Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:A Guide to Invasive Species of the Galveston Bay Area
Ctenopharyngodon idella, Hypophthalmichthys nobilis, H. molitrix, Mylopharyngodon piceus, Carassius auratus, Cyprinus carpio
| ITIS TSN: | 163537; 163692; 163691; 639618; 163350; 163344 |
| Presence: | Current Invaders |
| Habitat: | Aquatic |
| Native Range: | China and Eastern Russia |
Human Health
This species poses no known human health impacts.Prohibited Lists
As of 2010, these genera are legally classified in Texas as exotic, harmful, or potentially harmful. No person may import, possess, sell, or place these species into state waters except as authorized by a rule or permit issued by the TPWD. A person may possess these species without a permit only if the fish has been gutted. Regarding grass carp, only triploid (sterile) grass carp can be legally used in Texas, and a permit is required to obtain them. Because grass carp is a potentially invasive species, an angler who catches one must immediately remove the intestines, except in waters where a valid Triploid Grass Carp Permit is in effect (e.g. Lake Conroe). In those waters, any grass carp caught must be immediately returned to the water unharmed (TPWD 2009a).Introduction Pathways
In 1963, grass carp was introduced into aquaculture facilities in Alabama and Arkansas for use as biological control of vegetation. Since this time, federal, state, and private entities have continued to stock grass carp. The species has spread widely due to escape from research and aquaculture facilities, and stocking programs (Nico et al. 2010b). Bighead carp and silver carp were imported for similar uses (Nico 2009; Nico and Fuller 2009a), or in the case of black carp, came in as contaminants in grass carp stocks (Nico 2010c). Due to their similar introduction history and subsequent usages, the spread of these species have been similar (albeit less widely distributed) to that of the grass carp.Geographic Distribution
In the U.S., grass carp have been established in 45 states. This species is widely distributed in Texas and is found in all five counties of the Lower Galveston Bay watershed (Nico et al. 2010b). Bighead carp are established in 23 states and have been found in Harris County in the San Jacinto River (Nico and Fuller 2009a). As of 2010, silver carp are not reported in Texas, but are established in 15 states, including LA and AR (Nico 2009). As of 2010, black carp are not reported in Texas, but are established in 5 states, including LA and AR (Nico 2010c).Specific Primary Habitats
Carp prefer well-vegetated, quiet, shallow waters (except during spawning) in large rivers, lakes, and reservoirs (Nico et al. 2010b). Carp are mostly found in subtropical and temperate climate zones, and prefer water temperatures of 25°C but can tolerate temperatures from 0-39°C. Carp have also been shown to tolerate low oxygen and high salinity conditions (up to 10 ppt) (ISSG 2005b).Ecological, Economic, or Social Impact
Grass carp do not exclusively feed on the species of aquatic plants that they are meant to control and may feed on native aquatic plants as well. Due to their ability to consume large amounts of vegetation, grass carp can alter the trophic structure of a water body by competing with native invertebrate and fish species for plant material. Studies have documented grass carp's detrimental effects associated with modification of habitat including removal of substrate used for spawning, disturbance of sediment, and eutrophication of waters. Carp also carry diseases and parasites and are believed to be the main vector for the Asian tapeworm (Bothriocephalus opsarichthydis). Asian tapeworms are known to infect native species of finfish such as golden shiner, fathead minnow and channel catfish (Nico et al. 2010b). Silver carp and bighead carp (H. nobilis and H. molitrix) have the potential to deplete zooplankton populations that many native fish and mussels rely on for food (Nico 2009; Nico and Fuller 2009a). Black carp (M. piceus) feed directly on native mussels and snails (Nico 2010c). Koi or common carp (Cyprinus carpio) feed on aquatic vegetation and increase water turbidity, thus degrading habitat used by native plants, birds, and fish (Nico et al. 2010a).Physical Description
In general, carp are dark gray, silver, or olive in color with black carp appearing darker than other species. Carp have oblong, slender bodies, with moderately large cycloid scales. They have a broad, scale-less head, and a short snout. The black carp (M. piceus) may be distinguished by its slightly pointed snout. Carp range in size from 0.7-1.5 m, and 27-70 kg. Silver carp (H. molitrix) are the smallest and black carp (M. piceus) are the largest of the group described here (Nico 2009; Nico 2010c).Reproduction Characteristics
Carp reproduce sexually via external fertilization of eggs. In Texas, spawning occurs during the spring, when water temperatures reach 15-17°C (59-63°F) (TPWD 2009a), during a period of rising water levels (water must be 20 cm or deeper). Long stretches of river with turbulent, well-oxygenated waters and gravel or sandy bottoms are required for spawning (Acosta and Kullander 2010). Carp will migrate up to 1,000 miles to find appropriate conditions to spawn (Nico et al. 2010b). Carp eggs are semi-pelagic, remaining suspended for up to two days before hatching. On average, female carp release 500,000 eggs during spawning (ISSG 2005b).Feeding
Juvenile carp eat planktonic crustaceans, rotifers, and insect larvae (ISSG 2005b). By the time they reach 3 inches in length, they are exclusively herbivorous (TPWD 2009a). Adult carp feed on a wide range of aquatic vegetation, with a preference for softer plants. Carp can consume 40-300% of their body weight per day and are used for the control of Eurasian watermilfoil (Myriophyllum spicatum), hydrilla (Hydrilla verticillata), pondweed (Potamoeton diversifolius) and other aquatic invasive plants (ISSG 2005b).Control
Early detection is key to preventing the spread and establishment of this species and regional/local monitoring or surveillance is essential. Nonnative species of fish should not be imported or released in local waterways. If found in local waters, note the capture location, and notify the TPWD. Only triploid (sterile) grass carp can be legally stocked in Texas and a triplid grass carp permit is required. In waters where no triploid permit is in effect, all grass carp caught must be immediately gutted (TPWD 2009a). In waters where a valid triploid grass carp permit is in effect (e.g. Lake Conroe), any grass carp that is caught must be immediately returned to the water unharmed (TPWD 2009a).Lists
This species belongs to the following lists:
Images
To view a larger version of an image, click on the thumbnail. Bighead carp (Hypophthalmichthys nobilis). Photo courtesy of Noel Burkhead., http://nas.er.usgs.gov. |
 Bighead carp (Hypophthalmichthys nobilis). Photo courtesy of USGS, USGS NAS Database, http://nas.er.usgs.gov. |
 Silver carp (Hypophthalmichthys molitrix). Photo courtesy of the Department of Fisheries and Allied Aquacultures, Auburn University, Alabama, USA, USGS NAS Database, http://nas.er.usgs.gov. |
 Black carp (Mylopharyngodon piceus). Photo courtesy of Leo Nico. USGS NAS Database, http://nas.er.usgs.gov. |
 Grass carp (Ctenopharyngodon idella). Photo courtesy of Noel Burkhead, USGS NAS Database, http://nas.er.usgs.gov. |
 Grass carp (Ctenopharyngodon idella). Photo courtesy of USGS, USGS NAS Database, http://nas.er.usgs.gov. |