Characteristics and Success of Wild Brown Trout Redds in 2 Western North Carolina Streams

Characteristics and success of 22 wild brown trout redds were studied in 2 western North Carolina streams. Choice of redd site by spawners was determined and intragravel characteristics of redds were followed throughout the incubation period. Spawning began during the last of October at a water temperature of 7° C. It appeared to have ceased by the middle of November. Redds were selected in pool-riffle transition areas or in riffles with a mean surface velocity of 34 cm/second and a mean water depth of 16 cm. Redd areas averaged 94 cm long and 47 cm wide. Egg pits averaged 31 cm in diameter and were 11 cm deep. During the incubation period, mean intragravel dissolved oxygen was 11.0 mg/1 , permeability 1,367 cm/h and apparent velocity 19 cm/h. About 3 weeks prior to emergence 5 alevins per redd were recovered from one creek and 68 per redd from another. Emergence occurred during the first 2 weeks of April. The number of fry emerging varied from 0 to 22 per redd. Anchor ice, scouring by high discharge, and deposition of fine sediment were environmental factors that affected the redds, and caused mortality even though dissolved oxygen, permeability, and apparent velocity were high.

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