Fish Ladder to be installed at Hutton Niobrara Ranch Wildlife Sanctuary

We’ve all seen videos of salmon jumping out of the water to get over a small waterfall.  They do this to get upstream to spawn.  But have you ever wondered how small fish move upstream?  Even though small fish do not make long-distance migrations like salmon, they do move up and down streams to take advantage of available food sources and access suitable habitats for various life stages. However, culverts that pass under roads can create a hinderance to their movements. As culverts age, a deep pool generally forms on the downstream side due to erosion, creating a drop in a couple inches to a couple feet of elevation between the drain and the surface of the pool.  There is no way a fish a couple inches long could possibly climb if the distance was more than a couple inches.

But why would anyone care about such small fish?  First, little fish are an important food source for larger fish, herons, and kingfishers.  Second, they are important component of a healthy stream ecosystem.  Lastly, there are several unique species of fish found in Willow Creek.  The cool water streams in the Sandhills of Nebraska support several species of fish whose nearest populations are in cooler climates of states such as Minnesota and Wisconsin.  It is believed the species expanded their ranges to Nebraska as glaciers advanced south about 12,000 years ago. As glaciers retreated, small pockets of the fish remained where cool groundwater flows into the stream to counteract summer heating.  Three fish occur in Willow Creek that are of particular interest to Nebraska Game and Parks.  The blacknose dace (Rhinichthys atratulus) is a species of concern in Nebraska. Blacknose dace have one of the most specialized habitat requirements of all Nebraska fishes. They need clear, small streams with moderate to swift currents and gravel bottoms. A second fish of interest is the Finescale x Northern Redbelly Dace hybrids. Its coloration from top to bottom starts with brown-gray back, then an iridescent, silvery band, and lastly a dark, thick gold-orange stripe along its side. They have a unique method of breeding compared to other fish – they breed parthenogenetically where females produce only daughters (males are not needed to complete reproduction).  Although considered secure in most of its range, Finescale x Northern Redbelly Dace is considered a threatened species in Nebraska.  Plains Topminnow is another species that was observed.  They are invaluable to the functioning of healthy streams and upland habitats because they feed heavily on mosquito larvae.  They are nearly endemic to the Nebraska, meaning that the species is rarely found outside of Nebraska. Plains Topminnow are doing well in the Sandhills but suffering substantial declines elsewhere due to habitat loss and the introduction of Gambusia (mosquitofish) which outcompete Plains Topminnow for habitat and food. Visit http://outdoornebraska.gov/wp-content/uploads/2015/09/Cool-Water-Stream-Management-Plan_FINAL_August2016.pdf for more information on the management of these and other unique plants and animals associated with Nebraska’s streams.

To allow a path for little fish to move upstream, Nebraska Game and Parks is testing ‘fish ladders’. These structures create a series of pools with 1-2 inch elevation changes between each pool. This allows little fish to move upstream.  One of these fish ladders was tested on Willow Creek on the Hutton Niobrara Ranch Wildlife Sanctuary for one week in mid-June. Before installation, a crew from Nebraska Game and Parks surveyed the fish above and below the culvert to see what is currently present. When the fish ladder was installed, they also placed a trap at the top of the ladder to determine which fish used it. After the one week study, blacknose dace used the fish ladder to travel upstream.  The researchers from Nebraska Game and Parks were pleased not only because the fish were able to use the ladder but also that the ladder withstood a heavy rainfall event. AOK plans on working with Nebraska Game and Parks to install a permanent ladder in the future.

We are honored to host these small fish with large importance at Hutton Niborara Ranch Wildlife Sanctuary.