Lets start looking at some of the studies being done concerning largemouth bass and see what kind of information we might glean from them. For this post, I want to look at a study out of Texas Tech concerning lure size. You can read a quick article mentioning the study at Texas Tech's Newsletter. For the full .pdf report you can link to the original study titled "Lure-size Restrictions in Recreational Fisheries" at the link provided.
The basic premise behind this research was to see if restricting anglers to certain size lures could act as a way to substitute for length limits in certain cases. The thought being that even with immediate catch and release, there is still going to be a certain level of mortality placed upon a bass population. Could anglers who were required to use a minimum lure size actually avoid catching certain smaller sized fish, thereby effectively acting as a type of preferential size limit by default? Part of this is based on studies that suggest that as predators get larger, so do their gape sizes, meaning they can eat larger meals because they have bigger mouths. Theoretically, at some point you could make a lure large enough that smaller fish with much smaller gapes would for the most part be unable to swallow that lure, effectively discriminating the size of your catch.
The spring fed lake they chose had little fishing pressure or harvest, good water clarity and heavy weedgrowth. It also had a very large population of bass, making for a stunted population. The majority of the bass were in the 8-10" range with few individuals over 14". However they had documented the occassional fish up to 23" in the lake. It was felt that this extreme stunted population would make for a very rigorous challenge to their hypothesis that lure size could be used to effectively minimize the catch of smaller non-targeted bass.
The lures chosen for this experiment were Original Rapalas in 4 different sizes ranging from the smallest at 2.75" to the largest at 7.00 inches. They also tested for color prefernces by utilizing 4 different colored lures. To determine size preferences, all lures used were of the original silver/black back type. To determine color preferences, they used only 3.5" lures but in 4 different color patterns. They rotated lure sizes and anglers every 30 minutes until a minimum of 50 bass were recorded for a given size lure.
Results: Mean catch rates for the 3 sizes of smaller lures were not significantly different when taking into account every fish caught. However, there was a significant difference between the largest sized lure and its smaller counterparts. The 3 smaller sized lures averaged between 10-13 bass per hour, whereas the 7" Rapala only averaged 3.29 bass per hour. This generally fits in line with traditional thinking that when targeting larger bass with larger lures, the number of bass you catch will go down. Of course, the hope is that size will then go up.
For only bass caught over 10" long, there was overlap of significance. There was no significant difference in catch rates when comparing the 3 smallest sized lures. There was also no significant difference when comparing just the 3 largest sized lures. There was a significant difference though when comparing the largest (7") only to the smallest (2.75"). Here catch rates ranged from about 1.5 bass per hour (largest lure) up to 4.25 bass per hour (smallest lure).
When this size exclusion was bumped up to only include fish over 12" long, again the exact same overlap of significances occurred. Once again, catch rates dropped further still ranging from 0.0 for the smallest lure up to 0.4-0.5 for the next 3 larger sized lures. This is kind of interesting from the standpoint that the smallest lure used never caught a bass greater than 11" long. There are a couple potential explanations given by the authors for this, but again this fits common belief that micro baits will, for the most part catch micro fish.
When looking at average size of fish caught for a given length lure, there was a pretty straight-forward correlation. The 2.75" lure caught an average sized bass of just over 9". The 3.5" and 5.25" Rapala both averaged right around 9.5" bass. The average sized bass caught using the 7" lure was right at 10.5". Again, this generally fits the theory of using larger lures to catch larger fish.
On the color study they found that all 4 colors had a very similar size catch average, basically meaning lure color made no difference in average size of bass caught. However, lure color did have an effect on catch rates with firetiger having the lowest. They didn't delve too far into the numbers for color though.
So an interesting study that somewhat backs common perception to a degree. Bigger lures, bigger averaged sized fish caught but at a considerably lower catch rate once a certain threshold has been exceeded, and not much difference when comparing lures grouped by size classes against some target sized fish.
Big bait/big fish commentary
While on the subject of big baits for big bass, Ralph Manns has posted another great overview concerning seasonality issues surrounding this concept. It can be found at this BFHP link.
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