A common misconception is that Bluegill stunting is the biggest problem with your average midwestern pond fish population. Once upon a time I believed that myself, and that is part of the reason that the first species we raised at Keystone Hatcheries was Hybrid Bluegill. However, it did not take long to realize that a far more common issue is Largemouth Bass stunting.
Largemouth Bass are the top of the food chain in your average pond and they are not fussy about spawning habitat. So, if the fisherman is not reducing their numbers thru harvesting, then it does not take long for them to decimate their available food supply and begin to stunt. In a typical case you will notice that there are many bass somewhere in the 10 to 15-inch size range, but few that are larger or smaller. In severe cases you will notice that the bass have large heads and skinny bodies. Either way, the solutions are the same.
The first thing you want to do with a stunted bass population is to harvest the most abundant size class. Think of a stunted bass population as a bell curve, with an abundant amount of the stunted size class in the middle at the top of the curve, and less and less smaller and larger as you move away from the top in either direction. What you want to do is catch and keep the most abundant size class, but throw back the largest and smallest. This in effect pushes down on the curve and makes it flatter. How many should I harvest you may ask? Well, this is just about impossible to say, but you can take out a surprising amount. Commonly people in the Midwest will remove 50 per surface acre annually, and still have an abundant population! In general, you want to keep harvesting until you notice the catch rate decreasing and the average size increasing.
Why will the average size increase? Think of it this way. Every pond has a finite amount of food available for the bass. Very generally speaking, if you have 500 bass in a pond, they will grow at rate X. But if you reduce the population to 250 bass they will have twice as much food available and will grow roughly twice as fast. And don’t think this takes years. You can sometimes notice a difference in months.
Although nothing takes the place of harvesting stunted bass, there are other things that can be done to help. The most important of these is to keep track of what is going on with the forage population. If you do not have Bluegill in the pond, then the forage fish will likely get wiped out. Bluegill are the species that stands the best chance of withstanding, and thereby providing food for a bass population. But their population may need to be managed, just like the bass. Many things can happen, including Bluegill stunting, disappearing, or growing very large. But in general, you want to manage the population to be balanced and diverse like the bass - you do not want another bell curve! See the article Bluegill Stunting for more info on this.
The other thing you can do with forage is to add minnows or shiners. This is a great short-term boost to the bass population, and they will thank you for it, but it is not a long-term strategy, unless you want to invest in ongoing monthly minnow stockings. We have customers that don’t mind spending the money, so we stock up to 100 pounds of minnows and/or shiners per surface acre every month, April thru November. And guess what, the minnows get wiped out within days of stocking. But those customers do have huge fish!
On the other end of the spectrum you can attack the problem by stocking top end predators that will help control the bass. Care must be taken here, otherwise the balance can rapidly swing in the other direction. Northern Pike, Tiger Muskie or Muskie are efficient predators of bass, and small quantities, like 1 or 2 per acre, will definitely help keep bass in check. Generally, we recommend not doing this in small ponds, under an acre, because those systems just are not dynamic enough to support large predators. Large Channel Catfish can also help serve in this capacity, to a limited extent.
The last thing to consider is aquatic habitat. If the pond is filled with weeds, the forage species can have too much protection from the bass. If this is the case, we recommend that you first identify the weeds and find out if they are good/native or bad/invasive/exotic. If they are good, then we recommend spot treating, or partial physical removal, to create areas in the pond where bass can get at the food. However, DO NOT ELIMINATE ALL BENEFICIAL WEEDS, as this will swing the pendulum too far in the other direction and is not healthy for the pond. If you do find that the weeds are invasive exotic species, we usually recommend complete removal, followed by reintroduction of beneficial native weeds (another subject for another day).
On the other hand, if there are not enough weeds, and little structure for hiding spots, then the forage species probably doesn’t stand a chance and will be decimated in short order. We commonly see this in ponds that are indiscriminately treated for weeds and algae on a regular basis, or ponds with a significant carp or grass carp population.
So, what it all comes down to is finding that nice balance. Whether you are talking about weeds, or bass or bluegill, what you want is a nice balance. Too much of just about anything can knock things out of whack, and require you, the pond-meister, to put it back to rights.