Risk assessment of parasitic helminths on cultured Nile tilapia (Oreochromis niloticus, L.)
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Date
2012
Journal Title
Journal ISSN
Volume Title
Publisher
Aquaculture
Abstract
Disease outbreaks constrain aquaculture development. Knowledge on the potential risks of pathogens to
farmed fish can help in designing management strategies for increased aquaculture productivity and sustainability.
This study compares the helminth infections in reservoirs and therein operated cages as well as earthen fish
ponds and the feeding stream in order to assess the significance of life cycle style and water sources in parasite
transmission. In addition field experiments were setup to determine loading time and transmission rate. From
650 fish examined, 8 helminth species were recorded (3 from caged- and all 8 from pond-raised fish). The parasite
community was dominated by trophically-transmitted species in both culture systems indicating the importance
of trophic pathway in helminth transmission. The occurrence of trophically-transmitted helminths in
caged-fish was positively related to their prevalence in reservoir-dwelling hosts indicating the importance of
water supply in spread of helminths. The prevalence in pond-raised fish was higher than in stream-dwelling
ones suggesting the presence of local sources of infective stages within ponds. Risk assessment revealed that
monogeneans are high-risk parasites while heteroxenous helminths pose low to negligible threats to farmed
fish. Although, cages appeared safer to heteroxenous parasites than ponds, their location in the water body,
especially the distance from shores and depth is critical.
Description
Keywords
Aquaculture, Aquatic ecology, Cage-culturing, Fish ponds, Freshwater fisheries, Risk analysis
Citation
Akoll, P., Konecny, R., Mwanja, W. W., & Schiemer, F. (2012). Risk assessment of parasitic helminths on cultured Nile tilapia (Oreochromis niloticus, L.). Aquaculture, 356, 123-127. doi:10.1016/j.aquaculture.2012.05.027