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PrimeBite Fishing Black Marlin Research & Methodology

What Conditions Turn On Black Marlin?

Last updated: 2026-10-03

Short answer

Black marlin fishing is shaped by the moon, the season and water temperature. Great Barrier Reef charter diaries show higher catch rates around the half-moons, roughly 30–40% lower on the new and full moon, and a September–December run with higher catches in October–November (Pepperell et al. 2025). The GBR spawning aggregation occurs October–December (Domeier & Speare 2012). Sea-surface temperature is a supporting input; Setyadji & Fahmi 2020 report high catches around 29–31°C in a different fishery.

This page explains the public Black Marlin model story: what PrimeBite uses, what the research supports, and what the limits are. We do not publish the exact numeric tuning or any reproduction-ready recipe.

On this page

How it works (overview)

Black Marlin is an offshore all-day rating built from three live drivers: moon phase, GBR-timed seasonality, and SST. PrimeBite does not show Major/Minor moon-position windows for Black Marlin, and the old overlap term is no longer part of the live score.

Research sets the drivers and their direction. The public 1.7.0 model follows the moon pattern in the GBR charter diaries and the studied September–December run. PrimeBite’s exact tuning remains private.

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 (quarter phases / “half-moons”)

Research-backed (GBR diaries): higher CPUE during half-moons and ~30–40% lower during new or full moons.

Pepperell et al. 2025 (open access): DOI • PDF • cached PDF p.7 / p.13

“Moon phase had a non-linear relationship with higher CPUE during a half moon and approximately 30%–40% lower during new or full moons (Fig. 7e).”

Research-backed direction: the public 1.7.0 moon driver follows Pepperell et al. 2025 Fig. 7e, favoring half-moons over new and full moons. PrimeBite’s exact tuning remains private.

Seasonality (GBR timing)

Research-backed: GBR charter catches were studied during September–December, with higher catch rates in October and November. Domeier & Speare describe the spawning aggregation during October–December; that timing is separate from the charter catch-rate peak.

Domeier & Speare 2012 (open access): PLOS ONE full text

Pepperell et al. 2025 (open access): PDF • cached PDF p.11

Calibrated limits: in public 1.7.0, season contributes zero outside the studied September–December run. The rating still uses moon phase and any available sea-surface temperature, with the note “outside the studied season”. January–August are unmeasured by these charter studies, not evidence of poor fishing. Applying GBR timing to other waters is a modeling choice.

Environmental variables (verification)

This section documents what the papers say (verbatim quotes) and then shows how PrimeBite maps that into a stable rating (calibrated thresholds + caps).

SST (SST-only ocean block)

Setyadji & Fahmi 2020 (open access): DOI • PDF • cached PDF p.6 / p.7

“In this study, high CPUE occurred between 29–31°C...”
“... SST and SSH were statistically significant when incorporated into the models, but it allegedly wasn’t the main driver...”

Calibrated: PrimeBite uses SST as a smaller ocean covariate, treats missing SST as neutral, and keeps the exact thresholds and caps private.

Limitations / caveats

  • The strongest moon-phase and seasonality evidence comes from one GBR charter-diary dataset family. PrimeBite uses one global Black Marlin profile; transferring this regional pattern to other waters is a modeling choice.
  • January–August are outside the studied September–December run. Season contributes zero with an “outside the studied season” note; these unmeasured months are not evidence of poor fishing.
  • SST support comes from a different fishery and region, so PrimeBite keeps the SST block smaller than the moon driver.
  • SSH appears in the literature, but it is not a live scored PrimeBite variable yet.
  • If SST is missing, PrimeBite keeps the ocean block neutral instead of guessing.

Sources

Changelog

  • 2026-10-03: aligned this page with public 1.7.0: the September model changes retain moon phase, season and sea-surface temperature; season contributes zero outside the studied run, with an “outside the studied season” note.
  • 2026-09-27: the moon driver was updated to follow the half-moon pattern in Pepperell et al. 2025 Fig. 7e.
  • 2026-09-11: the model was updated to use the studied September–December season without an off-season penalty.
  • 2026-03-30: removed the unsupported overlap term from the live Black Marlin score and rebuilt the remaining 3-driver model.
  • 2026-03-30: updated the public page to describe the driver set at that time.