Line of action:

Status:

Execution date:

The common pen shell (Pinna nobilis) is a bivalve mollusc endemic to the Mediterranean, currently listed as “endangered” according to the Spanish Catalogue of Threatened Species. This situation is due to parasitosis caused by a species of protozoan, Haplosporidium pinnae, which causes mortalities close to 100% of the population.

The studies of gonadal maturation and reproduction in captivity proposed in this project, according to the entity, are essential to be able to save the species. Thus, once the reproductive cycle of the nacre is closed, it would be possible to apply the same techniques on the few resistant individuals, to produce seed with greater tolerance to the disease. In addition, the production of seed from non-resistant individuals would allow them to be used to locate disease-free areas and repopulate these areas with juveniles, as well as to better investigate the disease and understand the reasons for its absence in the Ebro Delta and the Mar Menor, information that could be key to the future of the prickly pear.

This project is framed in the context of biodiversity protection and conservation of the common pen shell, an endangered species, through the development of aquaculture techniques for its potential reintroduction. The achievement of these objectives would allow the rehabilitation of the species, not only at the level of Spanish territorial waters, but also of other Mediterranean countries that are being affected by the expansion of the protozoan disease caused by Haplosporidium pinnae.

The specific objectives of the initiative have been the following:

• Maturation of Pinna nobilis broodstock under housing conditions at the facilities of the Institute for Research in Environment and Marine Science of the Catholic University of Valencia (IMEDMAR-UCV).
• To achieve the production of viable seed of this species from the remaining broodstock in the bays of the Ebro Delta.

• Optimization of the maturation of the gonads through the application of water temperature treatments and progressive increases in feeding doses, achieving the release of gametes in 17 females and 19 males in captivity.
• Thermal shocks to obtain nacre gametes, combined with the administration of serotonin to force their release, to adults matured in situ.
• Optimisation of rearing conditions, including the production and selection of phytoplankton diets, density of embryos, larvae and postlarvae, physicochemical conditions, type and dose of prophylactic and therapeutic products, factors inducing metamorphosis and settlement, and post-larval development to the production of juveniles or seeds suitable for culture at sea.
• Dissemination and communication of the project.

The entity highlights that the project has meant a significant advance in the conservation of the pen shell (Pinna nobilis). 43 specimens have been received, mostly from the Ebro Delta, although 4 have originated from the Mar Menor. With these specimens, various experiments of energetic physiology and conditioning of the gonads have been carried out, in order to optimize the maintenance and feeding of the species, achieving the maturation of 19 males and 17 females in captivity and the possibility of obtaining gametes outside the reproductive period.

In addition, 6 clutches of a range between 500,000 and 70,800,000 oocytes (female germ cells that are in the process of becoming a mature egg) have been obtained from field specimens collected in the Bahía dels Alfacs. From the gametes obtained from both wild individuals and those matured in captivity, larval cultures have been carried out in which larvae in trochophore and veligger phases have been obtained.

Although no artificially bred juvenile specimens have been obtained, the specific requirements of common pen shell have been identified, which are very useful for the future achievement of the pen shell seed and its continuity as a species.