Abstract

There is a long-standing belief that the Colorado River once created brackish-water estuarine conditions in the Northern Gulf of California, and that this affected the ecosystem of the Upper Gulf. However, a thorough review of the literature reveals this not to be the case. There has never been published documentation of brackish water in the Northern Gulf south of the river’s mouth, at Isla Montague. (Data from multiple independent investigations have never shown brackish or estuarine conditions south of Isla Montague.) Furthermore, the average daily tidal exchange in the Upper Gulf exceeds the highest annual river discharge ever estimated, suggesting the impossibility of brackish conditions in the Northern Gulf. Species such as vaquita (Phocoena sinus), totoaba (Totoaba macdonaldi), corvina (Cynoscion othonopterus), and others have always lived in marine conditions

Keywords:Colorado river; Colorado delta; Upper gulf of California; Northern gulf of California; Totoab, Corvina; Vaquita; Shrimp