Mason D. Bryant

A Hierarchical Approach to Classifying Stream Habitat Features

Abstract We propose a hierarchical system of classifying stream habitats based on three increasingly fine descriptions of the morphological and hydraulic properties of channel geomorphic units. We define channel geomorphic units as areas of relatively homogeneous depth and flow that are bounded by sharp gradients in both depth and flow. Differences among these units provide a natural basis for habitat classification that is independent of spatial scale. At the most general level of resolution, we divide channel units into fast- and slow-water categories that approximately correspond to the commonly used terms “riffle” and “pool.” Within the fast-water category, we identify two subcategories of habitats, those that are highly turbulent (falls, cascades, chutes, rapids and riffles) and those with low turbulence (sheets and runs). Slow-water habitats include pools formed by channel scour (eddy pools, trench pools, mid-channel pools, convergence pools, lateral scour pools and plunge pools) and those formed be...

Characteristics of channel steps and reach morphology in headwater streams, southeast Alaska

Abstract The effect of timber harvesting and mass movement on channel steps and reach morphology was examined in 16 headwater streams of SE Alaska. Channel steps formed by woody debris and boulders are significant channel units in headwater streams. Numbers, intervals, and heights of steps did not differ among management and disturbance regimes. A negative exponential relationship between channel gradient and mean length of step intervals was observed in the fluvial reaches (

Estimating Fish Populations by Removal Methods with Minnow Traps in Southeast Alaska Streams

Abstract Passive capture methods, such as minnow traps, are commonly used to capture fish for mark–recapture population estimates; however, they have not been used for removal methods. Minnow traps set for 90-min periods during three or four sequential capture occasions during the summer of 1996 were used to capture coho salmon Oncorhynchus kisutch fry and parr, Dolly Varden Salvelinus malma, cutthroat trout O. clarki, and juvenile steelhead O. mykiss to estimate population size with the Zippin or generalized removal method. More than 45% of the total catch was obtained during the first capture occasion, and in most cases, the catch during the fourth occasion was less than 15% of the total catch. In most pools, the probability of capture was greater than 0.4 but was lower for coho salmon fry than for coho salmon parr and other species. Mean population estimates for coho salmon parr made with concurrent mark–recapture and removal methods differed significantly in small streams. Estimates from mark–recaptur...

Colonization of a Watershed by Anadromous Salmonids following the Installation of a Fish Ladder in Margaret Creek, Southeast Alaska

Abstract We evaluated the colonization of a watershed blocked by a 7-m falls following the installation of an Alaska steeppass fish ladder to provide access for anadromous salmonids. Coho salmon Oncorhynchus kisutch, pink salmon O. gorbuscha, and chum salmon O. keta were present below the falls. Fry of sockeye salmon O. nerka were stocked into Margaret Lake once in 1988 and annually from 1990 through 1994. Pink salmon were the most numerous species to colonize habitat above the falls. Coho salmon moved up the ladder during all years. However, progeny from 25,000 coho salmon presmolts that were stocked in 1991 were the greatest proportion of the returns in 1992, 1995, and 1996. During the study, only 1,595 sockeye salmon returned from more than 1.4 million that were stocked. The rapidity of colonization by naturally occurring anadromous salmonids, including cutthroat trout O. clarki, Dolly Varden Salvelinus malma, and steelhead O. mykiss, underscores a life history strategy of exploiting newly accessible h...

Effect of Temperature Extremes on the Mortality and Development Rates of Coho Salmon Embryos and Alevins

Abstract The effect of water temperature extremes on embryo and alevin development rates and upper and lower lethal temperature limits for hatching have been defined for two coho salmon (Oncorhynchus kisutch) stocks. When held at constant incubation temperatures, embryos withstood temperatures between 1.3 and 12.4°C. Nearly 100% mortality occurred at 14°C in the upper range and below 1.3°C in the lower range. Most mortality occurred in the early embryonic stages, usually before the blastopore closed. Abrupt temporary changes in incubation temperature lasting 8 h and ranging from + 8.4 to - 6.2°C (including a drop to 0.1°C), resulted in little or no increase in embryo mortality except at the highest (10.2°C) incubation temperature. Temperature effects on development time were not linear, and small changes in temperature resulted in large changes in development rates, particularly at upper and lower extremes of temperature. A set of equations describes the relationship between temperature and centigrade uni...

Salmonids on the Fringe: Abundance, Species Composition, and Habitat Use of Salmonids in High-Gradient Headwater Streams, Southeast Alaska

Abstract We evaluated the species distribution, abundance, and habitat relationships of salmonids in small first- to second-order headwater streams in southeast Alaska. Streams were separated into three zones based on gradient and sampled during the spring, summer, and fall. Dolly Varden Salvelinus malma were found in all streams where fish were present. They were the dominant species in moderate- (mean gradient = 5.5%) and high-gradient (mean gradient = 12.9%) zones. Coho salmon Oncorhynchus kisutch fry and parr were the dominant species in the low-gradient zone (mean gradient = 3.1%) but were present in higher-gradient zones. Small numbers of steelhead O. mykiss parr were present in all three zones in the spring and fall. Few were captured during the summer. Coastal cutthroat trout O. clarkii were found primarily in one stream and in all three zones. The density of all species decreased as gradient increased. Anadromous Dolly Varden in spawning condition were observed in the fall up to the highest acces...

Pulsed Monitoring for Watershed and Stream Restoration

Abstract Long-term habitat degradation has increased public recognition of the need for watershed and stream habitat restoration. With such recognition is the demand for accountability, but the effects of restoration and recovery of watersheds are complex and long-term. A monitoring program that provides sufficient information to evaluate the effectiveness of these efforts will be expensive. A pulsed monitoring strategy that consists of a series of short-term (3–5 years), high-intensity studies separated by longer periods (10–15 years) of low-density data collection can provide an effective means of implementing a long-term monitoring program with a reasonable degree of success and cost.

Evaluating Stream Habitat Survey Data and Statistical Power Using an Example from Southeast Alaska

Abstract Stream habitat surveys and watershed assessments have been developed and used as monitoring tools for decades. Most rely on type I error as the primary criterion, with minor consideration of statistical power and effect size. We test for statistical differences in fish habitat condition between harvested and nonharvested watersheds from habitat survey data collected in southeast Alaska. We apply statistical power analysis to judge whether nonsignificant results can be interpreted with confidence. None of the fish habitat variables we examined were significant at α = 0.05; however, several P-values were less than 0.10 and consistent differences between harvested and nonharvested reaches were observed among channel types. Statistical power is low and the probability of not detecting differences is high when the effect size, scaled to the standard deviation of the measurement, is small to medium. For large effect sizes, the ability to detect differences was greater but did not exceed 85% for any mea...

Managing young upland forests in southeast Alaska for wood products, wildlife, aquatic resources, and fishes: problem analysis and study plan.

Wipfli, Mark S.; Deal, Robert L.; Hennon, Paul E.; Johnson, Adelaide C.; De Santo, Toni L.; Hanley, Thomas A.; Schultz, Mark E.; Bryant, Mason D.; Edwards, Richard T.; Orlikowska, Ewa H.; Gomi, Takashi. 2002. Managing young upland forests in southeast Alaska for wood products, wildlife, aquatic resources, and fishes: problem analysis and study plan. Gen. Tech. Rep. PNW-GTR-558. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 64 p. Red alder (Alnus rubra Bong.) appears to influence the productivity of young-growth conifer forests and affect the major resources (timber, wildlife, and fisheries) of forested ecosystems in southeast Alaska. We propose an integrated approach to understanding how alder influences trophic links and processes in young-growth ecosystems. The presence of red alder is expected to increase understory biomass, and aquatic, riparian, and terrestrial invertebrate abundance, providing more food for herbivores, fish, and birds. We predict that most red alder trees will die standing, and woody debris will be small and mobile in streams. Nitrogen fixation by red alder in mixed stands may result in larger, more commercially valuable conifers. Inclusion of red alder in the regenerating stand may therefore mitigate some negative impacts of clearcutting, and may increase total wood production from the landscape.

Coho Salmon Populations in the Karst Landscape of North Prince of Wales Island, Southeast Alaska

Abstract Karst topography is a unique and distinct landscape and its geology may have important implications for salmon productivity in streams. The relationship between salmonid communities and water chemistry and the influence of habitat was examined in a set of streams on north Prince of Wales Island, southeast Alaska. Streams in karst landscapes showed higher alkalinities (1,500–2,300 μeq/L) than streams not influenced by karst landscapes (750–770 μeq/L). A significant, positive relationship was observed between alkalinity and density of coho salmon parr Oncorhynchus kitsutch. Backwater pools supported higher densities of coho salmon than did other habitat units. Both coho salmon fry and parr tended to be larger in most karst-influenced streams than in nonkarst streams. Although past timber harvest practices in the riparian areas of several of the streams appeared to influence stream habitat and water temperature, streams flowing through karst landscapes had a distinct water chemistry. Furthermore, th...