Biology of the endangered cyprinodontid Aphanius iberus in a saline wetland (SE Iberian Peninsula)

For the last few decades, Aphanius iberus, an endemic cyprinodontid from the Iberian Peninsula and included in international red lists, has been declining despite several management efforts. In this study we present the biology of the species in an isolated wetland managed for salt exploitation (its most common habitat type in the southeastern Iberian Peninsula). The population studied is found under conditions of extreme high salinity and water temperature. We have examined the effects of extractive management on catchability, population structure, growth and reproduction traits. The stock was characterized by significant differences in abundance between seasons (higher values: end of summer and early autumn). Drastic changes in salinity and water level have negatively affected the species abundance. The population structure was characterized by three age groups (0+, 1+ and 2+ in both sexes), a high degree of group-size overlapping into the 0+ (. 2 groups), a short life span and a long reproductive period (April/May to September). Gonadal mass represented a maximum of 19.6 +/- 0.5% of the total mass in females. We detected changes in life-history traits which could be related to the management of the salt extraction, variations in water level that increase the salinity should be indirect effects on fish population by reducing vegetation mats.