Information Center for the Environment

Biodiversity Maps of Fishes in California

Steps in Producing Biodiversity Maps

Fish range maps were created by the Department of Wildlife, Fisheries and Conservation Department of the University of California at Davis as part of a contract with the Nature Conservancy. For more details of how these range maps were developed, link to fish maps. A majority of the polygon coverages of fish distributions in California were used to create the fish biodiversity (species richness) maps. In addition, polygon coverages for threatened and endangered species were obtained from the CA Department of Fish and Game Natural Diversity Database, which provided The Nature Conservancy with these GIS data sets, to make a total of 120 fish species range maps in California. These polygons were compiled together, then overlaid using the California 1:24,000 scale USGS quadrangle map grid lines. This step was accomplished by Michael Byrne of CA Dept. of Fish and Game, Inland Fisheries Division. Using ARC/INFOs Macro Language (AML) Mr. Byrne produced several maps showing total number of native and introduced fishes as well as a percent nativeness for each 1:24,000 quadrangle.

Click on any of the maps below for a larger image
Native fish
species richness
Non-native fish
species richness
Total fish
species richness
Percent native
species richness

Work in Progress

The analysis of native versus non-native fish species was processed in duplicate files so the polygons themselves do not contain a nativeness attribute. This creates a problem for native species that do not occur in their native range (such as squawfish in the Eel River or trout in the High Sierra). Currently we are updating some of the native species range polygons to include a nativeness attribute. This will allow us to depict native fishes in non-native ranges as well as native ranges. Only those polygons having a rating of probable”were used in the biodiversity maps. Some particularly rare species, such as some fishes in the Salton Sea, have a rating of only possible so were not included in the final maps. As a result, less than the total 118 were used for the biodiversity maps. We are working to include those species with only possible ranges into the species richness maps. We are currently working to display the individual species range maps on a seperate web page.

Information Center for the Environment / Search / Notices / January 17, 1997