AGE STRUCTURE, GROWTH AND REPRODUCTION OF LEUCISCUS-PYRENAICUS IN AN INTERMITTENT-STREAM IN THE GUADALQUIVIR RIVER BASIN, SOUTHERN SPAIN

The age, growth and reproduction of Leuciscus pyrenaicus (Gunther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7+. Maximum ages observed were 7+ in males and 8+ in females. There were no significant differences in the annual growth increments between sexes. Seasonal growth period started in March and continued for 5 to 6 months. Mean lengths of 1+ specimens onwards diminished during summer and/or autumn. Males and females matured in their third and fourth year of life respectively. The overall sex ratio (272 males : 310 females) differed significantly from equality. Spawning began in May and ended in July. L. prenaicus is a multiple spawner that releases a minimum of two batches of eggs per female each year. Eggs in each batch were similar in both size (egg diameter) and number released. The relationship between fecundity (Fee) and fork length (mm) was represented by the formula: Fec=1.96 10(-3) L(2.50).