Alopias vulpinus · Alopiidae · predator
Slender shark with a whip-like tail as long as the rest of its body and a white patch above the pectoral fins. Considered a sport fish in other countries, but Critically Endangered (CR) in Brazil: capture banned.
Also called: tubarão-raposa, cação-raposa, cação-pena, rabilongo
Choose the place and the species. The index, from 0 to 100, combines weather, sun, moon and tide with each fish's habits. Up to 28 days, with each day's confidence.
Reading the weather across 3 global models and 31 simulations…
Each card shows the day's index (0 to 100) and, below it, a strip with the index for each hour, from 0h to 23h. from poor to excellent.
Choose how many fishing days. We compare each stretch by its average index, discount days with a warning or closed season, and show the 3 best.
Line: the middle value of 31 simulations of the American GEFS model. Band: where 8 out of 10 fall. Narrow, firm trend; wide, high uncertainty.
The common thresher is the largest of the threshers and lives in tropical and temperate seas around the world, on the shelf and in open sea, more abundant near land; the pups stay in shallow waters and bays. The upper lobe of the tail, as long as the rest of the body, serves as a whip to round up and stun schools of mackerel, sardines, squid and other pelagic fish. It has 2 to 4 pups per litter (usually 2), born at 114 to 150 cm, and maturity comes at about 3.5 m. It is caught by commercial fishing, which uses the meat, liver, leather and fins. It is Critically Endangered (CR) on the national list; globally, Vulnerable (VU) according to the IUCN. Do not seek out the species.
Upper tail lobe ribbon-shaped, as long as the rest of the body. Relatively small eyes, curved pectoral fins with narrow tips and, at the base of the pectorals, a clear white patch: the white belly extends onto them. Back brown, grey, blue-grey or nearly black, paler on the flanks and abruptly white below. The second dorsal fin starts well behind the tips of the pelvic fins. The bigeye thresher has huge eyes and no white patch; the pelagic thresher is smaller, dark blue and also lacks the patch.
Cosmopolitan in tropical and temperate seas (FishBase: 74°N to 58°S). In Brazil, open sea and shelf along the coast, with juveniles closer to land. In Latin America FishBase records it from Mexico and the Caribbean to Argentina and Chile; in Uruguay it is known as azotador.
Habitat: Continental shelf and open sea, from the surface to more than 600 m; juveniles in bays and shallow waters near the coast.
coast
Estimate: no well-documented season in Brazil; the weights are neutral. Capture is banned all year.
Any time. Hunts schools by day and by night; there is no reliable local data on timing in Brazil.
Prefers temperate to lukewarm water; the exact range varies by region.
Little known effect.
No known effect.
Not very relevant.
Not applicable at sea.
Not well known.
Rough seas end trips offshore.
No relevant tide in the ocean; currents and forage fish schools matter.
From the surface to more than 600 m; it usually stays shallow.
accessories
If a thresher shark bites by accident, release it beside the boat, in the water, cutting the line flush with the hook. Watch out for the tail whip and the animal's weight: it is a large shark.
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
Conservation: On the national list of threatened species as CR (already on the previous list). Global: Vulnerable (VU, assessed 06/11/2018 by the IUCN). Since 2017 all thresher sharks have been in Appendix II of CITES.
The national list (Portaria GM/MMA nº 1.667/2026) classifies the species as CR. Under Portaria GM/MMA nº 1.666/2026 (art. 3), VU, EN and CR species have full protection: catch, transport, storage, processing and trade are banned. If you hook one by accident, release it right away, with minimal handling.
Source: Portaria GM/MMA nº 1.666/2026, art. 3º, and Portaria GM/MMA nº 1.667/2026
In Brazil, finning is banned: cutting off the fins and discarding the rest of the body. The rule covers landing, transport, and trade by fishing vessels: every shark or ray must arrive whole, with its fins naturally attached to the body (partially folding them against the body is allowed); carrying an animal aboard without fins or with loose fins, and transferring sharks and rays between vessels, is prohibited. This does not authorize catching this species, which is banned.
In recreational sport fishing in Mexican saltwaters, the limit for sharks is one specimen per angler per day, which counts as five toward the total limit of ten fish. Fish caught in sport fishing may not be sold. Catch and release does not count toward the limit: prefer releasing.
In 2021 Colombia stopped considering sharks and marine rays a fishery resource and began treating them as a hydrobiological resource; the recitals of Decree 281/2021 state that they may not be extracted for commercial or sport purposes, and the decree created an environmental protection plan. Later AUNAP rules dealt with incidental catch in artisanal fishing; we did not check the consolidated text. When in doubt, release it into the water.
Federal Fisheries Council Resolution 8/2021 (Consejo Federal Pesquero) bans directed fishing for chondrichthyans (sharks, rays and chimaeras), finning (cutting off the fins and discarding the body) and the use of gaffs to return live animals to the sea, and requires that sharks caught by chance be returned quickly and with minimal trauma, except cazón, gatuzo, pez ángel, espinoso and pintarroja. The text refers to trips and vessels, that is, the federal commercial fleet, and invites the provinces to adopt similar measures; we did not find a specific rule for sport fishing in Buenos Aires. For sport anglers, good practice is to release the shark in the water, without a gaff.
Law 9 of 2006 bans finning in Panama's jurisdictional waters. The law's definition of shark fishing covers directed or incidental catch by artisanal, commercial, industrial and sport vessels. The fine for artisanal fishing reaches 1,000 balboas, without prejudice to criminal liability. In the sources we checked, we did not find a specific Panamanian rule on retention or release for sport anglers.
Law 20.525 (2011) added art. 5 bis to the General Law on Fisheries and Aquaculture: it is forbidden to cut the fins of any shark on board fishing vessels or during transshipment, and landing must be done with the fins fully or partially attached to the body. A loose fin without the corresponding trunk on board is presumed to be an offense. The fine for the vessel owner ranges from 50 to 500 UTM. We did not verify a specific Chilean rule on shark retention in marine recreational fishing.
This is not catch and release: it is release of accidental catch. Do not bring the shark aboard; keep it beside the boat, in the water, and cut the line as close to the hook as possible. Watch the tail and do not take photos.
Capture and trade banned in Brazil. In other countries the meat, liver, leather and fins are used (FishBase), but the species is threatened: release it.
Length-weight relationship W = a·Lb (a = 0.00832, b = 2.86; FishBase (relação peso-comprimento bayesiana, estimativa da própria espécie)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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The seasonal weights (months), the time of day and the sensitivities (cold, pressure, moon, wind, rain, tide, strong light, murky water and noise) are the app's editorial estimates, based on the literature below and on field experience from anglers and guides. The water temperature range and the common size range are also editorial estimates, supported by FishBase. The months show when an angler usually finds the species, not a catch season. They are not official data or measurements made for this species, and they may vary by region and year. Legal rules appear in the rules section, with the norm and a link.
The weather comes from three independent global models, cross-checked hour by hour: when they agree, confidence goes up; when they diverge, the band between them shows on the chart. Beyond 16 days, we use the GEFS ensemble of 31 simulations: if 20 of the 31 predict rain, the chance of rain is 65%. Sun and moon are calculated astronomically, with no uncertainty.
The index adds up, weighted for each species: time of day (species curve anchored to real sunrise and sunset), moon (transits, rise and set, phase), pressure (3 h trend and 24 h swing), water temperature (in rivers, estimated from air temperature; at sea, estimated by an ocean model), wind, rain, clouds, tide and the month in the species' cycle.
Accuracy measured in the reference project (4 regions, 93 days, forecast vs. observed): maximum temperature is off by 0.6 °C on average the next day and 1.7 °C at 7 days; rain of 5 mm or more is detected 76% of the time the next day and 57% at 7 days. Detection isn't everything: the false alarm rate isn't published here yet, and 93 days in 4 regions is still a small sample. We now also measure every day, at the app's destinations:
Your location is saved only on this device and feeds the forecast, the map and the "today" on the home page.
