AGE, GROWTH AND REPRODUCTION OF THE CYPRINID TROPIDOPHOXINELLUS-ALBURNOIDES (STEPHANIDIS, 1974) IN RIVER AGUEDA, WEST-CENTRAL SPAIN

Age, growth and reproduction of the T. alburnoides population of the R iver Agueda, Duero basin are analysed. Females dominated all age class es and lived up to 6 years (5+) while males only reached 4 years (3+). The growing season extended from March to September. 0+ fish conditio n increased during their firs summer and spring and in older fish, con dition cycle was related to gonad development. Only 23% of the individ uals are mature at the first year (1 +) and biggest fecundity is found in the 2+ and 3+ age-classes. A high sex-ratio (r = 0.032) favourable to females is found in all age-classes.