Most of the time I like to have the drag set at about one third of the breaking test of the line when trolling. That's my normal strike setting. I'll jack the drag up if we are missing a lot of strikes, fish coming up and hitting a lure but not getting hooked up. Then, I'll back it off to a little less than one third once the fish is on early in the fight. I've heard so many theories about whether or not marlin can see color that I'm not sure anyone really knows.
Some scientists say yes, others disagree.
Here in Kona, where my experience can speak for itself, I feel there are definitely days when these fish key in on specific primary colors such a blue, purple or black. When they show a preference, they'll usually stick with it all day long. If it's not the actual colors they are responding to, they must at least see shades or respond to the reflective quality of different colors under varying light or water conditions, possibly the way a specific color silhouettes against the sky above. On that note, let's delve into some particulars. For example, there are many days when the fish want relatively small lures.