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At least 1,351 records · Page 75Linked to original sources
USGS2022

Occurrence, abundance, movement, and habitat associations of Bonneville Cutthroat Trout in tributaries to Bear Lake, Idaho-Utah

Bonneville Cutthroat Trout (BCT) Oncorhynchus clarkii utah in Bear Lake, Idaho–Utah, is an important endemic and recreational species and plays a vital ecological role in systems throughout the basin. Although the distribution and abundance of BCT have declined due to anthropogenic disturbances, production of wild BCT in Bear Lake has increased over the past decade as a result of extensive habitat improvement in spawning tributaries. The objective of this study was to assess the occurrence, distribution, and out-migration of BCT in tributaries of Bear Lake. Surveys were conducted at 75 stream reaches across three study streams (i.e., St. Charles, Fish Haven, and Swan creeks) during 2019 and 2020. A total of 1,064 BCT was sampled from 55 of 75 total reaches (73%). Total length of BCT varied from 22 to 650 mm, and the average TL was 117 mm (SE = 2.2). Regression models were used to identify abiotic and biotic features associated with BCT distribution, abundance, and probability of out-migration. Regardless of the tributary, elevation was negatively related to BCT occurrence and relative abundance. Other habitat characteristics associated with the presence and abundance of BCT were similar to those of other Cutthroat Trout species. For example, BCT were often associated with large substrates, instream cover, canopy cover, and heterogeneity in several habitat characteristics. The probability of a BCT out-migrating was positively associated with fish length and age but negatively related to distance to Bear Lake and number of downstream irrigation diversions. Results from this study provide critical information on the ecology and early life history characteristics of BCT that can be used to guide additional conservation and management efforts (i.e., removal of nonnative fish species; continued habitat restoration efforts).

Idaho, Utah↗
USGS2023

Conservation decision support for Silver Chub habitat in Lake Erie

Objective Conservation and restoration of aquatic species is difficult, especially for rare species, because their habitats are typically disturbed, obscuring the natural ability of the habitat to support each species. The Lake Erie population of Silver Chub Macrhybopsis storeriana struggles to sustain itself in a habitat disturbed by a wide spectrum of anthropogenic factors. Application of multiple model predictions can provide indications of conservation or restoration opportunities for this species. Methods A combination of models that predict the best potential for Lake Erie habitat to support Silver Chub and the effects of anthropogenic disturbances on that population were used to identify habitat conditions throughout the western aquatic lake unit. Result As many as 76 combinations of best habitat potential and disturbance conditions were present, but the best opportunities occurred in <12% of the study area. Some of the best protection opportunities were farthest offshore, and extensive areas of least disturbed habitat for restoration were near the southern and western shores. The location-specific model predictions provide fine-scale decision support for Silver Chub habitat protection or restoration. Conclusion The approach applied here may help identify compatibilities among species to achieve the desirable fish community for Lake Erie and reconcile conflicting management actions.

Michigan, Ohio, Ontario↗
USGS2015

Effects of water temperature and fish size on predation vulnerability of juvenile humpback chub to rainbow trout and brown trout

Predation on juvenile native fish by introduced Rainbow Trout and Brown Trout is considered a significant threat to the persistence of endangered Humpback Chub Gila cypha in the Colorado River in the Grand Canyon. Diet studies of Rainbow Trout and Brown Trout in Glen and Grand canyons indicate that these species do eat native fish, but impacts are difficult to assess because predation vulnerability is highly variable, depending on prey size, predator size, and the water temperatures under which the predation interactions take place. We conducted laboratory experiments to evaluate how short-term predation vulnerability of juvenile native fish changes in response to fish size and water temperature using captivity-reared Humpback Chub, Bonytail, and Roundtail Chub. Juvenile chub 45&ndash;90 mm total length (TL) were exposed to adult Rainbow and Brown trouts at 10, 15, and 20&deg;C to measure predation vulnerability as a function of water temperature and fish size. A 1&deg;C increase in water temperature decreased short-term predation vulnerability of Humpback Chub to Rainbow Trout by about 5%, although the relationship is not linear. Brown Trout were highly piscivorous in the laboratory at any size > 220 mm TL and at all water temperatures we tested. Understanding the effects of predation by trout on endangered Humpback Chub is critical in evaluating management options aimed at preserving native fishes in Grand Canyon National Park.

Transactions of the American Fisheries Society↗
USGS2016

Feeding ecology of native and nonnative salmonids during the expansion of a nonnative apex predator in Yellowstone Lake, Yellowstone National Park

The illegal introduction of Lake Trout Salvelinus namaycush into Yellowstone Lake, Yellowstone National Park, preceded the collapse of the native population of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri , producing a four-level trophic cascade. The Yellowstone Cutthroat Trout population&rsquo;s collapse and the coinciding increase in Lake Trout abundance provided a rare opportunity to evaluate the feeding ecology of a native prey species and a nonnative piscivore species after the restructuring of a large lentic ecosystem. We assessed diets, stable isotope signatures, and depth-related CPUE patterns for Yellowstone Cutthroat Trout and Lake Trout during 2011&ndash;2013 to evaluate trophic overlap. To evaluate diet shifts related to density, we also compared 2011&ndash;2013 diets to those from studies conducted during previous periods with contrasting Yellowstone Cutthroat Trout and Lake Trout CPUEs. We illustrate the complex interactions between predator and prey in a simple assemblage and demonstrate how a nonnative apex predator can alter competitive interactions. The diets of Yellowstone Cutthroat Trout were dominated by zooplankton during a period when the Yellowstone Cutthroat Trout CPUE was high and were dominated by amphipods when the CPUE was reduced. Lake Trout shifted from a diet that was dominated by Yellowstone Cutthroat Trout during the early stages of the invasion to a diet that was dominated by amphipods after Lake Trout abundance had increased and after Yellowstone Cutthroat Trout prey had declined. The shifts in Yellowstone Cutthroat Trout and Lake Trout diets resulted in increased trophic similarity of these species through time due to their shared reliance on benthic amphipods. Yellowstone Cutthroat Trout not only face the threat posed by Lake Trout predation but also face the potential threat of competition with Lake Trout if amphipods are limiting. Our results demonstrate the importance of studying the long-term feeding ecology of fishes in invaded ecosystems.

Wyoming↗
USGS2011

Movement and spawning of American shad transported above dams on the Roanoke River, North Carolina and Virginia

American shad Alosa sapidissima are in decline throughout much of their native range as a result of overfishing, pollution, and habitat alteration in coastal rivers where they spawn. One approach to restoration in regulated rivers is to provide access to historical spawning habitat above dams through a trap-and-transport program. We examined the initial survival, movement patterns, spawning, and downstream passage of sonic-tagged adult American shad transported to reservoir and riverine habitats upstream of hydroelectric dams on the Roanoke River, North Carolina and Virginia, during 2007&ndash;2009. Average survival to release in 2007&ndash;2008 was 85%, but survival decreased with increasing water temperature. Some tagged fish released in reservoirs migrated upstream to rivers; however, most meandered back and forth within the reservoir. A higher percentage of fish migrated through a smaller (8,215-ha) than a larger (20,234-ha) reservoir, suggesting that the population-level effects of transport may depend on upper basin characteristics. Transported American shad spent little time in upper basin rivers but were there when temperatures were appropriate for spawning. No American shad eggs were collected during weekly plankton sampling in upper basin rivers. The estimated initial survival of sonic-tagged American shad after downstream passage through each dam was 71&ndash;100%; however, only 1% of the detected fish migrated downstream through all three dams and many were relocated just upstream of a dam late in the season. Although adult American shad were successfully transported to upstream habitats in the Roanoke River basin, under present conditions transported individuals may have reduced effective fecundity and postspawning survival compared with nontransported fish that spawn in the lower Roanoke River.

North Carolina, Virginia↗
USGS2012

Assessment of freshwater fish assemblages and their habitats in the National Park Service system of the southeastern United States

The southeast region of the United States contains the highest diversity of freshwater fish species in the country: approximately 662 species. Existing protected areas like units of the National Park Service (NPS) should reflect this biodiversity, but there has been no broad-scale assessment. We compiled several data sets identifying native freshwater fish species distributions in and surrounding NPS units and threats to those resources. Focusing on the 26 NPS units containing only freshwater fish species, we documented 288 species within NPS boundaries. The largest NPS units tended to have the most fish species and aquatic habitat but also the greatest amount of alteration. Increasing rates of urbanization, declines in percentage agriculture land cover, and increased density of road-stream crossings in surrounding watersheds were good predictors of nonindigenous species presence within NPS unit boundaries. These results help document the role of NPS units in conserving freshwater fish diversity and, in this region, suggest that measures aimed at controlling urbanization in the adjacent watersheds could affect the diversity of freshwater fish communities in these units.

Fisheries↗
USGS2018

Post‐release predation mortality of age‐0 hatchery‐reared Chinook salmon from non‐native smallmouth bass in the Snake River

Release of age‐0 hatchery‐reared fall Chinook salmon, Oncorhynchus tshawytscha (Walbaum), in the Snake River resulted in up to 30‐fold increases in salmon consumption by non‐native smallmouth bass, Micropterus dolomieu Lacepѐde. In an upper river reach, smallmouth bass fed intensively during a release in May, but Chinook salmon consumption returned to pre‐release levels within 1–2 days as hatchery‐reared fish quickly emigrated downstream. The predation response during a June release located farther downstream was dissimilar. Chinook salmon consumption increased to a lesser extent (11‐fold), lasted several days (~4) and no changes in feeding intensity were evident. Estimated numbers of age‐0 hatchery‐reared Chinook salmon lost to short‐term predation varied by year and study reach and ranged from 12,007 (6.03% of those released) to 210,580 (14.6% of those released) fish. Short‐term, intense feeding by smallmouth bass can contribute significantly to mortality of hatchery‐reared fish and should be considered when supplementing populations with hatchery juveniles.

Idaho, Washington↗
USGS2018

A laboratory-calibrated model of coho salmon growth with utility for ecological analyses

We conducted a meta-analysis of laboratory- and hatchery-based growth data to estimate broadly applicable parameters of mass- and temperature-dependent growth of juvenile coho salmon ( Oncorhynchus kisutch ). Following studies of other salmonid species, we incorporated the Ratkowsky growth model into an allometric model and fit this model to growth observations from eight studies spanning ten different populations. To account for changes in growth patterns with food availability, we reparameterized the Ratkowsky model to scale several of its parameters relative to ration. The resulting model was robust across a wide range of ration allocations and experimental conditions, accounting for 99% of the variation in final body mass. We fit this model to growth data from coho salmon inhabiting tributaries and constructed ponds in the Klamath Basin by estimating habitat-specific indices of food availability. The model produced evidence that constructed ponds provided higher food availability than natural tributaries. Because of their simplicity (only mass and temperature are required as inputs) and robustness, ration-varying Ratkowsky models have utility as an ecological tool for capturing growth in freshwater fish populations.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2018

Long-term population dynamics and conservation risk of migratory bull trout in the upper Columbia River basin

We used redd count data from 88 bull trout (Salvelinus confluentus) populations in the upper Columbia River basin to quantify local and regional patterns in population dynamics, including adult abundance, long-term trend, and population synchrony. We further used this information to assess conservation risk of metapopulations using eight population dynamic metrics associated with persistence. Local population abundances were generally low (<20 redds annually) and the majority of trends were either stable (85%) or declining (13%). Evidence of synchrony among populations was apparent but not related to fluvial distance between streams. Variability in annual abundances was 1.4–2.5 times lower in metapopulations than local populations, indicating moderate portfolio effects across the regional stock complex. Importantly, most metrics of conservation risk were uncorrelated with one another, emphasizing that multiple statistics describing population dynamics at various scales are needed for monitoring and assessing recovery. We provide a composite description of conservation risk based on local and regional population dynamics that can help inform conservation management decisions for bull trout and other freshwater fishes.

Idaho, Montana↗
USGS2011

Response of non-native lake trout (Salvelinus namaycush) to 15 years of harvest in Yellowstone Lake, Yellowstone National Park

Introduced lake trout (Salvelinus namaycush) threaten to extirpate native Yellowstone cutthroat trout (Oncorhynchus clarkii bouvieri) in the 34 000 ha Yellowstone Lake in Yellowstone National Park, USA. Suppression (and eventual eradication) of the lake trout population is deemed necessary for the conservation of Yellowstone cutthroat trout. A US National Park Service gill-netting program removed nearly 450 000 lake trout from Yellowstone Lake from 1995 through 2009. We examined temporal variation in individual growth, body condition, length and age at maturity, fecundity, mortality, and population models to assess the efficacy of the lake trout suppression program. Population metrics did not indicate overharvest despite more than a decade of fish removal. The current rate of population growth is positive; however, it is lower than it would be in the absence of lake trout suppression. Fishing effort needs to increase above observed levels to reduce population growth rate below replacement. Additionally, high sensitivity of population growth rate to reproductive vital rates indicates that increasing fishing mortality for sexually mature lake trout may increase the effectiveness of suppression. Lake trout suppression in Yellowstone Lake illustrates the complexities of trying to remove an apex predator to restore a relatively large remote lentic ecosystem with a simple fish assemblage.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1974

Serological diagnosis of corynebacterial kidney disease of salmonids

An immunodiffusion test is described which provides a rapid, sensitive, and definitive diagnosis of corynebacterial kidney disease of salmonid fishes. Specific precipitin lines are formed within 24 h when rabbit antiserum is reacted with kidney disease cell suspensions or internal tissue homogenates containing the specific bacterium. No precipitin lines are formed with tissue homogenates from healthy fish or from those injected with other fish pathogenic bacteria.

Journal of the Fisheries Research Board of Canada↗
USGS1981

Sterilization of sea lampreys ( Petromyzon marinus ) by immersion in an aqueous solution of bisazir

Groups of sea lamprey ( Petromyzon marinus ) eggs fertilized by males previously immersed in an aqueous solution of p , p -bis(1-aziridinyl)- N -methylphosphinothioic amide (bisazir) at concentrations of 10&ndash;100&ensp;mg/L produced fewer normal, live prolarvae after 15&ndash;17&ensp;d of incubation than did groups of eggs fertilized by normal males. Mortality of embryos or prolarvae was nearly 100% in groups of eggs fertilized by males that had been immersed in a 50&ensp;mg/L solution of bisazir for 4&ensp;h or in a 100&ensp;mg/L solution for 2&ensp;h. The immersion technique appears to be an efficient method of sterilizing large numbers of male sea lampreys for use in a proposed sterile-male-release program. Key words : sea lamprey, Petromyzon marinus ; pest control, fish control, sterile-male technique, sterilization, chemosterilants, bisazir, Great Lakes

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1982

Pathogenesis of infectious hematopoietic necrosis virus in adult sockeye salmon ( Oncorhynchus nerka )

The concentration of infectious hematopoietic necrosis (IHN) virus was determined in eight organs and two body fluids from each of 60 adult sockeye salmon ( Oncorhynchus nerka ). Included in the sample were 4 males and 56 prespawning, spawning, or spent female fish. All fish were infected, and virus was present in nearly all organs. There was an overall tendency for the mean concentration to increase in many of the organs over time as the fish progressed in ripeness. In prespawning females, IHN virus could be detected in all organs and in ovarian fluid but not in serum; the incidences were highest in the gills, spleen, and pyloric ceca, and the titers were highest in the pyloric ceca and liver. Incidences of infection in the organs were higher in spawning than in prespawning females and higher still in spent females in which the incidence of virus was 100% in all organs except brains (78%) and sera (67%). Virus concentrations in organs or fluids ranged from 5 to 4.0 × 10 9 plaque-forming units per millilitre. In males, the highest incidences of virus were found in gills, pyloric ceca, and liver. The gills were the only organ in which the virus concentration in males exceeded that of females. Key words : infectious hematopoietic necrosis, IHN, fish virus, viral pathogenesis, sockeye salmon

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1995

Estimating number of species and relative abundances in stream-fish communities: effects of sampling effort and discontinuous spatial distributions

We sampled fishes and measured microhabitat in series of contiguous habitat units (riffles, runs, pools) in three Virginia streams. We used Monte Carlo simulations to construct hypothetical series of habitat units, then examined how number of species, similarity in relative abundances, and number of microhabitats accumulated with increasing number of habitat units (i.e., sampling effort). Proportions of all species and microhabitats represented were relatively low and variable at low sampling effort, but increased asymptotically and became less variable with greater sampling effort. To facilitate comparisons among streams, we fitted simulation results to negative exponential curves. The curves indicated that 90% of the species present were usually found by sampling 5 to 14 habitat units (stream length of 22&ndash;67 stream widths). Estimates of species relative abundances required less sampling effort for a given accuracy than estimates of number of species. Rates of species accumulation (with effort) varied among streams and reflected discontinuity in species distributions among habitat units. Most discontinuity seemed to be due to low population density rather than to habitat selectivity. Results from an Illinois stream corroborated our findings from Virginia, and suggested that greater sampling effort is needed to characterize fish community structure in more homogeneous stream reaches.

Virginia↗
USGS1992

Performance of nine external tags on hatchery-reared rainbow trout

We evaluated nine commercially available tags to determine their suitability for marking yearling rainbow trout Oncorhynchus mykiss reared in raceways and circular tanks. The tags tested were Floy vinyl tubing tags FD‐67 anchor, FT‐2 dart, FT‐4 cinch‐up, and FT‐4 lock‐on; modified Carlin; modified Petersen disk; Monel strap 4‐1005; Monel butt end 4‐1242; and Stoffel fish seal. After 9 months, tag losses from raceway fish were lowest (8%) for the FT‐4 lock‐on tag; in tanks, none of the FT‐2 dart, FT‐4 cinch‐up, FT‐4 lock‐on, or the Monel butt end tags were lost. At 90 d after tagging, raceway fish marked with the Monel strap or the modified Carlin tags showed significantly less growth than did fish marked with the FD‐67 anchor tag; the converse was true for fish in tanks. After 9 months, raceway fish marked with the Monel butt end tag and tank fish marked with the FD‐67 anchor tag were least injured. Injury was greater in raceways than in tanks for all tag types. Judged by overall performance, the FD‐67 anchor was the most effective tag for fish maintained in raceways and the FT‐4 cinch‐up was a suitable alternative; the FT‐2 dart, FT‐4 cinch‐up, and Monel butt end tags were equally suitable for fish in tank culture.

Transactions of the American Fisheries Society↗
USGS1997

Slow growth did not decouple the otolith size-fish size relationship in striped bass

Eight‐day‐old striped bass Morone saxatilis (6.17–6.22 mm, total length) were fed twice daily at three feeding rates to produce three growth rates. Fish were sampled once per week for 4 weeks to determine total length and otolith radius. Feed ration treatments resulted in discrete size‐classes of striped bass after 4 weeks with a 27% difference in mean length between the low and high feed ration treatments. No significant differences in slope or intercept for the regression of fish length on otolith radius were observed among treatments, suggesting that slow growth alone may not be sufficient to result in decoupling of the otolith size–fish size relationship in striped bass.

Transactions of the American Fisheries Society↗
USGS1999

Acute toxicity of an acid mine drainage mixing zone to juvenile bluegill and largemouth bass

The toxicity of an acid mixing zone produced at the confluence of a stream that was contaminated by acid mine drainage (AMD) and a pH-neutral stream was investigated in toxicity tests with juvenile bluegill Lepomis macrochirus and largemouth bass Micropterus salmoides. Fish mortalities in instream cages located in the mixing zone, below the mixing zone, and upstream in both tributaries were compared to determine relative toxicity at each site. In all tests and for both species, significantly higher mortality was observed in the mixing zone than at any other location, including the acid stream, which had lower pH (2.9-4.3). The mixing zone was defined chemically by rapid precipitation of dissolved aluminum and iron, which arrived from the low-pH stream, and by the presence of white precipitates, which were attached to the substratum and which extended below the confluence. Possible seasonal changes in mixing zone toxicity were investigated by conducting field tests with bluegill in June, July, and August 1996 and in January 1997 and by conducting field tests with largemouth bass in April and May 1997. Toxicity was not significantly different at the extremes of temperature, pH, and metal concentration that occurred in June and July, as compared with January. Toxicity was significantly lower in August; however, elevated stream discharge during the August test may have disturbed mixing zone characteristics. High toxicity in AMD mixing zones may lower the survival of fishes in streams, reduce available habitat, and impede movements of migratory fish.

Transactions of the American Fisheries Society↗