Impact of weather on off-flavour episodes at a Louisiana commercial catfish farm

The catfish aquaculture industry is hampered by off-flavour events that affect timely fish sales. In this study, weather data were correlated with geosmin and 2-methylisoborneol (2-MIB) levels in 21 commercial pond's water samples. Samples were collected weekly for 44 weeks. The off-flavour compounds, geosmin and 2-MIB, were quantified using gas chromatography–mass spectrometry. Weather data were collected near the catfish farm and included maximum and minimum air temperature, rainfall, average wind velocity, maximum and minimum humidity, and maximum and minimum soil temperature. Geosmin was weakly and positively correlated with air and soil temperatures, and weakly and negatively correlated with wind velocity. 2-MIB was strongly and positively correlated with air and soil temperatures, moderately and negatively correlated with wind velocity, and weakly and positively correlated with maximum humidity. There were no bivariate relationships between rainfall, minimum humidity or pond size, and levels of either off-flavour compound. Using logistic regression, the best predictors for off-flavour status based on geosmin levels included minimum soil temperature, rainfall and minimum humidity. The best predictors for off-flavour status based on 2-MIB levels included minimum soil temperature and average wind velocity. Soil temperature and rainfall were risk factors for off-flavour, while humidity and wind velocity were protective factors.