Bigeye Thresher Shark

About the Bigeye Thresher Shark

The Bigeye Thresher is easily recognized by its exceptionally large eyes, designed for low-light hunting, which are set in unique keyhole-shaped sockets allowing them to rotate upwards. Like its thresher relatives, nearly half of its total body length is comprised of the incredibly long, whip-like upper lobe of its caudal (tail) fin. Its body is stout, typically dark purplish-brown to gray dorsally, fading to white on its underside, providing camouflage in the open ocean. A pair of distinct deep grooves on the top of its head further aids in identification.

Source: FishBase & iNaturalist

Habitat

This pelagic shark prefers deeper waters offshore, typically found over continental and insular shelves and slopes, though it can venture closer to the surface during cooler, darker periods. It inhabits both temperate and tropical oceans globally, often preferring temperatures between 16-25°C. Juveniles may be found in shallower, coastal areas.

Distribution

The Bigeye Thresher roams widely across all temperate and tropical oceans worldwide, from the Atlantic to the Pacific and Indian Ocean basins. It is truly a cosmopolitan species, though often preferring warmer waters.

Behaviour

A formidable nocturnal predator, the Bigeye Thresher utilizes its enormous eyes to hunt cephalopods and schooling fish in mesopelagic depths. Its extraordinarily long tail is not just for show; it's a specialized weapon, used to stun prey with powerful whip-like strikes before consumption. While usually found at depths during the day, it undertakes diel vertical migrations, rising to shallower waters at night to feed. Anglers often encounter them as powerful, acrobatic fighters, capable of impressive aerial displays once hooked.

Edibility

★★★★★

The meat of the Bigeye Thresher is firm, white, and flaky, possessing a mild, swordfish-like flavor. It holds up well to grilling, baking, or frying, making it a desirable catch for the table.

Lure suggestion

Targeting Bigeye Threshers typically involves deep-water angling techniques. Large, natural baits such as mackerel, squid, or bonito rigged on heavy-duty circle hooks with steel leaders are highly effective, often fished on the drift or from a slow-trolling vessel. Look for them around seamounts, canyons, and ledges where baitfish congregate, deploying baits at varying depths, particularly during dawn and dusk or at night.