Franciscana
Pontoporia blainvillei

Other Names: La Plata Dolphin

Habitat: Inshore

Status: Locally common

Population: Unknown

Threats: Pollution, habitat destruction, human disturbance, and entanglement in fishing nets

Group Size: 1-5

Fin Position: Slightly behind center

Newborns: 28-32 in (70-80 cm), 16-19 lbs. (7.3-8.5 kg)

Adults: 4 ¼-5 ¾ ft (1.3-1.7 m), 65-115 lbs. (30 -53 kg)

Diet: Fish, squid or octopus, and krill or other crustaceans

Teeth: 106-116 on top row, 102-112 on bottom row

Description

Dorsal Fin:

- slightly rounded tip
- long base

Flukes:

- pointed tips
- slight notch in middle
- slightly concave trailing edges
- extremely broad flukes; width up to one-third of body length

Flippers:

- bones noticeable through skin
- broad, almost triangular flippers
- strongly curved leading edges
- serrated trailing edges

Head:

- moderate neck crease
- crescent-shaped blowhole
- small but well-developed eyes
- straight mouth line
- long beak
- area around eye slightly darker
- streamlined head (older animals)
- shorter beak (juvenile)
- chubbier head (juvenile)

Other characteristics:

- grayish brown upper side
- dorsal fin continues as ridge to tail stock
- slender body tapers to tail
- underside paler grayish brown than upper side and sides

Behavior

- moves very smoothly
- seldom rolls or splashes at surface and shows little of itself when rising to breathe, very difficult to detect except in clear, calm water
- generally tends to avoid boats, although there are records of it approaching small fishing boats
- thought to feed mostly at or near the sea floor, probing for food and pulling away vegetation
- seems to be fond of rippled sand
- has been spotted on hot, sunny days lying on sand in very shallow water, as if resting, and rising to the surface at intervals to breathe
- dive interval believed to be a little more than half a minute
- when in the presence of a predator, such as a Seven-gill Shark, will remain completely motionless at or near the surface of the water

Distribution

- temperate coastal waters of eastern South America
- the only member of the river dolphin family living in the sea
- it prefers shallow coastal waters
- most sightings are close to land, usually where depth is no more than about 30 ft (9 m)
- known range extends from the Doce River, near Regencia, Brazil, south through Uruguay to Bahía Blanca, Argentina; may occur as far south as the northern coast of Golfo San Matias, Argentina
- once occurred as far south as Peninsula Valdés, Argentina, but is rarely sighted there nowadays
- most common on the Uruguayan side of the La Plata estuary
- although common in the La Plata estuary, does not inhabit rivers and has never been recorded further upstream than Buenos Aires, Argentina
- rarely seen in winter, suggesting some kind of seasonal movement


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This page was created by:Candice Orca Mottet