Transport of Granitic Sediment in Streams and Its Effects on Insects and Fish

We assessed the transport of granitic bedload sediment ( 2/3 cobble imbeddedness) was one-half that in unsedimented riffles, but the abundance of drifting insects in the sedimented channels was not significantly smaller. In a natural stream riffle, benthic insects were 1.5 times more abundant in a plot cleaned of sediment, with mayflies and stoneflies 4 and 8 times more abundant, respectively. Riffle beetles (Elmidae) were more abundant in the uncleaned plot. During both summer and winter, fewer fish remained in the artificial stream channels where sediment was added to the pools. The interstices between the large rocks in the pools provided essential cover necessary to maintain large densities of fish. Fish in sedimented channels exhibited hierarchical behavior, while those in unsedimented channels were territorial in behavior. In small natural pools ( 100 to 200 m2 ), a loss in pool volume or in area deeper than 0.3 m from additions of sediment resulted in a proportional decrease in fish numbers. We did not, however, find significant correlations between riffle sedimentation and fish density in the two natural streams we studied. Fish abundance was significantly correlated with insect drift abundance in one stream, but not in the other. The amounts of sediment in the two streams studied did not have an obvious adverse effect on the abundance of fish or the insect drift on which they feed

Opinions and Preferences of Idaho Hunters and Department of Fish and Game Employees

The report summarizes the findings of questionnaires sent to both residents who purchased Idaho hunting licenses and Idaho Department of Fish and Game employees to compare their opinions on wildlife management issues

Survival, Production, and Yield of Trout and Chinook Salmon in the Lemhi River, Idaho

The bulletin provides a summary of studies of Chinook salmon and steelhead trout in the Lemhi River and one of its tributaries, Big Springs Creek. Topics include producing fry using the incubation channel, the viability of fry from the incubation channel versus stack incubators, the yield of juvenile steelhead and adult return, production and yield of sympatric and allopatric populations of salmon and steelhead, effects of steelhead fry releases on resident fish, and Chinook salmon spawning escapement, smolt yield, and adult return

Seaward Migration of Dworshak Hatchery Steelhead Trout in 1976

This report describes an evaluation of juvenile steelhead trout reared at Dworshak National Fish Hatchery to assess their transformation from parr to smolt and seaward migration

Seaward Migration of Dworshak Hatchery Steelhead Trout in 1977 as Related to Rearing History

This report evaluates selected procedures for rearing and releasing steelhead trout at Dworshak National Fish Hatchery

Migration Response of Juvenile Chinook Salmon to Substrates and Temperatures

I assessed downstream migration of age 0+ chinook salmon from stream channels with rock and rubble (good) or gravel or shale (poor) substrates and constant or declining water temperatures during the fall months of 1970 and 1971. As water temperatures declined juvenile chinook left stream channels with gravel or shale substrates or moved into available hiding spaces in stream channels with rock and rubble substrate . Fish initially emigrated as temperatures declined below 10 C. I believe the number of emigrants reflects the holding capacity of the substrate and the density of the fish population. The migration response varied with size and race of fish. I attribute most of the response difference between races to differences in fish size. I contend that juvenile spring chinook find rock and rubble substrate an important component of their winter habitat

Habitat Conditions in Three Streams in the Idaho Batholith as Related to Aquatic Organisms

The following is a report of a study of sediment transport in stream channels and its effects on the aquatic biota. There are two major phases of this study, the laboratory stream channels and field studies of natural stream channels. This report summarizes our findings of the field studies for summer, 1972

Sediment in Streams and Its Effects on Aquatic Life

A team of investigators from the disciplines of engineering, entomology and fisheries cooperated in a study to assess the temporal and spatial impact of decomposed granite bedload sediment on insect and fish populations, and on the capability of mountain streams in the Idaho batholith to transport this sediment . This investigation was designed to provide information for resource managers who formulate watershed management guidelines for streams of the Idaho batholith and other areas with granitic baseroc

Transport of Granitic Sediment in Streams and Its Effects on Insects and Fish

The bulletin presents information about the amounts of fine sediment in streams that had detrimental impacts on aquatic insects and juvenile fish and the ability of streams to transport such sediment

A Survey of Behavior, Preferences and Opinions of Idaho Hunters

The bulletin presents the results of a questionnaire survey to describe the people who hunted in Idaho, their hunting activities, and their preferences and opinions on management issues