Parasitosi per coccidis en mascles d’anxova

Abstract

The European anchovy (Engraulis encrasicolus) is one of the pelagic species with biggest commercial interest and at the same time, one of the most threatened by overfishing in the Mediterranean Sea. It is a species with external fecundation which releases thousands of eggs in each lay and presents a high mortality rate, so only a low percentage of eggs finally hatch. However, the anchovy lives in an environment with constant fluctuations and its reproductive strategy allows it to handle high population drops. Notwithstanding, overexploitation threshold in which the species is subdued nowadays staggers its individuals resilience and is able to affect Mediterranean populations subsistence in the long term. In this context of threat in which anchovy is in the Mediterranean, it is important to also consider the possible impact of coccidian parasitism in males’ gonads. Hosts’ infection can worsen the health status of the Mediterranean stocks. Infected males can suffer parasitism consequences in their testicular development, the creation and the release of sperm. Moreover and besides the effects that coccidia can directly have on the species reproduction, this project also studies if these parasites compromise hosts health. In the first place, it studies which kind of coccidia parasite male anchovy’s gonads. After that, this project analyses the parasites prevalence on the basis of different variables such as the months of the year, the testicular development stages or the amount of mesenteric fat of the individuals. Finally it studies the relationship between the presence or the absence of parasites and other factors like gonadosomatic index or the physiological condition factor, through which it is possible to infer parasitism effects on the reproductive potential and the health condition of the infected individuals. On the whole, the study analyses coccidian parasitism effects on a population which is also threatened by the fishing pressure at which it is subdued