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

Abstract

This paper describes and compares the different reproductive strategies of two cyprinid species, Barbus sclateri (GUNTHER 1868), barbel, and Leuciscus pyrenaicus (GUNTHER 1868), Iberian chub, in the Palancar Stream, SW Spain. B. sclateri only spawns once per year, during June. Intermediate age classes contribute most to the fecundity of the population, because of the decrease 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. The females of L. pyrenaicus use a reproduction strategy not previously described in other populations of this genus: females of L. pyrenaicus with a total length greater than 101 mm (mean length of age class 5+) spawn twice whereas smaller individuals (<100mm) of this species spawn only once per year. This behaviour increases the length of the spawning period and increases the fecundity of the population. The male: female ratio is 1:1. These conclusions are based on a detailed morphometric and histological study of the ovarian development in the populations.