(A) Larvae densities found in Ebro river (left) and the Cortes II reservoir (right); the spawning period and larval peaks are indicated for each study period. (No data June and August 2016). (B) Relationship between larval density and the duration of each breeding period (in weeks) for both study areas. (C) Duration of the spawning season and the time period elapsed from the first positive larvae sample until the water reaches 14 °C.