Are We Training Fish to Avoid Lures ?

Fishing LureAfter a modest return from a recent Far North fishing trip I was left wondering how I could have done so poorly.

YES, IT WAS WINTER, so I might not expect the fish to be hot on the bite, but I had spent a couple of full days plopping soft baits along an extremely fishy coastline without any luck. This result shouldn’t have come as a surprise; however, since I started using soft baits in 2007, I have noticed that those mind blowing sessions have become harder and harder to come by. I have even dropped my line weight down to 6lb to see if that would help increase my catch rates without any improvement. It’s unlikely that snapper numbers have declined over this time period, which leads to an awkward question: have snapper and maybe other fish started to cotton onto soft baits and other lures? I have heard others talk about fish being lure shy before, so was curious to find out if there was any more to it.

There is actually a lot of anecdotal information and research to back up the concept that with time, lures can become less effective. This process can work in two ways.

The first occurs when fish repetitively see a lure, learn that it isn’t food and don’t bother attacking the lure if they see it again. If the fish is hooked during this process and either escapes or is caught and released, then this is likely to create a powerful negative association with the lure. You may have heard of “Pavlov’s dog”, which after repetitive association between food and a dinner bell began salivating at just the sound of the bell by itself. The response of fish to lures, as described here, could be thought of as the opposite to the dinner bell.

In the US largemouth bass fisheries this process is called “fish conditioning”, and there is a lot of discussion on the topic, with many pro bass fishermen confident that in heavily fished lakes the bass become conditioned to the most commonly used lures. Some of the best evidence for fish conditioning comes from the company behind Berkley Gulp! Pure Fishing. In lab experiments, researchers would expose groups of bass to a particular lure by casting it across the tank five times. Upon first seeing the lure all of the bass would hit it, with the number of strikes decreasing with each successive cast.

Essentially the bass weren’t getting the food they expected, so they became less interested. This process was then repeated on separate groups of bass with similar results. All of the bass were then left alone for three months before the same lure was again cast repetitively across the tank. This time each group of bass were uninterested in the lure, only striking at it a few times.

When a different type of lure was cast into the tank, however, the bass struck at it as often as they had when they first saw the original lure. This shows that not only were the bass able to remember that the lure wasn’t food for at least three months, they were also able to distinguish between similar lures. There is plenty of other evidence from fisheries around the world suggesting that fish can modify their behaviour in response to encounters with lures or hooks.

For example, catch and release trout fisheries have resulted in a pattern where the most heavily fished streams have the lowest catch rates. UK carp fisheries are well known for ‘bait shy’ fish, with some carp having a reduced probability of recapture for over a year after initially being caught. Some fish farming operations even use the remarkable learning capacity of fish to their advantage. When hatchery raised fish are stocked into the wild, the farmers continue to feed the fish, and each time they put food out they play a specific tone into the water. They keep this practice up for a while but eventually let the fish find their own food. After the fish have grown large enough to harvest, the farmers simply play the tone into the water allowing the expectant fish to be easily encircled with a net.

The other way that lure effectiveness can be reduced is through selection. Essentially some fish are more aggressive than others and are therefore more likely to attack a lure as it darts past. These individuals are therefore the most likely to be caught on lures, and as they are removed by fishing the whole population becomes less aggressive and lures become less effective as a result.

Experimental fishing conducted on largemouth bass simulated this scenario, by removing individual bass that were captured by anglers and allowing the remaining bass to interbreed. After this selection had been repeated for four generations of bass, the resulting population was much more cautious towards fishing gear than the fish originally stocked into the lake.

This result goes beyond changing the number of fish willing to take a lure, it demonstrates that reduced aggressiveness has a genetic component, suggesting that fishing could even determine how vulnerable future generations of fish will be to capture!

While there is compelling evidence that reduced lure effectiveness can  occur in tank experiments and within small constrained lake fisheries, these results are not New Zealand relevant, and aren’t at the scale of a large marine fishery where millions of fish mix over hundreds of kilometres of coastline. There are indications that similar things could occur in New Zealand though.

Have you ever been for a swim in the Goat Island Marine Reserve and noticed how close you can get to the snapper? There are a lot of potential explanations for this, but most of them involve the capacity of the fish to learn and the lack of negative experiences associated with people inside the reserve.

Also, emphasising the capacity of snapper to respond to particular influences, tagging experiments have shown that snapper caught by longline were more likely to be recaptured by trawl and those captured by trawl were more likely to be recaptured by longline. This shows that snapper could remember the negative capture experience and learnt how to avoid that fishing method in the future.

So ‘fish conditioning’ and ‘lure shyness’ sound like a plausible explanation for my bad fishing trip, but are others noticing it occurring as well? NZFisher spoke to a few very experienced charter skippers and got mixed responses. Rick Pollock of Pursuit Charters is adamant that it has already occurred for White Island kingfish. Rick  refers to the extreme effectiveness of long jigs and mechanical jigging when this technique first came online in about 2005.

Jigging catch rates at White Island quickly declined, however, while live bait effectiveness remained high. Today Rick states that jigging at White Island mostly produces rat kingies, while the live bait fishery is as good as it’s ever been. These kind of results are very compatible with how we would expect lure shyness to work.

Mechanical jigging is hugely efficient, enabling anglers to catch many more fish per day than would be possible using live baits. This combined with the one fish limit in operation at White Island and the popularity of catch and release amongst jig fishermen in general means that many fish can quickly become conditioned to lures. Rat kingies remain vulnerable to capture as they are new on the scene; they haven’t seen jigs before. live bait fishery for kingfish remains productive as this method not only results in fewer encounters between kingfish and fishing gear, but kingfish are also less able to distinguish between a live bait and their actual food.

Furthermore, kingfish tagged at White Island are seldom recaptured away from White Island, suggesting that the kingfish there are a constrained population, making repetitive exposure to jigs a more likely occurrence. Other experienced charter operators that we spoke to didn’t consider lure shyness to be an important issue for either kingfish and jigs or snapper and soft baits.

In summary fish have the capacity to recognise lures and to learn to avoid them, and there are suspicions that this might be occurring in fisheries around the world. The jury will probably always be out as to whether it is actually occurring in our fisheries though. So what can you do to overcome the possibility that it might be affecting your catch rates?

The answer is undoubtedly keep it fresh. Whether that be through using a lure with a different shape, swimming style, or colour, retrieving the lure in a different (potentially slower) way, or using actual fresh or live bait.

A combination of these techniques will ensure that you are placing something that the fish hasn’t seen before or something that it can’t distinguish from real food in front of its face. For snapper the lure options are endless due to the advent of bottom ships, cabura jigs, micro jigs, slow jigs etc… This allows us to engage in a lure arms race, always keeping one step ahead of the fish.

By Neil Wagener

If you found this interesting, you may enjoy Catching flounder in the Manukau Harbour (+ video)

For more great articles like this subscribe to the FREE e-magazine - delivered straight to your inbox every month.

Love fishing? Subscribe to NZ Fisher, the free e-magazine for Kiwi fishing enthusiasts.

Subscribe for free!

* indicates required

Get new issues straight to your inbox and be in to win cool prizes every month!