Bigeye Tuna — Research & Methodology (v1)
Last updated: 2026-02-15
This page documents the variables we use for Bigeye (v1), the open-access URLs behind each driver, verbatim quotes, and what is research-backed vs calibrated. We do not publish proprietary weights, caps, or equations.
How it works (overview)
Bigeye is an offshore all-day rating built from phase (full-moon peak), night-availability lift, and a small capped ocean block (SST + optional chlorophyll). Research chooses the drivers; we calibrate weights and caps. Bigeye v1 is intentionally conservative. Exact values are proprietary.
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 curve shape/thresholds/weights/caps to produce a stable 1.0–5.0 score and to avoid overclaiming from region- or gear-specific studies.
Moon phase (L_phase)
Research-backed: Jatmiko et al. (2016) report significant differences among moon phases with the highest average catch rate at full moon in their dataset.
Source: Jatmiko et al. 2016 — ILMU KELAUTAN (open access)
“The result showed that the average catch rate of bigeye tuna differed significantly among the moon phases. Tukey post-hoc tests showed that the average catch rate at full moon was the highest among the groups with around 0.3/100 hooks.” (PDF p.1 / journal p.101)
Calibrated: the exact curve shape and scale are product choices (smoothness + stability); values are proprietary.
Night availability (L_time_avg)
Research-backed: tagging studies show strong diel vertical behavior (shallower at night).
Source (open PDF): Musyl et al. 2003 — Bigeye vertical movements
“At night, however, bigeye tuna generally restrict their vertical movements to the surface layer.” (PDF p.2)
Calibrated: we translate this into a small, fixed all-day-average lift; exact value is proprietary.
Oceanography (SST + chlorophyll-a/SSC) (L_ocean)
Research-backed: regional studies support SST and chlorophyll (or SSC proxies) as predictors/covariates for Bigeye catchability/habitat.
Source (open PDF): Syamsuddin et al. 2013 — Fishery Bulletin (open access)
“SST was a more important oceanographic predictor of Bigeye Tuna catches than were the other environmental variables (SSHA and chlorophyll-a) in this region.” (PDF p.10)
Calibrated: we keep the ocean effect small and capped and apply a cold-water gate; exact cap and thresholds are proprietary.
Environmental variables (verification)
This section highlights the key open-access quotes behind the SST/CHL bands used in Bigeye v1.
SST anchors
Syamsuddin et al. 2013 (open PDF): PDF
“Our results indicate that Bigeye Tuna catches increased in areas with relatively low temperatures (24–27.5°C) and decreased at temperatures >27.5°C (Fig. 6B).” (PDF p.10)
Setiawati & Miura 2014 (ResearchGate landing page): Link
“Statistical analysis showed the optimum of SST for bigeye tuna is less than 29.1°C and more than 27.4°C.” (Abstract)
Chlorophyll / SSC anchors
“High probabilities of Bigeye Tuna presence were observed … for chlorophyll-a levels ranging from 0.04 to 0.16 mg m–3.” (Syamsuddin 2013, PDF p.8)
“In addition, the optimum value of SSC was 0.055 to 0.175 mg m-3.” (Setiawati & Miura 2014, Abstract)
Song et al. 2009 (open access PDF): PDF
“0.090–0.099μg·L−1” (PDF p.12, Table 5; units note: μg/L = mg/m³)