Crayfish Barrier Flume Study
The invasion of non-native crayfish species, particularly signal crayfish, is the single greatest threat to the continued existence of the federally and state-listed endangered Shasta crayfish (Pacifastacus fortis). Barriers to the upstream migration of signal crayfish need to be installed at several sites to protect the remaining allopatric Shasta crayfish populations. The objective of the Crayfish Barrier Flume Study is to design and test crayfish migration barriers that will:
- Be effective at halting the upstream movement of the non-native signal crayfish.
- Remain stable on the streambed under the hydraulic conditions at barrier locations.
- Pass sediment and dislodged vegetation downstream.
- Allow fish passage upstream.
- Be constructed of a material that will resist corrosion and deterioration for a long period of time.
The Crayfish Barrier Flume Study, which is to develop and test crayfish barrier designs in controlled flume studies, is a first priority recovery task in the Shasta crayfish Recovery Plan, which was published by the United States Fish and Wildlife Service in August 1998. Priority-1 recovery tasks are actions that must be taken to prevent extinction or to prevent the species from declining irreversibly. In addition, several other priority-1 recovery tasks await the results of this barrier study, including the installation of barriers to protect the allopatric Shasta crayfish populations in upper Fall River and Rising River.
Shasta crayfish, Pacifastacus fortis (© B. Moose Peterson, Wildlife Research Photography).
Signal crayfish, Pacifastacus leniusculus, a non-native invasive species (© Tom Hesseldenz).