Native trout of the Baja Pensinsula Trout of the Acaponeta watershed Trout of the Rio Baluarte watershed Trout of the Rio del Presidio Trout of the Rio Piaxtla and tributaries Trout of the Rio San Lorenzo watershed Oncorhynchus chrysogaster Trout of the Rio Mayo watershed Trout of the Rio Yaqui watershed

Oncorhynchus sp.

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The Rio Acaponeta is the southernmost watershed in North America that is known to have native trout.  The headwaters of the Rio Acaponeta rise directly to the east of the Rio Baluarte, and flow south-southeast to the Pacific Ocean.  Trout are currently known only from the more easily accessible northern tributaries.   As do most major rivers in the Sierra Madre Occidental, the Rio Acaponeta flows through a deep and rugged barranca.  It is not known if trout occur in the Rio Acaponeta proper, as the mainstem is entrenched in the canyon at a much lower altitude than the tributaries.  Hence, populations of trout in the high tributaries may have been "thermally isolated"

from each other for thousands of years by subtropical water conditions in the mainstem Acaponeta. 

To date, four tributaries in the Acaponeta have been investigated for trout, and all are believed to contain native trout.  The watershed is vast, and a large area has yet to be sampled for trout.   The first collections of Acaponeta trout were made in June of 2001 by Gorgonio Ruiz-Campos, Alejandro Varela Romero, and Faustino Camarena of the Universidad Autónoma de Baja California in Ensenada.  The Acaponeta trout are thought to be related to the Baluarte and Presidio trouts, but typically exhibit rounded and much larger auxiliary parr marks than other trouts.