Brown trout (Salmo trutta, Linnaeus, 1758) spawning habitat improvement in the Ebro River Basin (eastern Spain)

• Published in: Journal of applied ichthyology Vol. 32; no. 1; pp. 171 - 179
• Main Authors: Lapesa, S, Ginés, E, González, J. M
• Format: Journal Article
• Language: English
• Published: Berlin Blackwell Wissenschafts-Verlag 01.02.2016; Blackwell Publishing Ltd; John Wiley & Sons, Inc
• Subjects: breeding; Calcium carbonate; females; Freshwater; Gravel; Habitat improvement; Habitats; Limestone; monitoring; River basins; Rivers; Salmo trutta; sediment deposition; Spain; Spawning; Streams; Substrates; watersheds; Spain; Spain, Ebro R. basin
• ISSN: 0175-8659; 1439-0426
• DOI: 10.1111/jai.13020

Limestone streams in Spain are subject to calcium carbonate precipitation processes, which make the substrate very cohesive. Many populations of brown trout (Salmo trutta, Linnaeus, 1758) in those rivers show reduced production due to unsuitable spawning habitats. This study presents data on S. trutta spawning habitat improvement in the Guadalope River Basin during 2011. The main objectives of this study were to (i) modify the substrate in order to make it easier for S. trutta females to dig when spawning, (ii) test the effect of the gravel quality improvement on the habitat, (iii) analyse the effect of habitat improvement on S. trutta recruitment, and (iv) monitor habitat improvement effectiveness in the long term. Three manual measures were adopted to make the gravel suitable for S. trutta breeding: the separation of the embedded gravel using an iron bar by hitting it with a mace‐hammer (‘substrate breaking’), the spreading out of the gravel loosened by the previous action with a rake (‘raking up’), and thirdly the elimination of fine sediment depositions (‘substrate cleaning’). Results of the first year of monitoring (2012) in improved and control areas were compared. Methodology effectiveness assessment requires monitoring over a longer period, but the data from the first year after habitat improvement provide encouraging results, mainly dealing with changes in spawning habitat parameters and an increase in the S. trutta age‐0 class in the improved areas.