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Smallmouth Bass

Smallmouth Bass

Characteristics

golden green sides and back with faint, wavy olive blotches along the sides, 5 olive-green bars radiate back from the red eye and 1 radiates forward; spiny and soft portions of dorsal fin broadly connected; fish over 3-4 pounds are trophy-sized

Distribution

Smallmouth Bass Distribution

northeastern 2/3 state in clear rivers, streams and some lakes; most abundant in northeast Iowa

Foods

fish, crustaceans, larger insects

State Record

7 pounds, 12 ounces - West Okoboji Lake, Dickinson County, September 1990 - Rick Gray, Dickinson, Iowa

Expert Tip

light spinning gear using crayfish colored crankbaits can produce hot smallmouth action!

Details

The smallmouth bass is primarily an inhabitant of swift flowing, less turbid waters in rivers and smaller streams. Smallmouth bass are most abundant and widely distributed in the rivers of central and eastern Iowa, but they are occasionally found in impoundments and natural lakes that contain suitable habitat. They are common to abundant in smaller tributary streams during spawning in late spring and are taken occasionally in the Mississippi. Since impoundment of this stream for navigation, smallmouth numbers have decreased.

The smallmouth bass is a slender, streamlined-shaped fish with a moderately large mouth, where the upper jaw reaches about to the rear margin of the eye in adults. Spiny and soft parts of the dorsal fin are broadly connected with only a shallow notch between the lobes. Body color is golden green on the sides and back with faint wavy olive blotches evenly spaced along the sides. There are five olive green bars radiating backward from the eye, and one forward to the end of the snout. The tail fin in young smallmouth is distinctly tri-colored with a black vertical bar separating the yellowish fin base. Pyloric caeca are not forked in contrast to forked pyloric caeca in the closely related largemouth bass.

Smallmouth bass are omnivorous in the food items that they consume. In the larger cool, clear interior streams of northeast Iowa smallmouth bass is the dominant predator, feeding mostly on fish, crustaceans and larger aquatic and terrestrial insects. Food habit studies have revealed that forage fish were present in 40 percent of the stomach samples, crayfish in 30 percent and insects in 20 percent. Where crayfish are abundant, they frequently comprise over two-thirds of the food. Newly hatched smallmouth consume copepods and cladocerans but begin to forage on insects when about one-half inch long. By the time fingerling smallmouth bass are 1 1/2 inches in length, insects and small fish comprise the bulk of the diet.

Smallmouth bass spawn in Iowa during the early part of May as water temperatures exceed 60' F. Preparatory to the spawning ritual, parent spawners move up larger streams, eventually reaching small tributaries where the actual spawning occurs. Male fish construct a saucer-shaped nest on the gravel, coarse sand or rock bottom by sweeping its tail over the substrate. The 14 to 25 inch diameter nest is located in quiet water near the shoreline downstream from a boulder or other natural structure that deflects and slows the current force.

The ripe male bass selects a gravid female after nest construction and nudges her toward the nest in a series of aggressive body contacts and bites. If the female refuses the nest, the male becomes more aggressive until the female is finally physically driven over the depression. Both fish lie side by side, facing the same direction during egg emission as the female vibrates her body by muscle action. The male releases milt for fertilization as the eggs are deposited. The female leaves the nest territory after spawning but may return later to the same nest or another if she has latent egg development. Male fish usually ripen again after a short period of time. Male fish protect the nest from predation and fan the eggs free of silt until the sac fry emerge in 3 to 5 days, depending on water temperature. Re-nesting is quite common for smallmouth, particularly when early nests are destroyed by natural events such as a flood.

The number of eggs laid by a female smallmouth bass varies greatly depending on body size. Average fecundity is 7,000 to 8,000 eggs per pound of body weight. Newly hatched sac fry swim over the nest in a school for about 6 to 15 days, moving sluggishly until all the nourishment in the yolk sac is consumed. The young fry are about one-half inch long when the yolk sac is absorbed, and they leave the nest to feed on small crustaceans and copepods.

Smallmouth bass growth varies with the amount of food eaten and water temperature. Most smallmouth bass in Iowa reach 3 to 5 inches by the first autumn, 6 to 7 inches in the second year, and 9 to 10 inches the third year. Smallmouth sexually mature in the second or third year of life, but where food is scarce or water is relatively cool in all seasons, maturation may not occur until the third or fourth year. Maximum weights of 6 or 7 pounds have been reported in Iowa, but fish over 3 to 4 pounds are trophy sized. The smallmouth bass record is 6 pounds, 8 ounces from Spirit Lake.


Return

Present in these Iowa water bodies:

Lake/Stream County Location Acres/Length
Big Spirit Lake Dickinson 1m N Spirit Lake 5684.00
Coralville Reservoir Johnson 4 miles north of Iowa City 5280.00
West Okoboji Lake Dickinson northwest edge of Arnolds Park 3847.00
Big Creek Lake Polk 2 miles north of Polk City 814.00
Twelve Mile Creek Lake Union 4 miles east of Creston 635.00
Center Lake Dickinson 2 miles west, 1/2 miles south of Spirit Lake 220.00
Nashua Impoundment (Cedar Lake) Chickasaw Located on the east edge of Nashua. 200.00
New Albin Big Lake Allamakee 200.00
Sand Lake Marshall On the Northeast edge of Marshalltown 95.00
Prairie Park Fishery Linn 1.5 miles SSE of Cargill on Otis Road, along the Cedar River in Cedar Rapids 42.00
Yellow River Allamakee T96N, R6W, S3 to T96N, R4W, S24 25.00
Paint Creek Allamakee Located in Yellow River State Forest, 3 miles west of Harpers Ferry off of State Forest Road or CR B25. 11.00
Scharnberg Pond Clay 3m E Everly 10.00
Bloody Run Creek Clayton Located 2 miles west of Marquette off of Highway 18. 6.50
Bear Creek Fayette Located 6 miles southeast of Fayette off of Kornhill Road or CR C24. Access from 128th Street. 1.20
Turkey River Clayton Located 6 miles northwest of Elkader at Big Spring Hatchery. 1.00
Mink Creek Fayette Located on private property 1.5 miles north of Wadena, access on Bighorn Road. 0.90

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