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Figure 35. Bighead Carp, SIUC 23919, 207 millimeter SL, from Washington County, Illinois.
The Bighead Carp (fig. 35; previously known as Aristichthys nobilis) is a large species that may grow larger than 1 meter TL and weigh up to 40 kg in as little as 9 years (Baltagi, 1979, in Jennings, 1988). It is deep-bodied and laterally compressed with a smooth keel that runs from the anus to near the base of the pelvic fins (fig. 36). The lateral line is complete with 91-120 scales and curved ventrally. The head is large (usually >1/3 the SL). Eyes are forward on the head and positioned ventrally. The mouth is terminal and large, with the lower jaw slightly longer than the upper one. The premaxillary and mandible form bony, rigid lips. Barbels are absent. The pharyngeal teeth are moderately long, bluntly rounded, and arranged in a single row (0,4-4,0; fig. 37). The gill rakers are long and thin, and number about 130 on the first arch. The numerous gill rakers are closely arranged with membranous septa, but are unfused. The dorsal fin is short, lacks a spine-like ray, and has ii-iii (7-10) rays. The dorsal-fin origin is posterior to the origin of the pelvic fins. The anal fin has ii-iii (10-17) rays. Coloration is dark gray dorsally, fading to off-white below. Young are silvery (fig. 38) until about the age of 8 weeks when numerous irregular blotches of grayish black appear on the body (Jennings, 1988). Meristics for Bighead Carp are given in appendix B.
Figure 36. Ventral keel of Bighead
Figure 37. Pharyngeal teeth (0,4-4,0) from
The Bighead Carp is sexually dimorphic. Males possess a bony, sharp edge along the dorsal surface of several of the anterior pectoral rays. This feature is absent in females. Chang (1966) suggested that this secondary sex characteristic is formed long before the males reach maturity, and lasts throughout life.
The presence of a ventral keel differentiates the Bighead and Silver Carps from all native cyprinids except the Golden Shiner. Bighead and Silver Carps have smaller and more numerous (>60) lateral-line scales than the Golden Shiner (39-51). Additionally, Bighead and Silver Carps have only four teeth in a single row (per side). In contrast, the Golden Shiner typically has five pharyngeal teeth in a single row (per side).
The Bighead Carp can be distinguished from the Silver Carp, its close relative, by differences in the ventral keel and gill rakers. Gill rakers of Bighead Carp lack the fused condition that forms a sponge-like apparatus in Silver Carp. The ventral keel of the Bighead Carp extends forward only to the base of the pelvic fins, whereas the ventral keel in Silver Carp extends to the anterior part of the breast, almost to the junction of the gill membranes (fig. 36). When apressed, the pectoral fin of the Bighead Carp extends beyond the pelvic base; however, the pectoral fin does not reach the pelvic base in Silver Carp. Typically, the eyes of the Bighead Carp are slightly lower on the head than those of the Silver Carp; however, this characteristic may not be diagnostic. Additionally, adult Bighead Carp have irregular gray or black blotches covering the body that are absent in Silver Carp.
The name “Bigheaded Carps” is often applied collectively to include all the Hypophthalmichthys species.
Bighead Carp have been artificially hybridized with Grass Carp (see Grass Carp account). Hybridization has also been achieved with Common Carp (Makeyeva, 1968, 1972) and Silver Carp (see Silver Carp account). Jennings (1988) reviewed the history of hybridization (including techniques used) and morphological characteristics of the hybrids.
Maturity is reached at 2-4 years in subtropical/tropical locales and 5-7 years in temperate regions (Kuronuma, 1968; Abdusamadov, 1987). Age to maturity varies with food supply and environmental conditions (Huet, 1970; Bardach and others, 1972). Males generally mature a year earlier than females (Opuszynski and Shireman, 1995). Opuszynski and Shireman (1995) reviewed gonad condition through the stages of development. Fecundity increases with mass (Verigin and others, 1990) and can range from about 280,000 to >1,000,000 eggs (Vinogradov and others, 1966; reviewed in Opuszynski and Shireman, 1995). Larval development was reviewed in Jennings (1988).
Figure 38. Juvenile Bighead Carp. (Photo by Noel Burkhead.)
In China, where they are native, Bighead Carp spawned at temperatures between 26-30 °C in the Yangtze River (Chang, 1966, in Opuszynski and Shireman, 1995) and as low as 18 °C in the Han River (Zhou and others, 1980). Spawning habits of Bighead Carp in the U.S. have not been well documented; although a preliminary study suggested that the lower Missouri River is conducive to spawning, due to its similarity with areas used for spawning in the native range (for example, rising water and 22 °C temperature) (Schrank and others, 2001). For additional information on spawning requirements, see the section entitled “Spawning requirements of Chinese carps” in the Grass Carp account.
The Bighead Carp is a large species that may grow >1 m TL and up to 40 kg in as few as 9 years (Baltagi, 1979, in Jennings, 1988). Individuals up to about 1.3 m TL have been captured (Xie Ping, 2003) and maximum size is probably >1.5 m TL. Maximum weight is >50 kg (Li and Mathias, 1994).
The Bighead Carp is one of several large Chinese carps introduced into the U.S. In its native range, the species occurs in large rivers from temperate to subtropical climates. An important aquaculture species, the Bighead Carp has been widely introduced throughout much of the world and now occurs in a variety of habitats and climates (Lever, 1996; Fuller and others, 1999; Xie Ping, 2003). Similar to Silver Carp, the Bighead Carp often swims near the water surface; however, it is less likely to leap out of the water when disturbed (Li and Mathias, 1994). The thermal maximum temperature (derived from laboratory studies) was 38.8 °C and the preferred temperature was 25.3 °C (Bettoli and others, 1985). Liang and Wang (1993) reported the maximum pH for culture was 9.24. Egg hatching was delayed below pH 6.5 and increased mortality and deformation of larvae occurred below pH 6.0 (Li and Zhang, 1992). However, sensitivity to low pH decreased with age (Li and Zhang, 1992). Median lethal concentration of ammonia was determined as 1.12 mg/L (Gulys and Fleit, 1990).
Oxygen consumption (per gram of body mass) has been shown to increase with increased water temperature and decrease with fish age and mass (Chen and Shih, 1955; Wozniewski and Opuszynski, 1988). Negonovskaya and Rudenko (1974) demonstrated that juveniles were tolerant of oxygen levels lower than 0.5 mg/L. Laboratory studies have shown that juveniles can tolerate salinities up to 8 ppt for a short period of time (Chervinski, 1980). Salinity tolerance of fry increased with fish age, ranging from 2.3 ppt for 11-day olds to 7.6 ppt for 35-day old fish (Garcia and others, 1999). Larvae are known to migrate to brackish-water areas of the Caspian Sea where salinities range from 6-12 ppt (Abdusamadov, 1987).
Bighead Carp larvae feed primarily on zooplankton and to a lesser extent on phytoplankton and other suspended material (Korniyenko, 1971; Cremer and Smitherman, 1980; Burke and others, 1986; Dong and Li, 1994; reviewed in Jennings, 1988). Adults are filterfeeders that primarily consume phytoplankton in the water column. Opportunistic feeding has been reported, with individuals seasonally shifting from zooplankton to phytoplankton, based on the abundance of the food source (Nikol'skiy and Aliyev, 1974; Burke and others, 1986; Xie Ping, 2003).
The Bighead Carp has been extensively transferred and cultured in aquaculture facilities for water-quality management. The species is thought to improve water quality of ponds by removing plankton, especially filamentous blue-green algae (Voropaev, 1968; Aliyev, 1976; Cremer and Smitherman, 1980; Opuszynski and Shireman, 1993; Dong and Li, 1994). However, some researchers reported that Bighead Carp made no difference in algal density (Burke and others, 1986).
The Bighead Carp is native to rivers of eastern Asia from southern China north into far eastern Russia (Li and Fang, 1990).
The first introduction of Bighead Carp in the U.S. was in 1972 when a private Arkansas fish farmer introduced the species in an attempt to improve water quality in fish ponds (Fuller and others, 1999). By the early 1980s, the species was taken from open waters of the Ohio and Mississippi rivers, likely as a result of escapes from aquaculture facilities (Jennings, 1988). The Bighead Carp is now firmly established in the Mississippi, Ohio, and Missouri rivers, which is not surprising, given the similarities of these systems to those in the native range. Juveniles have also been taken in small (4 m width) streams in southern Illinois (J. Stewart, SIUC, personal commun. need date).
Plate 7. Distribution of Bighead Carp in the United States. See Methods for details regarding data
Commercial fisherman in Louisiana hauling in hoop net full of
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