Fish recovery in terminal lakes and rivers of the Great Basin

Background/Question/Methods

Lahontan cutthroat trout (Oncorhynchus clarkii henshawi) (LCT), a subspecies endemic to the Lahontan hydrographic basin of northern Nevada, eastern California and southeastern Oregon, has been listed as threatened since the early 1970’s. The historic distribution of this subspecies included large interconnected stream systems and stream and lake systems.  Fragmentation of these interconnected habitats has led to extensive population extirpation.   Pyramid Lake retained the fish assemblage and forage base that supported the largest Lahontan cutthroat trout, cui-ui (Chasmistes cujus), a long-lived endemic sucker fish, and tui chub, until the arrival of European settlers in the late 1800’s.  Agricultural development and turn of the century calls to “make the desert bloom” resulted in over diversion of the Truckee River and fragmentation of the watershed that blocked migration for both cui-ui and LCT.  This resulted in extirpation of LCT, the top predator, from Pyramid Lake by the mid-1940’s and the near extinction of cui-ui.  

Results/Conclusions

The FWS-LNFHC,has developed a program that combines use of a conservation hatchery, fishery management, and scientific partnerships to develop and implement river restoration, watershed connectivity and LCT reintroduction programs for the lake form of LCT in the Tahoe, Walker and Truckee basins.  Concurrent programs were initiated by the FWS in 1995: to restore the connectivity between Pyramid Lake and the Truckee River through improved instream flow management, fish passage and identifying and raising a native strain of LCT for reintroduction into Pyramid Lake.  An out-of-basin population purported to be of Pyramid Lake origin was discovered in the 1970’s and based upon the morphological evidence a broodstock was developed at Lahontan NFH.   New methods allowing geneticists to isolate DNA from museum preserved specimens confirmed the identity of this population as the original Pyramid strain. This strain was reintroduced to Pyramid in 2006 in collaboration with the Pyramid Lake Paiute Tribe.  The use of this strain has facilitated public interest in the LCT native to this watershed and its remarkable history, a critical aspect of any recovery strategy.  A collaborative, adaptive management strategy employed in this complex arena has yielded significant results and may represent a model for restoration in similar systems.