Carcharhinus signatus · Carcharhinidae · predator
Slender shark with a long, pointed snout and large eyes, that hunts at night in schools on the shelf edge. Endangered (EN) in Brazil and worldwide: capture banned.
Also called: tubarão-noturno, cação-noturno
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 night shark is a slender, coastal and semi-oceanic shark that lives on the continental shelf edge and around islands, usually between 50 and 100 m and down to about 600 m. It forms schools and hunts small bony fish and squid at night, which explains its name. Each female has 4 to 12 pups of about 60 cm. In the western Atlantic FishBase records it from Delaware (USA) to Cuba and from southern Brazil to Argentina; in the east, from Senegal to Namibia. It is Endangered (EN) on the national list and in the IUCN global assessment (2019). FishBase does not consider it dangerous to people. Do not seek out the species.
Slender shark with a very long, pointed snout, large eyes and small jaws, with serrated, slanted upper teeth. Low dorsal fins with elongated rear tips, and a ridge between the dorsal fins. Greyish-brown back, white belly, no marks on the fins. It resembles other slender Carcharhinus; the combination of long snout, large eyes and low dorsal fins helps tell it apart. If the shark has a ridge between the dorsal fins and you are unsure, release it.
Western Atlantic from Delaware (USA) to Cuba and the Bahamas, and from southern Brazil to Argentina (FishBase); in the east, from Senegal to Namibia. In Brazil, FishBase cites the south. On FishBase's Latin American country list: Mexico, the Caribbean, Venezuela, Brazil, Uruguay and Argentina.
Habitat: Shelf edge and slope, near the bottom or in midwater, usually 50 to 100 m, sometimes down to 600 m; forms schools.
coast
Estimate: no well-documented season in Brazil; the weights are neutral. Capture is banned all year.
Nighttime. Nocturnal: hunts small fish and squid at night, in schools (FishBase).
In West Africa it was found in water of 11 to 16 °C, at 90 to 285 m depth.
Little known effect.
No known effect; it is a nocturnal species.
Not very relevant.
Not applicable at sea.
Not well known.
Rough seas end trips offshore.
No relevant tide at the shelf edge; currents matter.
Usually 50 to 100 m; can go down to 600 m.
accessories
If a night shark bites by accident while bottom fishing on the shelf edge, release it in the water, cutting the line flush with the hook. When bottom fishing with a barbless circle hook, the hook comes out more easily.
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 EN (already on the previous list). Global: Endangered (EN, assessed 21/06/2019 by the IUCN). The whole family Carcharhinidae has been in Appendix II of CITES since 25/11/2023.
The national list (Portaria GM/MMA nº 1.667/2026) classifies the species as EN. Under Portaria GM/MMA nº 1.666/2026 (art. 3), species listed as VU, EN and CR have full protection: capture, transport, storage, processing and sale 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.
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.
This is not catch and release: it is release of an accidental catch. Keep the shark in the water and cut the line as close to the hook as possible. Don't lift it by the tail or take photos out of the water.
Capture and trade banned in Brazil. In other countries the meat is used (FishBase), but the species is Endangered: release it.
Length-weight relationship W = a·Lb (a = 0.00468, b = 3.07; 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.
