Adapting stream barriers to remove invasive fish during their seasonal migrations
This project seeks to develop a system to remove large numbers of invasive common carp during their spawning and seasonal migrations at existing barrier sites in streams in Minnesota. In order to take advantage of carps’ strong migration instincts in spring, this project will include a newly developed fish transport system and an electric fish guidance system. The electric barrier will be placed in a stream to guide fish toward a chute, at which time they will be channeled into the Whooshh System and removed. This barrier, developed by Procom Systems, is unique because it is a very mild electric field to guide fish rather than stun them, and is portable so it can easily be modified to fit specific study sites. An electric barrier is used so water and debris can still flow freely.
The Whooshh System was originally developed to move salmon safely around barriers such as dams in the western U.S., and is now being adapted for removal of carp. Once carp enter the front chamber of the Whooshh system, they are pneumatically pushed through a flexible plastic tube and into a holding pen for removal.
This project includes installing and testing the electric fish guidance system, testing and adapting the existing Whooshh system to allow for removal of carp, and laboratory work to optimize both systems.
As of January 2019, study sites have been selected and a portable, low-voltage electric guidance system to guide the migrating carp into the Whooshh system was installed. Researchers also analyzed existing data on water levels, flows and carp movement through Rice Creek to anticipate when Whooshh tests should occur; data shows that the Whooshh system needs to be in place by mid-March. Researchers also added a floating fish ladder which serves as an entrance to the Whooshh System, as well as electronic PIT antennas and underwater cameras to monitor the passage of carp through the fish ladder and Whooshh.
Tests of carp passage have been conducted daily since ice-out, first during natural carp spawning migration, and then using carp placed within a fenced in experimental arena. The guidance system blocked ~90% of carp passage attempts despite high water flows that occurred during natural spring migration. Field tests of the Whooshh system also went well and showed that the Whooshh was capable of transporting carp of a broad size range. Researchers hope to use the system to remove carp during the spring 2019 migration.