PrimeBite Fishing Yellowfin Tuna Full Transparency

Yellowfin Tuna — Full Transparency (v1)

Last updated: January 2026

This page is designed to leave nothing out: the exact equations, every variable we use, the open-access URLs behind each driver, verbatim quotes (with page pointers where available), and a plain-English explanation of what is research-backed vs what is calibrated.

On this page

The exact math (Yellowfin v1)

Yellowfin is an offshore all-day rating (no Major/Minor windows) built from “lifts” that map to a 1.0–5.0 rating.

L_ocean_raw = L_sst + L_chl + L_gradient
L_ocean     = clamp(L_ocean_raw, -0.06, +0.10)   // ocean sub-cap (anti-double-counting)

L_total_raw = L_phase + L_illum + L_ocean
L_total     = clamp(L_total_raw, 0, L_REF)       // global clamp

rating = 1 + 4 × (L_total / L_REF)               // where L_REF = 0.28

Calculation methodology (All‑day rating)

This section is the “how it’s calculated” reference for Yellowfin v1. Yellowfin combines a phase lift, an illumination lift, and a capped ocean block (SST + chlorophyll‑a + gradients) before mapping into the 1.0–5.0 scale. 

Step 1) Phase lift
phaseBoostValue = moonPhaseBoostYellowfinMahi(f)  // shared Yellowfin/Mahi family
L_phase = (phaseBoostValue × phaseWeight / 2.0) × 0.31

Step 2) Illumination lift (separate mechanism from phase)
L_illum = yellowfinLunarIlluminationLift(moonIllumFraction)

Step 3) Ocean block (SST + CHL + gradients) with anti-double-counting cap
L_ocean = clamp(L_sst + L_chl + L_gradient, -0.06, +0.10)

Step 4) Total lift → rating
L_total = clamp(L_phase + L_illum + L_ocean, 0, 0.28)
Rating  = 1 + 4 × (L_total / 0.28)

Variables (what’s research-backed vs calibrated)

Research-backed means the driver/pattern/mechanism is supported by open-access sources. Calibrated means we chose the exact thresholds/weights/caps to make a stable 1–5 score and to avoid double-counting.

Moon phase (L_phase)

Research-backed: an open-access offshore tournament summary reports Yellowfin catch-rate peak at First Quarter.

Calibrated: the exact smooth curve shape is a product choice (continuity + stability).

Source (open PDF): NC Sea Grant — Hook, Line & Science (Winter 2020)

“Scientists found a relationship between catch rates and lunar phase for 5 of the 8 species as shown here…
Yellowfin tuna  first quarter”

(PDF p.2)

Lunar illumination (L_illum)

Research-backed: Yellowfin night depth varies with illumination.

Calibrated: lift sizes are conservative; illumination is modeled separately from phase.

Source (open PDF): Wright et al. 2021 — Frontiers in Marine Science

“The average depth during the night varied with the lunar phase, with shallower dives (averaging around 20 m) when there was low illumination (new moon), and significantly deeper dives (averaging between 30 and 40 m) when illumination levels exceeded 0.85 (full moon; Supplementary Figure 3).”

(PDF p.5)

Environmental variables (verification)

This section focuses on the ocean data inputs (SST, chlorophyll‑a, and fronts/edges) and provides the primary open-access sources and quotes that support using them as drivers. Exact thresholds and lift magnitudes are calibrated and disclosed in-app and in code.

Sea surface temperature (SST) (L_sst)

Research-backed: regional “optimal SST” bands exist in open-access habitat modeling.

Calibrated: we translate those bands into conservative scoring bands for a global 1–5 scale.

Source (open PDF): Siregar et al. 2025 — AACL Bioflux

“In June, the optimal SST for the presence of this fish was in the range of 31.0-31.2°C. In July, the range shifted to a lower temperature, namely 30.5-31.0°C… in August… 31.3-31.6°C.”

(PDF p.1540)

Chlorophyll-a (CHL) (L_chl)

Research-backed: open-access response curves support a productive chlorophyll band for Yellowfin presence.

Calibrated: we keep CHL lifts capped and conservative to avoid coastal “false highs.”

Source (open PDF): Siregar et al. 2025 — AACL Bioflux

“…the high probability of Yellowfin tuna presence occurs in the range of 0.1-0.3 mg m-³ (Figure 7).”

(PDF p.1540)

Fronts/edges (gradients) (L_gradient)

Research-backed: Yellowfin habitat suitability is linked to mesoscale oceanographic features and boundary regions between eddies.

Calibrated: our gradient thresholds are heuristics (kept small) because papers don’t provide universal °C/10km thresholds.

Source (open access): Ramírez‑Mendoza et al. 2024 — Scientific Reports

“Our results suggest that the spatiotemporal distribution of yellowfin tuna is linked mainly to mesoscale oceanographic features… especially towards boundary regions between cyclonic and anticyclonic eddies…”

(PDF p.4)

Worked example (inputs → lifts → rating)

These are “math-complete” examples showing how the model reaches the ends of the 1–5 scale. A fully reproducible real-world example (with fixed ocean inputs for a specific date/location) is planned next.

Best case (can reach 5.0/5)

Worst case (can reach 1.0/5)

Model changelog (Yellowfin)

Canonical doc source

The canonical version of this content lives in the PrimeBite app repository docs (and is mirrored here for public transparency): docs/YELLOWFIN_TRANSPARENCY.md.