Pelagic thresher (Alopias pelagicus), illustration

Regulated · catch and release Alopias pelagicus

Pelagic thresher in Los Cabos

The smallest of the three thresher sharks, with an upper tail lobe almost as long as its body. It shows up only now and then off Los Cabos, and it is globally Endangered, which is why we release every one.

Up to ~3.9 mMax length

2 pupsPer litter

0–300 mDepth range

EndangeredIUCN Red List

Season in Los Cabos

Jan·Feb·Mar·Apr·May·Jun·Jul·Aug·Sep·Oct·Nov·Dec·

●● best months · ● regular · · occasional. Based on local fishing reports; conditions change year to year.

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How to recognize it

A slim shark with a short, pointed snout and an enormous, scythe-like upper tail lobe that ends in a very narrow tip. It is dark blue to gray-blue on the back and sides and white below, and the white does not extend up over the base of the pectoral fins. The pectoral fins are long, nearly straight and broad at the tips. The eyes are moderate in size, with no grooves on top of the head.

Biology

Pelagic threshers live in tropical oceans around the world, mostly in the open sea from the surface to 300 m, usually above 150 m. In the eastern Pacific they are found from the Gulf of California to the Galápagos; the first record from the Gulf of California was published in 1997. Genetic studies link the threshers of Mexico with those of Ecuador.

They feed on small schooling fish and squid. Each female carries just one embryo in each uterus, so a litter is two very large pups, born well over a meter long, and the embryos feed on unfertilized eggs while they grow. Females mature at roughly 9 to 13 years and the species may live 24 to 28 years. With only two pups at a time, a population can grow just a few percent a year, so it recovers very slowly from fishing.

Things you probably didn't know

The tail is a weapon

Underwater video of pelagic threshers in the Philippines showed them hunting sardine schools with overhead tail-slaps that stun the fish, and a single strike let a shark eat more than one sardine.

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Only two pups

Pelagic threshers sampled in Ecuador carried one embryo in each uterus, a litter of two, among the smallest of any shark.

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A late arrival in the Gulf

The pelagic thresher was first reported from the Gulf of California only in 1997.

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Autumn mothers in the Gulf

In autumn 1998, pelagic threshers made up 25.6% of the artisanal shark and ray landings on the Gulf coast of Baja California. Almost 73% of the 143 examined were females, many of them pregnant.

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Down more than 70%

Catch-rate data from the Pacific and Indian oceans show declines of more than 70% over about 55 years (three generations), the basis for its Endangered listing.

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Protected as a migrant

In March 2026 the Convention on Migratory Species moved all three thresher sharks to its Appendix I, which calls for strict protection across their range.

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How it's caught in Los Cabos

Off Los Cabos, pelagic threshers are an occasional encounter in open water; the Cabo San Lucas Important Shark and Ray Area lists them among the sharks recorded there. Elsewhere in the Gulf they turn up in local catches by season: they were a large share of autumn landings on the Gulf coast of Baja California in 1998, and on the Gulf coast of Baja California Sur they were landed only in spring, in small numbers.

We release every thresher. Best practice: circle hooks that aren’t stainless steel, keep the shark in the water, unhook it quickly or cut the leader close to the hook, and hold it facing forward while the boat moves slowly so water runs over its gills. Keep clear of the long tail, and never lift a shark by the tail or gills.

Rules, records & conservation

Daily limit (NOM-017-PESC-1994)	Sharks: 1 per angler per day, and it counts as 5 of the 10 fish
Closed season (Pacific)	All shark species, May 1 – July 31; no shark fishing during the closure
IUCN Red List	Endangered (assessed 2018, published 2019): more than 70% decline over three generations
CITES	Appendix II since October 4, 2017 (all thresher sharks): international trade needs permits
IGFA all-tackle record	No separate category; the thresher shark record (767 lb 3 oz, 348 kg, Bay of Islands, New Zealand, 1983) is a common thresher

Top Anglers practices catch-and-release for all sharks.

Don't confuse it with

The bigeye thresher has very large eyes and deep grooves along the top of the head, and its belly is a solid, pale cream. The common thresher has white on the belly that extends up above the pectoral fins and pectorals that are curved with pointed tips. The pelagic thresher has moderate eyes, no head grooves, no white patch over the pectoral bases, and straight, broad-tipped pectoral fins.

Questions

Can you keep a pelagic thresher in Mexico?

By law a sport angler may keep one shark per day outside the Pacific closed season (May 1 – July 31). The pelagic thresher is Endangered, and we release every one.

How do you tell a pelagic thresher from a common thresher?

Look at the pectoral fins and belly. The common thresher has white that reaches up over the pectoral fin bases and curved, pointed pectorals; the pelagic thresher has no white there and its pectorals are straight with broad tips.