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Scientific rva.luarlon of Biological Opinions on Endangered and Threatened t'ishcs in the Klamath RivorRa4m, Interim Rcpott (2002) <br />�rtp.Iltat�. inn. ednlo�CnhnnlulHIWI1N ,iapVl6+mi?Jl�oifl. Cc+j+YClpht 21111 ZIKII 'I'6C Nminftpi ACIMMY nl VLCaM%nn ripht ctamd <br />E ANGEMD AND TWEAMED FISHES W jrHE KLAMATH RAER BASIN <br />derived cool water with much larger amounts of warm water from points upstream. <br />Progressive depletion of flows in the Klamath River main stem would at some <br />point be detrimental to coho salmon through stranding or predation losses. Thus, <br />incremental depletions beyond those that are reflected in the recent historical record <br />could be accomplished only with increased risk to coho salmon. At the same time, the <br />available information provides little support for benefits presumed to occur through the <br />increase of flows beyond those of the last decade. While single -year or multiple -year <br />averages of low -flow extremes beyond those presently reflected in the record cannot be <br />supported, there also is presently little evidence of a scientific nature that increased low <br />flows will improve the welfare of the coho salmon. <br />Modeling of temperature and habitat may be useful, but convincing evidence of a <br />relationship between the welfare of the coho and environmental conditions must be <br />drawn to some extent from direct observation. For example, year class strength, <br />abundance of various life history stages, or other biological indicators of success, when <br />related to specific flow conditions, would greatly improve the utility of modeling and <br />other information. The small size and scattered nature of the present native coho <br />population will make collection of such data difficult, however. <br />The RPA requirements related to ramping rates and coordination seem <br />supportable. Given direct field observation of the stranding of coho at the current <br />ramping rates (NNES 2001) and the mortality that is implicit in these observations, <br />reduction in ramping, rates seems a reasonable and prudent measure for protection of <br />coho. Coordination, a final requirement of the RPA, is an obvious necessity given the <br />need to optimize use of water for multiple purposes. <br />20 <br />966 -d 6E0/EE0'd 9EZ -1 899E998EOE saodnosu innm iow ad W H ZOOZ- 80 -93d <br />