Blue sharkBSH

Prionace glauca

Prionace glauca ventral head
Prionace glauca upper and lower teeth

Characteristic features:

  • First dorsal-fin base closer to pelvic fin than pectoral-fin base
  • Pectoral fin very long and scythe-like
  • Caudal peduncle with weak lateral keels
  • Upper surfaces indigo blue; white below
  • Snout very long and narrowly rounded
  • Upper teeth narrowly triangular, oblique and finely serrated (somewhat hooked in adults)
  • Lower teeth slender, erect and finely serrated

Colour:

Dorsal surfaces indigo blue, often fading to dull grey after death. Fins without distinct markings, except for dusky ventral pectoral-fin tips. Ventral surfaces white.

Size:

Maximum size up to 383 cm TL; birth size 35 – 50 cm TL.

Distribution:

Cosmopolitan in all tropical and temperate seas.

Habitat:

Oceanic and pelagic, usually well offshore but also occurs inshore where the continental shelf is narrow. Found from the surface to at least 1000 meters depth; prefers water temperatures of 12 – 20 °C.

Biology:

Feeds primarily on bony fish and cephalopods, but also small sharks and seabirds. Migrate seasonally to warmer waters in some areas; capable of undertaking trans-Atlantic migrations and from Northern to Southern Hemisphere; reported to frequently dive from the surface to more than 600 m depth. Size classes and sexes segregate. Potentially dangerous because of its persistence, but not very aggressive. Length at maturity is 207 – 220 cm TL and 182 – 220 cm TL for females and males respectively. Reproductive mode is viviparous with yolk-sac placenta. Females give birth to 4 – 135 (usually 15 – 30) pups after a gestation period of 9 – 12 months, and breed every 1 or 2 years.

Indonesian fisheries:

Very common bycatch of tuna and shark longline fisheries. Utilised for its fins (high value in adults), meat, skin jaws and cartilage. One of the most heavily fished sharks globally.

Similar species:

A distinctive species. Rarely misidentified as Isurus paucus.

Isurus paucus
Longfin mako shark
Isurus paucus
Isurus paucus is similar in having a similar pointed snout, dark-blue colouration and long pectoral fins, but differs in having a lunate caudal fin, with upper and lower lobes of similar length (vs. asymmetrical, with a much longer upper lobe and shorter lower lobe).

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM