C.1 – Captive breeding population and reinforcements of naiads (Unio elongatulus)

The captive breeding of naiads will be carried out in the laboratory of breeding naiads in Consorci de l’Estany, which was implemented in the framework of a previous LIFE Project (LIFE08 NAT/E/000078). The laboratory is located in Porqueres, near the lake. An expansion planning of its current facilities will be done, with the aim to have different production lines for each river basin and juvenile production to ensure an increase in overall productivity.

The breeding of naiads extends from April to late July. Between 120 and 200 parental individuals are captured each year. After spending a month in captivity they will be returned to the same stretch of river where they have been extracted. The production process of naiads includes the following phases: 1) obtaining glochids of naiads adult, 2) intensive fish infestations with local host glochids 3) isolation of infected fish to get youth naiads recent detached, 4) sowing youth growing in containers. Glochid surpluses that are not used for infestations in the laboratory, are used to infest wild fish directly to the river environment.

The reinforcements population will be carried out in appropriate sectors of the rivers Ter, Fluvià, Llémena, Brugent, Ser and other water bodies in the area covered by the project. Because there may be some genetic differentiation between basins, the units used must come from production lines based parent of the same watershed.

Every year there will be a production run of spring in summer. The juveniles obtained are not released until after at least one year.

EXPECTED RESULTS

In the river sections where cores naiads are still present, it’s expected to get an increase in density and especially the relative rejuvenation of the population, to prevent its disappearance. In sectors where the species has disappeared, this will create a total of 14 to 20 new populations.

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