Cetacean Society International

Working for whales, dolphins and porpoises worldwide

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(Pontoporia blainvillei)

Franciscana is the best of many names for this tiny dolphin, also called the La Plata River Dolphin, toninha, and boto amarelo by fishermen in small villages that know it all too well from net entanglements. Found along the coast from the Province of Chubut, Argentina, to Espírito Santo State, Brazil, genetic and parasite studies suggest at least one isolated population of franciscana near Rio de Janeiro. (Photo courtesy of Pablo Bordino, Argentina)
The franciscana rarely swims in water deeper than 30 meters, catching squid, octopus, and many species of small fish. They use tidal currents in bays and estuaries for hunting, as many other species do worldwide. Their long jaws can be 15 percent of an adult's length, and with many small teeth are well suited to catching elusive prey in water so murky or turbid that a dolphin might not see another dolphin swimming right alongside. Although groups of up to 20 have been seen, probably brought together by rich hunting, the mean group size is only four dolphins. (Photo courtesy of Pablo Bordino, Argentina)
Most babies are born between October and February, after a gestation period just over 11 months. Mothers with nursing calves tend to be in deeper waters than other franciscana. Fully weaned after seven months, still learning how to hunt for food but not knowing the dangers, these young franciscana are most vulnerable to becoming entangled in fishing nets. (Photo courtesy of Pablo Bordino, Argentina)
Fishermen don't want their nets to kill franciscana, like this. So many die in nets every year that many scientists fear, but cannot yet prove, that the species' numbers have to be declining. Until there is better scientific information effective management of the "incidental entrapments" cannot be legislated and enforced. "Pingers" on nets have reduced dolphin deaths, but cannot be used as they attract southern sea lions that catch the fish trapped in the nets. (Photo courtesy of Pablo Bordino, Argentina)
The World Conservation Union (IUCN) "Red List" includes the franciscana as "Data Deficient", but even though recent research is providing more information, it has yet to be verified and applied to make the dolphin's IUCN status "Vulnerable". This would help to produce national solutions. Local public education and management programs are experimenting with fishing farther offshore, or reducing some fishing in spring and summer. It's believed that entanglements depend more on the fishing area, depth and target species than on the mesh size of the nets. (Photo courtesy of Pablo Bordino, Argentina)
CSI has helped to support several franciscana projects, including the most recent scientific workshop. Everyone agrees that the franciscana is the cetacean species most impacted by human activities in the western South Atlantic, especially by incidental catches in gillnet fisheries. Until that crisis is documented and solved, almost all research on the species is directed at conservation. (Photo courtesy of Pablo Bordino, Argentina)