Red LED lights used to attract certain kinds of fish is what I read. I saw something about this a while back. Here's something:
One Redditor pointed out that the glow was most likely caused by red LED lights attached to fishing vessels looking to attract saury. The fish are attracted to the lights and vacuumed aboard, allowing the fishermen to catch thousands of saury at a time.
The fishing method is often used to catch Pacific saury, particularly by Taiwanese, Japanese, and Chinese fishermen. Atlantic saury is found as far north as the Gulf of Saint Lawrence all the way down to Bermuda and also from Iceland down to Morocco. So though it's unclear where in the Atlantic the pilot took these photos, it's entirely possible that the red glow is due to the LED lights.
https://mymodernmet.com/red-clouds-led-fishing/
Here's a photo of a big boat loaded with red LEDs
