Spotter plane AOIs
Spotter plane activity map (AOIs)
An AOI, or area of interest, on the Catalysst SoCal chart is airplane activity: a patch of ocean where a fish-spotting airplane has been circling. Spotter pilots circle when they are working fish, bait or kelp paddies for the boats below them, so the places they circle are some of the best clues you can get about where fish were found.
What is an AOI?
An AOI is not a forecast or a model. It marks real airplane activity. Spotter planes broadcast their position over ADS-B, the same signal airliners use. Catalysst follows the known fish-spotting aircraft, and when one flies a tight circle over the water, that spot is recorded.
Circles that land close together over the last 7 days are grouped into one AOI and drawn on the chart. The more circling in an area, the stronger the signal that something was there worth working.
Why spotter planes circle
A spotter pilot's job is to find fish from the air and talk boats onto them. When they find a school, a bait ball, a foamer or a productive kelp paddy, they hold over it by flying circles while the boats run in. Ordinary traffic flies from A to B; a spotter that is working fish turns and turns again in the same patch.
That turning is what Catalysst detects. A plane passing through an area does not create an AOI. A plane that keeps coming back around does.
Pelagic AOIs and Swordfish AOIs
AOIs come in two layers. Pelagic AOIs (green) mark circling by planes that work tuna, yellowtail and other surface pelagics. Swordfish AOIs (purple) mark circling by planes that hunt swordfish, which is a different kind of flying over different water. You can turn each layer on and off.
The chart shows the area and the category. It does not show which plane did the circling or who it was working for.
How to fish an AOI
Treat an AOI as where fish were recently found, then check it against the water. Turn on sea surface temperature and look for a temperature break running through or near the AOI. Turn on chlorophyll and look for a green-to-blue edge. An AOI that sits on a break or an edge is a much stronger lead than one in flat, featureless water.
Then check the fleet. AIS shows where the sportboats are now and where they stopped, so you can see whether boats are still working the same area or have moved on. Fresh circling, a good break and boats stopping in the same spot is the strongest signal you can get on the chart.
What AOIs can't tell you
Spotter planes do not fly every day. Weather, season and charter schedules decide when they go up, so there can be quiet stretches with no new AOIs. Coverage also depends on ADS-B receivers on shore, so a plane working far offshore can drop out of range.
An AOI tells you where airplanes were working, not that fish are still there. Use it alongside the water charts and the fleet, not on its own.
Frequently asked
What does AOI mean on the Catalysst chart?
AOI stands for area of interest. On the Catalysst SoCal chart an AOI is airplane activity: an area where a fish-spotting airplane has been circling over the water in the last 7 days.
How does Catalysst know where spotter planes are circling?
Spotter planes broadcast their position over ADS-B. Catalysst follows the known fish-spotting aircraft and records each spot where one flies a tight circle over the water, then groups nearby circles from the last 7 days into AOIs.
What is the difference between a Pelagic AOI and a Swordfish AOI?
Pelagic AOIs (green) come from planes that work tuna, yellowtail and other surface pelagics. Swordfish AOIs (purple) come from planes that hunt swordfish. They are separate layers you can switch on and off.
Does an AOI mean fish are there right now?
No. It means spotter planes were working that area recently. Check it against the SST break, the chlorophyll edge and where the fleet is stopping before you commit to it.