Rio Santiago




Salvador Contreras Balderas (Universidad Autónoma de Nuevo León), Jennifer Hales



Major Habitat Type

Tropical and subtropical coastal rivers

Drainages flowing into

Drainages of this ecoregion flow into the Pacific Ocean.

Main rivers to other water bodies

The extent of this ecoregion is largely defined by the watersheds of the Río San Pedro, the Río Santiago, and their tributaries, including the Río Mezquital, Río Grande de Santiago, Río BolaZos, and Río Juchipila. Río Santiago drains Lake Chapala, part of the Lerma – Chapala ecoregion [165].



The ecoregion lies on the Pacific coast and includes the Islas Marías. The ecoregion covers the states of Durango, Nayarit, Jalisco, Zacatecas, Aguascalientes, and Guanajuato.


The topography is defined primarily by deep canyons of the Sierra Madre Occidental as well as the Trans-Mexican Volcanic Belt in the east. Elevations range from sea level to over 3000 m.

Freshwater habitats

Freshwater habitats include major rivers with sand and rocks. This region is distinguished in part by its subterranean ecology. Aguascalientes is a warm aquifer located in the Mexican state that bears its name. It harbors unique populations of aquatic invertebrates such as rotifers.

Terrestrial habitats

Terrestrial habitats include mangroves and dry forests along the coast, Sierra Madre Occidental pine-oak forests at higher elevations, and matorral and Bajío dry forests in the interior. Characteristic species of the Bajío dry forest include Bursera, Ipomoea, and Ceiba.

Description of endemic fishes

The Santiago ecoregion is located on the western slope of the Sierra Madre Occidental and harbors relatively few known endemic aquatic species. Strict endemics to the ecoregion include the remote chub (Algansea avia), mountain chub (Algansea monticola), and Chapala catfish (Ictalurus ochoterenai). Some of the near-endemics include the spottail chub (A. tincella), Jalisco chub (Yuriria alta), yellow shiner (Notropis calientis), Lerma catfish (Ictalurus dugesii), largetooth silverside, shortfin silverside, olive skiffia (Skiffia lermae), spotted skiffia (Skiffia multipunctata), Lerma livebearer, blackstripe livebearer, and chubby livebearer.

Justification for delineation

Ecoregion delineations were based on qualitative similarity/dissimilarity assessments of major basins, using the standard administrative hydrographical regions of the Mexican federal government.  In this ecoregion there was a high number of near- endemics, especially in Rìo Santiago.

Level of taxonomic exploration

Relatively poor, due to inaccessibility.


  • Barbour, C. D. (1973). "The systematics and evolution of the genus Chirostoma Swainson (Pises: Atherinidae)" Tulane Stud. Zool. Bot. 18 pp. 97-41.
  • Crossin, R. S., Soule, O. H., Webb, R. G., et al. (1973). "Biotic relationships in the Canon del Rio Mezquital, Durango, México" Southwest. Nat. 18 (2) pp. 187-200.
  • Contreras-Balderas, A. J.;Contreras-Balderas, S. (1988). "Los peces de Aguascalientes" México: Publ. Biol.. U. A. N. L..
  • Abell, R. A.,Olson, D. M.,Dinerstein, E.,Hurley, P. T.,Diggs, J. T.,Eichbaum, W.,Walters, S.,Wettengel, W.,Allnutt, T.,Loucks, C. J.;Hedao, P. (2000). "Freshwater Ecoregions of North America: A Conservation Assessment" Washington, DC, USA: Island Press.