Small Dolphins in Risk of Extinction in Rio
mal na foto toninhas
The “Toninha” as small dolphins of the Pontoporia Species are called in Brazil are part of the Group denominated Odontocetos Cetacean. It is one of the smallest existing species of dolphins. Its coloration varies from pale gray to light yellow with its lower part being lighter. Their face is visibly elongated and it has more than 200 teeth. Their eyes are small and so is their dorsal fin, when compared to other species of dolphins. Its dorsal fin is also rounded at the extremities. The full name of the species is Pontoporia blainvillei.
Today there are only 2,000 toninhas left off the coast of the states of Rio de Janeiro and Espirito Santo. This number represents less than half of the minimum population number considered safe. The safe population number is around 5,500 individuals. The toninhas are the only dolphins in risk of extinction in Brazil.
In order to have a clear idea of the problem the toninhas face in the coasts of Rio and Espirito Santo, and how this number is extremely low, we can compare it to the number of toninhas found between the states of Rio Grande do Sul in south Brazil and Uruguai, which is 42 thousand (although these numbers are from 1996).
Researchers from the NGO Aqualie Intitute, with help from five Brazilian universities and support from the Chico Mendes institute for the Conservation of Biodiversity (ICMbio) and from NOAA (National Oceanic and Atmospheric Administration), have made several overflights along the coasts of Rio and ES, where they identified 46 toninhas in 20 groups composed of 1 to 6 dolphins.
After the many identification flights over coastal waters and extensive field work researchers came to the conclusion that the main cause of the decline of the Toninha is due to accidental fishing, where they end up tangled in huge fishing nets another important cause may be large oil spills, athough there is not dependable data at the moment to prove this. However some Toninhas have been found dead due to oil poisoning. . No Toninhas were found along the coast of the city of Rio and the largest quantities were found near the Jurubatiba Ecological Park northeast of the city of Rio, just north of the city of Macae. Many more identification flights will be needed to get an accurate number on the Toninhas that are left because they are comparatively small animals, that live mainly in the dark waters next to rivermouths.
For more information check out the dedicated site http://www.querovertoninha.co.br/
• river mouth
Claudio Paschoa is Marine Technology Reporter's correspondent in Brazil.
Email: [email protected]