We assessed the influence of riparian forest canopy type on macroinvertebrate and detritus export from headwater streams to downstream habitats in the Tongass National Forest, southeastern Alaska. Twenty-four fishless headwater streams were sampled monthly, from April to August 1998, across four riparian canopy types: old growth, clearcut, young-growth alder, and young-growth conifer. Young-growth alder sites exported significantly greater count (mean = 9.4 individuals·m–3 water, standard error (SE) = 3.7) and biomass (mean = 3.1 mg dry mass·m–3 water, SE = 1.2) densities of macroinvertebrates than did young-growth conifer sites (mean = 2.7 individuals·m–3 water, SE = 0.4, and mean = 1.0 mg dry mass·m–3 water, SE = 0.2), enough prey to support up to four times more fish biomass if downstream habitat is suitable. We detected no significant differences in macroinvertebrate export between other canopy types or in detritus export among different canopy types. Roughly 70% of the invertebrates were aquatic; the rest were terrestrial or could not be identified. Although we do not recommend clearcutting as a means of generating red alder, maintaining an alder component in previously harvested stands may offset other potentially negative effects of timber harvest (such as sedimentation and loss of coarse woody debris) on downstream, salmonid-bearing food webs.

We developed a standard weight (W s ) equation for lake trout Salvelinus namaycush using the regression-line-percentile technique. Length and weight data from 58 populations of lake trout over most of the species* geographic range were used in development of the equations. In metric units (W St weight in grams; TL, total length in millimeters): logio^= -5.681 + 3.2462 logioTL. In English units (W s , pounds; TL, inches): logioW* = -3.778 + 3.2462 logi 0 TL. A systematic change in relative weight with increasing fish length was not evident.The use of condition indices in assessing the relative plumpness offish in a population is widespread in fisheries management. Recently, the concept of relative weight (W r ) has been applied frequently by fisheries managers (Wege and Anderson 1978) when standard weight (W s ) equations are available for target species (Murphy et al. 1991). Murphy et al. (1990) developed the regressionline-percentile (RLP) technique as a method for deriving standard-weight equations, and they recommended its use as a standardized approach for deriving W s equations. We used the RLP technique to develop a W s equation for lake trout Salvelinus namaycush. This is the first proposed W s equation for a salmonid species that has been developed using the RLP technique.The lake trout is native to North America, its range coinciding with the limits of Pleistocene glaciation (Scott and Crossman 1973). The lake trout is found throughout Canada, and in the United States it is native to several northerly states-Alaska,

We focus on headwater streams originating in the mountainous terrain of northern temperate rain forests. These streams rapidly descend from gradients greater than 20% to less than 5% in U-shaped glacial valleys. We use a set of studies on headwater streams in southeast Alaska to define headwater stream catchments, link physical and biological processes, and describe their significance within watersheds. We separate headwater stream systems into four units that have distinct hydrologic and geomorphic processes that link terrestrial processes to aquatic systems. Headwater streams collect, process, and transport material downstream. Physical and biological processes in headwater streams are complex and closely tied to terrestrial processes. Steps and step pools formed by large wood are keystone structures that link physical processes to biological processes and increase channel complexity. Large and coarse wood debris dams form in-channel step structures and act as valves that regulate the downstream flow of material. A large amount of inorganic and organic sediment is stored in step structures, which may be biological hotspots in headwater streams. Step pools formed by large woody debris are critical habitat for Dolly Varden (Salvelinus malma), juvenile coho salmon (Oncorhynchus kisutch), steelhead (O. mykiss), and cutthroat trout (O. clarkii) in reaches with gradients from less than 4% to those greater than 10%. Landslides and debris flows are the dominant channel-altering processes in headwater streams and remove the step profile. Management activities that increase the number and frequency of channel disturbance events in headwater streams can have important and long-term consequences throughout a watershed.

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