It’s a well known fact that smallmouth bass eat crayfish and largemouth are more likely to eat another fish. Why the difference? It is really quite simple. From birth, smallmouth utilize rock structure for cover. Largemouth consistently seek out thick brushy cover. Considering the preferred habitat types it is only logical that the diet of each species will be dominated by the most abundant food source in the neighborhood. Crayfish live in and under rocks while most small pan fish and minnows seek out weeds and brush for nursery cover habitat. So a smallmouth living in the rocks will encounter crayfish more often than small forage fish. Examination of the smallmouth stomach will most often reveal crayfish. That is the food most available to him and that is what is eaten. Conversely, largemouth bass live with the minnows in the weeds and their stomachs will be full of fish.
All bass species are opportunistic feeders that are proud to have anyone over for dinner. A largemouth in a really brushy or weedy lake may have an entirely different diet than a largemouth in a lake without weeds. In a study from Florida, the largemouth bass diet from weedy lakes was compared to the largemouth bass diet in lakes where grass carp had been used to remove most vegetation. Differences were dramatic.
It started with the youngest fish. Largemouth bass in weedy lakes didn’t start to eat other fish until the bass were almost 5 inches long. Their counterparts in lakes without "grass" got on fish when they were only 2.5 inches long. Forage fish in weedy lakes were unavailable to small bass. Minnows were just too good at hiding in the dense protection of thick weeds until bass got big enough to go in after them.
Eating fish early makes for a faster first year growth rate. This head start made largemouth bass in the weedless lakes bigger fish for the majority of their life. It wasn’t until age 5 that bass in weedy lakes achieved the same size. Fish are really adaptable creatures and as usually occurs in nature, all things tend to even out in the end.
So what do we do with our backyard pond where we are growing our own bass for fun and profit? Do we throw in a few grass carp to chomp the weeds and make young bass grow faster? Let’s investigate further.
Elimination of weeds makes the young of all species more vulnerable to predation. Some species can even be eliminated in short order if not protected when they are learning to swim and hide from strangers. In fact, bass themselves will be less numerous due to predation from their own kind in weedless lakes.
Weedless lakes then will grow bass faster but they will be fewer in number. Ten bass will grow faster than 100 bass confined to the same space. Forage fish, bugs and crawdads without weeds will be more accessible and therefore, vulnerable to be eaten and maybe even be totally eliminated. The best fisheries are created when widely diverse habitats are available. A pond choked with hydrilla is not producing as well as it could. The same pond without any weeds also underachieves its potential. The best mix is a few weedy areas combined with clear areas where all makes, models and sizes of fish and forage can find their own niche.
If just fishing on one of the huge impoundments anywhere in the U. S. it is possible to increase your catch by studying available habitat. Bass need food and they get it in the most efficient manner within the confines of the water they live in. With a 90% surface covering of lily pads or water hyacinth, fish will be guarding each little two foot open space for any intruder that ventures out of cover. Their home range may be measured in feet instead of miles. Dragging a plastic lizard slowly across the surface is a dynamite idea here. In deep canyon lakes without any vegetation to speak of, the lizard might not work as well as a shad imitating crankbait that can cover hundreds of yards of shoreline in a short time. The home range of a largemouth bass in this lake may be 3-5 miles, depending on time of year and what the forage is up to.
Habitat determines where fish live and what they will eat. It is up to the angler to recognize these signs and react to them in a manner that will put more fish in the live well. Much of the work of finding fish can be done by studying lake structure, habitat, vegetation and forage species mix. A call to the local fish manager will usually be an excellent place to start. Then just match existing conditions in the new fishery with those you have previously encountered to get you started in the process of catching fish.