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Gail McCormick (editor), Animal Diversity Web Staff.
living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.
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.
uses smells or other chemicals to communicate
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
fertilization takes place outside the female's body
union of egg and spermatozoan
a method of feeding where small food particles are filtered from the surrounding water by various mechanisms. Used mainly by aquatic invertebrates, especially plankton, but also by baleen whales.
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
having the capacity to move from one place to another.
specialized for swimming
the area in which the animal is naturally found, the region in which it is endemic.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
an animal that mainly eats plankton
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
movements of a hard surface that are produced by animals as signals to others
uses sight to communicate
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
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