ABSTRACT
Culverts that impede or inhibit fish migration are, among other river structures, a growing concern in habitat conservation efforts globally. Small-bodied fish species, which are often weaker swimmers than larger specimen, can be impacted by shallow depths and high water velocities encountered in culverts. Retrofitting of culverts is commonly used to enable fish migration. Here, we present a fish friendly remediation design, imitating filamentous algae, and discuss the suitability for fish passage. We describe how instantaneous turbulent flow structures can be assessed for the remediation design. The studied remediation design is a dense layer of filamentous algae that has been observed to provide small-bodied whitebait with a means to overcome an almost vertical weir. We describe a laboratory model that is used for flow field quantification.
