Biology
Life history
In a stream, a smallmouth bass typically inhabits a short reach, sometimes a single pool, throughout its entire life. Nesting in Ozark streams and reservoirs begins in April, when water temperatures reach 60 degrees F, and usually continues through May and early June.
Stream nests are constructed in quiet waters where there is little current, often behind obstructions, such as logs or boulders. The male smallmouth fans out a saucer-shaped depression in the gravel with its tail, removing small gravel, sand and silt. One or more females may join the male, depositing as many as 10,000 adhesive eggs in a single nest. The male continues to guard the nest and the eggs hatch in two to three days.
As the dark-colored fry develop, they leave the gravel and may be observed swimming in a dense cloud over the nest, carefully guarded by the male parent until they leave. Young smallmouth disperse into shallow stream margins, usually close to aquatic vegetation like water willow.
By September, many of the young smallmouth have fallen prey to large aquatic insects, fish and fish-eating birds. The remaining young move to submerged cover in the deeper pools as winter approaches.
What do smallmouth bass eat?
Newly hatched smallmouth eat microscopic organisms, but begin to forage on insects when about one-half inch long. By the time smallmouth bass are 1.5 inches in length, insects and small fish make up their diet. Small fish and crayfish make up an increasing proportion of a smallmouth’s diet as the fish continues to grow.
For adult smallmouth bass, the preferred food is crayfish, followed by fish. Where crayfish are abundant, they frequently comprise more than two-thirds of the food. Occasionally, large aquatic insects are eaten.
During the day, adult smallmouth spend their time near submerged cover, preferring to eat whatever might happen by. In periods of low light, adult fish will venture away from cover and move into shallow water to feed, especially at the head and tail of deeper pools where the current increases.
How fast do smallmouth bass grow?
Smallmouth bass in streams average about 3.5 inches long at one year of age, attaining average lengths of 6.5, 9.5, 11.5, 13.5 and 14.5 inches in each succeeding year. Growth in reservoirs is typically better, with smallmouth bass reaching 15 inches or greater in five years. A 15-inch smallmouth will weigh about 1 pound, 10 ounces. Few fish exceed 22 inches, 6 pounds or 10 years of age.
Smallmouth habitat
Smallmouth bass can be found in flowing waters, from small creeks to large float streams, and in large reservoirs. Regardless of size, all quality smallmouth bass streams include good water quality, a rocky stream bottom, abundant cover, and deeper pools.
Smallmouth bass are often found in clear streams, but may also be found in streams that are slightly less clear. The water must be relatively free of excess nutrients, sediment and contaminants. Gravel and larger rock are key to providing good spawning sites and habitat for the insects and crayfish that are prey for smallmouth.
Root wads, logs, boulders and undercut banks provide the critical cover for smallmouth, especially during winter months and periods of high flow. Deeper pools are the final ingredient that smallmouth seek for refuge and feeding areas.
