Istiompax indica · Istiophoridae · predator
The giant of the billfishes, with fish over 700 kg. In the American Pacific it is the great trophy of Panama, Costa Rica, Colombia, Ecuador and northern Peru.
Also called: marlim-negro, black marlin
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.
Indo-Pacific tropical and subtropical marlin, which on the American continent appears along the Pacific coast from Mexico to Peru. Unlike other marlins, it tends to stay close to the coast, islands, seamounts and shelf edges, in the layer above the thermocline. It eats small tunas, squid, octopus and other fish. It is the largest marlin, with records over 4.5 m and 750 kg. Its pectoral fins are rigid and do not fold against the body, the surest mark of the species. It is caught trolling live bait (mainly bonito) pulled slowly, from lodges and boats in Panama, Costa Rica, Colombia and Ecuador. Nearly all sport fishing is catch and release.
Thick, slightly compressed body, short sturdy bill. The first dorsal fin is low, lower than the body depth. The pectoral fins are rigid and stay open, not folding against the body, even on a dead fish. Dark blue back, silver-white belly, sometimes with light blue stripes. The blue marlin has pectoral fins that fold; the striped marlin has a first dorsal fin taller than the body and well-marked stripes.
Does not occur regularly in Brazil; in the Atlantic there are only records of stray fish. Tropical and subtropical Indo-Pacific; in the Americas, the Pacific from Mexico to Peru. Classic destinations: Piñas Bay and Hannibal Bank (Panama), Costa Rica, the Pacific coast of Colombia, Ecuador and Cabo Blanco in northern Peru.
Habitat: Surface layer above the thermocline, near the coast, islands, seamounts, shelf edges and banks with schools of bonito and tuna.
In the Pacific off Panama and Costa Rica it is fished all year; many operators point to the dry season, December to April, as the best window. The presence of bonito schools over the banks matters more than the month.
Daytime. Strikes all day; tide and current changes over the banks often concentrate the bites.
Water below 22 °C often drives the fish away; look for thermal fronts and warmer blue water.
Little direct effect; a front with rough seas makes fishing hard.
At the dock they say a full moon makes fish feed at night; the effect counts for less than bait and water.
Light rain is no problem; a thunderstorm with lightning at sea: head in.
Does not apply at sea. The equivalent is clear blue water with bait over the bank.
Engine and wake attract; noisy teasers help bring the fish up.
Moderate swell helps the baits; strong wind makes leaving dangerous.
Tide and current changes over banks and seamounts concentrate the strikes.
Hunts from the surface down to about 200 m; fish the edges of banks and seamounts.
lures
natural baits
accessories
Find the bonito school over the bank, put a live bait in front of it and pull very slowly. With a circle hook, don't strike: let the line tighten and let the drag do the work.
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: Highly migratory; stocks are assessed by regional tuna commissions in the Pacific.
Within the 50 nautical mile strip off the Mexican coast, marlins, sailfish and swordfish (the billfish) are reserved for recreational sport fishing. The limit is 1 billfish per angler per day, which counts as 5 toward the total limit of 10 marine fish. Filleting billfish on board is prohibited, fish above the quota must be released alive, and fish caught in sport fishing may not be sold.
Release with the fish in the water, cutting the leader near the hook when it cannot be removed safely. Revive it with the boat moving slowly forward. Never haul a large marlin aboard for a photo.
Good-quality meat, eaten in some countries, but in sport fishing in the Americas the practice is release.
Length-weight relationship W = a·Lb (a = 0.00447, b = 3.13; FishBase (estimativa bayesiana)). It's an average: a fat or lean fish can vary by 10% to 20%.
estimated weight
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The season 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 the field experience of anglers and guides. They are not official data nor a measurement made for this species, and they may vary by region and year. Closed seasons and 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.
