Bigeye thresherBTH

Alopias superciliosus

Alo.sup secondary
Alo.sup upper tooth

Characteristic features:

  • Upper caudal lobe nearly as long as rest of shark
  • Profile of head nearly straight between eyes
  • A deep groove on each side of nape
  • Eyes very large, droslaterally positioned directed upwards, the top almost level with dorsal surface of head
  • First dorsal-fin closer to pelvic-fin base than pectoral fin rear tip
  • White part of belly not extending over pectoral-fin base

Colour:

Dorsal surfaces purple to violet greyish, often with a metallic sheen. Ventral surfaces white.

Size:

Up to at least 480 cm TL; birth size 100–140 cm TL.

Distribution:

Circumglobal in all tropical and warm temperate seas. From the surface to at least 700 meters depth.
View FAO distribution map

Habitat:

A pelagic and mostly oceanic species that occasionally enters shallower waters near outer reef edges or seamounts; during the day found mostly in deeper waters (300–500 meters, 6–12°C) and at night in shallower waters (0–100 meters, 20–26°C).

Biology:

Feeds primarily on cephalopods and small to medium pelagic fishes, using its long whip-like upper caudal lobe to stun its schooling prey. Length at maturity is 330–350 cm TL and 270–290 cm TL for females and males respectively. Age at maturity is 12–13 years and 9–10 years for females and males respectively. Reproductive mode is viviparous with oophagy with no reproductive seasonality. Litter size is 2–4 pups.

Indonesian fisheries:

Caught primarily by pelagic longline and possibly as bycatch in the purse seine fishery.

Similar species:

Alopias pelagicus
Alopias pelagicus
Alopias pelagicus differs in having a deep groove on the nape (vs. no groove present on the nape) and eyes dorsolaterally positioned directed upward (vs. laterally positioned, not directed upwards).

External links:

FishBase
The IUCN Red List of Threatened SpeciesTM