Key risk factors, farming practices and economic losses associated with tilapia mortality in Egypt

Abstract

Egypt is the topmost aquaculture producer in Africa and the third largest tilapia producer globally. Nile tilapia in particular is the cornerstone of fish farming in Egypt. Recently, fish farms have experienced unusual tilapia mortality during summer season, threatening further growth of the sector. In order to understand risk factors, a questionnaire based cross-sectional study was conducted using tilapia epidemiology and health economics online survey tools. We surveyed 113 tilapia farms in four of the largest tilapia producer governorates (Kafr El Sheikh, Beheira, Sharqia, Faiyum) and one governorate with less farming activity (Minya). Farming practices, biosecurity measures and estimated losses were also assessed. Results indicate that a combination of risk factors contributed to the observed mortality events. We observed significant correlation between water source (surface and irrigation canals) and both occurrence and level of unusual mortality events (p < .001). Similarly, higher average water temperature, salinity, and polyculture of tilapia with wild sourced mullet favored the occurrence of unusual mortality (p < .001). Unusual mortality level was higher with low inclusion of tilapia in polyculture settings compared to other species (p = .014). Average fish weight at mortality peaks also contributed to mortality level (p = .029). Farming practices that affected mortality incidences included sharing of equipment between farms (p < .001). The overall losses from unusual mortality were estimated at about 11,304,400 EGP (around 720,000 USD). Results of this study indicate further studies are needed to understand better the interactions between necessary pathogens and component (risk factors) causes for tilapia mortalities in Egypt.