Alopias superciliosus


Bigeye thresher BTH
Characteristic features:
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:

A regular catch in the tuna and shark longline, and drift net fisheries. Utilised for its fins (high value), meat (salted), skin and cartilage.

Similar species:

Alopias pelagicus
Pelagic thresher

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).

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