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Methodology

How This Works

Pelagic Studio simulates how fish perceive fishing lures using peer-reviewed visual neuroscience. Every parameter in the model is grounded in published research — not guesswork.

Supported Species

Each species profile is built from the best available evidence. Evidence quality varies — we clearly indicate the confidence level for each species.

Direct MSP — measured on the species
Related species MSP — from a close relative
Genomic inference — gene expression + ERG

Yellowfin Tuna

Thunnus albacares

Direct MSP

Dichromat (2 cones) · Rods: 483 nm

Twin cones: λmax = 485 nm

Blue-green — dominant channel, primary brightness and motion detection

Single cones: λmax = 426 nm

Violet — secondary channel, short-wavelength discrimination

No long-wavelength cones. Red, orange, and most yellow appear as dark grey or black.

Loew, McFarland & Margulies (2002). Developmental Changes in the Visual Pigments of the Yellowfin Tuna. Marine and Freshwater Behaviour and Physiology, 35(4), 235-246.

Giant Trevally

Caranx ignobilis

Related species MSP

Dichromat (2 cones) · Rods: 495 nm

Twin cones: λmax = 495 nm

Blue-green — ~10nm green-shifted from tuna, dominant channel

Single cones: λmax = 430 nm

Blue — secondary channel

Similar to tuna but slightly green-shifted. Blind to red/orange. Inferred from yellowtail kingfish (Seriola lalandi) MSP data.

Nagloo, Hart & Collin (2016). The accessory optic system in yellowtail kingfish. Aquaculture, 474, 130-137.

Red Snapper

Lutjanus campechanus

Related species MSP

Trichromat (3 cones) · Rods: 497 nm

Double cone (RH2): λmax = 520 nm

Green — dominant channel, enables green/chartreuse detection

Double cone (LWS): λmax = 555 nm

Yellow-green — enables warm-color perception at shallow depths

Single cone (SWS2): λmax = 440 nm

Blue — short-wavelength discrimination

Can see greens, yellows, and some oranges that tuna cannot. LWS cone provides broader spectral range, especially at shallow depths.

Lythgoe, Muntz, Partridge, Shand & Williams (1994). The ecology of the visual pigments of snappers on the Great Barrier Reef. J Comp Physiol A, 174, 461-467.

Coral Grouper

Plectropomus leopardus

Genomic inference

Trichromat (3 cones) · Rods: 500 nm

Double cone (RH2): λmax = 515 nm

Green — dominant channel, fine-tuned for reef background contrast

Double cone (LWS): λmax = 555 nm

Yellow-green — warm-color detection for prey contrast

Single cone (SWS2): λmax = 440 nm

Blue — short-wavelength discrimination

Reef ambush predator. Highest uncertainty — no direct MSP data for any sport fishing grouper. Inferred from Epinephelus ERG + genomics.

Kim et al. (2015). ERG evaluation and opsin gene expression in longtooth grouper (E. bruneus). Marine and Freshwater Behaviour and Physiology, 48(6).

The Vision Algorithm

For each pixel in the uploaded image, the algorithm performs the following steps:

  1. Extract RGB values and convert to HSL to estimate the pixel's dominant wavelength in the visible spectrum (380-700nm).
  2. Apply depth attenuation using Jerlov Type I open ocean water coefficients. Red wavelengths are absorbed ~21x faster than blue at the selected depth.
  3. Compute cone photoreceptor responses using the Govardovskii et al. (2000) visual pigment nomogram — a mathematically rigorous model of vertebrate photoreceptor spectral sensitivity.
  4. Weight the responses by each cone type's relative abundance in the retina. Dichromats use 2-cone mapping; trichromats use 3-cone mapping with an additional LWS channel for warm-color perception.
  5. Reconstruct a displayable image in the species' perceptual color space. Dichromat output is blue-dominant; trichromat output includes broader green/warm tones.

Note: Exact fish perception cannot be measured — we can only model it from physiological data. The output is the best scientific approximation, not a definitive rendering of subjective fish experience.

Water Depth Model

The depth slider applies the Beer-Lambert law of light attenuation through water: I(d) = I₀ × e^(−Kd × d), where Kd is the diffuse attenuation coefficient for each wavelength band. Coefficients are from Jerlov (1976) Type I water — clear open ocean conditions typical of offshore pelagic fishing grounds.

WavelengthColorKd (per m)% at 10m% at 50m
420-460 nmViolet-Blue0.02578%29%
460-500 nmBlue0.02082%37%
500-540 nmBlue-Green0.03074%22%
540-580 nmGreen-Yellow0.06552%4%
580-620 nmYellow-Orange0.13027%<1%
620-660 nmOrange-Red0.2906%~0%
660-700 nmRed0.4301%~0%

References

Loew, E.R., McFarland, W.N. & Margulies, D. (2002). Developmental Changes in the Visual Pigments of the Yellowfin Tuna, Thunnus albacares. Marine and Freshwater Behaviour and Physiology, 35(4), 235-246.

Nagloo, N., Hart, N.S. & Collin, S.P. (2016). The accessory optic system and retinal topography of the yellowtail kingfish (Seriola lalandi). Aquaculture, 474, 130-137.

Lythgoe, J.N., Muntz, W.R.A., Partridge, J.C., Shand, J. & Williams, D.M. (1994). The ecology of the visual pigments of snappers (Lutjanidae) on the Great Barrier Reef. J Comp Physiol A, 174, 461-467.

Kim, S.J. et al. (2015). Electroretinographic evaluation and SWS1 opsin gene expression in the vision of juvenile longtooth grouper (Epinephelus bruneus). Marine and Freshwater Behaviour and Physiology, 48(6).

Govardovskii, V.I., Fyhrquist, N., Reuter, T., Kuzmin, D.G. & Donner, K. (2000). In search of the visual pigment template. Visual Neuroscience, 17(4), 509-528.

Jerlov, N.G. (1976). Marine Optics (2nd ed.). Elsevier Oceanography Series 14, Amsterdam.

Cortesi, F. et al. (2020). Visual system diversity in coral reef fishes. Seminars in Cell & Developmental Biology, 106, 31-42.