This project is based on the study and optimization of several relevant aspects in the culture of the three fish key species in Spanish aquaculture: turbot (Scophthalmus maximus), sea bream (Sparus aurata) and sea bass (Dicentrarchus labrax), from a genomic and biotechnological perspective. Since Spanish aquaculture involves several different animal species with different geographical dominance in the North and South of the Peninsula, a joint effort is required to address industrial needs.
The three species studied in this project, share several aspects with a high incidence in culture profitability such as those caused by infectious diseases. Mortalities due to pathogenic agents are normally high. Although there are vaccines that help in the prevention of numerous diseases, there is a lack of knowledge concerning the basic aspects of the fish immune system that is fundamental for the improvement of existing vaccines and for the development of new vaccination strategies.
Among the pathogens that affect turbot culture, scuticociliatida protozoa Philasterides dicentrarchi is responsible for important losses. In the gilthead sea bream and sea bass, pasteurelosis, caused by Photobacterium damselae subsp. piscicida, is one of the most common diseases since it can produce important losses and may threaten the survival of the industry. Finally, some viruses such as the Viral Hemorrhagic Septicemia (VHS) or nodavirus, are also direct or indirect causes of decreased production in these species.
Another common aspect that affects the three fish species considered here is the need to develop strategies to optimize and increase their productivity. In particular, growth in terms of muscle development, larval development, nutrition and feeding are prioritary aspects in the present proposal. In the case of turbot, this is particularly relevant not only because of its clear economical importance but also because there are significant knowledge gaps concerning the biology of this species.
One of main problems of gilthead sea bream culture is the presence of morphological abnormalities (lordosis, operculum lack, jaw anomalies) that in some cases can affect more than 50% of the individuals of a particular lot. Another important aspect related to culture improvement of this species is, as in turbot, increasing growth rates.
Finally, reproduction is a central issues in fish production particularly in sea bass and turbot. Sea bass has become an established model for research on the reproductive physiology of marine species of commercial interest that may help to solve problems in other related species. The control of sex differentiation and puberty are key aspects to enhance industrial competitiveness in sea bass culture. Although sea bass culture is well developed; there are other important problems in addition to those above such as the lack of genetic studies (relationship type variant-productive character).
As it is now possible to breed turbot in captivity, although there exist some methodological limitations related to the control of its reproduction. At the laboratory level, it is possible to produce both triploid and gynogenetic fish. In general, turbot does not exhibit problems associated to male precocity as this occurs late in the production process. Nevertheless, among the cultivated species in Spain, turbot exhibits the highest differential growth among sexes. Females reach a marketable size two-three months earlier than males. Consequently, the production of female dominant populations is an important industrial aim, as this would decrease size dispersion and maximize the production capacity thereby decreasing production costs.