 Of the fish , there were 26 species found in the lower Central Valley portion of the river , including Sacramento sucker , smallmouth bass , largemouth bass and carp , all but three of which are resident species , and some of which were intentionally introduced by humans . The three anadromous fish species that still use the lower Merced are the chinook salmon , Pacific lamprey and striped bass . The upper section of the river , defined as the stretch from Lake McClure to the headwaters , had 11 species of fish . Historically , the range of anadromous fish extended to the head of Yosemite Valley , but by the 1950s and 1960s , except in the wettest years , not enough water flowed down the Merced and San Joaquin Rivers at all to allow them to spawn in significant numbers . New water use requirements have allowed many anadromous species to revitalize , from a low of 500 chinook salmon in the mid @-@ 20th century to a high of 30 @,@ 000 fish in 1984 . After the 1970s , the annual run was about 5 @,@ 300 fish . 
