The Board of Castile and León has activated a rescue operation de peces in the Tera River, at the height of Espejo de Tera (Soria), due to the low flow of these weeks. The intervention focuses on specimens trapped in isolated pools, where the lack of water renewal reduces the oxygen at critical levels. For this, they use specific techniques to prevent the mortality of fish fauna and ensure their survival.
The device involves environmental agents of the Board and caretakers of the Urbión Hunting Reserve, with the aim of preventing the mortality of fish fauna. The work has been planned to act quickly in the most vulnerable areas and ensure survival of all the species present.
A low water level that tightens on the Tera River
The summer low water level, accentuated by the high temperatures and rain shortage, has left sections of the riverbed practically dry. This situation fragments the river into small, disconnected pools where the dissolved oxygen plummets, turning the environment into a trap for fish.
The phenomenon is recurrent every summer in the province of Soria, and the Tera River is once again experiencing it with intensity. To reduce the impact, the Environmental Service keeps the area under observation and evaluates similar interventions in other sections with flow problems.
How the rescue is executed step by step
The team uses a portable electric fishing device that emits a soft, controlled shock. This stimulus momentarily stuns the fish and allows them to be attracted to the landing nets for manual capture, without causing harm. Highlights that aim and caution are essential to maintain the integrity of the specimens.
- Location of pools: Critical enclaves where there are isolated fish are identified.
- Application of mild current: Electrofishing stuns briefly and facilitates safe handling.
- Catching with landing nets: The specimens are collected one by one to avoid stress and injuries.
- Immediate stabilization: The fish are placed in tanks with a continuous supply of oxygen.
Transport and release in safe areas
Once captured, the specimens are transported in a water tank with continuous oxygen installed in the bed of a pick-up vehicle belonging to the Junta de Castilla y León. This system maintains the optimal conditions during the journey, ensuring their well-being.
The release is carried out in sections of the same Tera river or, failing that, within its same watershed. Areas with guaranteed flow are chosen until the arrival of the autumn rains, minimizing stress and avoiding translocations between different basins.
Coordination and surveillance in the province
The performance is coordinated by the Territorial Environmental Service of Soria, which maintains continuous monitoring of the river network. In other rivers in the province with symptoms similar to low water measures to protect wildlife are being evaluated.
This type of rescue is repeated every summer, when the hydrology is most adverse. The combination of constant monitoring, proper technique and controlled transfer allows to reduce the impact of the low water and preserve natural heritage of the river courses of Soria.
From the coordination of agents and guards in Espejo de Tera, a quick and well-planned intervention is prioritized: detection of pools, electrofishing without damage, transport in oxygenated tanks, and release in stretches with stable flow. All of this forms a chain of actions that, coordinated by the Environment Department, prevent mortality and maintain the ecological functionality of the river until the flows are recovered.