Gila orcuttii

Hybridizes with G. bicolor mohavensis and with Lavinia symmetricus under stressed conditions (Lee et al. 1980). Placed with the closely related G. purpurea in the subgenus Temeculina.

This species exhibits a relatively small range limited to the southern California coastal plain where its range and abundance have been significantly reduced by habitat degradation associated with urbanization and impacts from introduced non-native fish species (on-going threats). Durable conservation measures are in place that when fully implemented will support remaining populations and possibly lead to population stability in areas where it is now declining.

The range extent of this species includes occupied coastal plain streams from southern San Luis Obispo County south through Los Angeles and Orange Counties and east to extreme western Riverside County, California, USA. Based on descriptions in Moyle et al (2015), Santos (2015), and analysis of recent observation data (GBIF 2024), this species range includes parts of 13 HUC 8 watersheds comprising about 29,000 km2. O’Brien and Barabe (2022) describe a native (excluding introduced populations) distribution of 7 watersheds extending over about 16,800 km2.

There are currently 8 described populations of this species (O’Brien and Barade 2022, Benjamin et al 2016) within its California, USA, range. For purposes of this assessment, those populations are considered the occurrences.

The primary threat to this species is dams and passage barriers created through road construction, culverts, and other barriers which eliminate access to suitable upstream spawning areas. Historical and remaining habitat for this species are within the highly urbanized southern California Coastal Plain where pollutants from urban roads and housing have reduced water quality with likely detrimental lethal and sub-lethal impacts on this species. Competition and predation from non-native invasive species and loss of genetic diversity through hybridization with these non-native invasive species are identified threats. Several introduced species have been identified in occupied streams and watersheds occupied by this species (see Moyle et al 2015). The effects of climate change are likely to affect this species although the severity of these impacts is unknown. In a comprehensive review of climate vulnerability of at-risk freshwater fish, Moyle et al (2013) assessed 164 taxa against exposure and sensitivity criteria within four generally accepted and relevant climate scenarios. This species was classified as “less vulnerable”.