Geographic Range
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.
- Biogeographic Regions
- nearctic
- palearctic
Habitat
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).
- Habitat Regions
- temperate
- freshwater
- Aquatic Biomes
- benthic
- lakes and ponds
- rivers and streams
Physical Description
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).
- Other Physical Features
- ectothermic
- heterothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
Development
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.
Reproduction
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.
- Mating System
- polygynandrous (promiscuous)
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- broadcast (group) spawning
- oviparous
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.
- Parental Investment
- no parental involvement
Lifespan/Longevity
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.
Behavior
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).
- Key Behaviors
- natatorial
- diurnal
- motile
- social
Home Range
Little information is available regarding the home range of silver carp.
Communication and Perception
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.
- Perception Channels
- visual
- tactile
- vibrations
- chemical
Food Habits
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.
- Primary Diet
- planktivore
- Animal Foods
- aquatic crustaceans
- zooplankton
- Plant Foods
- algae
- phytoplankton
- Other Foods
- detritus
- Foraging Behavior
- filter-feeding
Predation
Adult silver carp do not have any natural predators. However, fry are subject to predation
from other fish and possibly birds.
Ecosystem Roles
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.
Economic Importance for Humans: Positive
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.
- Positive Impacts
- food
- controls pest population
Economic Importance for Humans: Negative
The lasting effects of silver carp as invasive spices on local ecosystems remains
to be seen.
Conservation Status
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.
Additional Links
Contributors
Filip Ancevski (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, Gail McCormick (editor), Animal Diversity Web Staff.
- Nearctic
-
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.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
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).
- freshwater
-
mainly lives in water that is not salty.
- benthic
-
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.
- ectothermic
-
animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature
- heterothermic
-
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.
- 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.
- polygynandrous
-
the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.
- iteroparous
-
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).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- external fertilization
-
fertilization takes place outside the female's body
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- natatorial
-
specialized for swimming
- diurnal
-
- active during the day, 2. lasting for one day.
- motile
-
having the capacity to move from one place to another.
- social
-
associates with others of its species; forms social groups.
- visual
-
uses sight to communicate
- chemical
-
uses smells or other chemicals to communicate
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- vibrations
-
movements of a hard surface that are produced by animals as signals to others
- chemical
-
uses smells or other chemicals to communicate
- zooplankton
-
animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)
- phytoplankton
-
photosynthetic or plant constituent of plankton; mainly unicellular algae. (Compare to zooplankton.)
- detritus
-
particles of organic material from dead and decomposing organisms. Detritus is the result of the activity of decomposers (organisms that decompose organic material).
- filter-feeding
-
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.
- food
-
A substance that provides both nutrients and energy to a living thing.
- planktivore
-
an animal that mainly eats plankton
References
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Dong, S., D. Li, X. Bing, Q. Shi, F. Wang. 1992. Suction volume and filtering efficiency of silver carp (Hypophthalmichthys molitrix Val.) and bighead carp (Aristichthys nobilis Rich.). Journal of Fish Biology , 41/5: 833-840.
Dong, S., D. Li. 1994. Comparative-Studies on the Feeding Selectivity of Silver Carp Hypophthalmichthys-molitrix and Bighead Carp Aristichthys-Nobilis. Journal of Fish Biology , 44/4: 621-626.
Gonzal, A., E. Aralar, J. Pavico. 1987. The Effects of Water Hardness on the Hatching and Viability of Silver carp (Hypophthalmichthys-Molitrix) Eggs. Aquaculture , 64/2: 111-118.
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