Australian sharpnose sharkRHY

Rhizoprionodon taylori

Rhizoprionodon taylori upper and lower teeth

Characteristic features:

  • Second dorsal-fin origin opposite anal-fin insertion
  • Anal fin larger than second dorsal fin, its posterior margin shallowly concave
  • Preanal ridges very long, about equal to length of anal-fin base
  • Snout long and narrowly rounded
  • Upper labial furrows very short, less than 1.3% of TL
  • 7 – 16 enlarged pores in total from each side near mouth corners
  • Teeth with narrowly triangular, smooth-edged, oblique cusps

Colour:

Dorsal surfaces bronze to greyish, fading to grey after death. Dorsal-fin anterior margins dark; upper lobe of caudal fin edged with black and tip black; pectoral and lower caudal-fin tips pale. Ventral surfaces white.

Size:

Maximum size up to 68 cm TL; birth size 22 – 26 cm TL.

Distribution:

Found only in northern Australia, southern West Papua and Papua New Guinea. In Papua New Guinea, confirmed from Western, Gulf, Central and East Sepik provinces.

Habitat:

Found over coastal and continental shelves, usually near the bottom, to depths to at least 110 meters.

Biology:

Diet consists of small bony fish, crustaceans and cephalopods. Length at maturity is 42 – 55 cm TL and 40 – 42 cm TL for females and males respectively. In Papua New Guinea age at maturity is around 1 year for females and 0.5 years for males. Reproductive mode is viviparous with yolk-sac placenta; females suppress the development of eggs for a number of months before embryonic development begins (embryonic diapause). Females give birth each January to 1 – 10 pups after 12 month gestation period. Rhizoprionodon taylori is one of the most biologically productive species of sharks. Maximum age for Papua New Guinea populations is 4.6 and 3.6 for females and males respectively.

Indonesian fisheries:

Caught in very high numbers by inshore demersal gillnet fisheries, off Papua, but rarely elsewhere. Utilised for its fins and meat, but of limited value due to its small size.

Similar species:

Rhizoprionodon oligolinx
Grey sharpnose shark
Rhizoprionodon oligolinx
Similar to Rhizoprionodon oligolinx but differs in having 15 – 22 enlarged pores in total near mouth corners (vs. 7 – 16).
Rhizoprionodon acutus
Milk shark
Rhizoprionodon acutus
Rhizoprionodon acutus differs in having upper labial furrows very long and prominent (vs. short upper labial furrows).

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM