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The Associació la Sorellona was a beneficiary in the 2018 Biodiversity Foundation call for grants with the project "SOS Margaritona. Strategic actions for the conservation of Margatifera auricularia: exhaustive prospection and identification of suitable river sections, and improvement of stocks of its host, the friar (Salaria fluviatilis)". The aim of the initiative is the long-term conservation of the margaritone (Margaritifera auricularia), by identifying suitable river stretches to establish new nuclei of specimens in the Ebro river basin, and improving the available stocks of its host fish, the friar (Salaria fluviatilis).

The auriculated naiad or daisy,Margaritifera auricularia is one of the rarest and currently the most endangered Spanish freshwater molluscs. The daisy is included in the category "In danger of extinction" within the Spanish Catalogue of Threatened Species. Its populations are only found on the Ebro River.

This is the first time that the Associació la Sorellona has been a beneficiary of the Biodiversity Foundation's call for grants.

The general objective of the project is the long-term conservation of the margaritone (Margaritifera auricularia), by identifying suitable river stretches to establish new nuclei of specimens in the Ebro basin and improving the populations of its host fish, the friar (Salaria fluviatilis).

The specific objectives are:

• Location of river stretches with hydromorphological and biotic characteristics suitable for the reception of specimens of Margaritifera auricularia, whether they are transferred adults or juvenile specimens obtained in captivity.
• Precise evaluation and updating of the conservation status of the populations of friarfish in the middle section of the Ebro river, the only native fish host of this naiad that survives in the basin.
• Creation of a network of ponds or other bodies of water in custody, with the capacity to house new stable nuclei of friar.
• Establishment of new populations of friar in these bodies of water, which constitute a reserve against their decline, and a source of specimens for the assisted reproduction of the daisy.
• To test low-cost specific measures to promote the reproduction of Margaritifera auricularia in its few currently known river nuclei.

• Drafting of a standardised protocol for assessing the suitability of the river habitat for the daisy. The objective of this action is the creation of a protocol that allows the assessment of the habitat of Margaritifera auricularia, based on a previous proposal, improved through a bibliographic review on the ecology and biology of the species, and with the consensus of experts and technicians involved in the conservation of this naiad.
• Precise diagnosis of pre-selected river sections to assess the suitability of the habitat to host Margaritifera auricularia. Evaluative sampling of the river habitat in a selection of 200 stations.
• Evaluation and update of the conservation status of Salaria fluviatilis, focusing on pre-selected river sections. Specific sampling to determine the current situation of friarfish in the 200 pre-selected stations.
• Creation of the network of ponds or other bodies of water in custody, with the capacity to house new stable nuclei of friar. Within the framework of this action, an agreement has been signed for a period of 4 years with the City Council of Zaragoza, extendable for 4 more years, for the establishment of 2 ponds in Zaragoza as recipients of friar reserve nuclei.
• Establishment and monitoring of new populations of friars in rafts with a signed agreement. Release of a founding stock of 117 specimens of friar on each raft.
• Experimental release of specimens of friarfish and simultaneous installation of temporary reefs for this species, with a view to the reproduction of the margaritona.
• Creation and maintenance of the project website.
• Environmental education and awareness actions aimed at schoolchildren, families, fishermen and the general population: educational workshops and dissemination of the initiative in the media, in addition to the installation of information panels in the custody ponds signed with the City Council of Zaragoza and which serve as reservoirs for friarfish.
• Transfer of technical-scientific results. The entity has collaborated closely with the University of Navarra, which may translate in the future into the publication of scientific articles in specialized journals.

• The actions carried out have contributed to achieving the long-term conservation objective of the margaritone (Margaritifera auricularia), by identifying suitable river sections to establish new nuclei of specimens in the Ebro basin and improving the available stocks of its host fish, the friar (Salaria fluviatilis).
• Significant work has been done to compile useful information on daisy. The preparation of a protocol for assessing the suitability of the river habitat of the Margaritifera auricularia in the Ebro river basin has been the point from which a habitat suitability index has been applied to diagnose the areas of the basin where the characteristics of the habitat would be most suitable for housing populations of this species.
• The conservation status of the friarfish (Salaria fluviatilis) has been evaluated.
• Work has been carried out to guard ponds to house population centers of friarfish, which serve as reservoirs for transfers to areas of the Ebro river basin.
• Actions aimed at raising awareness and better knowledge of the species.