Amazon home to over 2,700 species of fish, study finds

The Amazon river basin is home to over 2,700 species of freshwater fish, accounting for roughly 15% of all known fish species worldwide. Nearly two-thirds of these unique species are found exclusively within the Amazon region, according to a report compiled by The Nature Conservancy (TNC) and 50 experts representing 30 organizations. Titled "Forgotten Fishes of the Amazon," the fourth edition of the study emphasizes the importance of preserving the Amazon as one of the world's last major, intact river basins.

The report underscores the vital role fish play in maintaining the health of the Amazon forest and the well-being of local communities. Certain species, such as tambaqui, pacu, and matrinxã, help maintain forest ecosystems by dispersing seeds and consuming fruits as they move through flooded forest areas. Other fish species contribute to the nutrient and energy exchange between aquatic and terrestrial environments.

River connectivity is crucial for the survival of fish populations, as exemplified by the gilt-head bream, which undertakes the longest freshwater migration ever recorded, traveling over 11,000 kilometers throughout its lifetime. Disruption of these migration routes, due to factors like hydroelectric dams, can lead to significant declines in fish stocks and harm other species that depend on them, including river dolphins, giant otters, and birds.

However, the Amazon's biodiversity is under pressure from various threats, including hydroelectric dams, deforestation, pollution, overfishing, and climate change. These factors can collectively disrupt river connectivity, fragment habitats, alter natural flow regimes, and degrade water quality. Projections suggest that annual river discharge could decrease by more than 40% in some key regions, exacerbating the impacts of these threats.

The study also highlights the importance of indigenous knowledge in river conservation. Indigenous communities recognize fish as integral to their identity, food systems, and cultural practices. They advocate for the recognition of indigenous territorial rights and the integration of ancestral knowledge in conservation strategies.