Ultrasonic telemetry of arapaima in the Lower Amazon, Brazil

Background/Question/Methods

Many floodplain fishes migrate laterally during high water periods, moving into habitats adjacent to permanent water bodies. That includes the giant South American arapaima, which are air-breathing food fishes that can attain 3 m in length and 200 kg. These highly valued but endangered fishes support local and regional economies. Various aspects of arapaima ecology, however, have not been fully studied, including elements important for management. For example, we do not know if arapaima return to the same water bodies each dry season, or alternatively, do they disperse to other lakes.  In this study, we use acoustic telemetry to investigate migration of arapaima in floodplain lakes of the lower Amazon. Thirty fish between 90 cm and 215 cm were tagged in the low water season.  Monitoring was conducted by strategically placing stationary receivers and conducting surveys using a mobile hydrophone. 

Results/Conclusions

Before water rose, some arapaima stayed on one end of the lake while others were found to move readily within isolated lakes.  As water levels rose, monitors tracked arapaima as they migrated into nearby floodplains and flooded forests.  This work ensures that conservation and management strategies for arapaima are based on their movements and habitat use.