Nutrition Spain , Palencia, Wednesday, May 08 of 2013, 10:48

Iberian inland fish swimming ability under study

In order to conduct these studies, the Grupo de Ecohidráulica Aplicada at the Universidad de Valladolid has build a swimming channel for fish only found in Europe

Cristina G. Pedraz/ DICYT The Grupo de Ecohidráulica Aplicada (GEA), an applied ecohydraulics team at the Universidad de Valladolid (Spain), linked to Itagra technology center, is working on a new research area focused on determining the swimming ability of Iberian inland fish such as trout, barbells and nase. The main goal is to understand which structures in rivers (such as dams) are actually barriers to their migration and to enhance the design of fish ladders and steps.

In order to conduct these experimental studies, the research team has built a swimming channel in the Douro River, in Vadocondes (Burgos, Spain), particularly at the Savasa hydroelectricity facilities. It is the first facility of its kind in Europe and the second worldwide, as DiCYT was told by professor Francisco Javier Sanz Ronda, talking about the process of these trials.

“We captured river fish specimens, marked them with electromagnetic sensors and released them in the channel. Then we studied their voluntary upstream swimming through the channel, which water speed was already known, until they get exhausted; on this basis, we determine the swimming ability of these specimens,” the researcher states, explaining that the channel was built with funding granted by the Junta de Castilla y León.

On one hand, these data “is allowing us to improve the design of fish steps (speed of water is a major limiting factor in these structures)”; on the other hand, they are useful to determine which structures may be barriers to fish migration. “For example, there are small dams containing stretched facing, in which the downstream part is barely sloped. If dams are not high enough, fish get away from the facing and depend on their strength to overcome it. With swimming speed data, we are able to know whether these structures are obstacles or not,” he states.

The GEA is using this information on the swimming ability to establish if gauging stations in all Spanish basins are actually obstacles. “In the Douro basin, about 80% of indigenous fish perform internal migration within the basin itself (a strategy to reproduce) and many gauging stations are a real problem for them”, he adds.

Brown Trout

The GEA is conducting studies with certain species performing migration such as brown trout, “an emblematic species in this community and in Spain, very important for sports and economic affairs”. The team is working with the American S.O. Conte Anadromous Fish Research Center (CAFRC) in Turner Falls (Massachusetts, USA), the first body in the world to develop studies on voluntary swimming speed. Spanish researchers have traveled there to understand their work and exchange experiences.

Since this collaboration began in 2008, the team has gotten interesting data on trout’s swimming speed, tiredness time (how long they can swim that fast) and maximum distance with different rates of flow.

Furthermore, they have independently analyzed barbell and nase swimming ability, “but data has not been published and remains unanalyzed”. Barbells and nase are indigenous species at the Douro basin and account for more than half of the entire fish biomass in Spanish rivers, so they are very important. Additionally, they are middle-distance migratory species.