Crisis in the Paraná River: 10 years of water scarcity and overfishing threaten the shad, challenging the ecosystem.

Biological studies in the Paraná River reveal an “impoverishment” in the diversity of fish and a drastic decrease in the quantity and size of the sábalo.

This species is essential for the ecosystem, as it constitutes the majority of the biomass and fishing exports of Argentina.

The last successful reproduction occurred between 2015 and 2016. Experts are calling for urgent protection measures to prevent a “collapse“.

The combination of sustained low water levels in the Paraná River and the wetlands, along with commercial fishing for export, is severely affecting the sábalo, a key species for the entire biodiversity of the river.

Recent research shows a significant reduction in the number of specimens and their size. Researchers describe this situation as “unsustainable” and demand regulations before reaching a “point of no return“.

Historical low water levels and their consequences in the Paraná River

Migratory species such as sábalo, dorado, and surubí depend on floods in the Delta to reproduce.

The ideal conditions for their eggs and larvae include warm temperatures, peaks of up to five meters of floods lasting at least two months. These floods allow water to overflow and connect isolated areas of the basin.

The last successful flood occurred in the spring of 2015 and the summer of 2016. Since the low water levels that began in 2019 (with a brief exception at the end of 2022), the minimum conditions necessary for reproduction have not been met. Technical reports reflect this reality.

According to the Biological and Fisheries Evaluation of Species of Interest (Ebipes), an entity that includes the Nation, provinces, and CONICET, the last assessment was carried out with extremely low water levels, the lowest in 20 years of the project’s history.

By the end of 2024, captures showed a “very reduced” variety of species compared to the previous year (30% less than in 2023). The total quantity of fish caught decreased by 60%, and the weight decreased by up to 70%. Although the 2025 report has not been published yet, it has been confirmed that the trend continues.

The researcher from CONICET, Ana Pía Rabuffetti, explained that the persistent low water levels have generated a “decade or dry period” that severely compromises fish populations, especially migratory ones that depend on the river’s fluctuation.

This diagnosis is shared by fishermen and researchers. The wetland is “receding“, meaning fewer fishing spots, fewer specimens, and fewer workers in the Paraná River. An anthropologist and a biologist have dedicated their efforts to “mapping the absence” of specimens in the Paraná River in recent years.

Two studies published in international journals by the Hydroecology Laboratory of the National Institute of Limnology (Inali), where Rabuffetti works, document with graphics the loss of surface water connectivity and the prolonged hydrological drought.

Some experts speak of a crisis that could lead to a “biological collapse” if no action is taken. Rabuffetti, while avoiding being so definitive, warned about the seriousness of the situation and called for “precautionary measures” with fishing policies that consider climate changes to ensure conservation.

The latest studies and their alarming results

The biological report from Ebipes in October 2024, focusing on the floodplain valley, details “very low” water levels and “very reduced” results in terms of variety, quantity, size, and weight of the studied fish.

In addition to the low water levels that prevent reproduction, the report mentions that “climatic events of very low temperatures” during the winter of 2024 could have led to high fish mortality in the lower basin. This is compounded by predators such as dorados, surubíes, and fish-eating birds, taking advantage of the reduced aquatic space.

One data point that alarmed specialists was the difference between the 2023 and 2024 studies. While in 2023 Ebipes captured 7,000 juvenile specimens in a sample, in the latest record only 160 were found. Although the samples have different sizes, the contrast is a clear sign of a crisis.

Fishing pressure and exports

The lack of nutrition has deteriorated the body condition of the sábalos, which could be related to the disconnection of the lagoons. At times, commercial fishing uses nets in the mouths of these watercourses and extracts all the “resource,” including fish below the allowed size.

Commercial fishing and fish processing plants have intensified pressure on the ecosystem. Of the 30,000 tons exported by Argentina at the beginning of the century, it decreased to 18,000 in 2019, 6,300 in 2022, and 3,200 in 2024, according to data from Senasa.

The Ebipes study warns that “the sábalo fisheries in the region will have to continue to be supported on the now scarce cohorts,” that is, on the older and larger fish. If conditions do not improve, this pressure on the younger cohorts could affect their development, generating a crisis for future generations.

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