The map shows where the species may occur based on oceanography. The species has not been recorded for all the states within the hypothetical range as shown on the map. States for which confirmed records of the species exist are included in the list of native range states.
Habitat and Ecology
Franciscanas are generally found in turbid waters < 30 m deep (Pinedo et al. 1989, Secchi and Ott 2000). Although they are found mainly in marine waters and only occasionally in estuaries, they are relatively common in the Uruguayan part of the La Plata River estuary (Praderi 1986). Franciscanas are primarily coastal, ranging no farther offshore than the 30 m isobath. Some sightings have been made in waters seaward of the 50 m isobath and 55 km offshore, but the density offshore is very low.
Franciscanas feed on several species of shallow-water fish (e.g., sciaenids, engraulids, gadids, and carangids), cephalopods, and crustaceans (Brownell 1989, Di Beneditto and Ramos 2001, Rodriguez et al. 2002, Danilewicz et al. 2002).
Life History and Behavior
Lifespan, longevity, and ageing
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Data Deficient(Baillie and Groombridge 1996)
- 1996Data Deficient
- 1994Insufficiently Known(Groombridge 1994)
- 1990Insufficiently Known(IUCN 1990)
- 1988Insufficiently Known(IUCN Conservation Monitoring Centre 1988)
Secchi et al. (2003a) proposed four provisional management units (Franciscana Management Areas, or FMAs) with the following ranges: FMA I - coastal waters of Espírito Santo and Rio de Janeiro states, Brazil (note: confirmation of the hiatus in the Espírito Santo State with increased survey effort will require further division of this FMA); FMA II - São Paulo, Paraná and Santa Catarina states, Brazil; FMA III - coastal waters of Rio Grande do Sul State, southern Brazil and Uruguay; and FMA IV - coastal waters of Argentina, including the provinces of Buenos Aires, Rio Negro and Chubut.
There is no current abundance estimate for the species as a whole, but there is an estimate for the management stock inhabiting FMA III (hereafter referred as the RS/URU management unit). During aerial surveys of coastal waters of Rio Grande do Sul State in 1996 (Secchi et al. 2001), this stock’s abundance was estimated at 42,078 (95% CI 33,047–53,542). This extrapolated result must be used very cautiously, however, because it is based on a density estimate for only a small fraction of the coastline, representing approximately 0.7% of the possible range of the subpopulation (ca. 64,045 sq. km), and there is limited information on the distribution pattern of Franciscanas within their total range. This and other estimates of Franciscana density and abundance need to be interpreted cautiously as they could be either positively or negatively biased. The IWC Scientific Committee concluded, after reviewing the methods and limitations of Franciscana surveys through 2003–2004, that it was not appropriate to consider them as providing minimum estimates of abundance (IWC 2005a).
While the overall abundance of the species would seem relatively high, in most areas the gillnet mortality alone is not thought to be sustainable. Secchi (2006) projected the four management units 25 years into the future based on a stage-structured matrix model using a variety of scenarios of fishing effort. Because there were estimates of Franciscana density and abundance only for FMA III and IV (Secchi et al. 2001, Crespo et al. 2004), Secchi (2006) used the density estimated for FMA III and applied a correction factor based on the ratio of capture per unit of effort (CPUE) between the other areas and FMA III. This was assumed to represent a valid index of abundance because the unit of fishing effort is the same and the fishing gears are similar among management units. The corrected densities were multiplied by the entire area of both FMA I and II to obtain the estimate of total abundance. Uncertainty in the parameter estimates was incorporated through appropriate probability distributions. The scenarios considered most realistic (i.e. those that aimed to compensate for underestimation of the bycatch and that modelled environmental stochasticity) resulted in relatively high probabilities that each management unit would decline by at least 30% below its initial size with the exception of FMA I. However, it should be noted that estimates of bycatch in FMA I come from only one fishing village and it is known that bycatch occurs in other parts of this FMA (e.g. Freitas-Neto and Barbosa 2003).
The modelling exercise described above is considered to underestimate the risk of decline of Franciscanas. The most recent data on bycatch (e.g. Rosas et al. 2002, Bordino and Albareda 2005, A. Zerbini as summarized in IWC 2005b) indicate that the numbers caught annually in FMAs II and IV are roughly twice as high as the values used by Secchi (2006) in his projections. In addition, other sources of potential threat (risk factors, as described in the Threats section below) were not considered in Secchi’s study.
Stomach contents of Franciscanas from Rio Grande do Sul have included many kinds of debris: discarded fishing gear such as pieces of nylon net (17% of 36 stomachs), cellophane, and plastic fragments (6%) (Bassoi 1997). This problem has also been reported in northern Argentina, where cellophane, fishing debris, and plastic were found in 45%, 32% and 16% of the stomachs (Bastida et al. 2000; Danilewicz et al. 2002). The effects of such debris ingestion on health status of individual Franciscanas have not been determined, and the subpopulation-level implications are uncertain. However, debris could have a negative effect in at least some areas.
Other potential threats include various forms of habitat degradation (e.g. overfishing; destruction of benthic community and bycatch of small sciaenid fish – main Franciscana prey – by trawling) (e.g. Bassoi and Secchi 2000, Danilewicz et al. 2002, Rodríguez et al. 2002).
Relevance to Humans and Ecosystems
IUCN Red List Category
IUCN Red List Category
La Plata dolphin
|This article needs additional citations for verification. (January 2009)|
The La Plata dolphin or Franciscana (Pontoporia blainvillei) is found in coastal Atlantic waters of southeastern South America. It is a member of the river dolphin group and the only one that actually lives in the ocean and saltwater estuaries, rather than inhabiting exclusively freshwater systems.
The La Plata dolphin is the only species in its genus, and is often placed in its own family, the Pontoporiidae. It was first described by Paul Gervais and Alcide d'Orbigny in 1844 (the species epithet blainvillei commemorates the French zoologist Henri Marie Ducrotay de Blainville). The La Plata dolphin is also widely known as the Franciscana - the Argentine and Uruguayan name that has been adopted internationally. Other common names are the toninha (the Brazilian name) and cachimbo.
The La Plata dolphin has the longest beak (as a proportion of body size) of any cetacean — as much as 15% in older adults. Males grow to 1.6 m (5 ft, 3 in) and females to 1.8 m (5 ft, 10 in). The body is a greyish brown colour, with a lighter underside. The flippers are also very large in comparison with body size and are very broad, but narrow on joining the body, so are almost triangular in shape. The trailing edges are serrated. The crescent-shaped blowhole lies just in front of a crease in the neck, giving the impression that dolphin forever has its head cricked upwards. The dorsal fin has a long base and a rounded tip.
The La Plata dolphin weighs up to 50 kg (110 lb), and lives for up to 20 years. The gestation period is around 10–11 months and juveniles take just a few years to mature. Females may be giving birth by the age of five.
Behavior and feeding
The animal is very inconspicuous - it moves very smoothly and slowly—and can be difficult to spot unless estuary conditions are very calm. They will commonly swim alone or in small groups. Exceptional groups as large as 15 have been seen. La Plata dolphins are bottom feeders and gut inspections have revealed they eat at least 24 different species of fish, depending on which species are most common. They will also take octopus, squid and shrimp. They are, in turn, hunted by killer whales (orcas) and several species of sharks.
Range and habitat
The La Plata dolphin is found in the coastal Atlantic waters of southeastern South America, including the Río de la Plata estuary. Its distribution ranges from the Tropic of Capricorn near Ubatuba, Brazil, south to Península Valdés, Argentina. It is the only member of the river dolphin group that actually lives in the ocean and saltwater estuaries, rather than freshwater. Although some members of the species do spend portions of their lives outside of river systems, many individuals live their entire lives within rivers, never venturing into the ocean proper.
The La Plata dolphin is listed as "Vulnerable" in the IUCN Red List of Threatened Species. However, the Franciscana is a particular conservation concern because of its restricted distribution and vulnerability to incidental capture in fishing gear. Large numbers are killed in gillnets. Although the largest documented catches in the 1970s were in Uruguay, catches in recent decades have also been high in southern Brazil and Argentina. Scientists from all three countries have voiced their concerns, and asked for international assistance in highlighting the plight of the dolphin (see Reeves et al., pg. 53).
The species is listed on Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). It is listed on Appendix I as this species has been categorized as being in danger of extinction throughout all or a significant proportion of its range, and CMS Parties strive towards strictly protecting these animals, conserving or restoring the places where they live, mitigating obstacles to migration and controlling other factors that might endanger them. It is listed on Appendix II as it has an unfavourable conservation status or would benefit significantly from international co-operation organised by tailored agreements.
A young La Plata dolphin was rescued in 2011 off of Montevideo, Uruguay. Images of the infant dolphin became viral on Facebook, highlighting the plight of the species. 
- Reeves, R., Dalebout, M., Jefferson, T.A., Karkzmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E., Slooten, E., Smith, B.D., Wang, J.Y. , Zerbini, A.N. & Zhou, K. (2012). "Pontoporia blainvillei". IUCN Red List of Threatened Species. Version 2012.2. International Union for Conservation of Nature. Retrieved 18 January 2013. Database entry includes a brief justification of why this species is of vulnerable.
- "Appendix I and Appendix II" of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). As amended by the Conference of the Parties in 1985, 1988, 1991, 1994, 1997, 1999, 2002, 2005 and 2008. Effective: 5 March 2009.
EOL content is automatically assembled from many different content providers. As a result, from time to time you may find pages on EOL that are confusing.
To request an improvement, please leave a comment on the page. Thank you!