Influence of ectoparasitism on the welfare of Micropogonias furnieri

Abstract

The Whitemouth croaker, Micropogonias furnieri, is commonly found in the estuary of Patos Lagoon, RS, Brazil.Like other cultivated Sciaenidae, M. furnieri has potential for aquaculture. However, several difficult-tocontrol ectoparasites have been shown to be serious fish culture pests. In this study, the parasite influence on M. furnieri is evaluated through examination of the relationship between abundance and host parasitism indexes, relative condition factor (Kn), and the hepatosomatic (RHS) and gonadosomatic relations (RGS). These indexes are qualitative fish welfare indicators. A total of 181 M. furnieri specimens were collected from the pre-limnic and estuarine sites of the Patos Lagoon. The parasites found were Gauchergasilus euripedesi (Copepoda), Myzobdella uruguayensis (Hirudinea), Neomacrovavitrema argentinensis and Neopterinotrematoides avaginata (both Monogenoidea). The relationship between the parasite abundance and the host indexes was verified, but no significant correlation was determined. This result suggests that the found parasite levels are tolerable. On the other hand, sample area differences affected the occurrence and intensity of parasitism, which suggests that the parasites have a preference for different salinities. This result suggests that different saline conditions could determine when the estuary would be optimal for M. furnieri aquaculture.