Oncorhynchus sp. nov. 'Presidio Trout'

TAXONOMIC NOTES Hendrickson and Tomelleri (In Press) discussed the provenance of trout in the Presidio basin, and determined that trout were indeed native to the drainage. JUSTIFICATION This species historically occurred in isolated headwater streams of the Río del Presidio. Based on current collection records, this species exhibits a restricted extent of occurrence (EOO) and area of occupancy (AOO). Recent collections show strong introgression in the watershed. More collections need to be made to determine the range and purity of remaining populations. Native trout from Arroyo Hondo (Quebrada de Vega) were historically abundant, but collections from 2004 show that stream to be compromised by Rainbow trout. Therefore, it is uncertain if this species still exists in pure form. As such, it is assessed as Data Deficient (DD) until more information regarding the distribution, populations status, and magnitude of introgression is available. GEOGRAPHIC RANGE INFORMATION Trout occur sporadically throughout the Río del Presidio in isolated headwater streams. It is unknown at this time which populations represent pure Presidio Trout. POPULATION INFORMATION Trout are locally common in isolated populations. However, it is not known which, if any of these populations represent pure Presidio trout populations. Trout were first collected from the Presidio watershed in 1906 by Walter C. Bishop (Needham and Gard, 1959). Later collections were made by Ralph G. Miller in 1946, and by "P.R. Needham and party" in 1952. Subsequent collections in the 2000s are suspected to show strong signs of introgression and lead to doubts as to whether any of these recent collections represent pure native Presidio trout. HABITAT AND ECOLOGY INFORMATION This species occurs in cold and clear headwater arroyos and canyons in the upper Río del Presidio watershed. Elevation ranges from 1800-2700 masl. Basic life history and basic ecology are uncertain and require additional research. THREATS INFORMATION The principal threat of overriding concern is hybridization with rainbow trout. There is uncertainty regarding the extent of introgression in the various subpopulations, but introgression is suspected to be widespread throughout the watershed (Escalante et al. 2014). Future genetic introgression with rainbow trout is expected, given government initiatives that promote the development of hatcheries within the region. USE AND TRADE INFORMATION There is no known trade in the taxon. CONSERVATION ACTIONS INFORMATION There are no species-specific conservation actions in place. The prevalence of hatcheries and grow-out facilities in the Presidio watershed present an obstacle to recovery. To conserve this species, it is necessary to document a pure lineage of Presidio trout and use it as a founder population for subsequent reintroductions. More research regarding taxonomy, distribution, population size, and population status of Presidio trout are needed to guide future conservation action.