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Project Location: Três Marias Dam, Brazil
Client: UFLA & Cemig
HTI Biologists: Sam Johnston & Colleen Sullivan

Hydrophone Deployment Plan for Acoustic Telemetry Study  


The Três Marias Dam is a 2,700 m (8,900 ft) long and 75 m (246 ft) high embankment with a reservoir surface area of 1,040 km2 (400 sq mi) and a capacity of 21 km3 (5.0 cu mi). It plays a central role in power production and flood control for the region. To improve fisheries management downstream, scientists needed to define the fine-scale fish behavior in one of the loudest areas at a hydroelectric dam: the tailrace.

The unprecedented project takes place in Brazil's São Francisco River. The Federal University of Lavras' Dept. of Biology (UFLA), the Companhia Energética de Minas Gerais (Cemig), one of Brazil's largest power generators and distributors, and HTI worked together to track fish using the Model 291 Acoustic Telemetry System.

Around 200 curimba (Prochilodus costatus) and mandi (Pimelodus maculatus) were tagged with Model 795 Acoustic Tags. The tag weights and tag life were ideal for study requirements, in addition to permitting numerous tags to be present at one time without any tag data collisions or false positives. To cover the tailrace area, 11 hydrophones were installed in fixed locations. Each hydrophone was attached to a simple fabricated housing on a metal rod and submersed in a specific location. Tags were simultaneously detected and identified in real-time at a distance up to 100 m (328 ft) in the turbulent, white water of the dam’s tailrace. Each fish was tracked in two dimensions (2D).


By the end of the project the group will have data with correlated animations (visualizations via HTI’s AcousticTag data acquisition and analysis software) that will accurately illustrate how fish approach the plant. This vital information will significantly help managers improve the regulation of fish that accumulate near generating units during various stages of operation. This work will also produce a PhD thesis for researcher and student, Fabio Suzuki.

Read about the Peixe Vivo Program, a Cemig conservation initiative or email Sam or Colleen to find out about methods used at

Plan view of hydrophone installation.  
Deploying and testing acoustic telemetry system.  
 Deploying in the dam's tailrace.  
 Detecting tag in real-time.  
 Our team of fisheries scientists.  
This technology will help us to elucidate the behavior of fish below Tres Marias Dam increasing our knowledge to develop management actions for conservation...our team (Fabio Suzuki, Paulo Pompeu and Carlos Alves) is very proud of that.  
Dr. Luiz Gustavo Martins da Silva, Biologist Federal University of Lavras' Dept. of Biology  
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