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At least 775 records · Page 43Linked to original sources

USGS2017

Spatial variability of Chinook salmon spawning distribution and habitat preferences

We investigated physical habitat conditions associated with the spawning sites of Chinook Salmon Oncorhynchus tshawytscha and the interannual consistency of spawning distribution across multiple spatial scales using a combination of spatially continuous and discrete sampling methods. We conducted a census of aquatic habitat in 76 km of the upper main-stem Yakima River in Washington and evaluated spawning site distribution using redd survey data from 2004 to 2008. Interannual reoccupation of spawning areas was high, ranging from an average Pearson’s correlation of 0.62 to 0.98 in channel subunits and 10-km reaches, respectively. Annual variance in the interannual correlation of spawning distribution was highest in channel units and subunits, but it was low at reach scales. In 13 of 15 models developed for individual years (2004–2008) and reach lengths (800 m, 3 km, 6 km), stream power and depth were the primary predictors of redd abundance. Multiple channels and overhead cover were patchy but were important secondary and tertiary predictors of reach-scale spawning site selection. Within channel units and subunits, pool tails and thermal variability, which may be associated with hyporheic exchange, were important predictors of spawning. We identified spawning habitat preferences within reaches and channel units that are relevant for salmonid habitat restoration planning. We also identified a threshold (i.e., 2-km reaches) beyond which interannual spawning distribution was markedly consistent, which may be informative for prioritizing habitat restoration or conservation. Management actions may be improved through enhanced understanding of spawning habitat preferences and the consistency with which Chinook Salmon reoccupy spawning areas at different spatial scales.

Washington↗

USGS2017

Fall and winter survival of brook trout and brown trout in a north-central Pennsylvania watershed

Stream-dwelling salmonids that spawn in the fall generally experience their lowest survival during the fall and winter due to behavioral changes associated with spawning and energetic deficiencies during this time of year. We used data from Brook Trout Salvelinus fontinalis and Brown Trout Salmo trutta implanted with radio transmitters in tributaries of the Hunts Run watershed of north-central Pennsylvania to estimate survival from the fall into the winter seasons (September 2012–February 2013). We examined the effects that individual-level covariates (trout species, size, and movement rates) and stream-level covariates (individual stream and cumulative drainage area of a stream) have on survival. Brook Trout experienced significantly lower survival than Brown Trout, especially in the early fall during their peak spawning period. Besides a significant species effect, none of the other covariates examined influenced survival for either species. A difference in life history between these species, with Brook Trout having a shorter life expectancy than Brown Trout, is likely the primary reason for the lower survival of Brook Trout. However, Brook Trout also spawn earlier in the fall than Brown Trout and low flows during Brook Trout spawning may have resulted in a greater risk of predation for Brook Trout compared with Brown Trout, thereby also contributing to the observed differences in survival between these species. Our estimates of survival can aid parameterization of future population models for Brook Trout and Brown Trout through the spawning season and into winter.

Pennsylvania↗

USGS1979

Potentials and limits for the use of ozone as a fish disease control agent

Ozone and chlorine inactivation curves were determined in three types of freshwater at 20 C for the destruction of the fish pathogens Aeromonas salmonicida the etiologic agent of furunculosis, and Yersinia ruckeri the enteric redmouth bacterium (ERM). Ozone and chlorine inactivation curves were also obtained in the same water types at 10 C for the fish pathogenic viruses infectious hematopoietic necrosis (IHNV), and infectious pancreatic necrosis (IPNV). Acute toxicity tests using the rainbow trout as a representative salmonid revealed that ozone was highly toxic at the dose levels used. Partial chronic (3. mo.) testing revealed that ozone exposure at 2 μg/L causes only minimal physiological changes, none of which would be expected to compromise biological function.

Ozone: Science and Engineering↗

USGS2011

Fish species composition two second-order headwater streams the North Central Appalachians ecoregion

Fish species composition was determined for two second-order headwater streams within the North Central Appalachians ecoregion in northern Pennsylvania. The two streams were widely spaced geographically (over 193 km apart) and occurred in different drainage systems. Streams were sampled in the spring and fall over two years (1996–98) yielding similar fish assemblages. A total of five species was collected. Mottled sculpin ( Cottus bairdli ), slimy sculpin ( Cottus cognatus ), brook trout ( Salvetinus fontinalis ), and brown trout ( Salmo trutta ) were the dominant adult fishes. Two creek chubs ( Semotilus atromaculatus ) were also collected. No significant differences were found in sculpin weight, sculpin length, salmonid length, or brook trout length between streams. Paired t-tests detected eight significant seasonal differences within sites. Brook trout and mottled sculpin lengths were significantly greater in fall versus spring, while the reverse was found with slimy sculpins. Catches per unit effort were similar between the two streams, yielding 8.46 and 8.07 fish per minute of electrofishing. Both streams were very similar in faunal assemblages attributed to small, coldwater, high quality headwater streams in other regions.

Pennsylvanaia↗

USGS2012

Field-based evaluations of horizontal flat-plate fish screens, II: Testing of a unique off-stream channel device - The Farmers Screen

Screens are installed at water diversion sites to reduce entrainment of fish. Recently, the Farmers Irrigation District (Oregon) developed a unique flat-plate screen (the “Farmers Screen”) that operates passively and may offer reduced installation and operating costs. To evaluate the effectiveness of this screen on fish, we conducted two separate field experiments. First, juvenile coho salmon Oncorhynchus kisutch were released over a working version of this screen under a range of inflows (0.02–0.42 m 3 /s) and diversion flows (0.02–0.34 m 3 /s) at different water depths. Mean approach velocities ranged from 0 to 5 cm/s and sweeping velocities ranged from 36 to 178 cm/s. Water depths over the screen surface ranged from 1 to 25 cm and were directly related to inflow. Passage of fish over the screen under these conditions did not severely injure them or cause delayed mortality, and no fish were observed becoming impinged on the screen surface. Second, juvenile coho salmon and steelhead O. mykiss were released at the upstream end of a 34-m flume and allowed to volitionally move downstream and pass over a 3.5-m section of the Farmers Screen to determine whether fish would refuse to pass over the screen after encountering its leading edge. For coho salmon, 75–95% of the fish passed over the screen within 5 min and 82–98% passed within 20 min, depending on hydraulic conditions. For steelhead, 47–90% of the fish passed over the screen within 5 min and 79–95% passed within 20 min. Our results indicate that when operated within its design criteria, the Farmers Screen provides safe and efficient downstream passage of juvenile salmonids under a variety of hydraulic conditions.

North American Journal of Fisheries Management↗

USGS2012

Movement patterns, habitat use, and survival of Lahontan cutthroat trout in the Truckee River

Habitat fragmentation, hybridization, and competition with nonnative salmonids are viewed as major threats to Lahontan cutthroat trout Oncorhynchus clarkii henshawi . Understanding Lahontan cutthroat trout behavior and survival is a necessary step in the reintroduction and establishment of naturally reproducing populations of Lahontan cutthroat trout. We used weekly radiotelemetry monitoring to examine movement patterns, habitat use, and apparent survival of 42 hatchery-reared Lahontan cutthroat trout in a 16.5-km stretch of the Truckee River, Nevada, across three reaches separated by barriers to upstream movement. We found differences in total movement distances and home range sizes of fish in different reaches within our study area. Fish used pool habitats more than fast water habitats in all reaches. Time of year, stream temperature, and fish standard length covariates had the strongest relationship with apparent survival. Monthly apparent survival was lowest in January, which coincided with the lowest flows and temperatures during the study period. Our results verify the mobility of Lahontan cutthroat trout and indicate that conditions during winter may limit the survival and reintroduction success in the portions of the Truckee River evaluated in this study.

California, Nevada↗

USGS2013

Juvenile movement among different populations of cutthroat trout introduced as embryos to vacant habitat

Translocations are frequently used to increase the abundance and range of endangered fishes. One factor likely to affect the outcome of translocations is fish movement. We introduced embryos from five Westslope Cutthroat Trout Oncorhynchus clarkii lewisi populations (both hatchery and wild) at five different locations within a fishless watershed. We then examined the movement of age‐1 and age‐2 fish and looked for differences in movement distance among source populations and among introduction sites; we also examined the interactions among age, population, and introduction site. At age 1, most individuals (90.9%) remained within 1,000 m their introduction sites. By age 2, the majority of individuals (58.3%) still remained within 1,000 m of their introduction site, but considerably more individuals had moved downstream, some more than 6,000 m from their introduction site. We observed a significant interaction between age and source population ( F 4, 1077 = 15.45, P < 0.0001) as well as between age and introduction site ( F 41, 1077 = 11.39, P < 0.0008), so we presented results in the context of these interactions. Within age‐groups, we observed differences in movement behavior among source populations and among donor populations of Westslope Cutthroat Trout. We discuss these findings in light of previous research on juvenile salmonid movement.

Montana↗

USGS2014

Using spatial resampling to assess redd count survey length requirements for Pacific Lamprey

Pacific Lamprey Entosphenus tridentatus has declined across its range along the West Coast of North America, and an understanding of all life history phases is needed to address population recovery. Spawning surveys (redd counts) are common tools currently used to monitor returning adult salmonids, but such methodologies are in their infancy for Pacific Lamprey. Our objective was to assess the minimum spawning survey distance required to detect the presence of Pacific Lamprey redds and obtain precise redd density estimates from these data. To do this, we statistically resampled existing spawning locations of Pacific Lamprey collected during spawning surveys in four streams of the Willamette River Basin, Oregon, during spring of 2013. We found that the minimum survey distance for Pacific Lamprey redd detection was inversely related to the observed redd density and was always less than 1.2 km. Survey distance requirements to obtain precise redd counts (±20% of observed redd densities) were also inversely related to redd density and habitat availability, and varied between 1.3 km and 13.7 km. Our results suggest that spawning surveys are a potential tool for monitoring adult Pacific Lamprey abundance, but the specific objectives of the monitoring programs and acknowledgment of unknowns must be considered prior to implementation into recovery plans.

Oregon↗

USGS2014

Annual variation of spawning Cutthroat Trout in a small Western USA stream: A case study with implications for the conservation of potamodromous trout life history diversity

Little is known about the variability in the spatial and temporal distribution of spawning potamodromous trout despite decades of research directed at salmonid spawning ecology and the increased awareness that conserving life history diversity should be a focus of management. We monitored a population of fluvial–resident Bonneville Cutthroat Trout Oncorhynchus clarkii utah in a tributary to the Logan River, Utah, from 2006 to 2012 to gain insight into the distribution and timing of spawning and what factors may influence these spawning activities. We monitored Bonneville Cutthroat Trout using redd surveys with multiple observers and georeferenced redd locations. We documented an extended spawning period that lasted from late April to mid‐July. The onset, median, and end of spawning was best predicted by the mean maximum water temperature during the first 13 weeks of the year ( F = 130. 4, df = 5, R 2 = 0.96, P < 0.0001) with spawning beginning and ending earlier in years that had warmer water temperatures prior to spawning. The distribution of redds was clumped each year and the relative density of redds was greater in a reach dominated by dams constructed by beavers Castor canadensis . Both dam failure and construction appeared to be responsible for creating new spawning habitat that was quickly occupied, demonstrating rapid temporal response to local habitat changes. Bonneville Cutthroat Trout appeared to establish and defend a redd for up to 2 d, and spawning most often occurred between similar‐sized individuals. Spawning surveys for potamodromous trout are an underutilized tool that could be used to better understand the distribution and timing of spawning as well as determine the size and trends of the reproducing portion of populations of management concern. Without efforts to document the diversity of this important aspect of potamodromous trout life history, prioritization of conservation will be problematic.

Utah↗

USGS2015

Survival, growth, and tag retention in age-0 Chinook Salmon implanted with 8-, 9-, and 12-mm PIT tags

The ability to represent a population of migratory juvenile fish with PIT tags becomes difficult when the minimum tagging size is larger than the average size at which fish begin to move downstream. Tags that are smaller (e.g., 8 and 9 mm) than the commonly used 12-mm PIT tags are currently available, but their effects on survival, growth, and tag retention in small salmonid juveniles have received little study. We evaluated growth, survival, and tag retention in age-0 Chinook Salmon Oncorhynchus tshawytscha of three size-groups: 40–49-mm fish were implanted with 8- and 9-mm tags, and 50– 59-mm and 60–69-mm fish were implanted with 8-, 9-, and 12-mm tags. Survival 28 d after tagging ranged from 97.8% to 100% across all trials, providing no strong evidence for a fish-size-related tagging effect or a tag size effect. No biologically significant effects of tagging on growth in FL (mm/d) or weight (g/d) were observed. Although FL growth in tagged fish was significantly reduced for the 40–49-mm and 50–59-mm groups over the first 7 d, growth rates were not different thereafter, and all fish were similar in size by the end of the trials (day 28). Tag retention across all tests ranged from 93% to 99%. We acknowledge that actual implantation of 8- or 9-mm tags into small fish in the field will pose additional challenges (e.g., capture and handling stress) beyond those observed in our laboratory. However, we conclude that experimental use of the smaller tags for small fish in the field is supported by our findings.

North American Journal of Fisheries Management↗

USGS2016

Life history characteristics and vital rates of Yellowstone Cutthroat Trout in two headwater basins

The Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri is native to the Rocky Mountains and has declined in abundance and distribution as a result of habitat degradation and introduced salmonid species. Many of its remaining strongholds are in headwater basins with minimal human disturbances. Understanding the life histories, vital rates, and behaviors of Yellowstone Cutthroat Trout within headwater stream networks remains limited yet is critical for effective management and conservation. We estimated annual relative growth in length and weight, annual survival rates, and movement patterns of Yellowstone Cutthroat Trout from three tributaries of Spread Creek, Wyoming, and two tributaries of Shields River, Montana, from 2011 through 2013 using PIT tag antennas within a mark–recapture framework. Mean annual growth rates varied among tributaries and size-classes, but were slow compared with populations of Yellowstone Cutthroat Trout from large, low-elevation streams. Survival rates were relatively high compared with those of other Cutthroat Trout subspecies, but we found an inverse relationship between survival and size, a pattern contrary to what has been reported for Cutthroat Trout in large streams. Mean annual survival rates ranged from 0.32 (SE = 0.04) to 0.68 (SE = 0.05) in the Spread Creek basin and from 0.30 (SE = 0.07) to 0.69 (SE = 0.10) in the Shields River basin. Downstream movements from tributaries were substantial, with as much as 26.5% of a tagging cohort leaving over the course of the study. Integrating our growth, survival, and movement results demonstrates the importance of considering strategies to enhance headwater stream habitats and highlights the importance of connectivity with larger stream networks.

North American Journal of Fisheries Management↗

USGS2017

Exploring the use of environmental DNA to determine the species of salmon redds

Annual redd counts are used to monitor the status and trends of salmonid populations, but methods to easily and reliably determine which of sympatric species made specific redds are lacking. We explored whether environmental DNA (eDNA) analysis might prove useful for determining the species of salmon redds. We collected eDNA samples from the interstitial spaces of redds of Chinook Salmon Oncorhynchus tshawytscha, redds of Coho Salmon O. kisutch, and areas of undisturbed gravel (n = 10, each), as well as from the water column adjacent to each of those sites in the Sandy River basin, Oregon, USA during the fall of 2013. The concentrations of Chinook and Coho eDNA were quantified within each sample using real-time PCR. The water in the interstitial spaces of redds contained significantly higher eDNA concentrations of the species that made the redd than (1) the other species and (2) the adjacent water column. In contrast, neither Chinook nor Coho eDNA was significantly more concentrated than the other in the water from the interstitial spaces of undisturbed gravel. The interstitial water of undisturbed gravel contained significantly higher eDNA concentrations of Coho than the adjacent water column. In contrast, Chinook eDNA concentration was similar in the interstitial water of undisturbed gravel and the adjacent water column. Both species’ redds had significantly higher concentrations of their respective species’ eDNA than did undisturbed gravel, but conclusions were confounded by differences in the timing and locations of sampling. This initial investigation highlights the potential value and some of the complexity of using eDNA analysis to indicate redd species.

Oregon↗

USGS2014

U.S. response to a report of infectious salmon anemia virus in Western North America

Federal, state, and tribal fishery managers, as well as the general public and their elected representatives in the United States, were concerned when infectious salmon anemia virus (ISAV) was suspected for the first time in free-ranging Pacific Salmon collected from the coastal areas of British Columbia, Canada. This article documents how national and regional fishery managers and fish health specialists of the U.S. worked together and planned and implemented actions in response to the reported finding of ISAV in British Columbia. To date, the reports by Simon Fraser University remain unconfirmed and preliminary results from collaborative U.S. surveillance indicate that there is no evidence of ISAV in U.S. populations of free-ranging or marine-farmed salmonids on the west coast of North America.

Fisheries↗

USGS2016

Who Knew? Inconnu

In 1999, I moved to Alaska to serve as unit leader of the U.S. Geological Survey Alaska Cooperative Fish and Wildlife Research Unit and professor of fisheries in the School of Fisheries and Ocean Sciences at the University of Alaska Fairbanks. What was unusual about this move was that before this I was an easterner and southerner, having done my graduate work in fisheries at Texas A&M University and been stationed in the Coop Unit Program in Ohio, West Virginia, and Maryland. I had never worked with salmonids of any sort. To me fish with adipose fins also had whiskers! I suddenly found myself working in the land of salmon experts, and I didn't even reliably know the names—scientific, common, or colloquial—of the five (or is it six?) common Pacific salmon species in Alaska. I had to quickly find a research niche that probably didn't involve salmon.

Fisheries↗

USGS2016

Conservation of native Pacific trout diversity in western North America

Pacific trout Oncorhynchus spp. in western North America are strongly valued in ecological, socioeconomic, and cultural views, and have been the subject of substantial research and conservation efforts. Despite this, the understanding of their evolutionary histories, overall diversity, and challenges to their conservation is incomplete. We review the state of knowledge on these important issues, focusing on Pacific trout in the genus Oncorhynchus. Although most research on salmonid fishes emphasizes Pacific salmon, we focus on Pacific trout because they share a common evolutionary history, and many taxa in western North America have not been formally described, particularly in the southern extent of their ranges. Research in recent decades has led to the revision of many hypotheses concerning the origin and diversification of Pacific trout throughout their range. Although there has been significant success at addressing past threats to Pacific trout, contemporary and future threats represented by nonnative species, land and water use activities, and climate change pose challenges and uncertainties. Ultimately, conservation of Pacific trout depends on how well these issues are understood and addressed, and on solutions that allow these species to coexist with a growing scope of human influences.

Fisheries↗

USGS1996

Ecology of kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) in Crater Lake, Oregon

Originally barren of fish, Crater Lake was stocked with approximately 1.8 million salmonids from 1888 to 1941. Rainbow trout ( Oncorhynchus mykiss ) and kokanee salmon ( O. nerka ) now inhabit the lake. This study was conducted from 1986 to 1991 to document and compare kokanee salmon and rainbow trout ecology in the lake to better evaluate the ecological implications of the presence of these non-native fish. Kokanee salmon exhibited cyclic patterns in population age structure, condition, abundance, and biomass from 1986 to 1991. One dominant year class of relatively low abundance and high condition was present from 1986 to 1987. Multiple year classes with increasing abundance and decreasing condition were present from 1989 through 1991. Rainbow trout maintained a diverse population structure throughout the study with a trend toward a relative increase of older age classes and larger fish. Vertical and horizontal migrations of kokanee salmon occurred within and between the nearshore and offshore zones of the lake. Rainbow trout were located along the edge of the lake. Kokanee salmon fed primarily offshore on zooplankton and small-bodied insects. Kokanee salmon cropped the Daphnia population and altered the zooplankton community structure during the study period. Rainbow trout fed nearshore on large-bodied vertebrates and invertebrates. Introduced fish in Crater Lake exhibited the potential to impact limnetic and benthic community structure and nutrient flux within and between these communities.

Oregon↗

USGS2012

Kinetics of viral load and erythrocytic inclusion body formation in pacific herring artificially infected with erythrocytic necrosis virus

Viral erythrocytic necrosis (VEN) is a condition that affects marine and anadromous fish species, including herrings and salmonids, in the Atlantic and Pacific oceans. Infection is frequently associated with severe anemia and causes episodic mortality among wild and hatchery fish when accompanied by additional stressors; VEN can be presumptively diagnosed by (1) light microscopic identification of a single characteristic—a round, magenta-colored, 0.8-μm-diameter inclusion body (IB) within the cytoplasm of erythrocytes and their precursors on Giemsa-stained blood films; or (2) observation (via transmission electron microscopy [TEM]) of the causative iridovirus, erythrocytic necrosis virus (ENV), within erythrocytes or their precursors. To better understand the kinetics of VEN, specific-pathogen-free Pacific herring Clupea pallasii were infected with ENV by intraperitoneal injection. At 1, 4, 7, 10, 14, 21, and 28 d postexposure, samples of blood, spleen, and kidney were collected and assessed (1) via light microscopy for the number of intracytoplasmic IBs in blood smears and (2) via TEM for the number of virions within erythrocytes. The mean prevalence of intracytoplasmic IBs in the blood cells increased from 0% at 0–4 d postexposure to 94% at 28 d postexposure. Viral load within circulating red blood cells peaked at 7 d postexposure, fell slightly, and then reached a plateau. However, blood cells observed within the kidney and spleen tissues demonstrated high levels of ENV between 14 and 28 d postexposure. The results indicate that the viral load within erythrocytes does not correlate well with IB prevalence and that the virus can persist in infected fish for more than 28 d.

Journal of Aquatic Animal Health↗

USGS2014

Susceptibility of Koi and Yellow Perch to infectious hematopoietic necrosis virus by experimental exposure

Infectious hematopoietic necrosis virus (IHNV) is a novirhabdoviral pathogen that originated in western North America among anadromous Pacific salmonids. Severe disease epidemics in the late 1970s resulting from IHNV's invasion into farmed Rainbow Trout Oncorhynchus mykiss in North America, Asia, and Europe emphasized IHNV's ability to adapt to new hosts under varying rearing conditions. Yellow Perch Perca flavescens and Koi Carp Cyprinus carpio (hereafter, “Koi”) are aquaculture-reared fish that are highly valued in sport fisheries and the ornamental fish trade, respectively, but it is unknown whether these fish species are vulnerable to IHNV infection. In this study, we exposed Yellow Perch, Koi, and steelhead (anadromous Rainbow Trout) to IHNV by intraperitoneal injection (10 6 PFU/fish) and by immersion (5.7×10 5 PFU/mL) for 7 h, and monitored fish for 28 d. The extended immersion exposure and high virus concentrations used in the challenges were to determine if the tested fish had any level of susceptibility. After experimental exposure, Yellow Perch and Koi experienced low mortality (<6%) compared with steelhead (>35%). Virus was found in dead fish of all species tested and in surviving Yellow Perch by plaque assay and quantitative reverse transcription polymerase chain reaction (qPCR), with a higher prevalence in Yellow Perch than Koi. Infectious virus was also detected in Yellow Perch out to 5 d after bath challenge. These findings indicate that Yellow Perch and Koi are highly resistant to IHNV disease under the conditions tested, but Yellow Perch are susceptible to infection and may serve as possible virus carriers.

Journal of Aquatic Animal Health↗