Apache Trout Conservation Exotic Fish Barrier

Mountain streams in Arizona

Sponsors

Trout Unlimited, White Mountain Apache Tribe, Arizona Game and Fish Department, National Fish and Wildlife Foundation, U. S. Fish and Wildlife Service

Scope of Work

Hydrology, Hydraulics, Structural Analysis, Fluvial Geomorphology, Biological Survey and Analysis, Design and Construction

Introduced nonnative fish species are rapidly being identified as a major factor in the decline of native fish species in the southwest.  Fish barriers which prevent non-natives from moving upstream into headwater habitats are an important and powerful conservation tool.  In order to remain reliable, barriers require inspection, occasional maintenance, and supplementation.  Importantly, existing barriers, based on older designs may exert negative impacts on stream morphology, reducing stream function and stability as well as barrier effectiveness.

The Arizona Game and Fish Department is responsible for the recovery of the endangered Apache trout (Onchorynchus gila apache).  The recovery strategy requires the establishment of new populations as well as the protection of existing populations in state streams.  Barriers that prevent the upstream movement of non-native species such as Brown trout (Salmo trutta) and Rainbow trout (Oncorhynchus mykiss), preserve headwater portions of streams and prevent predation, competition and hybridization threats to Apache trout.  Currently, the conservation program relies on a series of fish barriers constructed by different entities over several decades using various designs and materials. 

Methodology used to evaluate fish passage at each barrier site is based on assessing the biological criteria of fish with the physical conditions of the barrier.  Enough field measurements are taken to allow hydraulic analysis of the barrier over a wide range of flows and compare current velocities and jump heights to the swimming and jumping abilities of non-native fish.  Additionally, a visual assessment of structural failure, leakage, or stream geomorphic instability is made for each barrier.  Whenever possible, the maintenance and sampling history of barriers are reconstructed and documented.  This information is summarized for the purpose of prioritizing maintenance and stocking activities, as well as providing guidance for design and construction of future barriers.  It is expected that the methodology developed for these projects will be beneficial for the assessment of other fish barriers for Apache trout and other threatened species.