Prionace glauca · Carcharhinidae · predator
The most common oceanic shark, indigo blue, slender with huge pectoral fins. It is not on the national list; in Brazil commercial fishing has a quota. In recreational fishing, the right thing to do is release it.
Also called: tubarão-azul, cação-azul, mole-mole, focinhudo, cação-focinhudo, tintureira
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 blue shark lives in all tropical and temperate oceans and is probably the most widely distributed shark. It prefers waters of 12 to 20 °C and becomes more abundant the farther it is from the equator. It is oceanic, but comes close to shore where the continental shelf is narrow. In the South Atlantic, southern and southeastern Brazil and Uruguay serve as a mating and nursery area, where young sharks grow in the zone where the Brazil and Falklands/Malvinas currents meet. It is the shark most caught by tuna longlines and, in Brazil, has an annual catch limit for the commercial fleet. In offshore sport fishing it is taken on chum and drifted bait and is usually released. Global assessment: Near Threatened.
Very slender body, intense indigo-blue back, bright blue flanks and white belly. Long, narrow, pointed snout, large eyes. Very long, narrow pectoral fins, sickle-shaped; small first dorsal fin set far back. The mako is also blue, but it is stocky, with a conical snout, a crescent-shaped tail and short pectoral fins. 'Tintureira' and 'bico-doce' are also names of other species.
Open sea along the whole coast, most abundant in the Southeast and South. In the western Atlantic it ranges from Canada to Argentina; in the Pacific, from Alaska to Chile.
Habitat: Open ocean and the continental shelf edge, from the surface to hundreds of meters; comes close to shore where the shelf is narrow.
coast
states
Amapá, Pará, Maranhão, Piauí, Ceará, Rio Grande do Norte, Paraíba, Pernambuco, Alagoas, Sergipe, Bahia, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul
Estimate: present year-round in the open sea of the South and Southeast, with more encounters in the cold months, when cold water moves north.
Any time. Active by day and night; usually rises to the surface at night and responds to chum by day.
Prefers cold to temperate water (12 to 20 °C).
Cold fronts bring rough seas that end the trips.
Little known effect.
Not very relevant.
Follows temperature fronts and the shelf edge.
Curious; often circles stopped boats that are chumming.
Rough seas prevent drifting.
No significant tide in the ocean; current is what matters.
From the surface to about 220 m; it descends below 1,000 m.
natural baits
accessories
With ground-fish chum, the blue shark comes circling the boat; use a circle hook, keep the fight short and release it beside the boat, cutting the leader close to the mouth.
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: Not on the national list (Ministerial Ordinance GM/MMA 1.667/2026). Global assessment: Near Threatened (IUCN, November 6, 2018). Listed in CITES Appendix II. The Atlantic stock is managed by ICCAT.
In Brazil, finning is prohibited (cutting off the fins and discarding the body). Every shark or ray landed must arrive with its fins attached to the body; it is prohibited to carry on board an animal without fins or with loose fins, and to transfer sharks between vessels. It applies to any shark that may be kept.
The blue shark fishery has an annual catch limit set by ordinance, valid only for the surface horizontal longline (modalities 1.1 and 1.2 of INI 10/2011). Other commercial fishing methods may not catch, retain or land the species and must release it by cutting the line with the animal in the water. All landings must be made with the fins attached to the body. The ordinance covers commercial fishing and does not mention recreational fishing; for anglers the general rules apply. Confirm the current status and the year's quota with the Ministry of Fisheries.
In Río Negro Province marine sport fishing (San Matías Gulf, El Cóndor, Bahía Creek), the blue shark (Prionace glauca) is under a special protection regime: killing during capture is prohibited and release is mandatory. In boat fishing targeting sharks: one hook per line (tandem rigs and tartuna-type galvanized hooks prohibited), a "J" hook with the barb filed or flattened, or a circle hook. A specimen on board only with scientific authorization.
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.
Don't bring it aboard: release it beside the boat with the shark in the water, cutting the leader close to the mouth. The blue shark needs to swim to breathe: if it comes in exhausted, hold it facing the boat's movement, very slowly, until it revives.
It may be kept under the general recreational fishing rules, but release is the best practice. Oceanic sharks accumulate mercury.
Length-weight relationship W = a·Lb (a = 0.00457, b = 3.08; FishBase (estimativa bayesiana para a espécie, comprimento total)). 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), time of day and 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 of anglers and guides. The months indicate the time of year when the angler usually finds the species near the coast, not a catch season. They are not official data or measurements made for this species and may vary by region and year. Legal rules appear in the rules section, with the regulation and 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.
