ABSTRACT With the decreasing runs of natural fall chinook salmon* Oncorhmchus tshawytscha.inthe Klamath River basin, concerns were raised regarding the accuracy ma significance 01 me mainstem Klamath River .1 chinook spawner estimates. The U.S. Fish and Wildlife Service, Coastal California Fish an - Wildlife Office (CCFWO) was funded through the Klamath River Fish and Wildlife Restoration Act (P. L.99-552) in the Fall of 1993-1996 to address this concern. The 1995 and 1996 survey season marked the third and fourth year that the CCFWO conducted investigations on the upper mainstem Klamath River to derive a reasonable estimate of natural * fall chinook spawners. A total of 339 redds were observed in the 1993 survey. In 1994 and 1995, redd counts increased to a total of 1,702 and 3,240 respectively. During the 1994 and 1995 spawning, seasons, there was evidence that unspawned surplus adult fall chinook salmon released from Iron Gate Hatchery (IGH) successfully spawned in the Klamath River. One hatchery fin clipped adult was observed spawning.30 miles downstream of the hatchery. In 1996, 1,372 redds were observed which wasa decrease of 43% from the previous year. There was complete retention of hatchery origin adults by IGH in 1996, although, the distribution of redds remained the same as previous years. With the new hatchery policy of excess return retention, mainstem escapement can now be considered a reasonable estimate of natural spawning adult chinook salmon. Reddsubstrate composition estimates remained consistent with previous spa- *:g survey data. Based upon 210 redd measurements from 1995-1996, the average redd size L ...e mainstem of the Klamath River was 9.6 nr. The average pit depth, mound depth, and adjacent depth for 1995-1996 was similar to previous survey results. Redds were most common along the wetted channel margins with numerous redds observed in side channels with suitable gravel and water velocities. Unlike 1993 and 1994 some redds were observed by 1995 and 1996 survey crews in rnid-channei areas. Recreational suction dredge mining was present throughout the survey from the confluence of Scott River downstream to the confluence of Indian Creek, although only two redds were observed on recent dredge tailings. Under the existing mining regulations, adverse impacts on redds could occur below the Scon River without protection of spawning areas.
"Funded by Klamath River Fish and Wildlife Restoration Act (P.L. 99-552)." ; "October, 1997." ; Includes bibliographical references (p. 27)