Line of action:

Status:

Execution date:

General objective:

Reduce the transfer of parasites from wild fish populations from fish reared in open ocean nurseries.

Specific objectives:

1. Know the species of wild fish associated with aquaculture farms.

2. To know the parasites shared by wild species associated with aquaculture farms and the species raised in them.

3. To study parasitic interactions and potential hazards to wild faura due to the transmission of parasites from animals reared in nurseries in the open sea.

4. Develop recommendations to minimize the impact of aquaculture farms on wildlife.

5. Disseminate the results of the project.

The beneficiary entity, CEU Cardenal Herrera University, and its partners (ADS ACCAN, ADS ACUIVAL), have carried out the following activities:

• Photo trapping: a system was designed to capture images of synanthropic species and carry out an evaluation of these populations. Cameras were installed at different depths (2, 8 and 15 m) that took images sequentially every 20 s. In total, more than 31,000 images are available that have been studied to identify the species present in the vicinity of aquaculture farms. The presence of sparids (bogas, pomfrets, alachas and different types of breams) stands out, as well as predators such as dolphins, barracudas and yellowtails.
• Analysis of aquaculture and synanthropic species: a total of 829 fish have been sampled throughout the project, 451 from aquaculture farms – sea bream (Sparus aurata), sea bass (Dicentrarchus labrax) and sea bass (Argyrosomus regius) – and 378 individuals of synanthropic species caught on farms in the Valencian Community and the Canary Islands participating. Among these are bogas, sea bass, mountain bass, different species of bream, horse mackerel, pomfret and mullet. Samples were taken from all the individuals of the main organs susceptible to being parasitized, such as gills and intestine, among others. In addition, the presence of parasites was assessed and they were identified. With the results obtained, recommendations were developed for each of the farms, with the aim of implementing preventive measures to reduce the transmission of parasites between farmed species and aquaculture species.
• Study of the population of the pen shell (Pinna nobilis): a study was carried out on the populations of pen shell associated with aquaculture farms in the Valencian Community. In most of the farms, there is evidence of the presence of mother-of-pearl juveniles, fixed in the floating structures. However, it cannot be assured that these references are actually from Pinna nobilis, as it could be confused with other species such as Pinna rudis. A search was conducted in the floating structures near the surface of the water. However, no individuals of Pinna nobilis were detected.

These are the conclusions of the actions developed around the eight participating aquaculture facilities (four in the Valencian Community and four in the Canary Islands):

• Population study of the fauna around the cages:

1. Among the most significant species that live around aquaculture cages in farms in the Valencian Community are: sparids, moorids and predators such as tuna or rays.
2. Among the most significant species around aquaculture cages on farms in the Canary Islands are: sparids such as bogas, pomfrets (Trachinotus ovatus) and scombridads, such as alachas (Sardinella aurita). Among the predators, the amberjack, manta rays and dolphins stand out.
3. The staff of the four farms in the Valencian Community reported the presence of juvenile pen shell (Pinna nobilis) individuals fixed in their structures, however, they were not observed in any of them.

• Parasitological study of intracage and extracage species:

1. A total of 829 fish were caught at the eight participating farms, from which 19 different species were identified. Intracage or farmed species had a higher percentage of parasitization compared to wild species; however, in wild species a greater variety of parasites was observed (per specimen and population).
2. The identified parasitic species are grouped within the class Monogenea, crustaceans of the order Isopodaand arthropods of the subclass Copepoda. Monogenids stand out as the most observed parasitic group, both in wild and farmed species in both autonomous communities, with Diplectanum being the most prevalent parasite.

Finally, it is worth highlighting the preparation of a document of recommendations to minimize the risk of spread of pathogens among wild and farmed species. In addition, training workshops were organized for the staff of aquaculture facilities in order to explain the actions developed, results and recommended measures to be applied to reduce the risk of parasite transmission between species inside and outside the cage, in addition to the celebration of two events, one in Valencia and the other in Las Palmas, and the production of a video within the Science with Conscience series of the UCH-CEU.

In conclusion, the development of new scientific knowledge on parasitic transmission between species reared in aquaculture farms in the open sea and wild fish species living around them, is recognized as a necessary path to follow. The objective is none other than to preserve and protect, from a health and welfare perspective, both farmed and wild species, with the consequent positive effect on the conservation of marine biodiversity and on the proper management of activities in the aquaculture sector.