As the treasured rainforest in the Amazon River region of South America is constantly shrinking, the river presents proof of other dangers: the overuse of freshwater fish.
At an Amazon River port in Iquitos, Peru, a man carries a large, freshwater Arapaima fish away from the landing. Image Credit: Sebastian Heilpern/Provided.
According to the first large-scale, pan-Amazonian examination, the biodiversity of the freshwater species in the Amazon has been subjected to powerful fishing pressure. This study has been performed by a group of international researchers and headed by Cornell researchers.
Their outcomes are based on analyzing decades of fishery landings (the places like ports where fishers leave their catch) records from Peru and Brazil. This denotes stress that threats the potential of the region to provide protein and other nutrients that are required.
The new study was reported in the Proceedings of the Royal Society B on June 8th, 2022.
We are seeing a decline in large-bodied species. Large-body species are more vulnerable as they are slower to develop. As they decline, we see they are also being replaced by smaller species. This pattern is consistent with overexploitation.
Sebastian Heilpern, Study Lead Author and Presidential Postdoctoral Fellow, Cornell University
Heilpern works with Peter McIntyre, associate professor, and Alex Flecker, professor, both in the College of Agriculture and Life Sciences.
Heilpern described that as fish species have been replaced, it is possible to retain harvests. However, in the end, proof from scientific models indicates that harvests could fall.
Heilpern stated, “The continued depletion of fish biodiversity reduces the pool of compensating species further diminishing the fishery resilience.”
Essentially, overfishing is withdrawing from the natural sustainability savings account and biological security found in diversity.
There is a bank of fish species able to compensate for the loss of one species. But as the bank is depleted, we experience a loss of compensatory potential. It indicates that the sustainability is declining.
Sebastian Heilpern, Study Lead Author and Presidential Postdoctoral Fellow, Cornell University
According to the study, the Amazon River is considered to be one of the most productive and different freshwater ecosystems present on the planet. The people residing in the region have some of the highest rates of fish consumption throughout the world, nearly 110 pounds per person on a yearly basis.
To gain a different point of view, the percentage of freshwater fish stocks along with biologically sustainable levels was around 90% in 1990. This is as per a 2020 Food and Agricultural Organization (United Nations) report. But sustainability had fallen to 65.8% by 2017.
The FAO report states that wherever there was a lack of fisheries management, or where the management was inefficient, fish stock status seemed poor and worsening.
In the Amazon, improved monitoring, enforcement of regulations, and governance are required to maintain fisheries.
Heilpern stated, “Additionally, expanding protected areas can maintain habitats that are critical for many fish species.”
We often see the Amazon from the outside as a massive forest. But the Amazon rainforest and the river—and its massive network of tributaries—are intimately connected. The health of the river is important for the health of the rainforest and vice versa. Sustainability of the river and its resources is priority.
Sebastian Heilpern, Study Lead Author and Presidential Postdoctoral Fellow, Cornell University
Rich biodiversity could delay the downfall of fisheries.
Helipern stated, “While existing landing data provide an incomplete snapshot of long-term dynamics our work shows that multispecies exploitation is affecting freshwater biodiversity and eroding fishery resilience in the Amazon.”
Besides Heilpern and senior author Flecker of the paper, “Biodiversity Underpins Fisheries Resilience to Exploitation in the Amazon River Basin,” the co-author of the study includes Suresh A. Sethi, assistant unit leader, of the New York Cooperative Fish and Wildlife Research Unit, and associate professor (courtesy) in the Department of Natural Resources and the Environment (CALS).
The non-Cornell authors on the paper include Shahid Naeem (senior author), Columbia University; Ronaldo B. Barthem, Museu Paraense Emilio Goeldi, Pará, Brazil; Vandick da Silva Batista, Universidade Federal de Alagoas, Maceio, Brazil; Carolina R. C. Doria, Universidade Federal de Rondônia, Brazil;
Additional authors of the study include Fabrice Duponchelle, Institute of Research for Development, Montpellier, France; Aurea García Vasquez, Instituto de Investigaciones de la Amazonía Peruana, Iquitos, Peru; Michael Goulding, Wildlife Conservation Society, Bronx, New York; and Victoria Isaac, Universidade Federal do Pará, Belem, Brazil.
The study was financially supported in parts by the Cornell Presidential Postdoctoral Fellows. Flecker, McIntyre, and Sethi are faculty fellows at the Cornell Atkinson Center for Sustainability.
Journal Reference:
Heilpern, S. A., et al. (2022) Biodiversity underpins fisheries resilience to exploitation in the Amazon river basin. Proceedings of the Royal Society B. doi.org/10.1098/rspb.2022.0726