Reconnecting Rivers for Sturgeon and Ecosystems

With over 85% of species at risk of extinction, sturgeons are the most imperiled group of organisms on earth.  While over-harvest has contributed to their decline, the most prevalent cause of sturgeon extirpation and extinction has been the construction of dams that have blocked migration pathways and inundated rapids in which these species historically spawned.  Recovery of these species will require reconnecting these pathways and critical habitats.  Fish passage will not be a successful strategy if these high gradient habitats no longer exist. Dam removal has the greatest likelihood of success as it both reconnects pathways and restores lotic habitat.  Where dams cannot be removed, a secondary strategy is the use of nature-like fish passage and conversion of low-head dams to emulate natural rapids. The rock arch rapids rock ramp design has been shown to both pass lake sturgeon and provide spawning habitat.  The first documented reproduction of reintroduced lake sturgeon in the St. Louis River of Lake Superior was observed in a rock arch rapids built to restore spawning habitat.  A systematic effort to reconnect the Red River of the North and reestablish extirpated lake sturgeon has used a combination of dam removal, rock arch rapids, and by-pass nature-like fishways.  A rock arch rapids is nearing completion on the Cape Fear River, NC to provide passage for endangered shortnose and Atlantic sturgeon as well as other anadromous species.  These case examples will be discussed in the context of a sturgeon recovery strategy.