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Rudd
Scardinius erythrophthalmus (Linnaeus 1758)

Figure 46. Rudd, SIUC 51749, 105 millimeter SL, from cultured stock in Gainesville, Florida. (The original brood stock came from Arkansas.)

Figure 46. Rudd, SIUC 51749, 105 millimeter SL, from cultured stock in
Gainesville, Florida. (The original brood stock came from Arkansas.)

Description

       The Rudd (fig. 46) is a medium-sized fish typically attaining about 30 cm TL and 0.8 kg, with a maximum size of about 45 cm TL and 2 kg (Berg, 1964; Wheeler, 1969, 1978; Muus, 1971). The body is deep and moderately compressed with an arched back and a scaled keel between the pelvic fins and anus. The lateral line is complete with 37-43 scales and distinctly curved downward anteriorly. The snout is blunt and the mouth is large, terminal, and oblique. The eyes are laterally positioned. The cranium profile is convex to straight, becoming slightly concave in some larger specimens. Gill rakers on the outer arch range in number 10-13. Pharyngeal teeth are strongly serrated and borne on a stout arch. The dental formula is typically 3,5-5,3 (fig. 47). The peritoneum is silvery and the intestine is S-shaped. The dorsal-fin origin is markedly posterior to the pelvic-fin insertion. The dorsal fin is slightly falcate and has i-iii (8-10) rays. The anal fin is moderately falcate and has i-iii (9-13) rays. The caudal fin is moderately forked, with the lower lobe slightly longer than the upper. Meristics for Rudd are given in appendix B.

Figure 47. Pharyngeal teeth (3,5-5,3) of Rudd, SIUC 51749, from cultured stock, Gainesville, Florida. (The original brood stock came from Arkansas.)

Figure 47. Pharyngeal teeth (3,5-5,3) of Rudd, SIUC
51749, from cultured stock, Gainesville, Florida. (The
original brood stock came from Arkansas.)

       Coloration of non-nuptial adult Rudd is silvery with a yellow-lime sheen on the upper sides grading to brassy on the back (fig. 48). Pigmentation on the back varies depending on the color of the habitat substrate. Fish from pale substrates often lack the distinctive broad middorsal stripe and have a dorsum that is silvery, brassy, or with a lime sheen. The dorsal surface of the head is straw-olive in color. The cheeks and opercles are silver. According to Wheeler (1978), all the fins are reddish and the ventral fins are brilliant blood red. Other authors have described the median fins as having a rose-orange wash and the paired fins as rose-orange (especially in the leading rays). The iris of the eye is golden with a red fleck above (Wheeler, 1978). The Rudd also has a golden color morph that is sometimes used as an ornamental pond fish (Maitland, 1977).

Figure 48. Adult Rudd, 104 millimeter SL, from cultured stock in Gainesville, Florida. (The original brood stock came from Arkansas; photo by Noel Burkhead.)

Figure 48. Adult Rudd, 104 millimeter SL, from cultured stock in Gainesville, Florida.
(The original brood stock came from Arkansas; photo by Noel Burkhead.)

       In nuptial males, the venter is silver and the sides are brassy progressing to bright translucent orange along the midback. The back and upper sides are oliveblack anterior and posterior to the dorsal fin. The dorsal surface of head is translucent orange. Cheeks and opercles are brassy-orange. The lips are orange and the iris is orange dorsally. The distal two-thirds of the dorsal fin is bright red, and the basal third is paler with oliveblack along the rays. The anal and caudal fins are bright red with distinct pale margins. Paired fins are red except the posterior 3-5 rays, which are pale. The coloration of mature females is similar to males, but more subdued.

       Nuptial males develop fine tubercles on the head and body (Berg, 1964; Wheeler, 1969). Two small (76 and 81 mm SL) sexually mature males reared in the laboratory exhibited fine, densely spaced tubercles on the head, anterior part of the body, and rays of pectoral, dorsal, and anal fins. Tubercles have not been reported in females. In both sexes, the urogenital opening is present just posterior to the anus and is located in a fleshy pit. The female urogenital opening is about twice the size of the male opening and is ringed with fleshy protuberances.

Similar Species

       The Rudd is distinguished from native North American cyprinids by two characteristics. The Rudd has a scaled midventral keel (fig. 49) and a 3,5-5,3 pharyngeal tooth formula (fig. 47). The blood-red color of the pelvic and anal fins in specimens about >40 mm SL may have diagnostic utility.

Figure 49. Ventrolateral and posterior aspect of abdomen showing (A) a scaled keel in Rudd, (B) a partially scaled keel in hybrid Rudd X Golden Shiner, and (C) a naked keel in Golden Shiner. (From Burkhead and Williams 1991.) (Also see to fig. 8)

Figure 49. Ventrolateral and posterior aspect
of abdomen showing (A) a scaled keel in Rudd,
(B) a partially scaled keel in hybrid Rudd X
Golden Shiner, and (C) a naked keel in Golden
Shiner. (From Burkhead and Williams 1991.)
(Also see to fig. 8.)

       The Rudd is most similar in appearance to the Golden Shiner, the only native North American cyprinid having a midventral keel. However, the keel of the Golden Shiner is scaleless, whereas the keel of the Rudd is crossed with scales. In Rudd X Golden Shiner hybrids the keel is partially scaled (fig 49; Burkhead and Williams, 1991). In both species the fins may be brightly colored; however, the fins of adult Golden Shiners are typically orange or reddish-orange, whereas those of Rudd are generally blood red. If there is any question of identity, the pharyngeal arches should be examined. The pharyngeal teeth of Rudd are in two rows (3,5-5,3); those of the Golden Shiner are in a single row (0,5-5,0).

       Early development of the Rudd has been described by Bracken and Kennedy (1967), Kennedy and Fitzmaurice (1974), Cadwallader (1977), and Cerny (1977). Newly hatched larvae possess adhesive organs on the head and anterior trunk. Adhesive organs have not been observed in the Golden Shiner (Lippson and Moran, 1974; Snyder and others, 1977).

Variation

       A golden color variety is sometimes used as an ornamental pond fish (Maitland, 1977).

       A number of subspecies have been recognized (Banarescu, 1964). Some are no longer considered valid; and a few have been elevated to distinct species (for example, Scardinius graecus and Scardinius scardafa; Bogutskaya, 1997; Bianco, 2004).

       The Rudd has been reported to hybridize with a number of Old World cyprinids, including Goldfish, Common Carp, and Tench (Schwartz, 1972, 1981). There is one report of Rudd X Northern Pike (Esox lucius) hybridization (Romashov and Golovinskaia, 1960, in Schwartz, 1972, 1981). The Rudd has also been artificially hybridized with Golden Shiner (Burkhead and Williams, 1991).

Reproduction

       Age at maturity varies with geographic latitude. Males may be sexually mature from 1-4 years and females from 2-5 years. Spawning occurs in late spring and summer when water temperatures are above 16 °C (Nikolsky, 1963). Holcik (1967) suggested that the Rudd may be a portional spawner, producing two batches of eggs in a spawning season; the first batch being larger than the second. Berg (1964) reported 96,000-232,000 eggs per female, but did not indicate the size range of the fish examined. Kennedy and Fitzmaurice (1974) reported a range of 108,000-211,000 eggs per kg of body mass.

       In preparation for spawning, mature males appear at the breeding sites first. Females are present 6-8 days later, although actual spawning reportedly does not occur for another 2-3 weeks (Holcik, 1967). Pre-spawning behavior in the shallow waters of a lake in Sweden was described by Svardson (1949). Large numbers of fish were involved in the spawning activities, with local aggregations near dense submerged vegetation. The adhesive eggs are shed on vegetation, usually along the shoreline (Wheeler, 1969; Cadwallader, 1977). Cerny (1977) reported spawning on rocky substrata close to the banks of a reservoir. The Rudd is also known to join in the spawning shoals of other cyprinids (Cadwallader, 1977; Cerny, 1977; Muus, 1971).

       Rudd eggs are demersal and adhesive, and newly fertilized eggs are translucent pale yellow to opaque gray-green (Cadwallader, 1977; Cerny, 1977). Developmental rates vary widely with temperature. For example, Kennedy and Fitzmaurice (1974) observed that incubation time ranged from 4-5 days at 17.5-21.5 °C to 19-20 days at 10.5-11.5 °C. Larvae are about 4.5-5.9 mm TL at hatching. Early development has been described by Bracken and Kennedy (1967), Kennedy and Fitzmaurice (1974), Cadwallader (1977), and Cerny (1977).

Ecology

       Berg (1964) stated that adult fish are typically 200-250 mm SL and weigh 100-300 g. However, Rudd from near Moscow may attain 360 mm SL and weigh 1.5-2.0 kg (Berg, 1964). According to Muus (1971), the maximum size is 450 mm and 1.7 kg; however, Wheeler (1969) reported the British angling record as 2.06 kg. The Rudd has a moderately long life span, and individuals >10 years of age are common. Kennedy and Fitzmaurice (1974) reported Rudd from Ireland as large as 1.4 kg and as old as 17 years. Coad (2005) commented that the Rudd life span is up to 30 years.

       The Rudd occurs in a variety of freshwater habitats, including subalpine oligotrophic lakes, lowland lakes, reservoirs, ponds, large rivers, oxbows, small streams, thermal springs, and in some areas, it enters brackish water (Wheeler, 1969; Kennedy and Fitzmaurice, 1974; Aneer and Nellbring, 1976; Rheinberger and others, 1987). The species occupies sites that range in elevation from sea level to 1,829 m (Schindler, 1957). The Rudd’s tolerance of a variety of habitats has likely contributed to its wide distribution. In streams and rivers, it usually occurs in long, slow pools and backwaters. In ponds, lakes and reservoirs, it is usually found in the littoral zone. The species is commonly associated vegetation that serves both as cover and a principal component of the diet (Wheeler, 1969; Kennedy and Fitzmaurice, 1974). The Rudd is able to tolerate low levels of salinity and is known to naturally enter brackish water. In Ireland, Kennedy and Fitzmaurice (1974) reported that Rudd occurred in tidal ponds of the Shannon Estuary and in Courtown Harbor where salinity ranges from 1-10 ppt. Individuals have also been captured in the northern Baltic Sea at a salinity of 7 ppt (Aneer and Nellbring, 1976). Experimental studies have shown an ability to tolerate salinity concentrations up to 17 ppt as well as heavy chloride pollution (Hynes, 1970).

       The Rudd has a diverse diet. Kennedy and Fitzmaurice (1974) noted that larval Rudd held in laboratory conditions first began to feed at 6.0-6.5 mm TL. At this size, they consumed unicellular algae and some phytoplankton. At approximately 10 mm TL the fish shifted their diet to cladocerans and copepods. Other items in the diet included larvae and pupae of chironomids, flies, and springtails, as well as a variety of small terrestrial insects. Adult Rudd (2+ years) are  omnivorous, feeding mainly on aquatic vegetation as well as surface and aerial insects, snails, crustaceans, diatoms, and occasionally fish eggs (Hartley, 1947; Muus, 1971; Coates and Turner, 1977; Smith, 1985).  Wheeler (1969) reported that Rudd in Europe consumed crustaceans (including copepods, ostracods, and amphipods) and occasionally small fishes.

Native Distribution

       The Rudd is widespread in Europe and middle Asia (Banarescu, 1964; Berg, 1964).

U.S. Introductions

       To date, the Rudd has been reported from at least 22 states, but it may exist in additional states. Because of incomplete data and contradictory information, the exact distribution of Rudd in the U.S. and the status of many introduced populations remain uncertain (Fuller and others, 1999).

Scardinius erythrophthalmus
Rudd
Plate 11. Distribution of Rudd in the United States. - click to enlarge
Plate 11. Distribution of Rudd in the United States. See Methods for details regarding data
used to create maps, definitions of “reproducing” and “reported” and shading of HUCs and states.


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