Although not a true freshwater dolphin, this primarily marine species is nonetheless related to them. The beak is extremely long and narrow, relatively the longest of any living species of cetacean. Although in calves, the beak is much shorter and stouter than it is older animals. The forehead is steep and rounded. The dorsal fin is low to moderately tall and triangular, with a rounded tip. The flippers are broad spatulate, sometimes with an undulating trailing edge. In many subadults, there are visible ridges along the surface, corresponding to the flipper bones. Morphological studies have documented the existence of two forms of franciscana, a smaller northern and a larger southern one. Males reach 1.63 m, and females 1.77 m in length. Maximum recorded weight is about 53 kg. Franciscana are countershaded brownish to dark gray above, and lighter brown (or even yellowish) to gray below and on the lower flanks. A faint dorsal cape is generally present. The long beak is lined with 50-62 fine pointed teeth per row, more than nearly any other species of cetacean.
Can be Confused With
Young franciscana may be confused with marine dolphins of the genus Sotalia, but can be identified by their very long beaks and more rounded dorsal fins, broad flippers, and small eyes. Bottlenose dolphins should be easy to distinguish, based on their much larger size and tall, falcate dorsal fins.
Franciscana is found only along the east coast of South America, from Golfo San Matias, central Argentina, to Espirito Santo, central Brazil. They are primarily coastal, ranging no farther offshore than the 30 m isobatch. However, they may also be found in some estuaries, and they sporadically enter the la Plata River.
Ecology and Behavior
Franciscana resides in coastal habitat. However, there is very little known about the franciscana's natural history. This is due to two factors the difficulty of observing them in nature, and the paucity of research effort. They are found singly or in small groups of up to 15 individuals. In general, they appear to avoid vessels, and are not aerially active.
Peak calving for this species is in November and December. There has not been much research on the life history of this species, but sexual maturity may occur as early as 3 years. At birth, franciscana measure about 60-80 cm.
Feeding and Prey
Franciscana are opportunistic feeders and feed mostly near the bottom on several species of fish, cephalopods, and crustaceans. Cooperative feeding has been observed in Argentina.
Threats and Status
Main threats include:
• Incidental mortality in gillnet fisheries (takes at least 1,500 animals per year)
• Habitat degradation
Total abundance of the species is not known, but the gillnet mortality alone is not thought to be sustainable. The current status of franciscana are “Data Deficient” (IUCN) and “Not Listed” (ESA).
Bordino, P., G. Thompson, and M. Iniquez. 1999. Ecology and behaviour of the franciscana (Pontoporia blainvillei) in Bahia Anegada, Argentina. Journal of Cetacean Research and Management 1:213-222.
Brownell, Jr., R.L. 1989. Franciscana Pontoporia blainvillei (Gervais and d'Orbigny, 1844). pp. 45-68 in S.H. Ridgway and R. Harrison, eds. Handbook of marine mammals, Vol. 4: River dolphins and the larger toothed whales. Academic Press.
Crespo, E.A. 2002. Franciscana Pontoporia blainvillei. pp. 482-485 in W.F. Perrin, B. Würsig and J.G.M. Thewissen, eds. Encyclopedia of marine mammals. Academic Press.
Crespo, E.A., G. Harris, and R. Gonzalez. 1998. Group size and distributional range of the franciscana, Pontoporia blainvillei. Marine Mammal Science 14:845-848.
Pinedo, M.C. 1991. Development and variation of the franciscana, Pontoporia blainvillei. Ph.D. dissertation, University of California, Santa Cruz.
Pinedo, M.C., R. Praderi, and R.L. Brownell, Jr. 1989. Review of the biology and status of the franciscana Pontoporia blainvillei. pp. 46-51 in W.F. Perrin, R.L. Brownell, Z. Kaiya and L. Jiankang, eds. Biology and conservation of the river dolphins. IUCN.