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1 December 2013 Effects of substrate composition and water temperature on the emergence success of lacustrine brown trout Salmo trutta m. lacustris L. fry from natural redds
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Abstract

The emergence of lake-migratory brown trout Salmo trutta m. lacustris L. fry from natural redds was observed in a small lake outlet stream. A total of 1104 emerging fry were captured in traps in nine of the 12 investigated redds during three seasons. In 2005, all the fry emerged during the daytime, but in 2007 and 2009 they emerged mostly at night. Furthermore, the timing of emergence was earlier than expected from temperature models. The fry left the redds at a water temperature range of 6.2–15.0 °C, and the emergence pattern was correlated with the moon phase. The number of fry captured was strongly affected by the percentage of fine particles < 1 mm and the 8–16 mm particle content, and was positively correlated with the geometric mean of substrate particle size (Dg) and the index of permeability: the fredle index (fi). The estimated survival rate between egg deposition and fry emergence ranged from 0.0 to 59.8 % in individual redds. Additionally, the greatest number of fry and the highest survival rate were observed in redds that had the high water velocity and shortest duration of intragravel period.

Grzegorz Radtke "Effects of substrate composition and water temperature on the emergence success of lacustrine brown trout Salmo trutta m. lacustris L. fry from natural redds," Folia Zoologica 62(4), 247-256, (1 December 2013). https://doi.org/10.25225/fozo.v62.i4.a1.2013
Received: 16 April 2013; Accepted: 1 October 2013; Published: 1 December 2013
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