Just how easy is it to fool a fish?
My first experience of fishing was at a very young age and the equipment involved consisted of a stick, some string, a bent pin and an unfortunate worm. This was used in a muddy pool which at the age of six passed for a ‘pond’. Needless to say the catch was negligible i.e. one dead worm.Real anglers have, of course, rather more sophisticated means of catching their prey, with lures in particular being considerably more high-tech than my worm ever was.
The appropriately named Kyle Waterman is marketing coordinator of Minnesota-based Northland Tackle, one of the USA’s leading producers of fishing baits. He says the most recent developments in fishing lures include sophisticated ultraviolet colour patterns and optically brightened finishes that absorb sunlight and UV light to glow brighter, since some fish species can see UV light, which is invisible to humans.
Indeed, a large part of the development of effective fishing lures revolves around understanding vision in fish. Fish eyes have a more spherical lens than land mammals and vertebrates, while their retinas generally have both rod cells and cone cells (for scotopic [low-?light] and photopic vision) and most species have very good colour vision. Some species are also sensitive to polarised as well as UV light and unlike humans, fish normally adjust focus by moving the lens closer to or further from the retina.
In addition, water offers a very different visual environment from air. Water absorbs light, hence the fact that it quickly becomes darker with increasing depth, and light of long wavelengths (e.g. red) is absorbed more quickly than that of short wavelengths (e.g. blue), so that reds can disappear within 10m (33ft), while UV light is absorbed faster than either long or short wavelength light.
It’s also necessary to understand the structure of fish eyes. For instance, many shallow-water species have highly evolved visual cortexes and their eyes can contain up to eight light-absorbing photo-pigments, compared with the red, blue and green which humans possess.
Fish lenses are usually denser and more spherical than those of terrestrial animals. In water, the lens has to do the majority of the refraction, unlike in air, and a refractive index gradient within the lens means that the spherical lenses of fish are able to form sharp images free from spherical aberration, which would result in an imperfect image.
Of particular importance when designing fishing lures is the ability of many fish species to see UV light (this is thought to be advantageous in foraging, communication, and particularly mate selection), although UV vision may not be present throughout the entire life of a fish. For example, brown trout only have the facility as juveniles when they live in shallow water and use ultraviolet vision to detect zooplankton. They lose this as they get older and move to deeper water where there is little ultraviolet light.
However, Waterman points out that “incorporating ultraviolet colour patterns and optically brightened finishes in lures will help any level of angler, but it does not completely remove the skills needed to catch a fish.
“There still needs to be an understanding of what colours will work best in dark and clear water conditions, what are the best rigging options with each bait and what action the fisherman needs to use depending on whether the fish are aggressive or are in a neutral state.”
What are the most important visual aspects of fishing lure? Culum Brown, associate professor of fish cognition at Macquarie University in Sydney, says: “Fishing lures are designed to appeal to the predatory instincts of fish. There are really three major aspects of a lure that are key.
“First is movement; movement is a key cue for predators to hone in on their prey, so a lure must mimic the movement of key prey items for it to be successful.
“Second is the lure colour. Unlike humans, fish have superb vision; most have at least four colour pigments in their eyes (humans have three) so they can see colour far better than we can. Since many shallow-water species can see into the UV spectrum, a lure should make the most of that channel as well.
“Third, for ‘sit and wait’ fish, the smell of a lure can be important as well – there are several smelly lures on the market these days.”
Brown agrees with Waterman, saying that “there is only so much a lure can do on its own. The important thing is to make sure you use the lure to its best effect. Obviously casting and reeling in is the key here – cast to the appropriate location and reel in the lure in such a way as to maximise its effect.”
He also points out that different species of fish have different behaviour and sensory capabilities, so it’s vital to match the lure to the fish.
Dr Keith Jones, director of fish research for the tackle producer Pure Fishing of Spirit Lake, Iowa, has explored both ‘smelly lures’ and the reaction of individual species to particular lure designs.
Fish have a sense of smell over 100,000 times keener than humans, so it’s only natural that this would be an important factor in attracting them to a hook. Jones’ team was able to synthesise odours from the prey of freshwater game fish like crayfish and minnows, and then test them to see which had the strongest response from their predators.
Jones then developed a proprietary polymer in which to embed the molecules and this was made into ‘worms’ which had a scent diffusion over 400 times greater than in nature. Naturally the fish loved it.
Jones has also worked with bass – a fisherman’s favourite – to find what triggers their natural response to feed and then use that information to develop lures. He found that soft-plastic baits appear more natural to a bass when compared to some other lures, whilst crankbaits, powerful one-time lures that can cause bass to strike the first time they see them, can overstimulate the fish, as well as being easier for them to remember and thus avoid them next time.
He also found that the more frequently a lure is used, the less likely bass are to continue to hit it. Introduce a new lure that the fish haven’t seen before and the chances are they’ll strike it.
Speaking to fishing writer John E Jones, Keith Jones pointed out: “The materials that we’re using to make baits now are far superior to the materials of baits in years past, including the hooks and the finishes on the baits, especially crankbaits. The castability and the way the lures run in the water are also much improved over the old lures.
“The new lures should catch more bass than the old lures do, unless the same lure is fished continuously in the same region”. However, he adds that older style lures don’t have anything intrinsically wrong with them other than not utilising the latest technology, but “if you can take some of the really hot old lures and revamp them with new technology, then you’ll have the best of both worlds, which may produce an outstanding bass lure.”
Another vital aspect of lure design is that where necessary, they should mimic the swimming action of the fishes’ prey. Keith Jones’s team has also worked on this by pulling different lures through schools of fish and then placing the most frequently attacked lures in a controlled underwater environment. They used high-speed photography and were able to analyse features such as oscillation frequency, pitch, yaw and roll to determine what movements attracted different species of game fish and incorporate these into lures.
Indeed, for Waterman, different actions with bait could be the next step in lure development. “Coming up with completely new actions for lures could have big success with catching fish,” he says.
Presumably none of these actions are likely to mimic a worm on a bent pin.