I saw a story on an Internet news page about a scientist who invented a product that makes baits light up so that fish home right in on them. It's a titanium dioxide spray that produces a color within the ultraviolet range, which is invisible to humans but supposedly drives fish crazy. Would this really work? The manufacturer also claims that it allows fish to see baits and lures up to a half-mile away. Is that possible?
Charleston, South Carolina
A: The jury is still out on whether most fishes can detect UV light. There is evidence that UV rays stimulate light-sensitive cells in some fishes' eyes. However, most species have not been tested for this, and some, including billfishes, have lenses that actually block UV light. Interestingly, most species of billfish "light up" when they're excited, and much of the light they radiate is in the UV portion of the spectrum.
As for fishes being able to see objects a half-mile away, it just isn't so. Most
fishes' eyes don't have as much resolving power as human eyes, which means a
person's ability to see underwater with a mask may be better than a fish's. And how far can you see underwater, even in
ideal conditions? Water absorbs light quickly and differentially, so light reflected from or emitted by a submerged object can't travel a half-mile to begin with.
- Ray Waldner