Prioritizing fish passage improvement in river networks

Dams, road crossings, and water diversions disconnect watersheds for fish movement and migration.  The cumulative effect of these structures can be substantial, even when individual barriers have negligible impact.  Rivers may be reconnected through dam removal and other means of fish passage improvement (e.g., fish ladders).  Here, we apply a graph-theoretic method to investigate fish passage connectivity issues.  We use hypothetical watershed configurations to assess general changes to fish passage connectivity with changes in watershed shape (e.g., linear v. highly-dendritic) and the quantity, location, and passability of each barrier.