Anecdotal evidence from someone with an uncounted number of sea miles.
On my 3rd trip from Frisco to Honolulu on a 50' Rhodes with a red bottom, I apparently hit a sleeping whale. A big bump brought us to a dead stop, then we rolled over a bit and continued on our way with no damage. Never saw the creature. In all the years and miles since, I've never hit or been hit by a whale, though encountering one surfing a big wave in the Lāhainā channel, it seemed a certainty he'd join me in the cockpit. He didn't, "Good boy." phew.
Never again had a red bottom on one of my boats. Black, blue, green or multicolor (new paint wearing back to old), but not red.
I sincerely doubt that whales use sight, with all their other attributes, to locate objects around them, so the color of a boat's bottom is rather a moot point, IMO. But scientists routinely go out of their way to make the facts fit their theories, so I have no doubt that there are at least several contradictory papers out there on the internet on this subject. Pick the bottom paint color you like and live dangerously!