In November of 2014, MSc student Taylor Ward and PhD student Vivian Nguyen from Dr. Steven Cooke’s lab at Carleton University traveled to Amazonian Brazil to study the fisheries of this region with local researchers, including Dr. Lisiane Hahn (Neotropical Consultants), Gustavo Hallwass (PhD candidate, Neotropical Consultants), and Maria Clara Bezerra (PhD student, Federal University of Rio Grande do Norte). The focus of the trip was to study fish ecology and fisheries dynamics in the Madeira River (The Amazon’s largest and muddiest tributary).
An important part of the diverse fish community of these rivers are large-bodied catfish species, including dourada (Brachyplatystoma rouseauxii) and relatives, that inhabit a vast stretch of the river, spanning from the Andean foothills where they spawn, to the Amazon delta where they rear as juveniles. Given this migratory behaviour, the impacts of potential barriers are of great interest not only for conservation practitioners, but also for local economies and cultures that are rooted in the Madeira’s fishery resources. With the development of two recently constructed “mega-dams”: the Santo Antonio Hydro Electric Dam near Porto Velho, and the Jirau Dam, located upstream of Santo Antonio, there is concern for the conservation of local fish species, which support important subsistence and recreational fisheries, as well as livelihoods of many rural communities.
Taylor and Vivian travelled to the Madeira River to begin their research, focusing on the behavioural ecology of catfishes in the region, and the dynamics of local fisheries using Local Ecological Knowledge (LEK). By integrating LEK with modern techniques for studying wild animal movement (radio and acoustic telemetry, behavioural energetics, and otolith microchemistry) the research team aims to create a holistic picture of not only the changing ecological reality of this species but the implications and interpretations of this change in the local social and cultural realm.
Taylor’s work focuses on the biology of these charismatic, large-bodied catfishes, examining life history characteristics, spatial ecology, and energetics. Ultimately, his objective is to provide some key information for improving the effectiveness of the fishway at the Santo Antonio Dam to improve habitat connectivity and reproductive success.As a preliminary exploration of their behaviour, wild-caught dourada were brought to a newly constructed aquaculture facility at the Santo Antonio Dam, and tagged with tri-axial accelerometer biologgers to continuously measure fine scale behaviours (i.e. swimming, coasting, resting) for a one-week period.
This research will provide insight into diel patterns of behaviour and activity, which is an important first step for understanding how dourada behaviour influences their probability of passage success in relation to hydropower operations in the region. In the future this information will be considered alongside radio telemetry to develop a picture of where and when these animals move, and hopefully the environmental constraints on their migratory behaviour.
The sheer size and biodiversity of the Amazon River and its tributaries make it incredibly challenging to quantify changes in fish populations, community composition, and resulting fisheries from anthropogenic stressors. As such, Vivian’s research aimed to characterize how local fisheries are changing by interviewing local subsistence fishing families to gain insight from LEK. The research team travelled to small fishing villages covering a span of nearly 600 km up- and down-river of the dam to interview people with the most intimate knowledge of the local fish communities. They travelled to a different village every day for two weeks, where fishers invited them into their homes, showed them all kinds of fishing gear (gillnet, harpoons, spears, etc.), and the different species that they catch. This was a great insight into just how interwoven the local culture is with the river, from seasonal changes in target species that coincide with flooding regimes, to the effects of a recent large flood in communities both up- and down-stream of the dam. Moving forward, information from these interviews will provide a basis for testing hypotheses related to the life history of these catfishes.
Taylor and Vivian were privileged to travel deep into the heart of the Brazilian Amazon to interact with welcoming people, remarkable fish and their habitats. They met hospitable people that shared their life experiences and some of their local foods! They were amazed by the diversity in flora and fauna of the Amazon. Being able to just pick up a mango on the ground and eat it, or watching people gather Brazil nuts from their backyard was an experience in itself. They would like to thank the principal investigators who made this experience possible: Dr. Michael Power, Dr. Priscila Lopes, Dr. Lisiane Hahn, and Dr. Steven Cooke, with financial support from an International Development Research Centre grant. Stay tuned for updates as the research progresses!