Hi All,
Chlorophyll in the water is generally produced by plankton, so what we are in effect looking at is the amount of plankton (food!) in the water. High levels of chlorophyll should indicate off color, nutrient rich water. Lower levels of chlorophyll should indicate cleaner water, and hopefully the very low levels will indicate clean blue water. Remember that the clean blue water is also most likely very low in nutrients. So the best combination for Tuna fishing would be to find where the clean blue water (assuming the temp is good) meets an area with a higher level of plankton. That area will be more likely to hold baitfish and to concentrate the fish. Sounds like we're fishing temp breaks, doesn't it? Essentially, we've probably been fishing plankton breaks all along. For Salmon fishing I will be doing in San Francisco next week, you typically look for the nutrient rich, off-color water. In that case, then you want the areas on the chart with the higher levels, shown in red / yellow.
These charts are for free. I subscribe to paid services. The difference is the frequency of updates and their are some private satellies that can "see" areas others cannot. The downside of satellite observation is that cloud cover is your enemy.
So, these charts are great to show where bait (the food chain) maybe.
Thanks guys,
Capt. Ed