Boundaries

This ecoregion is bordered by the Gulf of California to the west and the Continental Divide to the east. It encompasses all of the coastal state of Sinaloa, from the southern tip of Sonora along the coast to the state of Nayarit, and inland to Chihuahua and Durango.

Topography

The ecoregion spans the rugged western slopes of the Sierra Madre Occidental down to the coast. Elevations in the ecoregion range from sea level to over 3000 m asl.

Freshwater habitats

Freshwater habitats in the ecoregion range from high sierra headwaters to coastal plain rivers and some coastal lagoons. The coastal rivers of this ecoregion have short courses and narrow floodplains.

Terrestrial habitats

Dry forest dominates the coast with dry forest trees and columnar cacti, including the kapok tree (Ceiba pentandra) and desert fern (Lysiloma watsonii). Higher elevations are dominated by Sierra Madre Occidental pine-oak forests, which boast some of the greatest terrestrial diversity in North America. Pseudotsuga and Pinus constitute the biggest trees. Unfortunately, overharvesting has left only two percent of the original habitat.

Description of endemic fishes

The Sinaloa ecoregion does not exhibit extraordinarily high levels of aquatic endemism. Endemics include the lowland livebearer (Poeciliopsis latidens), clearfin livebearer (P. lucida), shorttail chub (Gila brevicauda), and one endemic species of crayfish. However, near-endemic species include the Sinaloa livebearer, blackstripe livebearer, chubby livebearer, blackfin silverside (Atherinella crystallina), and mountain clingfish (Gobiesox fluviatilis).

Ecological phenomena

Rivers are short and floodplains narrow, with little exchange between rivers except through marine waters.

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. There are a high number of near-endemics in this ecoregion, particularly in the all-female strains of Poeciliopsis. 

Level of taxonomic exploration

Relatively good, excellent along the lowlands, but poor in the high sierras.