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USGS2012

Efficacy of a glycoprotein DNA vaccine against viral haemorrhagic septicaemia (VHS) in Pacific herring, Clupea pallasii Valenciennes

Viral haemorrhagic septicaemia virus (VHSV) and its associated disease state, viral haemorrhagic septicaemia (VHS), is hypothesized to be a proximate factor accounting for the decline and failed recovery of Pacific herring populations in Prince William Sound, AK (Marty et al. 1998, 2003, 2010). Survivors of laboratory-induced VHSV epizootics develop resistance to subsequent viral exposure (Kocan et al. 2001; Hershberger et al. 2007, 2010), which is likely the result of immune system recognition of the viral glycoprotein (G) (Lecocq-Xhonneux et al. 1994), a surface antigen that contains neutralizing epitopes (Lorenzen, Olesen & Jorgensen 1990; Jørgensen et al. 1995) and cell attachment domains (Lecocq-Xhonneux et al. 1994; Estepa & Coll 1996). These properties have proven useful in the development of G-gene-based DNA vaccines for VHSV and a related rhabdovirus, infectious haematopoietic necrosis virus (IHNV) (Anderson et al. 1996; Heppell et al. 1998; Corbeil et al. 1999; Einer-Jensen et al. 2009). Rainbow trout fingerlings, Oncorhynchus mykiss (Walbaum), vaccinated with 1 µg of either the VHS or IHN vaccine are protected from VHS when exposed to virus as early as 4 days (44 degree days) post-vaccination (p.v.) (Lorenzen et al. 2002). At later time points (80 days p.v.; 880 degree days), the level of cross-protection against VHS by IHN vaccination is either completely lost (60 days p.v.; 660 degree days) (3 g rainbow trout; 1 µg vaccine dose) (Lorenzen et al. 2002) or present at intermediate levels (6.5 g rainbow trout; 1 µg vaccine dose) (Einer-Jensen et al. 2009). Comparatively, VHS vaccination remains effective as long as 9 months (2520 degree days) p.v. (100 g rainbow trout; 0.5 µg vaccine dose) (McLauchlan et al. 2003). These results suggest that IHN and VHS vaccination activate a rapid transitory innate immune response against VHSV that is followed by long-term adaptive immunity in VHS-vaccinated trout (Lorenzen et al. 2002).

Journal of Fish Diseases↗

USGS2021

Effects of a diatom ecosystem engineer (Didymosphenia geminata) on stream food webs: Implications for native fishes

Stream habitat changes affecting primary consumers often indirectly impact secondary consumers such as fishes. Blooms of the benthic algae Didymosphenia geminata (Didymo) are known to affect stream macroinvertebrates, but the potential indirect trophic impacts on fish consumers are poorly understood. In streams of the Kootenai River basin, we quantified the diet, condition, and growth rate of species of trout, char, and sculpin. In 2018, macroinvertebrate taxa composition was different between a stream with Didymo and a stream without, but trout diets, energy demand, and growth rates were similar. Trout abundance was higher in the stream with Didymo, but the amount of drifting invertebrates was higher in the stream without. In 2019, we surveyed 28 streams with a gradient of coverage. Didymo abundance was correlated only with the percentage of aquatic invertebrates in trout diets and was not related to diets of char or sculpin or condition of any species. Thus, we found no evidence for a trophic link between Didymo blooms and the condition or growth of trout, char, or sculpin in mountainous headwater streams.

Alberta, British Columbia, Idaho, Montana↗

USGS1968

Species succession and fishery exploitation in the Great Lakes

The species composition of fish in the Great Lakes has undergone continual change since the earliest records. Some changes were caused by enrichment of the environment, but others primarily by an intensive and selective fishery for certain species. Major changes related to the fishery were less frequent before the late 1930's than in recent years and involved few species. Lake sturgeon (Acipenser fulvescens) were overexploited knowingly during the late 1800's because they interfered with fishing for preferred species; sturgeon were greatly reduced in all lakes by the early 1900's. Heavy exploitation accompanied sharp declines of lake herring (Leucichthys artedi) in Lake Erie during the 1920's and lake whitefish (Coregonus clupeaformis) in Lake Huron during the 1930's. A rapid succession of fish species in Lakes Huron, Michigan, and Superior that started about 1940 has been caused by selective predation by the sea lamprey (Petromyzon marinus) on native predatory species, and the resultant shifting emphasis of the fishery and species interaction as various species declined. Lake trout (Salvelinus namaycush) and burbot (Lota lota), the deepwater predators, were depleted first; this favored their prey, the chubs (Leucichthys spp.). The seven species of chubs were influenced differently according to differences in size. Fishing emphasis and predation by sea lampreys were selective for the largest species of chubs as lake trout and burbot declined. A single slow-growing chub, the bloater, was favored and increased, but as the large chubs declined the bloater was exploited by a new trawl fishery. The growth rate and size of the bloater increased, making it more vulnerable to conventional gillnet fishery and lamprey predation. This situation in Lakes Michigan and Huron favored the small alewife (Alosa pseudoharengus) which had recently become established in the upper Great Lakes, and the alewife increased rapidly and dominated the fish stocks of the lakes. The successive collapses of various stocks after periods of stable production may give some indication of their sustainable yield. The sea lamprey is being brought under control in Lakes Superior, Michigan, and Huron; lake trout are being established; and chinook salmon (Oncorhynchus tshawytscha), coho salmon (O. kisutch), kokanee salmon (O. nerka), and the splake, a hybrid of lake trout and brook trout (Salvelinus fontinalis), are being introduced to reestablish a new species balance. Fish stocks are in a state of extreme instability in these lakes. Careful control of stocking programs and fisheries, and coordination of management among the various states of the United States and the province of Canada (Ontario) which manage the fish stocks, will be required to restore and maintain a useful fishery balance.

Journal of the Fisheries Research Board of Canada↗

USGS2004

An evaluation of multipass electrofishing for estimating the abundance of stream-dwelling salmonids

Failure to estimate capture efficiency, defined as the probability of capturing individual fish, can introduce a systematic error or bias into estimates of fish abundance. We evaluated the efficacy of multipass electrofishing removal methods for estimating fish abundance by comparing estimates of capture efficiency from multipass removal estimates to capture efficiencies measured by the recapture of known numbers of marked individuals for bull trout Salvelinus confluentus and westslope cutthroat trout Oncorhynchus clarki lewisi. Electrofishing capture efficiency measured by the recapture of marked fish was greatest for westslope cutthroat trout and for the largest size-classes of both species. Capture efficiency measured by the recapture of marked fish also was low for the first electrofishing pass (mean, 28%) and decreased considerably (mean, 1.71 times lower) with successive passes, which suggested that fish were responding to the electrofishing procedures. On average, the removal methods overestimated three-pass capture efficiency by 39% and under-estimated fish abundance by 88%, across both species and all size-classes. The overestimates of efficiency were positively related to the cross-sectional area of the stream and the amount of undercut banks and negatively related to the number of removal passes for bull trout, whereas for westslope cutthroat trout, the overestimates were positively related to the amount of cobble substrate. Three-pass capture efficiency measured by the recapture of marked fish was related to the same stream habitat characteristics that influenced (biased) the removal estimates and did not appear to be influenced by our sampling procedures, including fish marking. Simulation modeling confirmed our field observations and indicated that underestimates of fish abundance by the removal method were negatively related to first-pass sampling efficiency and the magnitude of the decrease in capture efficiency with successive passes. Our results, and those of other researchers, suggest that most electrofishing-removal-based estimates of fish abundance are likely to be biased and that these biases are related to stream characteristics, fish species, and size. We suggest that biologists regard electrofishing-removal- based estimates as biased indices and encourage them to measure and model the efficiency of their sampling methods to avoid introducing systematic errors into their data.

Transactions of the American Fisheries Society↗

USGS1963

A new geographic and host record for infectious pancreatic necrosis

The occurrence of infectious pancreatic necrosis in rainbow trout (Salmo gairdneri), brook trout (Salvelinus fontinalis), and cutthroat trout (Salmo clarki) has been experimentally authenticated for the first time in the western United States. The cutthroat trout represents a new host. Brook trout fin tissue culture inoculated with bacteria-free filtrate from the diseased fish tissue showed marked degenerative changes after 24 hours. Chinook salmon (Oncorhynchus tshawytscha), kokanee (O. nerka), and silver salmon (O. kisutch) were not susceptible to the virus when inoculated. Histologically, extensive pancreatic necrosis was observed in the original and experimental materials, but striated muscle hyalinization was detected only in the original material.

Transactions of the American Fisheries Society↗

USGS1982

Immersion and injection vaccination of salmonids against furunculosis with an avirulent strain of Aeromonas salmonicida

Replicate groups of brook trout (Salvelinus fontinalis) immunized by intraperitoneal injection of graded dilutions of an avirulent strain of Aeromonas salmonicida were protected from a virulent challenge. Mean mortality after challenge was 88% in control trout, 66% in trout immunized with 3 × 10 6 or 3 × 10 5 cells, and 39% in trout immunized with 3 × 10 4 to 3 × 10¹ cells. In brook trout challenged after immersion for 60 s in a culture containing 2.3 × 10 9 avirulent cells of A. salmonicida per milliliter, mortality was 44%, compared with 94% in controls. In Atlantic salmon (Salmo salar), similarly vaccinated by immersion, mortality was 12.5% after challenge compared with 87.5% in controls. In additional studies, mean mortality of Atlantic salmon vaccinated by immersion was 14%, whereas that of control salmon was 92%.

Progressive Fish-Culturist↗

USGS2011

Temperature-associated population diversity in salmon confers benefits to mobile consumers

Habitat heterogeneity can generate intraspecific diversity through local adaptation of populations. While it is becoming increasingly clear that population diversity can increase stability in species abundance, less is known about how population diversity can benefit consumers that can integrate across population diversity in their prey. Here we demonstrate cascading effects of thermal heterogeneity on trout–salmon interactions in streams where rainbow trout rely heavily on the seasonal availability of anadromous salmon eggs. Water temperature in an Alaskan stream varied spatially from 5°C to 17.5°C, and spawning sockeye salmon showed population differentiation associated with this thermal heterogeneity. Individuals that spawned early in cool regions of the 5 km long stream were genetically differentiated from those spawning in warmer regions later in the season. Sockeye salmon spawning generates a pulsed resource subsidy that supports the majority of seasonal growth in stream-dwelling rainbow trout. The spatial and temporal structuring of sockeye salmon spawn timing in our focal stream extended the duration of the pulsed subsidy compared to a thermally homogeneous stream with a single population of salmon. Further, rainbow trout adopted movement strategies that exploited the multiple pulses of egg subsidies in the thermally heterogeneous stream. Fish that moved to track the resource pulse grew at rates about 2.5 times higher than those that remained stationary or trout in the reference stream with a single seasonal pulse of eggs. Our results demonstrate that habitat heterogeneity can have important effects on the population diversity of dominant species, and in turn, influence their value to species that prey upon them. Therefore, habitat homogenization may have farther-reaching ecological effects than previously considered.

Ecology↗

USGS2013

Limitation and facilitation of one of the world's most invasive fish: an intercontinental comparison

Purposeful species introductions offer opportunities to inform our understanding of both invasion success and conservation hurdles. We evaluated factors determining the energetic limitations of brown trout (Salmo trutta) in both their native and introduced ranges. Our focus was on brown trout because they are nearly globally distributed, considered one of the world's worst invaders, yet imperiled in much of their native habitat. We synthesized and compared data describing temperature regime, diet, growth, and maximum body size across multiple spatial and temporal scales, from country (both exotic and native habitats) and major geographic area (MGA) to rivers and years within MGA. Using these data as inputs, we next used bioenergetic efficiency (BioEff), a relative scalar representing a realized percentage of maximum possible consumption (0–100%) as our primary response variable and a multi-scale, nested, mixed statistical model (GLIMMIX) to evaluate variation among and within spatial scales and as a function of density and elevation. MGA and year (the residual) explained the greatest proportion of variance in BioEff. Temperature varied widely among MGA and was a strong driver of variation in BioEff. We observed surprisingly little variation in the diet of brown trout, except the overwhelming influence of the switch to piscivory observed only in exotic MGA. We observed only a weak signal of density-dependent effects on BioEff; however, BioEff remained <50% at densities >2.5 fish/m2. The trajectory of BioEff across the life span of the fish elucidated the substantial variation in performance among MGAs; the maximum body size attained by brown trout was consistently below 400 mm in native habitat but reached 600 mm outside their native range, where brown trout grew rapidly, feeding in part on naive prey fishes. The integrative, physiological approach, in combination with the intercontinental and comparative nature of our study, allowed us to overcome challenges associated with context-dependent variation in determining invasion success. Overall our results indicate “growth plasticity across the life span” was important for facilitating invasion, and should be added to lists of factors characterizing successful invaders.

Ecology↗

USGS2000

Mercury bioaccumulation in fish in a region affected by historic gold mining: The South Yuba River, Deer Creek, and Bear River watersheds, California, 1999

Mercury that was used historically for gold recovery in mining areas of the Sierra Nevada continues to enter local and downstream water bodies, including the Sacramento Delta and the San Francisco Bay of northern California. Methylmercury is of particular concern because it is the most prevalent form of mercury in fish and is a potent neurotoxin that bioaccumulates at successive trophic levels within food webs. In April 1999, the U.S. Geological Survey, in cooperation with several other agencies the Forest Service (U.S. Department of Agriculture), the Bureau of Land Management, the U.S. Environmental Protection Agency, the California State Water Resources Control Board, and the Nevada County Resource Conservation District began a pilot investigation to characterize the occurrence and distribution of mercury in water, sediment, and biota in the South Yuba River, Deer Creek, and Bear River watersheds of California. Biological samples consisted of semi-aquatic and aquatic insects, amphibians, bird eggs, and fish. Fish were collected from 5 reservoirs and 14 stream sites during August through October 1999 to assess the distribution of mercury in these watersheds. Fish that were collected from reservoirs included top trophic level predators (black basses, Micropterus spp.) intermediate trophic level predators [sunfish (blue gill, Lepomis macrochirus; green sunfish, Lepomis cyanellus; and black crappie, Poxomis nigromaculatus)] and benthic omnivores (channel catfish, Ictularus punctatus). At stream sites, the species collected were upper trophic level salmonids (brown trout, Salmo trutta) and upper-to-intermediate trophic level salmonids (rainbow trout, Oncorhynchus mykiss). Boneless and skinless fillet portions from 161 fish were analyzed for total mercury; 131 samples were individual fish, and the remaining 30 fish were combined into 10 composite samples of three fish each of the same species and size class. Mercury concentrations in samples of black basses (Micropterus spp.), including largemouth, smallmouth, and spotted bass, ranged from 0.20 to 1.5 parts per million (ppm), wet basis. Mercury concentrations in sunfish ranged from less than 0.10 to 0.41 ppm (wet). Channel catfish had mercury concentrations from 0.16 to 0.75 ppm (wet). The range of mercury concentrations observed in rainbow trout was from 0.06 to 0.38 ppm (wet), and in brown trout was from 0.02 to 0.43 ppm (wet). Mercury concentrations in trout were greater than 0.3 ppm in samples from three of 14 stream sites. Mercury at elevated concentrations may pose a health risk to piscivorous wildlife and to humans who eat fish on a regular basis. Data presented in this report may be useful to local, state, and federal agencies responsible for assessing the potential risks associated with elevated levels of mercury in fish in the South Yuba River, Deer Creek, and Bear River watersheds.

California↗

USGS2019

Effectiveness of fish screens in protecting lamprey (Entosphenus and Lampetra spp.) ammocoetes—Pilot testing of variable screen angle

Thousands of screened water diversions throughout the Columbia River Basin of the Pacific Northwest are sources of entrainment (unintended diversion into an unsafe passage route), injury, and mortality for a range of fish species and screening criteria have been developed to reduce and mitigate these effects. Large knowledge gaps exist concerning the potential effects of these screens on juvenile and larval lampreys ( Entosphenus and Lampetra spp. ) that may be particularly vulnerable to screening effects owing to their small size, unique morphology, and poor swimming performance. The few studies that have evaluated screen impacts for lampreys have compared common screen materials in a laboratory setting using a large, recirculating flume, and have reported that screen size and material influence the risk of entrainment. We compared entrainment rate, impingement rate and duration, injury rate, and delayed (24-hour) mortality of larval lamprey (ammocoetes) exposed to two screen angles. A 20-degree screen was tested because it is a common configuration, and a 12-degree screen was selected to represent a screen more parallel to flow than the 20-degree screen. We included juvenile rainbow trout ( Oncorhynchus mykiss ) in tests for both screen angles so that any screen interaction improvements observed for lamprey could be considered in light of their effect on salmonids ( Oncorhynchus spp. ). Study fish were released singly into the flume at two locations: near-screen (SCR) releases at about 30 centimeters upstream of the screen and mid-channel (MID) releases at about 1.4 meters upstream of the screen. We completed 120 screen trials with ammocoetes and 117 screen trials with juvenile tout during April–May 2018. Ammocoetes had short mean trial durations (less than 30 seconds) and were most frequently bypassed. Over one-half of the ammocoetes briefly (for less than 1 second) contacted the screen. Rates of screen contact were similar between the two screen angles, but higher for SCR releases (about 83–90 percent) than for MID releases (about 28–44 percent). Screen impingements were not common (8.3 percent of ammocoetes) and did not result in significant injury or delayed mortality. The final logistic regression model showed that screen angle and release location did not significantly affect whether ammocoetes were bypassed. The size of the lamprey, expressed as mass or length, was the only significant predictor of fate. We noted an estimated 4.7-percent increase in the odds of being bypassed for every 1-milligram increase in ammocoete mass and a 49-percent increase in the odds of being bypassed for every 1-millimeter increase in length. Trout did not experience negative effects with the 12-degree screen; they had short mean trial durations (less than 40 seconds) and limited contact with the screens (11.1 percent of trout), were most commonly bypassed, and none were entrained. Screen angle and release location were not significant drivers of fate for trout. The 12-degree and 20-degree screens performed comparably for both lamprey and trout and effectively bypassed these fishes. Some metrics showed advantages for the 12-degree screen, suggesting that screens installed more parallel to flow might warrant further testing.

Columbia River Basin↗

USGS2026

Spatial and temporal trends of mercury in fish from Duck Valley Reservation Reservoirs, southwestern Idaho and northern Nevada, 2007–24

The Shoshone-Paiute (Sho-Pai) Tribes of the Duck Valley Reservation, Nevada, manage reservoirs that support commercial and recreational activities, including robust Oncorhynchus mykiss (rainbow trout) fisheries that attract anglers year-round. Reservoirs are common environments for methylation and bioaccumulation of mercury, which is a potent neurotoxin when elevated levels are consumed. The U.S. Geological Survey (USGS), in cooperation with the Sho-Pai Tribes, measured total mercury concentrations in the muscle tissue of rainbow trout from three Reservation reservoirs in Idaho and Nevada in 2007, 2009, 2013, and 2024. This report highlights spatial and temporal trends of mercury concentrations in rainbow trout in the Duck Valley Reservation reservoirs from 2007 through 2024, and presents limited data on other commonly consumed species, specifically Perca flavescens (yellow perch), Micropterus dolomieu (smallmouth bass), and Micropterus salmoides (largemouth bass). Mercury data are also presented for nearby sites and lower trophic level species. In 2024, two fish sampling methods were used and compared: biopsy muscle plugs and muscle fillets. Results show good agreement between mercury concentrations of biopsy and fillet muscle samples taken from the same fish, with most sample pairs differing by less than 20 percent, though biopsied fish had an unexpectedly high mortality rate. Mercury concentrations increased in Sheep Creek Reservoir during the study period, but no significant trend was observed in Mountain View Reservoir or Lake Billy Shaw. Only 1 rainbow trout out of 160 sampled in the Reservation reservoirs during the study period exceeded the U.S. Environmental Protection Agency’s recommended methylmercury criterion of 0.3 milligram per kilogram of wet weight (mg/kg ww). Largemouth bass, smallmouth bass, and yellow perch had higher mercury concentrations than rainbow trout and may pose a greater risk to consumers. Mercury concentrations in largemouth bass exceeded 0.3 mg/kg ww, although only two fish were sampled, both from Sheep Creek Reservoir. Fish consumption advisories on Tribal lands are determined by the Tribes, and these results may help Sho-Pai managers determine the mercury exposure risk to Tribal members and visiting anglers.

Idaho, Nevada↗

USGS2000

Contaminant trends in sport fish from Lake Roosevelt and the upper Columbia River, Washington, 1994-1998

Fish from Lake Roosevelt were first reported to contain elevated concentrations of contaminants in the early 1980?s, with mercury, dioxins and furans, and polychlorinated biphenyls (PCBs) identified as being of most concern to human health. Over the following years there were a series of studies by United States and Canadian agencies addressing contaminants in fish from both a human and environmental perspective. In the early 1990?s, industrial discharges to the Columbia River above the international boundary decreased. The dominant changes in industrial practices included a reduction in slag and effluent discharges from a lead-zinc smelter, and a reduction in dioxins and furans due to processing changes at a Canadian pulp mill. It is believed that these two alterations in industrial practices may have greatly reduced the loading of selected contaminants to the Columbia River system. In response to these recent changes, the U.S. Geological Survey initiated this present study for the purpose of determining the present concentrations of mercury, dioxins and furans, and PCBs in fish, and, if possible, to determine if concentrations have changed since the 1994 studies. All contaminant analysis was done on fish fillets in order to address human health concerns. Our study concluded that the concentrations of contaminants in fish that were identified as a potential threat to human health have either not changed since the 1994 studies, or have decreased. PCBs, as determined by Aroclor 1254, do not appear to have changed between 1994 and 1998; sources of PCBs are presently unknown. In contrast, dioxins and furans, as indicated by 2,3,7,8-TCDF, did show a significant decrease in rainbow trout fillets from 1994 to 1998. However, there was no apparent change in the average 2,3,7,8-TCDF concentrations in mountain whitefish, with the reason uncertain at this time. Average concentrations of 2,3,7,8-TCDF were higher in mountain whitefish than in rainbow trout. Toxicity equivalence concentrations (TEC) are determined by summing the relative toxicity of individual congeners of dioxins, furans, and toxic ?dioxin-like? PCB congeners in individual fish. Rainbow trout from the upper reach have higher TECs than rainbow trout from the lower reach, with trout from the upper reach having a higher percentage of the toxicity from toxic ?dioxin-like? PCBs than dioxin and furan compounds. In relation to mercury, the concentrations of total mercury in walleye have significantly decreased by about 50 percent from 1994 to 1998.

Water-Resources Investigations Report↗

USGS1990

Hydrology, aquatic macrophytes, and water quality of Black Earth Creek and its tributaries, Dane County, Wisconsin, 1985-86

An intensive data-collection program for the Black Earth Creek basin in southern Wisconsin was conducted from October 1984 through September 1986 to assess the hydrology, aquatic macrophytes, and water quality in Black Earth Creek by the U.S. Geological Survey, in cooperation with the Wisconsin Department of Natural Resources. Three sites on two cold-water trout streams Black Earth Creek at Cross Plains, Black Earth Creek near Cross Plains, and Garfoot Creek near Cross Plains were continuously monitored for streamflow and water-quality data. One site in a warm-water stream, Brewery Creek at Cross Plains, also was monitored. Aquatic macrophyte biomass was determined for three sites on Black Earth Creek. Streamflow at Black Earth Creek at Black Earth during the 1985 and 1986 water years (WY) were 44 and 60 percent greater than the long-term mean discharge of 33.3 ft3/s (cubic feet per second) for the period 1955-86. Water year 1986 had the highest annual mean discharge, 53.4 ft3/s, since records began in 1954 at the most downstream site Black Earth Creek at Black Earth. Although there have been considerable fluctuations in streamflow, it has tended to increase since WY 1965 as a result of above-average precipitation and consequent rising ground-water levels. Trout population densities may be related to annual mean streamflow. A regression analysis of adult trout populations and the 3-year moving annual mean discharge had a correlation coefficient of 0.75 with a standard error of 83 percent. Aquatic macrophyte biomass in Black Earth Creek was substantially less in 1986 than in 1985 as a result of substrate scouring from the flood of July 25, 1985. The frequency of occurrence of species during 1985 and 1986 was similar to that of 1981, and seasonal succession of species also was similar; Potamogeton crispus dominated early in the year and senesced in July. P. crispus and P. pectinatus, both indicative of eutrophic conditions, dominated upstream and downstream, respectively; neither species is native to the area. In 1985, the greatest biomass was found upstream from Cross Plains. This large biomass caused diurnal fluctuations in dissolved-oxygen concentration of 5 to 6 mg/L (milligrams per liter) as a result of photosynthesis and respiration. Many of the dissolved-oxygen minimums, recorded at night, were less than the State 6.0-mg/L water-quality standard for trout waters. Discharge from point sources may adversely affect Black Earth Creek's water quality. Warm water discharged to Black Earth Creek from a gravel pit operation upstream from Cross Plains increased water temperatures 2 to 4 degrees Celsius and decreased the dissolved oxygen about 1 mg/L at a site 1.8 miles downstream. Runoff from a settling pond from a landfill operation in the headwaters of the Black Earth Creek basin drains through a wetland that drains to Black Earth Creek and contained as much as 60 mg/L ammonia nitrogen, 980 mg/L biochemical oxygen demand, and 1,300 mg/L chemical oxygen demand, which may be detrimental to trout. Garfoot Creek had the highest suspended-sediment and phosphorus yields per unit area of the three upstream basins during low to moderate runoff. Detention ponds in the Brewery Creek basin appear to be less effective in controlling suspended-sediment and phosphorus loads during periods of high runoff than during moderate runoff. Brewery Creek had the highest concentrations of suspended sediment and total phosphorus during low and high flows. The water quality at the Black Earth Creek gaging station at Black Earth was affected by Garfoot Creek and unnamed tributaries. As a result, yields of suspended sediment, phosphorus, and nitrogen increased between Cross Plains and Black Earth. High streamflows during WY 1985 resulted in suspendedsediment yields at Black Earth Creek at Black Earth that were 29 percent greater than the 12-year (1955-65, 85-86) mean; yields ranged from 69.5 ton/mi2 (tons per square mile) in Black Earth Creek at Cross Plains to 116 ton/mi2 in the Brewery Creek basin. Phosphorus yields ranged from 312 lb/mi2 (pounds per square mile) in Black Earth Creek at Cross Plains to 628 lb/mi2 in the Brewery Creek basin. Total nitrogen yields ranged from 3,280 lb/mi2 in the Brewery Creek basin to 6,920 lb/mi2 in the Garfoot Creek basin. An increase in oxygen demand, caused by agricultural runoff, has resulted in reduced dissolved-oxygen content of the water in both Black Earth and Garfoot Creeks. The most substantial reduction occurred at Black Earth Creek at Cross Plains on July 25, 1985, as a result of the largest storm runoff event during the study. A rainfall of 5.54 inches caused streamflow discharges to increase from 9 to 122 ft3/s and dissolved-oxygen concentrations to decline to 3.0 mg/L; the dissolved-oxygen concentration was less than 6.0 mg/L for 30 hours.

Wisconsin↗

USGS2026

Unveiling a legacy of fish introductions to mountain lakes using historical records and eDNA surveys in a National Park

Across the western United States, introductions of non-native fish into historically fishless mountain lakes have impacted native biota. Understanding the impacts of fish introductions is essential for conservation in Olympic National Park, a Biosphere Reserve. We reconstructed fish plantings using records dating back to 1930, followed by environmental DNA (eDNA) surveys to estimate the current distribution of fish and amphibians in 117 remote mountain lakes. We used Bayesian multiscale occupancy models to determine how lake attributes and planting history related to fish and amphibian occupancy. The most frequently detected species were Brook Trout, Rainbow Trout, Cascades Frog, and Northwestern Salamander. eDNA sampling revealed 52 lakes with amphibians only, 45 with fish and amphibians, 14 with fish only, and 6 unoccupied. Of the 53 lakes with planting records, 38 had fish eDNA detected. Fish eDNA was also detected in 21 lakes lacking planting records, which could reflect incomplete records, unauthorized plantings, and false positive detections. Of the three species planted, Cutthroat Trout had the highest failure rate and did not become established in 23 of 28 historically planted lakes. In a subset of 9 lakes sampled for up to 7 years, those with known fish and amphibian presence showed consistent eDNA detections over time. The number of times a lake was stocked was the best predictor of occupancy for Brook and Rainbow trout, while higher occupancy for Brook Trout was also associated with lower elevations, lower solar radiation, and larger lake area. We did not observe widespread negative associations between amphibian occupancy and fish presence, although there was a negative relationship between fish presence and Rough-skinned Newt and Long-toed Salamander occupancy. Cascades Frog occupancy showed no relationship to fish presence or lake traits. Our results suggest mechanisms of fish persistence over time and highlight areas where native amphibians are impacted by introduced fish. These results can guide management options like targeted fish removals that benefit native fauna while still supporting recreational fishing. More broadly, our work demonstrates the value of combining historical records with contemporary surveys and the utility of eDNA for broad-scale surveys of species distribution in remote wilderness areas.

Washington↗

USGS2001

Effects of exotic species on Yellowstone's grizzly bears

Humans have affected grizzly bears ( Ursus arctos horribilis ) by direct mortality, competition for space and resources, and introduction of exotic species. Exotic organisms that have affected grizzly bears in the Greater Yellowstone Area include common dandelion ( Taraxacum officinale ), nonnative clovers ( Trifolium spp.), domesticated livestock, bovine brucellosis ( Brucella abortus ), lake trout ( Salvelinus namaycush ), and white pine blister rust ( Cronartium ribicola ). Some bears consume substantial amounts of dandelion and clover. However, these exotic foods provide little digested energy compared to higher-quality bear foods. Domestic livestock are of greater energetic value, but use of this food by bears often leads to conflicts with humans and subsequent increases in bear mortality. Lake trout, blister rust, and brucellosis diminish grizzly bears foods. Lake trout prey on native cutthroat trout ( Oncorhynchus clarkii ) in Yellowstone Lake; white pine blister rust has the potential to destroy native whitebark pine ( Pinus albicaulis ) stands; and management response to bovine brucellosis, a disease found in the Yellowstone bison (Bison bison) and elk ( Cervus elaphus ), could reduce populations of these 2 species. Exotic species will likely cause more harm than good for Yellowstone grizzly bears. Managers have few options to mitigate or contain the impacts of exotics on Yellowstone's grizzly bears. Moreover, their potential negative impacts have only begun to unfold. Exotic species may lead to the loss of substantial highquality grizzly bear foods, including much of the bison, trout, and pine seeds that Yellowstone grizzly bears currently depend upon.

Wyoming↗

USGS1979

Ethyl-p-aminobenzoate (Benzocaine): efficacy as an anesthetic for five species of freshwater fish

Ethyl-p-aminobenzoate (benzocaine) was tested for its efficacy as an anesthetic for rainbow trout (Salmo gairdnerii, brown trout (Salmo truttas, northern pike (Esox lucius). carp (Cyprinus carpio), and largemouth bass (Mieropterus salmoidesi. Since benzocaine is not water soluble, it was applied with acetone as a carrier. Concentrations of 100 to 200 mg!l were required for large adult northern pike, compared with 50 to 100 mg/l for small fish. Rates of sedation and recovery were slower in cold water than in warm water. Water hardness had little influence on the activity of benzocaine. Fish were anesthetized faster and recovered more slowly in acid than in alkaline water. Benzocaine produced deep anesthesia, but concentrations that rendered the fish handleable within 5 min were generally not safe for exposures longer than 15 min. Concentrations of benzocaine efficacious for fish were not acutely toxic to eggs of coho salmon (Oncorhynchus kisutch), chinook salmon (Oncorhynchus tshauiytschas, rainbow trout, brown trout, or lake trout (Salvelinus namaycush). Benzocaine is not registered for fishery use and is neither more effective nor safer than the registered anesthetic, tricaine methanesulfonate (MS-222l.

Investigations in Fish Control↗

USGS2015

Wind River subbasin restoration: Annual report of U.S. Geological Survey activities January 2014 through December 2014

Executive Summary The Wind River subbasin in southwest Washington State provides habitat for a population of wild Lower Columbia River steelhead Oncorhynchus mykiss , which are listed as threatened under the Endangered Species Act. No hatchery steelhead have been planted in the Wind River subbasin since 1994, and hatchery adults are estimated to be less than one percent of adults in any year (Thomas Buehrens, Washington Department of Fish and Wildlife, personal communication). Numerous restoration actions have been implemented in the subbasin, including the removal of Hemlock Dam on Trout Creek in 2009. We used Passive Integrated Transponder (PIT) tagging and a series of instream PIT-tag interrogation systems (PTIS) to investigate life-histories, populations, and efficacy of habitat restoration actions for these steelhead. Data from our study, and companion work by Washington Department of Fish and Wildlife (WDFW), will contribute to Bonneville Power Administration’s (BPA) Research Monitoring and Evaluation (RM&E) Program Strategy of Fish Population Status Monitoring ( www.cbfish.org/ProgramStrategy.mvc/ViewProgramStrategySummary/1 ), specifically the sub-strategies of: 1) Assessing the Status and Trends of Diversity of Natural Origin Fish Populations and to Uncertainties Research regarding differing life histories of a wild steelhead population, 2) Assessing the Status and Trend of Adult Natural Origin Fish Populations, and 3) Monitoring and Evaluating the Effectiveness of Tributary Habitat Actions Relative to Environmental, Physical, or Biological Performance Objectives. During summer 2014, we PIT-tagged steelhead parr in headwater areas of the Wind River subbasin to investigate life-history diversity, specifically to compare fate of those juvenile steelhead that move downstream prior to smolting with those that remain in their natal areas until smolting. A series of instream PTISs monitored movement of these fish. We added a new multi-antenna PTIS on Trout Creek and made improvements to two of our smaller tributary PTISs during 2014. Detections at the instream PTISs showed trends of parr emigration during summer and fall, in addition to the expected movement of parr and smolts in spring. Long-term monitoring of PIT-tagged fish will provide information on contribution of various life-history strategies to smolt production and adult returns, as well as helping to identify factors influencing parr movement. Movements of PIT-tagged adult steelhead were tracked with our instream PTISs. These data will contribute to a better understanding of timing and distribution of spawning by this population of wild steelhead within the Wind River subbasin. Additionally, these data have provided information on timing of adult movements to various parts of the watershed, which is allowing us to assess adult use of tributary watersheds within the Wind River subbasin. These data are contributing to evaluating steelhead response to the removal of Hemlock Dam from Trout Creek. Hemlock Dam, which was located at rkm 2.0 of Trout Creek, was removed in summer 2009 and had contributed to hydrologic impairment of Trout Creek and potentially caused some deterrent to upstream adult steelhead migration. Evaluating restoration efforts is of interest to many managers and agencies so that funding and time are allocated for best results. The evaluation of various life-histories of Lower Columbia River steelhead within the Wind River subbasin provides information to better track populations, and more effectively direct habitat restoration and water allocation planning. Increasingly detailed Viable Salmonid Population information (Crawford and Rumsey 2009), such as that provided by PIT-tagging and instream PTISs networks like those we build and operate in the Wind River subbasin, provide data to better inform policy and management, as life-history strategies and production bottlenecks are identified and understood.

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USGS2004

Geospatial techniques for developing a sampling frame of watersheds across a region

Current land-management decisions that affect the persistence of native salmonids are often influenced by studies of individual sites that are selected based on judgment and convenience. Although this approach is useful for some purposes, extrapolating results to areas that were not sampled is statistically inappropriate because the sampling design is usually biased. Therefore, in recent investigations of coastal cutthroat trout (Oncorhynchus clarki clarki) located above natural barriers to anadromous salmonids, we used a methodology for extending the statistical scope of inference. The purpose of this paper is to apply geospatial tools to identify a population of watersheds and develop a probability-based sampling design for coastal cutthroat trout in western Oregon, USA. The population of mid-size watersheds (500-5800 ha) west of the Cascade Range divide was derived from watershed delineations based on digital elevation models. Because a database with locations of isolated populations of coastal cutthroat trout did not exist, a sampling frame of isolated watersheds containing cutthroat trout had to be developed. After the sampling frame of watersheds was established, isolated watersheds with coastal cutthroat trout were stratified by ecoregion and erosion potential based on dominant bedrock lithology (i.e., sedimentary and igneous). A stratified random sample of 60 watersheds was selected with proportional allocation in each stratum. By comparing watershed drainage areas of streams in the general population to those in the sampling frame and the resulting sample (n = 60), we were able to evaluate the how representative the subset of watersheds was in relation to the population of watersheds. Geospatial tools provided a relatively inexpensive means to generate the information necessary to develop a statistically robust, probability-based sampling design.

Conference Paper↗