Franciscana Dolphin: Pontoporia blainvillei

Abstract

This chapter discusses the characteristics and taxonomy, distribution and abundance, ecology, behavior, and physiology of the franciscana dolphin or pontoporia blainvillei. Franciscana is also known as the La Plata River dolphin. In Uruguay and Argentina it is called franciscana, whereas in Brazil it is called toninha or cachimbo. Although both this species and the Yangtze River dolphin, Lipotes vexillifer, were until recently regarded as of the family Pontoporiidae, the franciscana is now the sole member of this family. The franciscana is the only one of the five river dolphins living in the marine environment. It is one of the smallest dolphins and has an extremely long and narrow beak and a bulky head. The franciscana is brownish to dark gray above, turning lighter to the flanks and belly. The number of teeth in the upper and lower jaws ranges from 53 to 58 and from 51 to 56, respectively. Based on the distribution of sightings and catches, the franciscana lives in a narrow strip of coastal waters beyond the surf to the 30-m isobath. The complete range known for the franciscana extends from Itaunas (18°25 S, 39°42 W) in Espirito Santo, Brazil, to the northern coast of Golfo San Matias (41°10'S) in northern Patagonia, Argentina. Recent surveys carried out in Argentina showed that franciscana is also found up to the 50-m isobath.