POPULATION-STRUCTURE, GROWTH AND REPRODUCTION OF TROPIDOPHOXINELLUS-ALBURNOIDES (STEINDACHNER 1866) IN AN INTERMITTENT-STREAM OF THE GUADALQUIVIR RIVER BASIN (SOUTHERN SPAIN)

The age, growth and reproduction of Tropidophoxinellus albumoides (STE INDACHNER 1866), an endemic cyprinid from the Iberian Peninsula, was s tudied for the first time for two years in a small seasonal tributary of the Guadalquivir River basin. Males reached a maximum age of 3+ yr (fork length, L = .51 mm) and females 6+ yr (L = 100 mm). Mean lengths of 3+ and 4+ age groups diminished during the summer. Both sexes matu red during their second year of life. The overall sex ratio was domina ted by females (319 males/2331 females) probably due to the effect of gynogenesis as the dominant reproductive strategy of the population. R eproduction began in March and lasted through June/July depending on t he climatic conditions in each year. T alburnoides is a multiple spawn er that releases at least two batches of eggs per female each year. Th e number of ripe females in the population was maximum five times duri ng the two reproductive seasons studied. The regression between fecund ity (Fec) and fork length (mm) was represented in 1988 by the equation Fec = 0.0167 L2.5717 and in 1989 by Fec = 0.0041 L2.4701. Maximum con tribution to the fecundity in the population was observed in intermedi ate ages.