Tatiana Sanabria reports for Pagina Siete:
The obstacles that alter fish migration.
Experts disclose the damages caused by the lack of movement of some fish species.
Whenever a shoal of shad, catfish or golden scrolls rivers in search of better living conditions, often find insurmountable obstacles to meet the migration process. These are large dams, excessive fishing in surrounding communities and sound problems and environmental pollution.
Under the World Migration Day Fish, experts from the National Museum of Natural History (MNHN), the Institute of Ecology and the Wildlife Conservation Society (WCS) perform actions to involve the public and create a space for discussion about how we can intervene in these problems.
Migration processes explains Jaime Sarmiento, researcher at MNHN, are related to reproduction for the maintenance of fish stocks and the search for food and more favorable shelter.
Therein lies the importance of this risky move, but necessary, to be carried out every season and, depending on species, can reach a distance of 100 to 4,500 kilometers between the Amazon and Paraná basins, among others in the region.
“Only in the Amazon, the 802 known species, at least 10 % of which weigh more than two kilos migrates between the delta of the Amazon and the base of the Andes,” says the ichthyologist.
Among these species are large catfish and shad, which is considered an icon of the Pilcomayo River in the south, for their contribution to the economy.
However, the absence of this fish in the markets was accentuated gradually for two decades. This not only affects the fishermen in the area, but also to larger fish that feed on the shad.
The biologist Guido Miranda, WCS believes that in addition to the construction of dams, which affects the ecosystem of these species is the alteration of rivers by finding construction materials such as gravel and sand, producing modification the structure of the banks and alter the path of the fish and thus their survival.
“This oil pollution and noise pollution is added when construction works are carried out in the rivers. All this can alter the migratory behavior,” he says.
Large fish, which can grow to two meters long and weigh 70 kilos, do not know borders. Many of them make their way from Argentina, through Paraguay, Bolivia, Uruguay, Brazil and Peru may even reach the rivers of the Amazon.
Researcher Soraya Barrera, a member of the Bolivian Fauna Collection, explains that in many regions, closed seasons are enacted, but this is a useless effort because, in the absence of boundaries for these animals, there is no coordination between countries.
Given this bleak outlook for fish, Barrera believes that an alternative is to “educate the local people to take ownership of its flagship fish and develop better management plans and regulations.”
And while some dams have fishways, in most cases do not fulfill their purpose because they are going through difficult steps for some of the species. “Then you can better tailor those steps not to cover the channels, in order to not see accumulation of fish,” Miranda added.
Experts agree that this problem, which undoubtedly has become a widespread and global concern, must find a concrete and definitive solution in the regional context, to eliminate interference in fish migrations and contribute to their welfare and permanence in the ecosystem.
Tracing the fish chipi chipi
In recent months, the Wildlife Conservation Society (WCS) conducted a new registry for science documentation to track the migratory route of a species called chipi chipi, a small catfish that makes a long journey of over 350 kilometers, for its size, represents an enormous effort.
The biologist Guido Miranda explains that start of the flood plain of the Beni River and pass through two straits at Rurrenabaque: the Suse and El Bala, which are narrow points where people catches them. Its journey concludes around Palos Blancos in Alto Beni.
“Fishermen come to capture up to 50 kilos, but is not a problem because millions of this fish move in less than a month and when the fish pass Rurrenabaque, they are fished intensively,” adds the expert.
As a species, as far as is known, is widely distributed and is the only area where they perform the migration. Families in the area consume fried as a season side dish similar to ispi.
“These floods caused the number to increase and became an alternative meal of Beni, because they are a good source of protein and energy intake,” says biologist Guido Miranda in the interview with the newspaper Página Siete.