polla drum
Umbrina xanti · Sciaenidae · predator
Sandy-bottom grunt of the eastern Pacific, from the Gulf of California to Peru, with commercial fishing.
Also called: roncador-de-cauda-amarela, polla, corvina rabo amarillo, surf croaker
- maximum
- 40 cm
- depth
- 0–35 m
the right time
to be on the water
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…
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hour by hour
slide your finger or mouse over the chart to see each hoursee hour-by-hour table
why this index at —?
choose the day
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.
the fishing month at a glance
what's the best window for the crew?
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.
trend for the coming weeks
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.
everything about the polla drum
who is the polla drum
A fish of the family Sciaenidae, with an oblong, compressed body, reaching 40 cm. Common size 22 cm. It lives over sandy bottoms, from 0 to 35 m, from the Gulf of California to Peru. Juveniles also stay in tide pools along the shore. It eats fish, crustaceans and bivalve mollusks. It is commercially fished. The mouth is small and inferior, with a stiff barbel on the chin, which tells it apart from the large-mouthed croakers.
Essential profile. Identification, where it occurs and rules, with data from FishBase and the cited regulations. Season, time of day, technique and bait are added once we have a good source for the polla drum; in the meantime, see the similar species.
identification
Oblong, compressed body, with an arched back profile and a projecting snout. The mouth is small and inferior, and the chin has a stiff barbel. The body is dark and silvery, with no stripes on the flanks, and the first ray of the pelvic fin is white, with a long tip.
where found
Eastern Pacific, from the Gulf of California, Mexico, to Peru, on sandy bottoms in coastal waters.
Habitat: Sandy bottom, 0 to 35 m; juveniles in tide pools.
rules for the polla drum
Summary of the regulations we found, with the source for each. Rules change; before keeping or transporting fish, check with the state environmental agency.
We found no species-specific rule beyond the region's general rules.
catch and release
catch and release Releasing the fish alive, quickly and with a wet hand. During a closed season it isn't always allowed: what the regulation says applies.
Harmless to people. If it comes up in the net or on the line, release it carefully.
how much it weighs without taking it out of the water
Length-weight relationship W = a·Lb (a = 0.00871, b = 3.13; 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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sources and references
Essential profile: size, length-weight, depth, countries and conservation come from FishBase and the cited regulations, and the texts were written from those sources. Season, time of day, sensitivities, technique and baits and lures are not included yet, because we did not find a good source for this species.
- scientific FishBase: Umbrina xanti (ficha da espécie)Size, length-weight, depth, habitat, distribution, biology, and IUCN status. Page checked on Oct 13, 2026.
- scientific FishBase: nomes populares de Umbrina xantiNames by country and language.
similar species
where each number comes from
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.
sources for this lookup
how accurate the forecast is
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: