To maintain or restore habitat necessary for a sustainable salmon fishery requires that the biophysical processes producing properly functioning habitat be maintained or restored. However, since watersheds and streams differ in their characteristic flow, temperature, sedimentation, nutrient levels, physical structure, biological components, etc.; specific habitat requirements of salmonids differ among species and life-history types; and, these requirements change with season, life stage, and presence/absence of other biota; there is no simple definition of salmonid habitat requirements. Table 3-4 is an overview of the general major habitat requirements and habitat concerns during each life stage of the salmon’s life cycle. The goal of salmonid conservation should be to ensure that salmonid habitat requirements are met by maintaining habitat features within the natural range for the particular system. The range of patterns and processes which define the properly functioning habitat conditions within which salmon can exist and evolve are enumerated in the first three columns of Table 3-3 ("Habitat Objectives").

Table 3-3, modified from the 1996 NMFS "Matrix of Pathways and Indicators" for evaluating the effects of human activities on anadromous salmonid habitat, lists nine major habitat elements/pathways (column 1), indicators associated with habitat function (column 2), and general parameters or criteria for the proper functioning of each habitat indicator (column 3). The habitat elements include stream water quality, habitat access, stream habitat elements, channel conditions and dynamics, flow/hydrology, watershed conditions, estuarine conditions, and estuarine water quality. The ranges of criteria presented in this table are generally applicable, but are by no means absolute, since each watershed has a unique geomorphology, hydrology, etc. Therefore, target habitat conditions should be established on a regional watershed or site-specific basis as needed to account for ecological variability.

An extensive review of existing information on salmonid habitat requirements generated the data summarized in Tables 2-1, 2-2, and 2-3("Chinook, Coho, and Pink salmon habitat use by life history stage"), Table 3-4 ("Summary of Major Habitat Requirements and Concerns During Each Stage of the Salmon’s Life Cycle"), and Table 3-3 ("Habitat Objectives").

• Tables 2-1 through 4.1 summarize, by species, the life history stage, diet, season/time, location in substrate and in water column, ocean features, and oxygen/temperature/salinity requirements for the stage.

• Table 3-4 reviews salmon movements and habitat use (e.g., for adult migration pathways, spawning and incubation, stream rearing, smolt migration, estuarine and marine residence), the characteristic features required in each habitat (e.g., gravel and cobble with sufficient water and oxygen during spawning and rearing), and the commonest expression of habitat degradation found (e.g., elevated temperatures, reduced pool frequency);

• Table 3-3, by describing indicators of the functioning of specified habitat elements or "pathways", as well as criteria for proper functioning/risk/malfunction of the listed habitat elements, sets the broad habitat conditions to be targeted by conservation and enhancement activities.

The information cited on salmonid life history, range of requirements, and types of adverse effects detailed in the tables are reconfirmed throughout the existing technical literature and appear to provide reliable descriptions of generalized baseline habitat.

TABLE 3-4. Summary of major habitat requirements and concerns during each stage of the salmon’s life cycle.