here is a quote from another site
The red color started out about 12 years ago, with many different companies doing red just as a new color at that time," he said. "Then they started doing studies where red is the first color of the light spectrum that disappears at a certain level in the water. Below about 10 feet or so in the water, red will actually disappear, so it looks like you have free-floating bait going through the water."
Schreck said some companies also offer red leaders for the same reason. In shallow water, the red color actually acts as an attractant, or like a gill flash or an injured baitfish with the blood coming out, he explained. The colored hook helps with the overall appearance of the bait.
billybono