Spatial-seasonal dynamics of fish in a drought-stressed Mediterranean reservoir: An integrated hydroacoustic approach for adaptive management
Non-invasive fish monitoring is essential in Mediterranean reservoirs where drought and drawdown demand rapid, whole water-column assessments. We combined hydroacoustics and standardized netting to quantify spatial and seasonal variation in fish density and biomass, size structure, and species compo...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2026 |
| País: | España |
| Institución: | Universidad de Sevilla (US) |
| Repositorio: | idUS. Depósito de Investigación de la Universidad de Sevilla |
| OAI Identifier: | oai:dnet:idus________::c6e1073c6a47ac4099f376b893906529 |
| Acceso en línea: | https://hdl.handle.net/11441/186098 https://doi.org/10.1016/j.ecoleng.2026.107948 |
| Access Level: | acceso abierto |
| Palabra clave: | Adaptive management Alburnus alburnus Drought Hydroacoustics Mediterranean reservoirs Monitoring Nets Zahara-El Gastor Reservoir |
| Sumario: | Non-invasive fish monitoring is essential in Mediterranean reservoirs where drought and drawdown demand rapid, whole water-column assessments. We combined hydroacoustics and standardized netting to quantify spatial and seasonal variation in fish density and biomass, size structure, and species composition in Zahara-El Gastor Reservoir (SW Spain) and to evaluate an integrated monitoring approach. We conducted four seasonal surveys combining split-beam horizontal (0–4 m) and vertical echosounding with CEN standard multi-mesh gillnets and trammel nets across dam, central, and riverine zones of the reservoir. Acoustic data, analysed at 300 m Elementary Sampling Distance Units (ESDUs), revealed strong spatial and seasonal patterns: approximately 70% of acoustic detections occurred in the upper 4 m, where fish density peaked in summer at 122 ± 179 ind⋅10- 3 m- 3, with consistently higher values near the surface. Catches were numerically dominated by invasive bleak Alburnus alburnus (≈96.6% of individuals), while Andalusian barbel Luciobarbus sclateri accounted for ≈40% of biomass. Overall density was about five times higher than early post-impoundment surveys, consistent with bleak proliferation and reduced storage volume during drought. Size-class distributions showed no coherent seasonal shifts, indicating a lack of clear seasonal changes in community structure. Integrating horizontal and vertical hydroacoustics with minimal netting enables rapid, fish-friendly, and cost-effective monitoring under climate-driven water-level fluctuations, providing a practical basis for adaptive reservoir monitoring. |
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