Chapter 6: Trip to the Negro River marked a reunion after pioneering expeditions in the 1990s

One of the fishing methods used to collect electric fish in the DEGy Negro River Expedition was employed for the first time on a large scale in freshwater during the Calhamazon project, which brought together researchers from Brazil and the United States between 1993 and 1996.

By André Julião and Phelipe Janning  |  Agência FAPESP – Even before it began, the DEGy Negro River Expedition had a taste of nostalgia. At least for four members of the group that spent two weeks traveling along the Negro River and its tributaries, from Manaus to Santa Isabel do Rio Negro. The trip was monitored by Agência FAPESP for the Field Diary – Negro River series.

It was a reunion, almost 31 years after the first expedition of the Calhamazon project. In 1993, 1994 and 1996, the researchers traveled the entire length of the Amazon River, collecting in the main channel and at the mouths of all the tributaries. The first trip took 40 days. The last two, 30. They collected 20,000 specimens of 510 species, leading to a series of scientific discoveries.

In 2024, the partnership started on those trips was repeated by fisherman and former employee of the National Institute for Amazonian Research (INPA) Roberval Pinto Ribeiro and research support technician at the University of São Paulo’s Museum of Zoology (MZ-USP) Osvaldo Oyakawa, who participated in all three expeditions. INPA researcher Lúcia Rapp Py-Daniel and Federal University of Bahia (UFBA) professor Angela Zanata participated in the last two excursions.

“It was my first experience in the Amazon and one of the most remarkable of my life, especially because of the diversity of fish. We do a lot of collecting in the Southeast, like in the Paraíba Valley and the Ribeira Valley, and if we come back with 30 species in two weeks, we can be satisfied. In the Amazon, you go to a small igarapé and collect 40, 50 species. So it’s very surprising,” says Oyakawa, who joined MZ-USP as a technician in 1989 and in 1993 was doing his doctorate at the institution.

The project, whose full title is “Fish diversity of the principal channels of the Amazon River,” was coordinated by John Lundberg, then a professor at Duke University who moved to the University of Arizona in 1993. Lundberg is currently retired from the Academy of Sciences of Drexel University, formerly the Academy of Natural Sciences of Philadelphia, both in the United States.

Osvaldo Oyakawa, Roberval Ribeiro, Angela Zanata and Lucia Py-Daniel: the DEGy Negro River Expedition marked a reunion three decades after the Calhamazon project (photo: Phelipe Janning/Agência FAPESP)

In Brazil, Calhamazon had the collaboration of Naércio Menezes, a professor at MZ-USP, where most of the material collected went. Funding was provided by the National Science Foundation.

“It took years of work, many publications describing new species, and other studies on taxonomy and biodiversity, including molecular genetics. Many graduate students from Brazil, the United States and other countries studied the material and obtained their degrees,” Lundberg told Agência FAPESP.

“The main legacy of Calhamazon was that for the first time we were able to collect a large number of species of Gymnotiformes, the electric fish, including poraquês, using a collection method that had never been used before, over a large area of the Amazon basin. This made it possible to increase the study of these fish in our country,” says Menezes, who coordinates the “Diversity and Evolution of Gymnotiformes (DEGy)” project, supported by FAPESP.

Innovation

The goal of Calhamazon was to collect as many fish as possible from the river channel, or calha, hence the name. This deepest part is difficult to reach with other fishing gear, so the organisms of this habitat were little known.

The innovation of the project was to use the equipment used for shrimp fishing at sea on the river. In trawling, as it is known, the bed is swept by a funnel-shaped net with two large heavy gates that keep the structure open at all times and at the bottom.

“Lundberg had done a preliminary study in the Orinoco in Venezuela, testing the bottom trawl in the river channel. It worked very well, so he and Professor Ning Labbish Chao of the Federal University of Amazonas [UFAM] planned to repeat it on a large scale in the Brazilian Amazon,” explains Py-Daniel, who was then a researcher at INPA and would go on to do her doctorate with Lundberg in the United States starting in 1993.

Before the project actually began in Brazil, the researchers carried out another pilot in 1991, this time on the Negro River. The idea was to test the viability of this type of collection in the country. Py-Daniel remembers being surprised by the diversity found even in those short-term collections near Manaus.

“There I was already enthralled by the type of fauna we had access to, groups of fish that I’d never even seen before. Then the project proposal began. It took two years to get funding,” she recalls.

A key figure in both Calhamazon and later projects, such as the one that led to the DEGy Negro River Expedition, was Roberval Pinto Ribeiro. A fisherman for as long as he can remember, Ribeiro had joined INPA as a mid-level technician shortly before the first expedition of the North American project. Already known to the scientists, he was the right man at the right time to lead the collections.

Alberto Akama and Roberval Ribeiro perform bottom trawling during a Calhamazon expedition (photo: acervo dos pesquisadores)

“I’ve always fished, and when I was hired by INPA, I was working on a fishing boat. I’d already been out to sea in Belém, on one of those shrimp boats. So I already knew more or less how bottom trawling worked. But I started making these nets during Calhamazon because many of them were destroyed during the work. While I was still on the boat, I made five of them,” Ribeiro recalls.

One of the problems with bottom trawling in rivers is the loss of nets. Tangled in logs or even uneven riverbeds, they can tear and get lost, or even cause serious accidents. None of this happened during DEGy Negro River.

However, Lundberg recalls that shortly after Calhamazon ended, a group of researchers from the United States, Venezuela and Peru had a serious accident on the Orinoco River after the net got caught somewhere along the way and the boat capsized. One Peruvian researcher died. Since then, precautions have been taken. Trawling must be done at low speed and always upstream to avoid something similar to what happened in the Orinoco. While the boat is moving, usually an aluminum speedboat with a small engine, one person throws the cables holding the net into the river, and immediately after that, another person throws the gates. While the boat pulls the net in a straight line for about 15 minutes, one of the researchers uses sonar to monitor the relief of the riverbed.

Legacy

After his experience on Calhamazon, Ribeiro was invited to participate in many other expeditions using this fishing method. Now 70 and retired from INPA, he continues to guide researchers in this and other fishing methods. Now living in Porto Velho, in the state of Rondônia, he also takes part in fish fauna monitoring carried out by companies and universities.

“They still call me a lot, ordering nets, calling me for some new project or to build cages for fish farming,” he says.

“It was an experience that opened many doors for me. While I was still doing my doctorate [with a FAPESP scholarship], I was invited to spend some time at the University of Arizona, organizing the material collected. It was my first time in the United States. Years later, Lundberg recommended me for a postdoctoral fellowship at the Smithsonian Institution, under the supervision of Professor Richard Vari. That time gave me a remarkable life experience, with tremendous learning and a super-important publication that helped me get my job,” says Zanata, who has been at UFBA for 20 years and recently became a full professor.

Angela Zanata holds a pirarara during collection for the Calhamazon project (photo: researchers’ archive)

Py-Daniel was already a researcher at INPA when she joined the project, but thanks to it, she started her doctorate at Duke University and finished it at the University of Arizona, both in the United States, under Lundberg’s supervision. Since then, bottom trawling has been used by INPA and other institutions in many other areas of the Amazon.

“It’s a type of fish fauna that we only find with this equipment. It was fantastic for my career, because I work with catfish that live in this part of the river, and I was able to collect fish for my thesis that had hardly existed in collections until then,” she recalls.

Now old enough to retire from the MZ-USP, Oyakawa even admits to leaving the bench, but expeditions should continue to be a part of his days.

“After working for 40 years, it’s natural for me to think about retiring, but to get rid of some obligations. I know people in various parts of Brazil, and if they call me on an expedition, I’d be happy to go. I like being in the field, it’s priceless for a biologist, and I’m very happy to have brought young people on this expedition who hadn’t seen the Amazon before,’ he concludes.

To view all the episodes of Field Diary – Negro River go to: agencia.fapesp.br/en/field-diary.

: The three friends: Osvaldo, Lucia and Angela repeating their routine from 30 years earlier, when they worked together on the Calhamazon project (photo: Phelipe Janning/Agência FAPESP)