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Brook Trout are readily recognized and distinguished from other trout by two main characteristics: vivid white lines on the front or leading edge of the lower fins, and the top portion or back is covered with light wormy streaks or mottlings on a darker background called vermiculations. The dorsal fin has ten rays and is also strongly mottled. The vomer is trough-shaped, with the teeth restricted to the front portion. Brook trout feel soft to the touch because of the very small scales that cover the entire body. About 230 occur along the lateral line, and they are more deeply embedded than other trout in the genus Salmo.
The Brook Trout is native to Iowa. They were originally found in abundance in most spring-fed streams of northeastern Iowa, although some fishery investigators believe they were wholly restricted to the Upper Iowa River drainage. Confirmation of the original distribution is difficult because early explorers referred only to the fish as "mountain" or "stream" trout, without bothering to describe identifying characteristics. Natural reproduction of Brook Trout is presently limited to only a few streams.
insects and other small aquatic life
7 pounds, 19.75 inches long- 1996 - Doug Kovarik, Marion, Iowa
use fine line and approach pools quietly to improve your fishing
A native species to Iowa, the Brook Trout is found almost exclusively in the northeastern portion of the state. Originally fishery investigators believed the Brook Trout was restricted to the Upper Iowa River drainage. However, it was in fact found in abundance in almost any spring-fed stream. Natural reproduction of Brook Trout is limited and confirmation of the distribution of the species is difficult due to periodic stocking.
The Brook Trout inhabits cool, clear headwater spring ponds, springs, and spring-fed streams containing shallow riffles over gravel and rubble bottoms. Synonymous with the cold waters, Brook Trout are seldom found in water with temperatures higher than 50-60F. Needing the coldest and cleanest of stream conditions, the Brook Trout is highly sensitive to pollution, siltation and water quality degradation.
Wild Brook Trout at spawning time are among the most beautiful of all fishes. Male trout, during this late fall period, develop a deep red-yellow-crimson coloration along the belly. The sides of the fish often have numerous red and pale yellow spots, with each spot sometimes surrounded by a blue-colored circle.
Brook Trout spawn from late October to November. Redds or nests are constructed by females in clean gravel areas, often near the headwaters of spring-fed streams. Females are capable of detecting upwelling springs or other gravel areas with ground-water flow and often deposit their eggs in these habitats. At a constant water temperature of 50 degrees F the eggs will hatch in about 45 days. In colder water the eggs might not hatch until January or February. The tiny fry stay buried in the stream gravel and survive on natural nutrients stored in the yolk sac until the water temperature begins to rise in early spring. At this time the fry swim up through the open crevices of the gravel bottom and begin searching for tiny insect life to feed upon.
Females mature at about two years of age, with most males becoming mature during the first year of life. Young females spawn between 200 to 500 eggs, but a larger fish may produce 2,500 or more. Brook Trout reach a length from 3 to 6 inches the first year, 7 to 9 inches the second, and 10 to 13 inches in the third year of life. Brook Trout weighing over one pound are considered a trophy since life expectancy is seldom longer than 3 years.
Individual Brook Trout live in the confined areas of our small streams, often spending most of its life in a single pool-riffle. Three habitat components are required for Brook Trout survival: resting areas in pools, feeding sites near riffles or swiftly flowing water, and escape cover which is normally found along undercut banks, beneath tree limbs or under large rock ledges.
The diet of Brook Trout includes fish, small crayfish, or even snails, but insects, both terrestrial and aquatic, generally make up the bulk of the forage. In streams containing watercress, brookies feed heavily on scuds, which are small amphipods often found in abundance near springs.
The fact that Brook Trout are native to this state will always make it paramount to our aquatic fauna. Its beautiful coloration and scarcity add measurably to its aesthetic value. In order to survive, Brook Trout must have the coldest and cleanest of stream conditions; continuous pollution, heavy siltation, or water quality degradation will extirpate the species forever. Should the Brook Trout disappear, so will the last of our purest coldwater streams.
Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.
Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.
Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames.
Illustration by Maynard Reece, from Iowa Fish and Fishing.