Mechanically reshaping stream banks alters fish community composition
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Published source details
Holmes R.J., Hayes J.W., Closs G.P., Beech M., Jary M. & Matthaei C.D. (2019) Mechanically reshaping stream banks alters fish community composition. River Research and Applications, 35, 247-258.
Published source details Holmes R.J., Hayes J.W., Closs G.P., Beech M., Jary M. & Matthaei C.D. (2019) Mechanically reshaping stream banks alters fish community composition. River Research and Applications, 35, 247-258.
Actions
This study is summarised as evidence for the following.
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Stabilize riverbanks Action Link |
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Stabilize riverbanks
A controlled, before-and-after study in 2014–2017 in a river in Southland, New Zealand (Holmes et al. 2019) found that after stabilizing riverbanks by creating a shallower slope, longfin eel Anguilla dieffenbachii biomass decreased after the first year but reached similar levels to before stabilization after 2–3 years. Average eel biomass decreased by 49% one year after stabilizing the riverbanks (5 g/m2) compared to two months before (9 g/m2). Average eel biomass did not differ significantly two (6 g/m2) and three years (11 g/m2) after riverbank stabilization compared to two months before. Meanwhile, over the same period in unmodified streams, eel biomass increased by 160% from two months before (12 g/m2) to one year after (32 g/m2) but did not differ significantly after two (11 g/m2) and three years (9 g/m2). In March 2014, three 40-m river sections that had previously been straightened were stabilized by reducing the angle of both banks to a 1:2 slope. Three 40-m unmodified river sections 4 km upstream were used as a comparison. A total of 432 eels were caught by electrofishing within stop-nets (6-mm mesh) over four 5-day periods: two months before and for three years after (2015–2017) stabilizing.
(Summarised by: Vanessa Cutts)
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