|
Features
Simular Species
Biology
Maximum Size
Distribution
Interest to Fisheries
Current Status
Impacts
Recommendations
References
Home
About the
Non-Native Species of the Gulf of Mexico
What is an Invasive
Species?
What's in your state?
Publications
and Related Materials
Regional
Panel Presentations
Non-Native
Species Summaries
Bibliography Database
Related
Sites
E-Mail
ListServ
Contact
Us
|
Scientific Name: Hypophthalmichthys molitrix
Integrated Taxonomic Information System (ITIS): 163691
Other scientific names appearing in the literature of this species:
Common Name: Silver carp
Distinguishing Features:
Silver carp are large, laterally compressed cyprinids with a uniform silver coloration. There are between 95 and 103 scales in the lateral line. The mouth is relatively large, upturned and toothless. Small specimens do not have spines on their fins, whereas large specimens have a hard, stiff spine with fine serrae on its posterior margin, at the front end of the pectoral, and moderately strong spines in their dorsal and anal fins. The dorsal fin origin is behind the pelvic fin insertion. There are 8 dorsal rays and 12-13 anal rays. The pharyngeal teeth count is 4-4. The gill rakers are fused into a sponge-like porous plate (Robison and Buchanan, 1988).
Similar Species:
Silver carp are similar to bighead carp, H. nobilis, but differ in having a longer ventral keel, which extends from the anal fin insertion to the isthmus (as opposed to the pelvic insertion in bighead), in lacking the small irregular dark blotches bighead possess, and in having their gill rakers fused into a sponge-like porous plate (Robison and Buchanan, 1988).
Biology:
Salinity Tolerance: This species occurs only in fresh waters.
Temperature Tolerance: The silver carp naturally occurs in temperate waters of China. Spawning is limited by water temperature. Spawning in the Syr Darya River was reported to occur between 18 and 22 °C (Verigin et al., 1978; Kamilov and Salikhov 1996).
Reproduction and Fecundity: Silver carp require bodies of water with some current for eggs to float and develop properly (Robison and Buchanan, 1988). Kamilov and Salikhov (1996) summarized the reproductive cycle of silver carp established in the Syr Darya River. They found carp carry out migrations to communal spawning grounds during the spring flood in April and May. They spawned in small groups of 15 to 25 fish at dusk and dawn, at water temperatures of between 18-20°C. Spawning fish were 3 to 10 years old. The total fecundity of females was 299 to 5400 eggs, and the relative fecundity was 79 to 392.3 eggs per g of gutted weight. These authors also presented data suggesting that females were slightly larger than males. However, this remains to be confirmed. Shubnikova (1979) presented evidence of sexual dimorphism in the silver carp, which included presence or absence of crenations on the inner surface of the pectoral fins, and variation in fin lengths and body depth, but the differences were small and not constant throughout age classes.
Trophic Interactions: Very little is known on the feeding ecology of the silver carp from the Gulf of Mexico drainages. The following account is mostly based on work carried out over its native range or under experimental conditions.
Adult silver carp mainly consume phytoplankton and detritus. For these reasons, it has been used in aquiculture and water management to improve water quality (Vovk, 1974; Cremer and Smitherman, 1980; Jirasek et al., 1981/82; Herodek et al., 1989). However, there are reports of ponds stocked with silver carp, increasing in phytoplankton biomass (Burke et al., 1986).
Typically this species is unable to ingest phytoplankton smaller than 10 µm (Herodek et al., 1989; Smith, 1989). Cremer and Smitherman (1980) reported silver carp to filter and ingest particles between 8-100 µm. The silver carp passively selects for phytoplankton over zooplankton based on particle size, and the mechanical aspects of its filtering apparatus (Smith, 1989; Dong and Li, 1994). It cannot select for individual types of plankters within a plankton patch, although it can select a particular feeding area (Cremer and Smitherman, 1980; Smith 1989; Dong and Li, 1994). Thus, composition of intestinal content is a reflection of the ambient composition of phytoplankton, at least for the size classes within its filtering range. Smith (1989) summarized feeding rates accounting for differences in size classes, particle sizes, and temperatures.
The silver carp has a characteristic feeding behavior, swimming about rapidly gulping water, closing its mouth and pumping it out through its opercula. Food items ingested are gound by the pharyngeal teeth against a cartilaginous plate (Robison and Buchanan, 1988). It actively feeds only when high concentrations of phytoplankton are present, which it detects through chemical cues (Smith, 1989). Breveridge et al. (1993) reported that silver carp can detect toxic strains of cyanobacteria by the presence of microcysins or related substances, and modify their behavior to avoid ingesting them.
Burke et al. (1986) reported individual gut contents examined to contain up to 99% phytoplankton, 90% detritus, and 5% zooplankton for fish stocked in catfish ponds. Adults may consume zooplankton (Herodek et al., 1989; Laws and Weisburd, 1994). Burke et al. (1986) suggested that the silver carp should be considered a versatile omnivore, due to reports of significant amounts of zooplankton from gut contents examined. In Lake Kinneret, Israel, the silver carp shifts from feeding on phytoplankton to zooplankton from September to January, when phytoplankton becomes scarce, competing with native fishes for this resource (Spataru and Gophen, 1985). Spataru (1977) reported some zooplankton secondarily consumed by silver carp in Dor, Israel, to pass through the intestine undigested, and found specimens of Brachionus and Rotaria, alive in the final portions of its gut. This author also reported Euglena and Phacus as commonly ingested, but not digested. The morphology of the specialized filtering apparatus of the silver carp is summarized by Jirasek et al. (1981/82) and Hampl et al. (1983).
Under experimental conditions, fry have been found to actively feed in the morning and late afternoon, with little if any feeding occurring at night (Herodek et al., 1989; Wang et al., 1989). Herodek et al. (1989) reported fry under 15 mm in length to mainly consume zooplankton. Wang et al. (1989), reported fry under 18 mm to actively select rotifers and nauplii, whereas fry between 18 and 26 mm select cladocerans and copepods. Over 26 mm these authors reported their diet to consist almost exclusively of phytoplankton. Fry at the smallest size class consume up to 140% of their body weight daily, declining to just over 30% by 63 mg and rising again to up to 63% for fingerlings between 70 and 166 mg (Wang et al., 1989).
Maximum Size:
Kamilov and Salikhov (1996) reported specimens of up to 1260 mm from the Syr Darya River. The same authors reported specimens of up to 10 years old.
Kamilov (1985) found the first ray of the pectoral fin, the vertebrae and the pterygiophore of the firs ray of the dorsal fin, suitable for ageing this species, whereas the operculum and the otoliths were not suitable.
Distribution:
This species naturally occurs in China. It has been introduced as a food fish and for water management purpose, in temperate waters of Asia, Europe and the United States.
Its status in the Gulf states is presently unclear. Boschung (1992) reported this species as established in the Tallapoosa drainage, Alabama. Museum records exist for Louisiana.
Interest to Fisheries:
Current Status of this Species in the Gulf of Mexico Ecosystem:
The silver carp has been introduced throughout the United States and the Gulf of Mexico drainages, to improve water quality in aquiculture ponds, reservoirs, and sewage pools. This species is possibly established in Sougahatchee Creek, Tallapoosa drainage, Alabama. Although this species is widespread throughout the Gulf states in most cases self-sustaining populations have not been confirmed (Courtney et al., 1991).
Potential Impacts:
Silver carp are capable of consuming large quantities of phytoplankton. Nonetheless, potential effects of the silver carp introductions are difficult to assess. If stable breeding populations were to form and the number of individuals became abundant, shifts in food web structure could be expected. Although reported to consume mostly phytoplankton, and equipped with a highly specialized filtering apparatus, silver carp consume whatever form of plankton is available in its environment. Where phtoplankton is scarce this species will consume zooplankton (Spataru and Gophen, 1985; Burke et al., 1986). Consequently, increases in algal biomass in ponds stocked with silver carp, have been reported (Burke et al., 1986), so its ecological impacts are not always predictable. Spataru and Gophen (1985) reported declines in zooplankton biomass in Lake Kinneret, Israel, which they attribute to stocked silver carp.
As is the case with most non-indigenous species, this species can transport diseases to new areas. Bocek et al. (1992) found silver carp to be an effective carrier of Salmonella typhimurium.
Recommendations:
References:
Beveridge, M.C.M., D.J. Baird, S.M. Rahmatullah, L.A. Lawton, K.A. Beattie, G.A. Codd. 1993. Grazing rates on toxic and non-toxic strains of cyanobacteria by Hypophthalmichthys molitrix and Oreochromis niloticus. Journal of Fish Biology 43:901-907.
Bocek, A. J., Y. J. Brady, W. A. Rogers. 1992. Exposure of silver carp Hypophthalmichthys molitrix, to Salmonella typhimurium. Aquaculture 103:9-16.
Boschung, H. T. 1992. Catalogue of freshwater and marine fishes of Alabama. Alabama Museum of Natural History Bulletin 14:1-266.
Burke, J.S., D.R. Bayne, H. Rea. 1986. Impact of silver carp and bighead carp on plankton communities of channel catfish ponds. Aquaculture 55:59-68.
Courtenay, W. R., Jr., D. P. Jennings, and J. D. Williams. 1991. Appendix 2, exotic fishes. Pages 97-107 in Robins, C. R., R. M. Bailey, C. E. Bond, J. R. Brokker, E. A. Lachner, R. N. Lea, and W. B. Scott, editors. Common and scientific names of fishes from the U.S. and Canada. Special Publication 20, American Fisheries Society, Bethesda, Md..
Cremer, M. C. And R. O. Smitherman. 1980. Food Habits And Growth Of Silver Carp And Bighead Carp In Cages And Ponds. Aquaculture 20:57-64.
Dong, S. and D. Li. 1994. Comparative studies on the feeding selectivity of silver carp Hypophthalmichthys molitrix and bighead carp Aristichthys nobilis. Journal of Fish Biology 44:621-626.
Hampl, A., J. Jirasek, D. Sirotek. 1983. Growth Morphology Of The Filtering Apparatus Of Silver Carp (Hypophthalmichthys Molitrix). II. Microscopic Anatomy. Aquaculture 31:153-158.
Herodek, S., I. Tatrai, J. Olah, L. Voros. 1989. Feeding experiments with silver carp (Hypophthalmichthys molitrix Val.) Fry. Aquaculture 83:331-344.
Howes, G. 1981. Anatomy and phylogeny of the Chinese major carps Ctenopharyngodon Steind., 1866 and Hypophthalmichthys Blkr., 1860. Bulletin of the British Museum (Natural History) Zoology Series 41(1):1-52.
Jirasek, J., A. Hampl, D. Sirotek. 1981. Growth morphology of the filtering apparatus of the silver carp (Hypophthalmichthys molitrix) I. Gross anatomy state. Aquaculture 26:41-48.
Kamilov, B.G. 1985. Morphology of growth structures in silver carp, Hypophthalmichthys molitrix, in relation to estimation of age and growth rate. Journal of Ichthyology 25(1):49-59.
Kamilov, B.G., T.V. Salikhov. 1996. Spawning and reproductive potential of the silver carp Hypophthalmichthys molitrix from the Syr Darya River. Journal of Ichthyology 36(8):600-606.
Laws, E.A., Weisburd, R.S.J. 1994. Algal Response To Silver Carp: Response To Comment. The Progressive Fish Culturist 56:77-80.
Robison, H. W., and T. M. Buchanan. 1988. Fishes of Arkansas. University of Arkansas Press, Fayetteville, AR.
Shubnikova, N.G. 1979. On sexual dimorphism in the silver carp, Hypophthalmichthys molitrix. Journal of Ichthyology 19(3):154-158.
Smith, D.W. 1989. The feeding selectivity of silver carp, Hypophthalmichthys molitrix Val. Journal of Fish Biology 34:819-828.
Spataru, P. 1977. Gut contents of silver carp- Hypophthalmichthys molitrix (Val.)- and some trophic relations to other fish species in a polyculture system. Aquaculture 11:137-146.
Spataru, P. and M. Gophen. 1985. Feeding behaviour of silver carp Hypophthalmichthys molitrix Val. and its impact on the food web of Lake Kinneret, Israel. Hydrobiologia 120:53-61.
Verigin, B. V., A. P. Makeyeva, and M. I. Zaki Mokhamed. 1978. Natural spawning of the silver carp, Hypophthalmichthys molitrix, the bighead caro, Aristichthys nobilis, and the grass carp, Ctenopharyngodon idella, in the Syr-Dar'ya River. Journal of Ichthyology 18(1):143-147.
Vovk, P.S. 1974. The possibility of using bighead carp (Hypophthalmichthys molitrix to increase the fish production of the Dnieper Reservoirs and to decrease eutrophication. Journal of Ichthyology 14(3):351-355.
Wang, J., S. Flickinger, K. Be, Y. Liu, H. Xu. 1989. Daily food consumption and feeding rythm of silver carp (Hypophthalmichthys molitrix) during fry to fingerling period. Aquaculture 83:73-79.
Other on-line references:
Date Created: 06/22/1998
Last Modified: 11/21/2003
|
