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Several previous posts have discussed the ecological importance of the Salton Sea, particularly its effect on migratory birds. However, the Salton Sea is also home to a much less obvious endangered species, the tiny desert pupfish. Desert pupfish, which are less than 3” long fully grown, are an unusual species due to their incredible tolerance for extreme water conditions. The desert pupfish can survive at salinities of up to 70 g/L—more than double the salt concentration of seawater.[1] This has historically allowed the desert pupfish to live in saline lakes, rivers, and marshes throughout the deserts of California, Arizona, Colorado, Nevada, and Mexico.

DesertPupfish_JohnRinne_FPWC_4.jpg
Desert Pupfish, Cyprinodon macularius, John Rinne

Unfortunately, habitat destruction and invasive species have decimated pupfish populations in the Southwest. Construction of modern infrastructure can result in pupfish habitats becoming isolated from food sources or drying out.[2]  In addition, a number of invasive species compete with the pupfish for food, resulting in a loss of pupfish populations after the introduction of tilapia and similar species. These species may also prey upon the desert pupfish; while there is no direct evidence of tilapia consuming pupfish, a study of fish in Salt Creek, on the shores of the Salton Sea, showed that longjaw mudsuckers had been eating the pupfish.[3] Due to these threats, the desert pupfish is now endangered and lives only in the Salton Sea, the surrounding canals and rivers, and in the Colorado River Delta in Mexico.

The high salinity at the Salton Sea appears to be protecting the desert pupfish, as the water conditions are so extreme that invasive species have been dying off, allowing the pupfish to survive in the marshes and creeks of the Salton Sea.[4] However, the salinity is continuing to rise, and will soon threaten the health of the pupfish. The Salton Sea currently has a salinity of 55 g/L, which is predicted to increase exponentially after 2017. According to one recent estimate, the Salton Sea will reach the fatal salinity limit of 70 g/L within the next 10 years.[5]

In order to preserve this endangered species, many restoration plans have been proposed that will provide marshes and protected areas of moderate salinity where the pupfish can survive. The SSRREI plan proposed by the Imperial Irrigation District (IID), for instance, calls for the construction of low-salinity connected ponds around the Salton Sea to serve as safe pupfish habitat. The Fish and Wildlife Service has teamed up with IID and recently broke ground on the Red Hill Bay Restoration Project to begin to accomplish this goal. As with so many other aspects of the restoration of the Salton Sea, the survival of the desert pupfish is dependent on taking further restoration action soon to protect the ecology of the Sea.

Written by Katherine Muller

 


[1] Sutton, Ron. The Desert Pupfish of the Salton Sea. Bureau of Reclamation. N.p. 5 August 1999.

[2] Sutton, Ron. Summer movements of desert pupfish among habitats at the Salton Sea. Hydrobiologia 473(1): 2002.

[3] Martin, Barbara A., and Michael K. Saiki. Trophic relationships of small nonnative fishes in a natural creek and several agricultural drains flowing into the Salton Sea, and their potential effects on the endangered desert pupfish. Southwestern Naturalist 54(2): 2009.

[4] Martin, Barbara A., and Michael K. Saiki. Relation of desert pupfish abundance to selected environmental variables in natural and manmade habitats in the Salton Sea basin. Environmental Biology of Fishes. 73(1): 2005.

[5] Cohen, Michael. Salton Sea Import/Export (Sea-to-Sea) Plans. Pacific Institute. N.p. 2015.