Effects of anthropogenic shoreline alteration on fish emigration from small lakes.

In lentic ecosystems (e.g., lakes and ponds), anthropogenic shoreline alterations, such as concrete embankments, severely degrade habitat, affecting fish assemblage structure. Since fishes have a significant influence on lake ecosystems, it is, however, also essential to assess the response of fish behavior to this degradation to better understand the impact of shoreline alteration on lake ecosystems. Here, we investigated freshwater fish migration behavior in 12 small lakes of norther Japan, in which shorelines are environmentally altered, to assess how the habitat alterations can affect fish emigration from the lake to its connecting channels. We collected fishes using traps installed in lake inflow channels and five focal species were selected for the analysis. A generalized linear mixed model showed that emigration of three of five focal fish increased with the increasing proportion of concrete embankment on the lake shorelines. This result suggests that anthropogenic alteration of a lake shoreline structure significantly impacts fish behavior and affects to their emigration from lakes. Further, this finding indicates that behavioral changes caused by anthropogenic alteration are important for understanding the dynamics of small lake ecosystems. [ABSTRACT FROM AUTHOR]