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At least 595 records · Page 33Linked to original sources
USGS1944

Facts about snakes

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Wildlife Leaflet↗
USGS2002

Whirling disease among snake river cutthroat trout in two spring streams in Wyoming

We assessed endemic age-0 cutthroat trout Oncorhynchus clarki for evidence of pathology associated with Myxobolus cerebralis in two streams formed by springs in western Wyoming. We hypothesized that the location of spawning sites in spring streams would affect the extent of exposure of cutthroat trout fry to M. cerebralis triactinomyxons (tams), occurrence of the parasite in their bodies, and clinical signs of whirling disease. The spring streams were warm relative to nearby streams flowing from the mountains or spawning and emergence of fry was early compared with fish in mountain streams. Tams were abundant early in the summer and clinical signs of whirling disease among age-0 fish were seen as early as mid-June in one stream. There were high densities of tams in one stream, and densities declined with upstream progression from May through July, whereas in the other stream, low densities of tams were observed in the downstream portion early in the summer, and they were not detected in July and August. Age-0 cutthroat trout were abundant; clinical signs of whirling disease were evident, and histological evidence of whirling disease was common in the stream where tams were abundant. Low densities of age-0 cutthroat trout and no clinical signs of whirling disease were observed in the stream where tams were not abundant. Among sentinel fish in the stream with abundant tams, we found extensive occurrence of M. cerebralis, with many fish showing clinical signs and histological evidence of pathology associated with M. cerebralis. The proportion of sentinel fish with clinical and histological signs of whirling disease decreased with upstream progression. In the stream with low tam, densities sentinel fish became infected with M. cerebralis, but there were essentially no clinical signs or histological indications of whirling disease. ?? 2002 by the American Fisheries Society.

American Fisheries Society Symposium↗
USGS2012

Snake River fall Chinook salmon life history investigations: Annual report 2010

This report summarizes three research activities conducted in 2010-2011. The first was a radiotelemetry study conducted in the lower Clearwater River. The second was a hydroacoustic study conducted in Lower Granite and Little Goose reservoirs. The third was an analysis of covariates affecting juvenile fall Chinook salmon survival and behavior. In 2010, we used radiotelemetry to evaluate the migratory behavior, delay, and relative mortality of subyearling fall Chinook salmon in the Clearwater River and Lower Granite Reservoir. We captured, tagged, and released a total of 100 run-at-large subyearlings in the Transition Zone of the lower Clearwater River in late July and monitored their downstream movement past fixed detection sites and by mobile tracking through the end of August. The Transition Zone is that portion of the river where it transitions from free-flowing to impounded habitat. Median residence time of fish that passed through the Transition Zone, Confluence, and Upper Reservoir reaches was relatively short (8.8-25.6 h). However, for fish that remained in the Transition Zone that were detected by mobile tracking, median residence time was over 30 d (N=6). Median migration rates through the study reaches were variable but slow (range 2.9-17.2 km/d) compared to that of more active migrants indicating that subyearlings from the Clearwater River were not actively migrating during July and August. The fate of radio-tagged subyearlings was determined from mobile tracking records. A total of 37 of the 71 fish detected during tracking were deemed to be dead, 22 were determined to be alive, and the fate of 16 was unknown. We also radio tagged 66 smallmouth bass in the Confluence reach and later detected 59 bass during mobile tracking. Predators were primarily located along shorelines in the Confluence reach, but a few fish did swim downstream into the Upper Reservoir reach. Most radio-tagged subyearlings that we determined to be dead were also located in shoreline areas suggesting that predation could account for some of the mortality we observed.

Oregon, Washington↗