DSC_9458 Most culverts are built with little concern for ﬁsh passage. The worst type is a ‘perched’ culvert such as this one – where water drops freely from a pipe into the waterway. Some of the native ﬁshes are impressive climbers but they cannot climb upside down or jump to get into these pipes. Many of our ﬁsh are highly migratory – with lifecycles involving movements between the sea and freshwater, or between rivers and lakes. However, artiﬁcial barriers to migration such as this, frequently halt their journeys. Shenandoah Saddle.