engleski

WHERE REARED TUNA LOOS THEIR PARASITES?

Remarkable diversity of Atlantic bluefin tuna (Thunnus thynnus) parasite communities has been related to its long distance migrations, highly predatory behavior and longevity, facilitating infections with mainly helminthic parasitic groups. Regular monitoring of parasite communities since 2003 in reared tuna during rearing cycle, has indicated that there is a significant decreasing trend in number of individual parasites and species towards the end of the cycle. Such event is rarely observed in other intensive productions, since aquaculture represents a suitable environment for the emergence, establishment and transmission of pathogens. Results suggest that specificities of parasite assemblages and their dynamics in tuna before and after farming have no similar precedents in aquaculture and that parasitic pauperization in tuna reared over couple of months repeats in each rearing cycle. Nonetheless parasitic dissipation over time, same species remain core parasites (D. katsuwonicola and K. intestinalis). Juvenile tuna transferred in cages exhibit significantly higher total parasite richness and mean parasites abundance, as well as the heteroxenous species richness and abundance, in comparison to pre-harvest fish, where for example monoxenous species vanish complitely. Eleven parasite species out of 26 taxa were selected as important in discriminating between transferred and reared fish parasites assemblages, whilst significantly the most abundant in transferred tuna are D. katsuwonicola, P. alalongae, K. intestinalis, K. internogastricus, D. abdominalis and Anisakis sp.

bluefin tuna; Adriatic; parasites

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