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8. Brazilian Guitarfish

Pseudobatus horkelii

About

Previously known as Rhinobatus horkelii, the Brazilian guitarfish displays an interesting reproduction mode by keeping embryos dormant when they are in cool deep waters for many months until they ascend to shallow waters.

When the adult ascends to coastal, warmer waters the dormant embryos begin to develop. They are all enclosed within a common shell called the candle, and their development starts when the shell brakes.  Females later give birth to between 4 and 12 pups. The size of the litter appears to be positively related with the size of females, who reach sexual maturity at approximately 120 cm.

Brazilian guitarfish populations have severely declined due to overfishing, with mortality from fisheries being higher in males than females. In the 1980s, this species was commercially important within its range, reaching peak catch in 1984 – since this time catch per unit effort (CPUE) has declined continuously. Currently, bycatch by inshore trawling fisheries is a major threat to this species. In Brazil, Pseudobatos horkelii has been listed as Critically Endangered within the Federal Law of Threatened and Overexploited Aquatic Species since 2004, with no permits for catch being issued and the transport and the sale of any individual being prohibited.

  • Order: Rajiformes
  • Family: Rhinobatidae
  • Population: Unknown
  • Trend: decreasing
  • Size: 138 cm (?)
  • Depth Range (m): 40 – 150 m

EDGE Score

EDGE Score: 6.53 (?)
ED Score: 42.04 (?)
GE / IUCN Red List (?)
Not Evaluated Data Deficient Least Concern Near Threatened Vulnerable Endangered Critically Endangered Extinct in the Wild Extinct

Distribution

The Brazilian guitarfish is endemic to the South-eastern Atlantic from Brazil to Argentina with the centre of their range being south Brazil. In Argentina, some individuals have been reported in the Rio de la Plata Estuary.

Habitat and Ecology

Brazilian guitarfishes are benthic (bottom-dwelling) species of the continental shelf. Adults spend most of the year at depths between 40 m and 150 m, moving to shallower inshore habitats below 20 m depths seasonally between November and March for reproduction and parturition (birth). Juveniles remain in coastal habitats while adults return to deeper waters. Local site fidelity is unknown.

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