Electronic Barrier Installed to Block Carp from Blitzen River
There have been numerous efforts over the years by Malheur National Wildlife Refuge staff to remove carp from Malheur Lake. Most recently, the refuge has been battling to keep the destructive fish out of the Donner und Blitzen River through fish traps. Working with the Harney Basin Wetlands Collaborative, funding was secured from the Oregon Watershed Enhancement Board and legislative funds. This funding made it possible to, in October, install an electronic barrier to block carp from Blitzen River.
The barrier installation involved installing buoys in the water with lights attached to them. The buoys give off a current that the fish instinctively avoid. This type of barrier works well in average water years. It can be removed in highwater years, when flooding occurs and there is water everywhere making it possible for the carp to skirt the barrier.
The barrier includes a fish trap that is about the size of a truck bed. The fish trap allows smaller fish to pass through, but the big 7- to 10-pound carp can be removed from the trap by a conveyor belt that allows them to be sorted. Bigger native fish can be collected and returned to the river while the carp are moved via conveyor into a trailer where they are hauled off.
The last two and half years have been healthy water years for the Harney Basin and as result, native fish, such as redband trout, have thrived to the point where some of them might be too big to pass through the electric barrier’s fish trap. These large native fish can be sorted off the conveyor belt and sent upstream.
The automated conveyor belt system will save refuge staff from having to physically lift fish from the water.
When many of the carp died out because of the drought in 2022, it allowed submergent and emergent vegetation to grow in and around Malheur Lake. Successive years allowed the refuge staff to see how the lake and its surrounding habitat could rebound without the vast numbers of destructive carp. Keeping them out of the Blitzen River is an important part of protecting the watershed and helping native fish thrive; the electric fish barrier will greatly help with that objective.
While the barrier was installed in October and functioning, the refuge will probably see the real benefits of it in the spring.
Photos by Linda Repplinger/Oregon Watshed Enhancement Board
