Populations of two species of freshwater dolphins are rapidly declining in the Amazon. These cetaceans are at risk of extinction for lack of drastic protection measures against fishing according to a study published on May 2, 2018 in the journal Plos One, based on 22 years of data collected in the Mamiraua Reserve in Brazil.
Once considered abundant in the Amazon Basin, the boto or pink dolphin of the Amazon (Inia geoffrensis) and the tucuxi or dolphin of the Orinoco (Sotalia fluviatilis) have seen their number halve every decade since 1994, according to the conclusions of the study conducted by Brazilian scientists.
Freshwater dolphins are increasingly killed as bait, threatening the survival of these species, particularly because females give birth to only one pup at a time and only four to five years. “Until the last decades, the boto was protected from ill-treatment to a certain extent thanks to legends and superstitions,” notes the study. But it is increasingly hunted for its flesh and fat, used by fishermen to attract catfish that meet a growing commercial success, deplore the South American researchers. “At the current rate, the boto population is reduced by half every ten years and that of tucuxi every nine years,” noted the study, the first to quantify the evolution of freshwater dolphins in the Amazon. “The results are extremely disturbing and show some of the highest rates of decline ever recorded for a cetacean population since the beginnings of modern whaling,” the researchers said.
For the moment, these two cetacean species are in the “Data Deficient” category of the International Union for the Conservation of Nature (IUCN) because until now statistics were missing to be able to determine the threat to them. For Brazilian scientists, if IUCN took into account their findings then these dolphins would be listed as “critically endangered”. In addition, although these dolphins are legally protected in the Amazon Basin, this legislation must be better respected, noted the researchers.