Density‐dependent effects of non‐native brown trout Salmo trutta on the species–area relationship in stream fish assemblages

Abstract

The spatial scale and density-dependent effects of non-native brown trout Salmo trutta on species richness of fish assemblages were examined at 48 study sites in Mamachi Stream, a tributary of Chitose River, Hokkaido, Japan. The density of age ≥1 year S. trutta was high in the upstream side of the main stem of Mamachi Stream. Fish species richness increased with increasing area of study sites (habitat size), but the increasing magnitude of the species richness with area decreased with increasing age of ≥1 year S. trutta density. The relationships between age ≥1 year S. trutta, however, and presence-absence of each species seemed to be different among species. Species richness was also determined by location and physical environmental variables, i.e. it was high on the downstream side and in structurally complex environments.

First insight into freshwater fish assemblages in the western part of the Endau-Rompin landscape, Malaysia

“…Fish species composition is marked by habitat heterogeneity, environmental gradients, and human activity (Sehr and Keckeis 2017;Shukla and Bhat 2017) at local and regional scales (Benke et al 2011;Hasegawa et al 2017;Nicol et al 2017;Cheng et al 2019). Comparably, the fish richness in this study increases across the substations following the river's gradient.…”

Brown trout in Japan − introduction history, distribution and genetic structure

“…Moreover, after an invasion that occurred above a collapsed dam in the Monbetsu stream in Hokkaido, brown trout replaced white-spotted charr through competition and possibly hybridization (Hasegawa, 2017). Brown trout have also reduced the number of species of fish fauna in other streams in Hokkaido (Shimoda 2012;Hasegawa et al, 2017).…”