Pontoporia blainvillei
franciscana

Franciscana dolphins are found along the costal waters of South America from the Doce River in Brazil south to the Valdez Peninsula in Argentina. Pontoporia blainvillei are also common in the estuaries of the Rio de la Plata, hence the other common name, La Plata dolphin.

Pontoporia blainvillei is the only member of the superfamily Platanistoidea that lives in salt water. They are found in the estuary of the Rio de la Plata during most of the seasons, but during winter they migrate either out to sea or upwards along the coast of Brazil.

Pontoporia blainvillei is one of the smaller species of cetaceans. They range from 1.25 to 1.74m in length, with the females slightly larger than the males. The cape color of these dolphins is grayish, but the ventral and lateral surfaces is paler. The young are distinguishable from adults by their brownish color, and by seven hairs on the upper rostrum that disappear with age. Their beak is extremely long and slender and is moderately demarked from the bulging forehead. Their blowhole is uniquely transverse and in the shape of a crescent. The dorsal fin is triangular in shape with a rounded tip, and ranges 7.0-10.0cm in height. The neck is distinct and apparent. There are 48-61 teeth in each side of the jaw, with the total ranging from 210-242.

Early weaning, short learning periods, and a solitary life-style could be related to their small brain size, as noted by Kasuya. They are not as playful as other dolphins and often shy away from boats.

Pontoporia blainvillei have echolocation clicks similar to harbour porpoises, Phocoena phocoena. They use low, high, and ultra-high frequency to communicate and locate food.

The franciscana dolphin inhabits waters that are sometimes murky from sediments. They locate bottom-dwelling species of fish by echolocation and by digging up the bottom with their long snout.

Only a few species account for the majority of the food. In Uruguayan waters the most common fish is Cynoscion striatus. In Brazil, the most common are Paralonchurus brasiliensis, C. striatus, Macrodon ancylodon, and Micropongonias furnieri.

Females eat more squid, Loligo sanpaulensis, than males. It was also observed that juveniles eat more shrimp, Artemesia longinaris, than adults.

None.

The local farmers use the franciscana dolphin for pig feed and as a source of oil. Their blubber is a good indicator for scientists studying the pesticide levels in the ecosystems in Brazil, Uruguay and Argentina.

Inadequate data available for complete risk assessment of species. However, about 1,500-2000 franciscana dolphins are killed annually in the nets of fishermen seeking to catch sharks.

The oldest female examined was 13 years old, and the female lifespan is thought to be about 15 years. This female did not show any eviedence of being postreproductuve or "senile." The oldest male was 16 years old, and the lifespan of males may be about 18-20 years.

Because of their pale colored bodies and their shy nature toward humans, Pontoporia blainvillei dolphins are known to fishermen as "the white ghost".