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Chapter 5 -- Anadromous Salmonids and Their Habitats (continued)

Difficulties in Identifying Critical Habitat

Identifying critical habitat for anadromous fish is difficult for several reasons. First, the location of critical habitat changes from year to year. Because a different subset of the stream network is available to fish each year due to variations in stream flow, different habitats perform critical functions in any year. Another difficulty is that the importance of a particular habitat cannot be directly determined through fish surveys. Finding large numbers of fish a stream segment does not necessarily indicate critical habitat or even suitable habitat. Fish may become concentrated in poor habitat when high and moderate quality habitat are lacking or fully occupied. Identification of important productive ("source") habitats is also complicated by migration of fry and juveniles away from their spawning and initial rearing areas. Although many areas of the watershed may produce large numbers of fry, the fish that actually survive to complete their life cycle may come only from certain areas. Despite the fluctuations and ambiguity, we need to decide which areas are probably the most consistent and/or productive source habitats so we can give these places the respect and protection they deserve.

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