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At least 1,099 records · Page 61Linked to original sources
USGS2000

Physiological measures of neurotoxicity of diazinon and malathion to larval rainbow trout ( Oncorhynchus mykiss ) and their correlation with behavioral measures

Relations between neurotoxicants and changes in physiological parameters and behavior were investigated in larval rainbow trout (RBT; Oncorhynchus mykiss ) exposed to sublethal concentrations of two organophosphate pesticides (OPs). Fish were exposed to diazinon and malathion in static-renewal experiments. After exposures for 24, 96, or 96 h, followed by 48 h of recovery, individual RBT were videotaped to assess locomotory behaviors. Brain tissue from the same fish was assayed for the physiological endpoints, cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number (B max ), and MChR affinity (K D ). Cholinesterase activity decreased significantly with increasing concentrations of both diazinon and malathion and differed significantly among exposure durations, with 24- and 96-h means less than 48-h recovery means. Decreases in B max with OP concentration were not significant for either chemical, and K D was unaffected. Changes in swimming speed and distance were significantly correlated with changes in ChE activity for both chemicals; rate of turning was significantly correlated with ChE activity in malathion exposures. These results suggest that correlations between physiological and behavioral changes previously seen in mammals also occur in fish.

Environmental Toxicology and Chemistry↗
USGS2001

Accumulation of 2,3,7,8-tetrachlorodibenzo-p-dioxin by rainbow trout ( Onchorhynchus mykiss ) at environmentally relevant dietary concentrations

Rainbow trout were fed a diet containing 1.8, 18, or 90 pg/g 3H-2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for up to 320 d. Concentrations of TCDD were determined in muscle, liver, and ovaries at 100, 150, 200, and 250 d. Concentrations of TCDD reached an apparent steady-state concentration in liver after 100 d of exposure, whereas concentrations in other tissues continued to increase until 150 d of exposure. The greatest portion of the total mass of TCDD was present in the muscle tissue with lesser proportions in other organs. As the ovaries developed before spawning, an increase occurred in the total mass of TCDD present in this tissue. The assimilation rate of TCDD during the initial 100 d of the exposure was determined to be between 10 and 30%. This is somewhat less than estimates derived based on both uptake and elimination constants determined during shorter exposures. Biomagnification factors (BMFs) were estimated for all tissues and exposure concentrations, and at all exposure periods. Lipid-normalized BMFs for muscle ranged from 0.38 to 1.51, which is consistent with the value of 1.0 predicted from fugacity theory. Uptake and depuration rate constants were determined and used to predict individual organ TCDD concentrations. Comparison with observed values indicated that the model could be used to predict tissue concentrations from the known concentrations of TCDD in food. This model will allow more refined risk assessments by predicting TCDD concentrations in sensitive tissues such as developing eggs.

Environmental Toxicology and Chemistry↗
USGS2023

Toxicity of wildland fire retardants to rainbow trout in short exposures

Long-term wildland fire retardants are one important tool used to control and suppress wildfires. During suppression activities, these retardants may enter waterbodies; thus, there is a need to understand their potential effects to aquatic biota. We investigated the effect of three current-use wildland fire retardants to juvenile rainbow trout ( Oncorhynchus mykiss) survival in short exposures more realistic to actual intrusion scenarios. Lethal effect concentrations decreased with time and varied among chemicals (LC95A-R > 259-Fx > MVP-Fx). The lowest effect concentrations observed were 2 to 10 times above the threshold used by federal agencies to assess potential impacts to aquatic organisms following a retardant intrusion. These data can be used by resource managers to balance wildfire control with potential environmental impacts of retardant use.

Environmental Toxicology and Chemistry↗
USGS2018

A portfolio framework for prioritizing conservation efforts for Yellowstone Cutthroat Trout populations

Managing and conserving native taxa are becoming increasingly challenging because of mounting threats and limited resources, predicating the need for frameworks to prioritize conservation actions. We integrated attributes of population persistence, genetic status, threats from nonnative species, and threats from climatic shifts to prioritize conservation actions for Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri . We used the individual attributes to rank populations and provide a framework for identifying the benefits of individual conservation actions. The majority of extant populations (57%) had a high probability (>0.75) of persistence, but nearly 70% of populations were either slightly hybridized or sympatric with nonnative species, and 44% of extant populations occupied habitat with low climatic resilience. Overall, we found that 36% of populations ranked as high (>0.75) conservation priority, and these populations primarily occupied large, relatively high‐elevation habitats. The prioritization framework provides a platform for identifying and ranking actions with the greatest conservation effectiveness.

Idaho, Montana, Nevada, Utah, Wyoming↗
USGS2019

Return of a giant: Coordinated conservation leads to the first wild reproduction of Lahontan Cutthroat Trout in the Truckee River in nearly a century

Many freshwater fish populations have been greatly reduced, with particular loss of migratory fishes. Recovering depleted populations is challenging as threats are often plentiful and complex, especially in arid environments where demands for water resources are high. Here, we describe how a collaborative, multifaceted approach has spurred natural reproduction—a major step towards Lahontan Cutthroat Trout Oncorhynchus clarkii henshawi (LCT) recovery in Pyramid Lake and the Truckee River, Nevada, once home to one of largest freshwater salmonids in North America. The factors limiting LCT were immense, including habitat fragmentation, degradation, and non‐native species attributes common in the declines of native salmonids. Yet for the first time in over 80 years and each year since 2014, adfluvial LCT have spawned in the lower Truckee River, resulting in the production of tens of thousands of young‐of‐year. The progress and positive trajectory towards recovery were driven by a holistic view of the Truckee River watershed beginning in the early 1990's that envisioned bringing numerous conservation building blocks together to expedite the conservation and recovery for the listed fishes of Pyramid Lake. Although additional challenges remain, the LCT recovery program in the Truckee River basin provides a template for the conservation of imperiled fishes.

Nevada↗
USGS2018

Effects of air exposure during simulated catch-and-release angling on survival and fitness of Yellowstone Cutthroat Trout

Concerns have been raised regarding the practice of exposing fish to air during catch-and-release (C&R) angling. The purpose of this study was to evaluate the effects of air exposure on short- and long-term survival and progeny production of Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri . Prespawn adults were sampled at a weir during upstream migration in 2016 and 2017, exposed to a simulated angling event of 102 s, and then exposed to air for a randomly selected duration of 0, 30, or 60 s. An additional control group was added during 2017 in which fish were not exposed to simulated angling or air. In total, 1,519 fish were sampled in 2016, and 744 fish were sampled in 2017. Additionally, age-0 fish (2016: n = 2,924; 2017: n = 1,492) were collected to evaluate the effects of air exposure on the production of progeny. No effect of angling itself or of angling and air exposure was observed on short-term (≤60 d posttreatment) or long-term (>1 year posttreatment) survival of adults, with one exception. During 2016, fish that had been air exposed for 60 s had a statistically higher short-term survival rate than fish that received no air exposure. Air exposure had no effect on the proportion of fish that successfully spawned. Regression analysis revealed that neither angling nor air exposure affected progeny production. Considering that much of the literature, as well as this study, reports little to no influence of air exposure on salmonid mortality or reproductive success, it seems highly unlikely that air exposure of less than 60 s during C&R angling would have negative population-level effects.

Idaho↗
USGS2019

Using a mechanistic model to develop management strategies to cool Apache Trout streams under the threat of climate change

User‐friendly stream temperature models populated with on‐site data may help in developing strategies to manage temperatures of individual stream reaches that are subject to climate change. We used the field‐tested Stream Segment Temperature model (U.S. Geological Survey) to simulate how altering discharge, groundwater input, channel wetted width, and shade prevents the temperatures of White Mountain, Arizona, stream reaches from exceeding the thermal tolerance of Apache Trout Oncorhynchus apache , both under existing conditions and under a climate change scenario. Simulations suggested increasing shade, either through streamside planting of specific numbers and species of plants or by other means, would be most effective and feasible for cooling the stream reaches we studied. Ponderosa pine Pinus ponderosa and Douglas fir Pseudotsuga menziesii provided the most shade followed in order by Engelman spruce Picea engelmannii , Bebb's willow Salix bebbiana , Arizona alder Alnus oblongifolia , and finally coyote willow Salix exigua . Vegetation survival depends on the appropriateness of site conditions at present and under climate change, and planting in buffer strips minimizes additional water removal from the watershed through evapotranspiration. Alternative shading options, including thick sedge growth, shade cloth, or felled woody vegetation, may be considered when environmental conditions do not support plantings. Increasing groundwater input can cool streams, but additional sources are scarce in the region. Decreasing the width‐to‐depth ratio would succeed best on reaches with widths greater than 2.0 m. Increasing discharge from upstream may lower water temperature on reaches with an initial discharge greater than 0.5 m 3 /s. Existing models provide suggestions to cool stream reaches. Further development of accessible software packages that incorporate evaporation, fragmentation, and other projected climate change effects into their routines will provide additional tools to help manage climate change effects.

Arizona↗
USGS2019

An importance–satisfaction analysis of trout license holders in Georgia

As anglers become increasingly diverse, fisheries managers are challenged to find ways to satisfy users with divergent preferences while conserving a limited resource on a limited budget. With this management challenge in mind, this study combines previous angler specialization research with an importance–satisfaction analysis (ISA) to aid fisheries managers in better understanding users with divergent preferences. An ISA involves asking stakeholders to simultaneously evaluate the importance of salient attributes of their fishing experience and their satisfaction with those attributes, which allows for graphical depiction of each attribute in one of four quadrants with managerial implications: Concentrate Here, Keep up the Good Work, Possible Overkill, and Low Priority. The data were collected via a mail-administered survey that was sent to 4,000 licensed trout anglers who were residents of Georgia. The anglers were asked to evaluate 10 catch and 7 noncatch attributes as well as answer questions that were used to measure levels of angler specialization. A K -means cluster analysis was used to segment the 469 respondents into three groups based on their specialization level. Analysis of variance (ANOVA) was used to determine whether anglers’ preferences differed by level of specialization. The results revealed that specialization groups differed in the level of importance that they placed on 6 catch and 4 noncatch attributes and in their levels of satisfaction with 5 catch and 2 noncatch attributes. There were also differences among the groups in quadrant placement for both catch and noncatch attributes. The respondents agreed that habitat improvement initiatives, adding new fishable water, and clear signage of regulations were of relatively high importance, with habitat improvement initiatives as the only attribute to fall in the Concentrate Here quadrant for all three clusters. The average responses for importance and satisfaction were highest for the most specialized group and lowest for the least specialized group. Combining segmenting techniques, like cluster analysis with ISA, offers fisheries managers the opportunity to gauge different user groups’ perceptions of salient fishery attributes.

Georgia↗
USGS2023

Combining expert knowledge of a threatened trout distribution with sparse occupancy data for climate-related projection

Objective To evaluate the vulnerability of Bull Trout Salvelinus confluentus to potential climate changes across its range in Oregon, we compiled disparate expert knowledge of the distribution of spawning and rearing and combined these probabilistic statements as data along with documented records of breeding and rearing in a joint occupancy model. Methods The joint expert knowledge–occupancy model, which was based on discrete patches of cold water (≤13°C) suitable for spawning and rearing, permitted the association of true occupancy with climate and other explanatory variables while accounting for variation in detection probability. We then applied estimated relationships of patch occupancy with explanatory variables to projected coldwater patch configurations in the years 2040 and 2080. Result Projections of the kilometers of occupied coldwater patch in future decades suggest precipitous declines if current relationships of occupancy with environmental variables are maintained. Impacts of climate changes in future decades manifest directly through the outright loss of coldwater patches and increases in winter high flows but also indirectly by increased isolation. Conclusion Combining probabilistic statements of species distributions from knowledgeable experts with sparse occupancy data may be a robust and timely alternative when large numbers of repeated occupancy surveys are infeasible.

Oregon↗
USGS2013

Estimating thermal regimes of bull trout and assessing the potential effects of climate warming on critical habitats

Understanding the vulnerability of aquatic species and habitats under climate change is critical for conservation and management of freshwater systems. Climate warming is predicted to increase water temperatures in freshwater ecosystems worldwide, yet few studies have developed spatially explicit modelling tools for understanding the potential impacts. We parameterized a nonspatial model, a spatial flow-routed model, and a spatial hierarchical model to predict August stream temperatures (22-m resolution) throughout the Flathead River Basin, USA and Canada. Model comparisons showed that the spatial models performed significantly better than the nonspatial model, explaining the spatial autocorrelation found between sites. The spatial hierarchical model explained 82% of the variation in summer mean (August) stream temperatures and was used to estimate thermal regimes for threatened bull trout (Salvelinus confluentus) habitats, one of the most thermally sensitive coldwater species in western North America. The model estimated summer thermal regimes of spawning and rearing habitats at <13 C&deg; and foraging, migrating, and overwintering habitats at <14 C&deg;. To illustrate the useful application of such a model, we simulated climate warming scenarios to quantify potential loss of critical habitats under forecasted climatic conditions. As air and water temperatures continue to increase, our model simulations show that lower portions of the Flathead River Basin drainage (foraging, migrating, and overwintering habitat) may become thermally unsuitable and headwater streams (spawning and rearing) may become isolated because of increasing thermal fragmentation during summer. Model results can be used to focus conservation and management efforts on populations of concern, by identifying critical habitats and assessing thermal changes at a local scale.

River Research and Applications↗
USGS2019

Acidification impacts and goals for gauging recovery of Brook Trout populations and fish communities in streams of the Western Adirondack Mountains, New York, USA

Results from several long‐term monitoring programs in the western Adirondack Mountains, New York, indicate that acid–base chemistry of headwater streams has remained unchanged or improved only marginally since the 1990s. A paucity of quantitative fishery data, however, limits our understanding of the pre‐acidified communities as well as present‐day impacts of acidification on fish assemblages, which impedes efforts to evaluate temporal trends and biological recovery in streams of the region. Fish communities were characterized at 48 streams (chemistry was assessed at 47 streams) in the western Adirondacks at least once during summer 2014–2016 to assess present‐day effects of acidification on fish assemblages, refine important relations, and identify biological targets and chemical effect thresholds that could help gauge biological recovery across the region. Concentrations of inorganic aluminum (Al i ) exceeded chronic and acute toxicity thresholds (1.0 and 2.0 μmol/L) in 21.3% and 8.5%, respectively, of 47 study streams sampled during summer 2014–2016 and in 64.0% and 44.0% of 25 streams sampled during spring 2014–2015. In streams with summer Al i concentrations less than 1.0 μmol/L, community richness, density, and biomass averaged 2.0 species, 444.2 fish/0.1 ha, and 1,924.4 g/0.1 ha, respectively, whereas density and biomass of Brook Trout Salvelinus fontinalis populations averaged 280.8 fish/0.1 ha and 1,384.0 g/0.1 ha, respectively. These findings identify defensible targets for biological recovery and show that Al i toxicity is not a major concern for fish assemblages in most streams during summer base flow periods but is potentially a serious issue for fish in as many as two‐thirds of streams during spring high flows. Though additional data are needed to address several limitations and information gaps, results from this study provide a sound foundation to gauge biological recovery, detect future effects of climatic stressors, and help ensure that functional stream ecosystems can be sustained or restored in parts of the Adirondacks.

New York↗
USGS2020

A multifaceted reconstruction of the population structure and life history expressions of a remnant metapopulation of Bonneville Cutthroat Trout: Implications for maintaining intermittent connectivity

Fishes that evolutionarily demonstrated a fluvial life history expression and migrated to spawning and rearing habitat by using lotic corridors are increasingly impacted by fragmentation. The overall goal of this study was to identify the contemporary importance of main-stem connectivity and tributaries for maintaining life history expression, population structure, and viability of a large metapopulation of Bonneville Cutthroat Trout (BCT) Oncorhynchus clarkii utah persisting in the highly fragmented Weber River, Utah. We used a multifaceted approach, including active sampling, mark–recapture, passive PIT tag detection, otolith microchemistry, and genetics. We collected BCT in all tributaries and the main stem, encountering age-0 fish in three tributaries, indicating successful reproduction. In tributaries, the size structure was bimodal and consisted of smaller fish that were classified as resident and larger fish that were deemed to be fluvial, whereas all sizes and ages (age ≥ 1) were present in the main stem. We identified up to eight age-classes; tributaries were dominated by ages 2 and 8, and the main stem was dominated by ages 2, 5, 6, and 7. Tributary BCT had lower growth rates than BCT in the main stem. We observed a surprising degree of fluvial life history expression, and fish also demonstrated very complex movement patterns across their life span. Average apparent survival (33%) was within the range estimated in similar studies for BCT, and the resight rate was best explained by angler management regulations. The fact that BCT in the Weber River and tributaries still reproduce successfully in most years and are still able to grow into large, fluvial fish suggests that connectivity must be occasionally available despite considerable fragmentation. Therefore, this metapopulation may need little further human intervention if barriers to fish passage can be removed, thereby improving connectivity, and it represents a high-priority metapopulation for conservation, thus highlighting the utility of our approach.

Utah↗
USGS2021

Interacting effects of density-dependent and density-independent factors on growth rates in southwestern Cutthroat Trout populations

Density-dependent (DD) and density-independent (DI) effects play an important role in shaping fish growth rates, an attribute that correlates with many life history traits in fishes. Consequently, understanding the extent to which DD and DI effects influence growth rates is valuable for fisheries assessments because it can inform managers about how populations may respond as environmental conditions continue to change (e.g., threats from climate change). We used a Rio Grande Cutthroat Trout Oncorhynchus clarkii virginalis (RGCT) capture–mark–recapture data set collected over 2 years along a temperature and density gradient in northern New Mexico streams to test the extent to which DD and DI effects interact to influence specific growth rates. We found that temperature (DI) and density (DD) interacted with RGCT life stage (i.e., immature or mature) to affect growth rates. We only detected evidence of a negative DD effect on RGCT growth for the immature fraction of a population when exposed to the warmest stream temperatures. Our results suggest that competition most strongly affected the immature portion of RGCT populations, and this effect was only detectable when temperatures were warmest and energetic stress was likely at its highest. The quadratic relationship between temperature and growth rates also demonstrated that stream temperatures were below as well as above optimal growth temperatures for RGCT. Growth rates in our RGCT populations were influenced by complex interactions of DD and DI effects, and our results suggest that the negative consequences of warming trends associated with climate change on RGCT populations may be exacerbated by DD effects.

New Mexico↗
USGS2021

Movement dynamics and survival of stocked Colorado River Cutthroat Trout

The ability of native fish to establish self-sustaining populations when reintroduced to vacant habitats is variable. We evaluated factors that potentially affect the reintroduction success of juvenile Colorado River Cutthroat Trout Oncorhynchus clarkii pleuriticus that were reintroduced to an isolated watershed and were experiencing suboptimal survival and recruitment. We conducted a 3-year mark–recapture study to model annual apparent survival probability as it related to (1) different ex situ rearing strategies and (2) initial release among different habitat types. The use of PIT tags also enabled the quantification of loss via emigration. Apparent survival was highest for small fish that were minimally exposed to ex situ rearing conditions, stocked in small, headwater stream reaches. However, maximum estimates of apparent survival remained low (≤0.38 ± 0.05 [estimate ± SE]) regardless of rearing treatment, stocking location, or interactive effects between covariates. Emigration of stocked fish (<1%) from the study area did not appear to limit their establishment. Our results suggest that variation in stocking and rearing strategy may have some effect on translocation success and the interaction between rearing and stocking strategy highlights the importance of considering the life history stage of stocked individuals when identifying stocking sites. Consistently low annual survival values may be indicative of a larger issue, requiring in-depth evaluation of adaptive potential within our brood source and other factors that potentially limit population persistence.

Wyoming↗
USGS2001

Cholinergic and behavioral neurotoxicity of carbaryl and cadmium to larval rainbow trout ( Oncorhynchus mykiss )

Pesticides and heavy metals are common environmental contaminants that can cause neurotoxicity to aquatic organisms, impairing reproduction and survival. Neurotoxic effects of cadmium and carbaryl exposures were estimated in larval rainbow trout (RBT; Oncorhynchus mykiss ) using changes in physiological endpoints and correlations with behavioral responses. Following exposures, RBT were videotaped to assess swimming speed. Brain tissue was used to measure cholinesterase (ChE) activity, muscarinic cholinergic receptor (MChR) number, and MChR affinity. ChE activity decreased with increasing concentrations of carbaryl but not of cadmium. MChR were not affected by exposure to either carbaryl or cadmium. Swimming speed correlated with ChE activity in carbaryl-exposed RBT, but no correlation occurred in cadmium-exposed fish. Thus, carbaryl exposure resulted in neurotoxicity reflected by changes in physiological and behavioral parameters measured, while cadmium exposure did not. Correlations between behavior and physiology provide a useful assessment of neurotoxicity.

Ecotoxicology and Environmental Safety↗
USGS2000

Distribution of metals during digestion by cutthroat trout fed benthic invertebrates contaminated in the Clark Fork River, Montana and the Coeur d'Alene River, Idaho, U.S.A., and fed artificially contaminated Artemia

The concentrations of essential amino acids in three, undigested invertebrate diets collected from the Clark Fork River (CFR) for cutthroat trout were similar to each other, but were c. 25–75% less than Artemia that were exposed to a mixture of arsenic, copper, cadmium, lead and zinc in the laboratory. The Artemia diet appeared less palatable and the texture, quantity and appearance of the intestinal contents differed between fish fed the Artemia and CFR diets. The Pb% in the fluid fraction of the intestinal contents was greater for the Artemia (29%) than for the CFR diets (10–17%), and the Cu% in the amino acid plus metal fraction of the intestinal contents was greater for the Artemia (78%) than for two of the three CFR diets (67% and 70%). Intestinal contents of fish fed invertebrate diets collected from various sites on the Coeur d'Alene River (CDA), Idaho, were similar in texture, quantity, and appearance. For fish fed the CDA diets, differences in the distribution of metals among fractions of the digestive fluids appeared to be related to concentrations of metals in the invertebrate diets. Pb% was lowest of all metals in the fluid portion of the intestinal contents. However, >80% of all metals in the hind gut were associated with the particulate fraction where they may still be available for uptake through pinocytosis.

Journal of Fish Biology↗
USGS1977

Inheritance of muscle and liver types of supernatant NADP-dependent isocitrate dehydrogenase in rainbow trout (Salmo gairdneri)

The genetics of allelic variation for NADP-dependent isocitrate dehydrogenase (IDH-s) found in the supernatant of liver and white muscle extracts of rainbow trout (Salmo gairdneri) was examined. Twenty progeny from each of 50 controlled matings were examined for IDH phenotypes. Progeny data clearly indicated that the IDH-s variation in the muscle is controlled by two loci—one fixed and one with two alleles producing molecules of different electrophoretic mobilities. IDH-s variation in the liver is controlled by two disomic loci which code for four alleles. No linkage between the loci controlling IDH-s in the liver and the loci controlling it in the muscle was detected.

Biochemical Genetics↗
USGS1990

Behavioral indicators of sublethal toxicity in rainbow trout

Four measures of behavior-spontaneous swimming activity, swimming capacity, feeding behavior, and vulnerability to predation-were assessed as indicators of sublethal toxicity in rainbow trout ( Oncorhynchus mykiss ) in 96-hr exposures to sublethal concentrations of six agricultural chemicals: carbaryl, chlordane, dimethylamine salt of 2,4-dichlorophenoxyacetic acid (2,4-DMA), tributyl phosphorotrithioate (DBF 1), methyl parathion, and pentachlorophenol. After exposures, behavioral changes consistently demonstrated sublethal toxicity, but effects on specific behaviors varied with contaminants and their concentrations were altered by the water quality criterion concentration for chlordane (2 μg/L), and at a concentration of DEF (5 μg/L) that had previously been shown to inhibit growth and survival after a 90-day exposure. Feeding behavior was inhibited most by exposure to DEF, 2,4-DMA, and methyl parathion. Vulnerability to predation was heightened most by exposure to carbaryl and pentachlorophenol. Although all chemicals inhibited spontaneous swimming activity, only carbaryl, DEF, and 2,4-DMA influenced swimming capacity.

Archives of Environmental Contamination and Toxico↗