Reproductive strategies of two species of cyprinids in a stream with Mediterranean regimen (SW Spain)

This paper describes and compares the different reproductive: strategies of two cyprinid species, Bap bus sclateri (GUNTHER 1868), barbel, and Leucisc us pyrenaicus (GUNTHER 1868), Iberian chub, in the Palancar Stream, SW Spai n. B. sclateri only spawns once per year, during June. Intermediate age cla sses contribute most to the fecundity of the population, because of the dec rease in numbers of individuals with increasing age. The male:female ratio is 3:1. Males and females mature at age classes 1+ and 4+, respectively. Th e females of L. pyrenaicus use a reproduction strategy not previously descr ibed in other populations of this genus: females of L. pyrenaicus with a to tal length greater than 101 mm (mean length of age class 5+:) spawn twice w hereas smaller individuals (<100 mm) of this species spawn only once per ye ar. This behaviour increases the length of the spawning period and increase s the fecundity of the population. The male:female ratio is 1:1. These conc lusions are based on a detailed morphometric and histological study of the ovarian development in the populations.