Understanding Chlorophyll for Fishing
Chlorophyll concentration indicates the presence of phytoplankton - microscopic plants that form the base of the ocean food chain. High chlorophyll areas attract zooplankton, which attract baitfish, which attract the gamefish you're after.
Reading the Chlorophyll Scale
<0.1
Blue Water
0.1-0.3
Clear
0.3-1.0
Bait Zone
1-5
Productive
>5
Bloom
The "Edge" Strategy
The most productive fishing often happens at the edges - where green (productive) water meets blue (clear) water. Here's why:
- Baitfish concentrate at these boundaries, feeding on plankton but staying near clear water to escape
- Predators patrol the clear side, using visibility to their advantage
- The edge moves - track it over multiple days to predict where fish will be
What Each Color Means for Fishing
- Deep Blue (Very Low) - "Blue water" - clear, offshore, good for tuna that hunt by sight
- Cyan (Low) - Clear water with some productivity, good visibility for gamefish
- Green (Moderate) - The "bait zone" - sardines, anchovies, and squid concentrate here
- Yellow/Orange (High) - Very productive but murky, fish may be deeper or scattered
- Red (Bloom) - Algae bloom conditions, can be too thick, fish often avoid
Combining with SST
The best fishing spots are often where:
- Temperature breaks coincide with chlorophyll edges
- Warm water pushes against a productive (green) area
- Upwelling brings cool, nutrient-rich water to the surface (creating blooms)
View the SST map →
Data Source
Chlorophyll data comes from NOAA's VIIRS (Visible Infrared Imaging Radiometer Suite) satellite sensor, which measures ocean color to estimate chlorophyll concentration in milligrams per cubic meter (mg/m³).