The Key to Building Stronger Bass Populations

Smallmouth are a different story. Shallow gravel and rubble seem important for good growth and survival of young.

The Adolescent Years

Bass that survive their first year by dodging predators and surviving an energy-sapping winter must continue to feed and grow. Yearling fish may range from 3 inches in the North to 5 to 10 inches or more in the South. Their food, mostly crayfish and fish, must be the right size—small bass can’t eat large prey. Conversely, bass can burn more energy chasing, catching, and consuming very small prey than they gain from eating it.

We explored the bass “foraging window” in the 2005 Bass Guide. Briefly, a largemouth readily consumes fish up to about one-third of its length; a smallmouth can easily ingest forage up to one-fourth its own length. So, abundant forage fish from 1 to 3 inches long provide good growth opportunities for most yearling bass.

Many varieties of small fish can fill the bellies of yearling bass. But consider that forage fish are growing, too. Shad are the primary prey in many waters outside the Far North. Typically, gizzard shad reach 4 to 6 inches in their first year. Where that’s the case, young shad only serve as bass food for part of the yearlings’ growing season. For good growth, yearling bass need a range of sizes of forage, and that means diverse forage species. Effective habitat management for intermediate-sized bass involves habitat manipulations that yield an array of prey species native to the waterway.

Aquatic vegetation generally benefits juvenile bass by providing prey. Dense vegetation often houses small minnows, topminnows, crayfish, and sunfish, but if the bass can’t find or catch them, they don’t grow much. Intermediate coverage of clumps of vegetation is better than vast areas of matted weeds.

Big Bass

Fast growth and high survival yield abundant big bass. Can optimal habitat build big bass? Certainly, but maybe not in the way many anglers think. Big bass come from little bass. Like smaller ones, they need food—lots of the right size of easily catchable prey. So, habitat for big bass really means habitat for their prey. The foraging-window principal still pertains, except that larger bass can eat larger prey, so their foraging window is much broader. More cover can mean more forage. For adolescent bass, however, too much cover can mean a lot of forage but poor bass growth, if they can’t catch their food.

Fishery managers often add bass-attracting structures (fish attractors) when cover is scarce. Although often effective, this is an expensive and time-consuming activity, and it requires a lot of fish attractors. Brushpiles and wooden structures don’t last long; rockpiles and artificial reefs are better, especially for smallmouth bass. Rockpiles last but building them takes special equipment, unless the rock can be dumped from trucks during a reservoir drawdown or placed during winter ice cover.

Aquatic vegetation is a low-cost, natural fish attractor. But not all lakes or reservoirs foster aquatic vegetation. Biologists are now learning effective methods for establishing native vegetation to benefit both fish and anglers, and to reduce invasions by non-native plants.

Habitat Management

The best bass populations have stable reproduction, fast growth, high survival, and a high bass biomass (weight of bass per acre), relative to the productivity of the lake or reservoir. Habitat affects all these factors, so careful habitat management is the smartest way both biologically and economically to maximize bass populations. Under high fishing pressure, harvest must also be limited either by voluntary selective harvest or by regulations. Conversely, where fishing or harvest pressure is low, such as in private ponds, removing bass increases growth rates and improves population structure. But good habitat management provides the best basis for large, stable, and fast-growing bass populations. n

*Dr. Hal Schramm leads the Mississippi Cooperative Fish and Wildlife Research Unit at Mississippi State University in Starkville. He’s an avid bass angler and frequent contributor to In-Fisherman publications.