The piraiba, an unbeknownst giant

The piraiba, an unbeknownst giant
November 9, 2020 Claudia Acosta

By Fish Collaboration Group – Citizen Science for the Amazon Network

The piraiba (Brachyplatystoma filamentosum) is a giant fish that can grow up to 3,6 meters and weigh up to 200 kg – the biggest fish in the Amazon. There are several theories about its behaviour. For instance, it is said that the piraibas like to turn over fishermen’s canoes. Stradelli, in his 1929 Nheengatu-Portuguese Vocabulary (published in Portuguese, page 608), states the fish’s name would mean: Pira=Fish; ayua=Bad, but this “bad” could be rather related to the unappreciated taste of its meat. Other stories call piraiba the mother of all fish.

The main fishing spot for piraibas is in the main channel of the Amazon River, but these catfish have a wide distribution in the Amazon Basin, from the coastal rivers in Brazil to the foothills of the Andes in Bolivia and Peru. A new specie called black piraiba (Brachyplatystoma capapretum) was described in 2005, while a recent study (available in Portuguese) showed how some genetic variations are strongly related to river types in the Amazon, and highlighted the urgent need for management measures aiming to conserve this flagship species.

What does the Ictio data show us so far?

Ictio App is a powerful tool to collect fishing data of the main migratory fish species in the Amazon. Ictio was launched in 2018 and until September 2020 has 240 users who have registered more than 7 thousand fish observations. These observations come from a total of 52 level 4 sub-basins in the Amazon Basin (Venticinque et al. 2016). As of June 2020, piraibas were recorded in 13 of these 52 sub-basins. The first piraiba register occured in March 2018, in Tefé (Amazonas, Brazil). The largest piraiba recorded so far in Ictio (May 2019) weighed 138 kilos. In 2020 we have only two piraiba records, both from the Amazon/Solimões basin (between the rivers Jandiatuba and Juruá, Brazil).

Information about piraibas comes by and large from the Amazon main stem and the Tapajós Basin, however, no Ictio user has yet recorded observations of these fish upstream of the Jirau and Santo Antônio (Brazil) hydroelectric plants on the River Madeira. Piraibas might be affected by the loss of connectivity in the River Madeira related to hydroelectric plants built in the area, which imposed a barrier to the migration of various fish, such as the dorado (Brachyplatystoma rousseauxii) and other migratory species.

Information about piraibas comes by and large from the Amazon main stem and the Tapajós Basin, however, no Ictio user has yet recorded observations of these fish upstream of the Jirau and Santo Antônio (Brazil) hydroelectric plants on the River Madeira. Piraibas might be affected by the loss of connectivity in the River Madeira related to hydroelectric plants built in the area, which imposed a barrier to the migration of various fish, such as the dorado (Brachyplatystoma rousseauxii) and other migratory species.

Although the Ictio app was only launched in 2018 on an experimental basis, the lack of piraiba records is striking. This highlights the importance of generating more information about this important fish. Ictio will be a key tool for data collection at the entire Amazon Basin level. Meant for users to register their catch, the app is free to download. A better understanding of distribution and abundance patterns of key migratory species such as dorado and piraiba, as well as how ecosystemic changes impact these fish, will be possible using shared data.

Impact on fishermen

Testimony of João Evangelista da Silva, fisherman from the community Teotônio, in Rondônia, Brazil.