Largemouth bass, water clarity & crankbaits

Largemouth bass are primarily visually feeding predators (1). They depend on their sight to find and stalk their prey. Because water clarity affects sight, and because sight affects a bass’ ability to find prey, we'd guess that water clarity influences a bass’ feeding patterns. But is this really the case? And if it is, how does it effect how bass feed?

Researchers tested the effects of water clarity on bass’ choice of prey by putting the predators in three different tanks filled with three kinds of prey. Each tank held the same kind of prey: gizzard shad, northern crayfish, and bluegills (pictures of each at the bottom). The first tank was filled with clear water, the second with slightly muddier water, and the last with muddy water. The researchers wanted to see if bass had a tendency to feed on certain prey in certain conditions. The results were fascinating (2):

• in clear water, bass selected fish prey and avoided northern crayfish
• in medium water, bass feasted on all prey equally
• in muddy water, bass selected bluegills more than crayfish or shad
• bass become less active and feed less in muddy water
• bass tend to select larger prey as water becomes muddier

Only three kinds of prey were used in the experiment, so we have to take the results with a grain of salt. But because they show that bass have a preference for fish prey in certain conditions, I think that they can help us figure out when crankbaits are most and least effective.

Clear Water

Crankbaits will be effective in clear water because bass can see well in this environment, and so they can easily find and stalk fish prey. That said, bass are also most active in this kind of water, and this is a factor that should be considered when deciding what kind of crankbait to throw. Because they eat more, bass don’t necessarily need to attack larger prey. This is a situation where a smaller lure can be more effective. In these conditions, bass will see smaller baits- and a bigger lure may not necessarily land a bigger fish.  Faster retrieve speeds will be more effective in this water since it is less likely that a bass will lose sight of your lure once it has seen it.

Medium Water

The results of the experiment suggest that crankbaits are least effective in somewhat muddy water. Bass cannot see as well, and are more likely to search for harder to find but slower and therefore easier to catch prey such as crayfish- maybe because spending more energy searching and actually catching prey is more efficient than chasing fish but ultimately losing sight of them. This isn’t to say that bass won’t hit crankbaits in these conditions- during the experiment, they fed on all prey equally in this kind of water. So if you do want to throw a crankbait in somewhat muddy water, make sure to slow down your retrieve- bass are looking for easier meals because their vision is impaired.

Muddy Water

In medium water, bass are more likely to search for harder to find but easier to catch prey. But in murky water, bass go back to chasing baitfish. The reason for this may be that a certain point, when water is very muddy, it is just too hard for bass to find prey like crayfish. And so it is more efficient for them to stay relatively inactive and become opportunistic feeders, chasing harder to catch but easier to find prey. This would explain why bass feed less in muddy water- overall it is harder for them to find their prey- and also why they tend to select larger prey in these conditions- when they do chase something, it has to be worth the effort. Crankbaits, then, will be effective in muddy water. Again, because it is difficult for bass to see, a slow retrieve will work better. Also, unlike in clear water, bigger, flashier lures will be better, since bass are looking for larger targets.

Conclusion

According to the results of this experiment, crankbaits should be less effective in slightly muddy water, and more effective in clear and muddy water. Smaller crankbaits and a faster retrieve should work better in clear water, whereas the speed of the retrieve should decrease as water becomes muddier, while the size of the lure should increase. Of course, these are all theoretical results, and I can’t wait to prove (or disprove) them on the water next summer. After all, fishing is both a science and an art.

Gizzard Shad

Northern Crayfish



Bluegill

(1) MA Nannini, DH Wahl, DP Philipp & SJ Cooke, "The influence of selection for vulnerability to angling on foraging ecology in largemouth bass Micropterus salmoides" (2011) 79 Journal of Fish Biology at 1024.

(2) Daniel E. Shoup & David H. Wahl, "The Effects of Turbidity on Prey Selection by Piscivorous Largemouth Bass" (2009) 138 Transactions of the American Fisheries Society.

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