J. Fish Biol. zyxwvut (1988) zyxwvuts 33,371-381 Age, growth and reproduction of the barbel, Barbus sclateri (Gunther, 1868), in a first-order stream in southern Spain M. HERRERA, J. A. HERNANDO, C. FERNANDEZ-DELGADO AND M. BELLIDO Seccion de Zoologia, Departamento de Biologia Animal, Facultad de Ciencias, Universidad de Cbrdoba, 14004 Cdrdoba, Spain (Received 7 August 1987, Accepted 10 March 1988) zyx This study was based on examination of 1476 barbels from a first-order stream located in the Guadalquivir River basin (38" N, 4" 43' W). This stock comprised nine age groups of male and I I of females. No growth was recorded between October and March, most occurring in April-June and, to a lesser extent, in July-September. A classification analysis revealed that this stock had the lowest growth rate of 37 different European barbel populations. Length-weight relationships were obtained for 12 barbel categories and used to estimate both condition and instantaneous growth rate. Relative condition (before and after subtracting gonad weight) was similar in both sexes and was affected by gonad growth and environmental summer conditions. Spawning occurred during the second half of May (15 May is suggested as the birthday). Gonads began to develop in September (females) and in February (males). Males matured at between 7 and 9cm fork length zyxwvu (F.L.) (2-4 years old) and females between 1 I and 16cm (67 years). The fecundity of this stock was represented by the formula F=6.07 10 zyxw ' F.L. (mm)30667. Larger and older fish showed a higher fecundity and bigger eggs. The overall sex ratio did not differ from 1 : 1. 1. INTRODUCTION Little is known about the biology of the genus Barbus in the Iberian Peninsula. Only B. graellsi (Stein., 1866) (Sostoa & Sostoa, 1983) and B. bocagei (Stein., 1866) (Lobon-Cervia & Fernandez-Delgado, 1984) have been studied in any detail. However, the parental species, Barbus barbus (L., 1758), is well known in several European rivers (Havlena, 1964; Hunt & Jones, 1975; Penaz, 1977; Kraiem, 1982). Barbus sclateri is relatively unknown; the few studies refer to isolated aspects of its biology (Lucena et al., 1979; Lucena, 1984). Therefore, the present study is the first on the basic biological characteristics (age, growth and reproduction) of this endemic species. 11. STUDY AREA This study was carried out in the River Mascatomiza, a first-order stream of the Guadalquivir river basin (38" N, 4" 43' W). It is about zyx 5 km long, 1 4 m wide and 25-75 cm deep. Table I shows some physico-chemical parameters of the water analysed. Bank vegetation consists of Securinega tinctoria (Rothm., 1940), Rubus ulmifolius (Schott, 18 18) and Nerium oleander (L., 1753); aquatic vegetation comprises Ceratophyllum demersum (L., 1753), Myriophyllum spicatum (L., 1753), Potamogeton nodosus and Ranunculus baudotii (Godron., 1840). 0022-1 112/88/090371+ 1 I $03.00/0 37 I zyxwvut 0 1988 The Fisheries Society of the British Isles