I'll try to find the link to the article I'm referencing. Basically it was a study of a controlled population of fish in a pond. All were tagged, identifying markers recorded, etc. The fish were all adults that were caught by biologist using electrical current from different reservoirs. It was a multi-year study. Anyway long story short, a certain portion of the population was caught repeatedly utilizing numerous baits (all artificial). Another percentage were rarely caught and only under certain light conditions, and only one or two presentations worked. The final portion of the population were never caught, these fish were easily spoked, apparently line shy etc. The study concluded that about 65-75% of the population of any lake were catchable bass, of that percent only 25% were easily caught. Of the ones easily caught their behavior remained that way throughout their life. Made no difference if they were a pound or ten pounds, these fish never learned. The group that proved difficult to catch remained that way throughout their life as well. They never showed any capacity for memory though and could be caught throughout their life. The group that proved to impossible to catch, remained that way. The percentage of catchable fish remained constant throughout the years. Spawn after spawn.
Here's where it gets interesting. Finally the pond was drained, the uncatchable bass relocated to a different pond. They were isolated from the catchable bass in order to study them further. Amazingly their offspring exhibited the same characteristics and were not catchable period, not even live bait worked.
In the other pond that contained the catchable bass. The population remained fairly constant, until they started removing the hard to catch fish, then the population experienced a shift where most fish were easily caught.
Finally the ponds were drained all the fish went into one large pond. The biologist then opened the pond for fishing, the only requirement was the fishermen were required to keep their catch. Within a couple of years the easy fishing ended, all that were left were the difficult to catch and the impossible to catch
The study concluded that liberal bag limits are very detrimental to fishing for sport. The overall population of bass remained constant, but catch rates dwindled.