pond farms of agricultural enterprises have also stopped their activities, the production has decreased significantly. At the same time, it has become popular among farmers to keep carp in small ponds near their farmsteads. Most of the stocking material used in Estonia originates from the Ilmatsalu breeding centre near Tartu, which keeps and breeds a selected broodstock of different strains and crossbreeds. The production of carp was < 50 t in the early 2000s. Bighead carp, Aristichthys nobilis (Richardson) E: kirju pakslaup (jämepea), Da: marmorkarpe, G: Gefleckter Silber Karpfen (Marmor Karpfen), La: raibais platbieris, Li: margasis plačiakaktis, Po: tołpyga pstra, R: пестрый толстолоб, S: marmorkarp Toomas Saat & Heli Špilev Description. Deep-bodied, laterally compressed fish with big head. Scales small, l.l. ~ 85–100 scales, 26–28 scale rows above lateral line. The fins of small specimens lack spines. Large specimens have heavy, non-serrate spine at origin of D and a slightly stiffened spine at origin of A. Db 8 (9), Ab 13 (14). The gill rakers long, comblike and close-set, not fused into porous plate. D.ph. 4–4. Ventral keel extending from anus only to the pelvic fin base. Small irregular black blotches along sides. The dorsal fin origin distinctly behind the pelvic fin insertion. Archives of the Estonian Marine Institute Distribution. Bighead carp are native to lowland rivers of the north China plain and south China. This species is cultured throughout temperate waters of the world, for use in water quality management. However, it is not always effective for this purpose. If established, the bighead carp could cause shifts in the food web 240 PDF processed with CutePDF evaluation edition www.CutePDF.com and compete with zooplanktivorous fishes and fish larvae for this resource. Lowering of zooplankton concentrations could facilitate eutrophication as has been the case in aquaculture ponds (Burke et al., 1986). Biology. Bighead carp is a benthopelagic freshwater species. It prefers large river habitats but occurs also in lakes. It is a filter feeder; feeds mainly on zooplankton. When concentrations of zooplankton are low, it may feed on phytoplankton and detritus. Bighead carp spawns at 28–30 ºC in water column. AF is typically between 660,000 and 872,000 (Verigin et al., 1990). One specimen (Tl 62.6 cm, Sl 54 cm, Tw 3645 g) was captured by local fishermen in Pärnu Bay, Gulf of Riga (close to the Audru River mouth) on 10 September 2002. It had Du 3, Db 8, Au 2, Ab 13, Pu 1, Pb 18, Vu 1, Vb 7, l.l. 100, D.ph. 4–4. Two other specimens were captured in Latvian waters of the Gulf of Riga (near the mouths of the Salaca and the Daugava rivers) in 1990 and 1992 (Plikšs & Aleksejevs, 1998). FAMILY COBITIDAE Spined loach, Cobitis taenia L. E: hink, Da: pigsmerling, Fi: rantaneula, G: Steinbeißer, La: akmeņgrauzis, Li: kirtiklis, Po: kózka, R: щиповка, S: nissöga Väino Vaino & Toomas Saat Description. Body elongated, laterally flattened. Head tapered, with blunt tip. An erectile movable two-forked spine below either eye. Mouth low, lips fleshy, lower lip doubled. D.ph. in one row. Three pairs of small barbels. Scales small and thin, l.l. incomplete. Caudal peduncle short, with well-developed fat (skin) keel on ventral edge. C cut off, borders rounded. In males the second ray of P thickened, with axe-shaped scale (organ of Canestrini) on the base. Basic coloration whitish with yellow tint on back and sides. Spots and dots brown, except for one small black dot on the base of C. Gambetta zones well-delineated, usually with 16–18 large dark spots on sides. Head with dark marbling, a dark stripe extending from snout beyond eye. Fins greyish, D and C with rows of dots. Варпаховский, 1898 241