Franciscana (Pontoporia blainvillei)
|Also known as:||La Plata River dolphin|
|French:||Dauphin De La Plata|
|Spanish:||Delfín De La Plata, Tonina|
|Size||Length of males: 121 – 158 cm (2)|
Length of females: 137 – 177 cm (2)
|Weight||36 – 50 kg (3)|
The franciscana is classified as Vulnerable (VU) on the IUCN Red List (1) and is listed on Appendices II and III of CITES (4).
The only river dolphin species to live in saltwater, the franciscana (Pontoporia blainvillei) is also one of the smallest dolphins. It has a particularly long and narrow beak, and a large head. It is brown-grey on the back, but lighter on the sides and belly (2). Its neck is flexible due to un-fused vertebrae, the blowhole is uniquely crescent-shaped and the dorsal fin is small and triangular, with a rounded tip. Juveniles are browner and have seven hairs on the upper jaw that disappear with age (5).
The franciscana inhabits the coastal regions and estuaries of the western South Atlantic Ocean, ranging from Brazil to Argentina, although it is absent from large areas of its range (1).
Found in shallow, turbid waters – usually marine, but occasionally brackish, when in estuaries (1).
Known to fisherman as the ‘white ghost’ for its pale skin and tendency to dart away from boats, the franciscana is a shy dolphin that forms groups of usually 2 to 15 individuals, but up to 40 have been seen together. They feed cooperatively by herding bottom-dwelling fish, using echolocation to find them in the cloudy water of their habitat and diving to a maximum depth of 25 metres (2).
Little is known about the breeding biology of this species, but it is thought to mate in January and February and give birth from October to January, when prey is more abundant. Franciscana are sexually mature by three years (2).
Franciscana are regularly accidentally caught in gillnets, constituting a major threat to the species. They are also at risk from habitat degradation as coastal industries develop causing increased coastal traffic and pollution (2).
A possibility for the advancement of conservation action for the franciscana is the development of a memorandum of understanding between Argentina, Brazil and Uruguay. This could enable collaborations researching the rate of incidental catch, the population status, the species’ biology and the extent of habitat degradation (2).
The franciscana is also listed on Appendices I and II of the Convention on Migratory Species (CMS or Bonn Convention), which aims to conserve migratory species throught their range (6).