engleski

Prevalence of the cymothoid isopod Ceratothoa oestroides (Risso, 1926) in cultured sea bass (Dicentrarchus labrax, L.)

In Croatia sea bass is cultured in floating cages. In these conditions direct contact between cultured and wild fish, drawn by easy to get food, can not be avoided. This lead to frequent parasitical diseases. Ceratothoa oestroides is a cymothoid isopod parasitic to the buccal cavity of sea bass. The parasite causes losses in the production of farmed sea bass due to the increased mortality rate in fingerlings and the lower market value achieved for the product. A three year health status monitoring of cultured sea bass was carried out in this study. The monitoring result confirmed that the prevalence of Ceratothoa oestroides was significantly higher in the samples taken in the first year than in the following year of the research. The parasitised fish had significantly lower weight and length than healthy fish of the same age. Condition factor is not a very sensitive measure of pathology effects caused by cymothoid parasites. Parasite length and weight are in positive correlation with the lenght and weight of the parasitised fish. The reproductive activity of Ceratothoa oestroides does not vary seasonelly, no positive influence of the sea temperature or moon phases on the reproductive activity of Ceratothoa oestroides was observed. The female fecundity of the female increases with the duration of daylight.

Ceratothoa; sea bass

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