Marlin hunt their prey primarily by sight. Their large eyes and vision-oriented brains are typical of sight-feeding predators. However, marlin vision is much different from human vision.

The reason: their environment. Even in the clear ocean, light is scattered, filtered and absorbed as it passes through water. Images underwater lose color, flicker and appear distorted.

The marlin’s food — mostly tunas, mackerels and flying fish — blend into the oceanic background, counter-shaded with dark backs and bright bellies for camouflage.

As a result, marlin have little need for color vision. In fact, they are color-blind, possessing only color receptors for the blue spectrum of light — the dominate color filtering into the depths of the ocean.

Instead, marlin rely most on spotting flashes of motion and contrast to detect swimming prey.

Differently colored lures provide a range of contrast and reflectivity that a color-blind fish can detect.

You can imagine the effect by looking at a black-and-white photograph of different-colored lures. Some will appear dark, while others seem light.

This shades-of-gray impression must resemble what marlin see, except that their image would appear in shades of blue.

For instance, the deep bright shades of red, purple, green, orange or yellow will represent dark shades of the blue spectrum. Any light colors of blue, green, orange, yellow, chartreuse or pink will all look similar shades of blue in the blue spectrum.

The best color lure is one that provides the most contrast with existing sea and light conditions when viewed from the side or below.

In any case, lure color matters little when a fish is looking up toward a lure on the surface, back-lit by the sun. All it will see is a dark silhouette, a bubble trail and perhaps some flash and splash.

The main point really isn’t what a billfish sees, but how it reacts to what you’re dragging in front of its face. Marlin under heavy fishing pressure recognize what they’re eating, and a smart angler imitates that as close as possible in not only size and shape, but color as well.

Marlin react to color as it relates to what they are feeding on at the time. Common sense tells you that whether these fish can visually recognize color or not, they are executing an aggressive response to the stimulus of a lure going by their nose.

Marlin exhibit territorial behavior. If a lure comes in their territory, it doesn’t matter what its color is — they’re going to take a whack at it. A billfish will often strike aggressively at an oddball lure that has no resemblance to any baitfish, but it will more readily take and swallow a lure that is colored more closely to what it is feeding on at that time.

Are lures designed to catch fish, or to catch fishermen? The aesthetics of a lure must first catch the eye of the fisherman before it will ever have a chance of attracting the fish.

So does lure color really make a difference, given the marlin’s ability to only see in shades of blue? Who knows? If people truly believed that lure color didn’t matter, then they would fish with all lures of the same color, all day, every day.

I have never met a fisherman, saltwater or freshwater, that fishes that way. Have you?