CS34 River Dynamics
Date: Wednesday, June 12, 2002
Time: 5:00:00 PM
Location: View Royal
 
RatschanC, Univ. of Vienna, Dep. of Ecology & Conserv. Biol., Vienna, Austria, clem.rat@gmx.at
Keckeis, H, , Univ. of Vienna, Dep. of Ecology & Conserv. Biol., Vienna, Austria, Hubert.Keckeis@univie.ac.at
 
MOVEMENT AND SITE FIDELITY OF RIVERINE FISH IN A NATURAL AND A RESTRUCTURED RIVER
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Adults of non-diadromous fish show a high degree of movements, which can be described by measures such as site fidelity and mobility. Little is known about dimension, seasonality and influence of environmental factors on these mechanisms, especially as far as riverine cyprinids are concerned. A nature-like and a restructured river were sampled in monthly intervals during one year. A total of over 1500 individuals of the two species chub, Leuciscus cephalus L., and brown trout, Salmo trutta L., were individually marked using PIT (passive integrated transponder) tags. Highly significant differences for mobility indices between the two species were observed, with higher values for chub compared to trout and higher values for chub in the restructured river than in the nature-like. A multivariate model was developed that predicts a large proportion of the variation in the seasonal mobility of chub and trout from abiotic variables. The data impressively support the hypothesis that mobility of riverine fishes is largely depending on river morphology, hydrology, temperature and season.