Today as one visits the many alpine lakes and streams of Yosemite National Park it will be noted that nearly all of these waters are the home of some type of fish. A goodly portion contain various kinds of trout ready to match wits with the visiting angler. However, such conditions have not always existed.

The Pleistocene glaciers which scoured and ground their way down through the major stream canyons of the Merced and Tuolumne rivers destroyed all fish life that may have occurred in those areas before the coming of the Ice Age. After the glaciers had receded, aquatic life slowly began to return to these systems. The high, free-leaping waterfalls left in the wake of the glaciers prevented fish from ascending into the headwaters and repopulating these sections of the rivers. In a letter on file in the Yosemite Museum library written to Mr. Chester Verteeg on July 12, 1924, Colonel H. C. Benson, one of the early park superintendents, verifies this view.

Colonel Benson stated: “When we [the Army] went into the Yosemite Park [in 1892] these were no fish in the park except those which were enabled to come directly up the Merced River to the Yosemite Valley and up the South Fork of the Merced to within a mile or two east of Wawona and up the Tuolumne to the falls of the Hetch Hetchy except the fish that were brought in by old man Kibbe in 1877. He had put fish in Lake Eleanor and Lake Vernon but they were unable to get back into the country behind the falls of Lake Eleanor.” The natural distribution of the fish in Yosemite National Park, therefore, was very limited.

The indigenous fish fauna also was very restricted in numbers, there being only six native species, representatives of four families. Until recently, it was thought that the rainbow trout and the Sacramento sucker were the only native species found within the park. Additional investigations have disclosed that the Sacramento squawfish, the hardhead, the Sierra chub-roach and the riffle sculpin are also native; but only the rainbow trout and the Sacramento sucker are of common occurrence.

In a recent Yosemite Nature Notes article, Hubbs and Wallis have discussed the native fish fauna in greater detail.²

2. Hubbs, Carl L. and Wallis, Orthello L. 1948. The native fish fauna of Yosemite National Park and its preservation. Yosemite Nature Notes, Vol. 27, No. 12. (December) pp. 131-144.

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