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At least 559 records · Page 31Linked to original sources
USGS2015

Landscape-scale determinants of native and nonnative Great Plains fish distributions

Aim Landscape-scale factors may have differential effects on the distribution of native and non-native fishes and may help explain invasion success and species declines. Location Great Plains, Wyoming, USA Methods We used hierarchical Bayesian mixture models and constrained ordination techniques to evaluate associations between landscape-scale factors on native and non-native fish species richness, reproductive guilds and individual species distributions. Results Predicted responses between landscape-scale factors and native and non-native fish species richness were similar, except non-native fish species richness that was positively associated with density of oil and gas wells. Non-native fish species richness was also positively associated with native fish species richness. Spawning guild composition differed between native and non-native fishes. Canonical correspondence analysis revealed that the most abundant non-native and only a few native species were positively associated with oil and gas wells. Main conclusions The similar relationships between native and non-native fish species richness are likely evidence that they share similar ecological rules, which supports that non-native species become naturalized and they may be affected by the same environmental factors that determine distribution of native species.

Diversity and Distributions↗
USGS2022

Circumpolar patterns of Arctic freshwater fish biodiversity: A baseline for monitoring

Climate change, biological invasions, and anthropogenic disturbance pose a threat to the biodiversity and function of Arctic freshwater ecosystems. Understanding potential changes in fish species distribution and richness is necessary, given the great importance of fish to the function of freshwater ecosystems and as a resource to humans. However, information gaps limit large-scale studies and our ability to determine patterns and trends in space and time. This study takes the first step in determining circumpolar patterns of fish species richness and composition, which provides a baseline to improve both monitoring and conservation of Arctic freshwater biodiversity. Information on species presence/absence was gathered from the Circumpolar Biodiversity Monitoring Program's Freshwater Database and used to examine patterns of freshwater fish γ-, α-, and β-diversity across 234° of longitude in the Arctic. The metrics of diversity provided information on species richness and composition across hydrobasins, ecoregions, and Arctic zones. Circumpolar patterns of fish species biodiversity varied with latitude, isolation, and coarse ecoregion characteristics; patterns were consistent with historic and contemporary barriers to colonisation and environmental characteristics. Gamma-diversity was lower in the high Arctic compared to lower latitude zones, but α-diversity did not decrease with increasing latitude below 71°N, reflecting glacial history. Alpha-diversity was reduced to a single species, Arctic charr Salvelinus alpinus , in ecoregions above 71°N, where γ-diversity was the lowest. Beta-diversity indicated little variation in the composition and richness of species across the High Arctic; at lower latitudes, ecoregions contained more species, although species composition turned over across large spatial extents. In an analysis of five ecoregions in the circumpolar Arctic, physical isolation, and ecoregion area and topography were identified as strong drivers of γ-, α-, and β-diversity. Physical isolation reduced the γ- and α-diversity, and changes in β-diversity between adjacent locations were due mainly to losses in species richness, rather than due to differences in species composition. Heterogeneity of habitats, environmental gradients, and geographic distance probably contributed to patterns of fish dissimilarity within and across ecoregions. This study presents the first analysis of large-scale patterns of freshwater fish biodiversity in the circumpolar Arctic. However, information gaps in space, time, and among taxonomic groups remain. Future inclusion of extensive archive and new data will allow future studies to test for changes and drivers of the observed patterns of biodiversity. This is important given the potential impacts of ongoing and accelerating climate change, land use, and biotic exchange on Arctic fish biodiversity.

Freshwater Biology↗
USGS2011

Variation in local abundance and species richness of stream fishes in relation to dispersal barriers: Implications for management and conservation

1.Barriers to immigration, all else being equal, should in principle depress local abundance and reduce local species richness. These issues are particularly relevant to stream-dwelling species when improperly designed road crossings act as barriers to migration with potential impacts on the viability of upstream populations. However, because abundance and richness are highly spatially and temporally heterogeneous and the relative importance of immigration on demography is uncertain, population- and community-level effects can be difficult to detect. 2.In this study, we tested the effects of potential barriers to upstream movements on the local abundance and species richness of a diverse assemblage of resident stream fishes in the Monongahela National Forest, West Virginia, U.S.A. Fishes were sampled using simple standard techniques above- and below road crossings that were either likely or unlikely to be barriers to upstream fish movements (based on physical dimensions of the crossing). We predicted that abundance of resident fishes would be lower in the upstream sections of streams with predicted impassable barriers, that the strength of the effect would vary among species and that variable effects on abundance would translate into lower species richness. 3.Supporting these predictions, the statistical model that best accounted for variation in abundance and species richness included a significant interaction between location (upstream or downstream of crossing) and type (passable or impassable crossing). Stream sections located above predicated impassable culverts had fewer than half the number of species and less than half the total fish abundance, while stream sections above and below passable culverts had essentially equivalent richness and abundance. 4.Our results are consistent with the importance of immigration and population connectivity to local abundance and species richness of stream fishes. In turn, these results suggest that when measured at appropriate scales (multiple streams within catchments), with simple protocols amenable to use by management agencies, differences in local abundance and species richness may serve as indicators of the extent to which road crossings are barriers to fish movement and help determine whether road-crossing improvements have restored connectivity to stream fish populations and communities. Published 2011. This article is a US Government work and is in the public domain in the USA.

Freshwater Biology↗
USGS2007

Connecting ground water influxes with fish species diversity in an urbanized watershed

Valley Creek watershed is a small stream system that feeds the Schuylkill River near Philadelphia, Pennsylvania. The watershed is highly urbanized, including over 17 percent impervious surface cover (ISC) by area. Imperviousness in a watershed has been linked to fish community structure and integrity. Generally, above 10 to 12 percent ISC there is marked decline in fish assemblages with fish being absent above 25 percent ISC. This study quantifies the importance of ground water in maintaining fish species diversity in subbasins with over 30 percent ISC. Valley Creek contains an atypical fish assemblage in that the majority of the fish are warm-water species, and the stream supports naturally reproducing brown trout, which were introduced and stocked from the early 1900s to 1985. Fish communities were quantified at 13 stations throughout the watershed, and Simpson's species diversity index was calculated. One hundred and nine springs were located, and their flow rates measured. A cross covariance analysis between Simpson's species diversity index and spring flow rates upstream of fish stations was performed to quantify the spatial correlation between these two variables. The correlation was found to be highest at lag distances up to about 400 m and drop off significantly beyond lag distances of about 800 m.

Pennsylvania↗
USGS2008

Forage fish of the Pacific Rim as revealed by diet of a piscivorous seabird: Synchrony and relationships with sea surface temperature

We tested the hypothesis of synchronous interannual changes in forage fish dynamics around the North Pacific Rim. To do this, we sampled forage fish communities using a seabird predator, the rhinoceros auklet ( Cerorhinca monocerata ), at six coastal study sites from Japan to California. We investigated whether take of forage fishes was related to local marine conditions as indexed by sea surface temperature (SST). SST was concordant across sites in the eastern Pacific, but inversely correlated between east and west. Forage fish communities consisted of anchovy ( Engraulis spp.), sandlance ( Ammodytes spp.), capelin ( Mallotus spp.), and juvenile rockfish ( Sebastes spp.), among others, and take of forage fish varied in response to interannual and possibly lower-frequency oceanographic variability. Take of primary forage species were significantly related to changes in SST only at the eastern sites. We found synchrony in interannual variation of primary forage fishes across several regions in the eastern Pacific, but no significant east–west correlations. Specifically in the Japan Sea, factors other than local SST or interannual variability may more strongly influence forage fishes. Predator diet sampling offers a fishery-independent, large-scale perspective on forage fish dynamics that may be difficult to obtain using conventional means of study.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2021

Time to refine mercury mass balance models for fish

Mercury mass balance models (MMBMs) for fish are powerful tools for understanding factors affecting growth and food consumption by free-ranging fish in rivers, lakes, and oceans. Moreover, MMBMs can be used to predict the consequences of global mercury reductions, overfishing, and climate change on mercury (Hg) concentration in commercially and recreationally valuable species of fish. Such predictions are useful in decision-making by resource managers and public health policy makers, because mercury is a neurotoxin and the primary route of exposure of mercury to humans is via consumption of fish. Recent evidence has emerged to indicate that the current-day version of MMBMs overestimates the rate at which fish eliminate mercury from their bodies. Consequently, MMBMs overestimate food consumption by fish and underestimate Hg concentration in fish. In this perspective, we explore underlying reasons for this overestimation of Hg-elimination rate, as well as consequences and implications of this overestimation. We highlight emerging studies that distinguish species and sex as contributing factors, in addition to body weight and water temperature, that can play an important role in how quickly Hg is eliminated from fish. Future research directions for refining MMBMs are discussed.

Facets↗
USGS2020

Mercury and selenium concentrations in fishes of the Upper Colorado River Basin, southwestern United States: A retrospective assessment

Mercury (Hg) and selenium (Se) are contaminants of concern for fish in the Upper Colorado River Basin (UCRB). We explored Hg and Se in fish tissues (2,324 individuals) collected over 50 years (1962–2011) from the UCRB. Samples include native and non-native fish collected from lotic waterbodies spanning 7 major tributaries to the Colorado River. There was little variation of total mercury (THg) in fish assemblages basin-wide and only 13% (272/1959) of individual fish samples exceeded the fish health benchmark (0.27 μg THg/g ww). Most THg exceedances were observed in the White-Yampa tributary whereas the San Juan had the lowest mean THg concentration. Risks associated with THg are species specific with exceedances dominated by Colorado Pikeminnow (mean = 0.38 and standard error ± 0.08 μg THg/g ww) and Roundtail Chub (0.24 ± 0.06 μg THg/g ww). For Se, 48% (827/1720) of all individuals exceeded the fish health benchmark (5.1 μg Se/g dw). The Gunnison river had the most individual exceedances of the Se benchmark (74%) whereas the Dirty Devil had the fewest. We identified that species of management concern accumulate THg and Se to levels above risk thresholds and that fishes of the White-Yampa (THg) and Gunnison (Se) rivers are at the greatest risk in the UCRB.

Upper Colorado River Basin↗
USGS2010

Linking ecosystems, food webs, and fish production: subsidies in salmonid watersheds

Physical characteristics of riverine habitats, such as large wood abundance, pool geometry and abundance, riparian vegetation cover, and surface flow conditions, have traditionally been thought to constrain fish production in these ecosystems. Conversely, the role of food resources (quantity and quality) in controlling fish production has received far less attention and consideration, though they can also be key productivity drivers. Traditional freshwater food web illustrations have typically conveyed the notion that most fish food is produced within the local aquatic habitat itself, but the concepts and model we synthesize in this article show that most fish food comes from external or very distant sources—including subsidies from marine systems borne from adult returns of anadromous fishes, from fishless headwater tributaries that transport prey to downstream fish, and from adjacent streamside vegetation and associated habitats. The model we propose further illustrates how key trophic pathways and food sources vary through time and space throughout watersheds. Insights into how food supplies affect fishes can help guide how we view riverine ecosystems, their structure and function, their interactions with marine and terrestrial systems, and how we manage natural resources, including fish, riparian habitats, and forests.

Fisheries↗
USGS1957

The control of the upstream movement of fish with pulsated direct current

Alternating-current electromechanical devices installed in the mouths of streams have proved effective in stopping the spawning migrations of the parasitic sea lamprey (Petromyzon marinus) which has seriously damaged Great Lakes fisheries. In a few streams, excessive mortality has occurred to other fish at the alternating-current barriers. A direct-current unit was developed in an attempt to reduce this mortality. This direct-current “diversion device” consists of a row of suspended negative electrodes which begins at the end of a trap wing and extends across the river at a downstream angle of 45° and a series of pipes (positive electrodes) driven into the stream bank. A second array, consisting of horizontal pipes installed downstream and parallel to the suspended electrodes and connected to a series of rods driven into the bank near the positive electrodes, controls the electrical field and dissipates the collecting influence of the positive side of the circuit. The electrical field is established from the end of the trap wing to the opposite bank. Fish are diverted away from the negative electrodes and toward the bank near which the trap is located. The array is activiated by pulsated direct current of essentially square wave shape with pulses at a duty cycle of 0.66 and a repetition rate of 3 per second. Direct-current diversion devices were operated in conjunction with alternating-current barriers during 1956 in the Chocolay River, Marquette County, and the Silver River, Baraga County, Michigan. A total of 15,814 fish comprising 21 species was handled at the Chocolay River with a mortality of 930, or 5.9 percent. If mortalities of fish moving downstream are disregarded, only 287, or 1.9 percent, of the fish moving upstream were killed in the Chocolay River. In the Silver River, 78,648 fish comprising 21 species were taken from the trap of the direct-current diversion device. The total kill of fish moving upstream, including 289 sea lampreys, was 1,016, or 1.3 percent. This river had presented a serious problem in the operation of an alternating-current control device during previous seasons. In 1955, 85.5 percent of three important species of fish were killed at the control structure. During 1956, this mortality was reduced to 8.1 percent by the operation of the direct-current equipment.

Transactions of the American Fisheries Society↗
USGS1984

Role of fish distribution on estimates of standing crop in a cooling reservoir

Estimates of fish standing crop from coves in Keowee Reservoir, South Carolina, were obtained in May and August for 3 consecutive years. Estimates were significantly higher in May than in August for most of the major species of fish collected, suggesting that considerable numbers of fish had migrated from the coves by August. This change in fish distribution may have resulted from the operation of a 2,580-megawatt nuclear power plant which altered reservoir stratification. Because fish distribution is sensitive to conditions of reservoir stratification, and because power plants often alter reservoir stratification, annual cove sampling in August may not be sufficient to produce comparable estimates of fish standing crop on which to assess the impact of power plant operations on fish populations. Comparable estimates of fish standing crop can probably be obtained from cooling reservoirs by collecting annual samples at similar water temperatures and concentrations of dissolved oxygen.

North American Journal of Fisheries Management↗
USGS1998

Evaluation of generalized habitat criteria for assessing impacts of altered flow regimes on warmwater fishes

Assessing potential effects of flow regulation on southeastern warmwater fish assemblages is problematic because of high species richness and poor knowledge of habitat requirements for most species. Our study investigated relationships between availability and temporal persistence of key habitats and fish assemblage structure at regulated and unregulated sites in the Tallapoosa River system. Fish assemblage characteristics at seven sites were quantified based on 1,400 electrofishing samples collected during 1994 and 1995. Physical Habitat Simulation (PHABSIM) programs were used to model availability and persistence of key habitats at regulated and unregulated sites. Associations between fish assemblages and availability or persistence of key habitats were identified via regression and analysis of variance. We found that hydropeaking dam operation reduced the average length of time that shallow‐water habitats persisted and also reduced year‐to‐year variation in the persistence of shallow‐water habitats compared with unregulated sites. Across sites and years, proportional representation of catostomids was positively correlated with persistence of shallow and slow‐water habitats during spring. Proportion of individuals as cyprinids was positively correlated with median availability of deep–fast habitat whereas proportion of percids was inversely related to median availability of deep–fast habitat. Mean fish density was positively correlated with the persistence of shallow and slow‐water habitats. Comparisons of key‐habitat measures and fish abundances between 1994 and 1995 at each site indicated that higher abundances of percids, catostomids, and cyprinids were associated with increased availability and persistence of shallow and slow‐water habitats in 1995. These findings demonstrate that the temporal and spatial availability of key habitats could serve as useful measures of the potential effects of flow alteration on lotic fish assemblages and suggest that both short‐term persistence of key habitats as well as annual variation in key‐habitat availability are important for maintaining diverse fish assemblages.

Transactions of the American Fisheries Society↗
USGS2005

Thiamine and thiaminase status in forage fish of salmonines from Lake Michigan

Dietary sources of thiamine (vitamin B 1 ) and thiamine-degrading enzymes (thiaminases) are thought to be primary factors in the development of thiamine deficiency among Great Lakes salmonines. We surveyed major forage fish species in Lake Michigan for their content of thiamine, thiamine vitamers, and thiaminase activity. Concentrations of total thiamine were similar ( P ≤ 0.05) among most forage fishes (alewife Alosa pseudoharengus , bloater Coregonus hoyi , spottail shiner Notropis hudsonius , deepwater sculpin Myoxocephalus thompsonii , yellow perch Perca flavescens , ninespine stickleback Pungitius pungitius , and round goby Neogobius melanostomus ) and slightly lower in rainbow smelt Osmerus mordax . Concentrations of total thiamine were all above the dietary requirements of coldwater fishes, suggesting the thiamine content of forage fish is not the critical factor in the development of thiamine deficiency in Lake Michigan salmonines. Thiamine pyrophosphate was the predominant form of thiamine in most species of forage fish, followed by free thiamine and thiamine monophosphate. Total thiamine was slightly greater in summer collections of alewife and rainbow smelt than in spring and fall collections, but the same was not true for bloater. Thiaminase activity varied among species and was greatest in gizzard shad Dorosoma cepedianum , spottail shiner, alewife, and rainbow smelt. Thiaminase activity in alewife varied among collection locations, season (greatest in spring), and size of the fish. Size and condition factors were positively correlated with both total thiamine and thiaminase activity in alewife. Thus, thiamine and thiaminase activity in forage fishes collected in Lake Michigan varied among species, seasons, year caught, and size (or condition). Therefore, multiple factors must be considered in the development of predictive models for the onset of thiamine deficiency in Great Lakes salmonines. Most importantly, thiaminase activity was great in alewives and rainbow smelt, suggesting that these prey fish are key causative factors of the thiamine deficiency in Great Lakes salmonines.

Journal of Aquatic Animal Health↗
USGS2004

Injury and mortality of warmwater fishes immobilized by electrofishing

Most studies of injury associated with electrofishing have focused on salmonids: few have given attention to warmwater fishes. Under controlled laboratory conditions, we treated bluegill Lepomis macrochirus, channel catfish Ictalurus punctatus, and largemouth bass Micropterus salmoides of various sizes to duty cycles ranging from 1.5% to 100%. This range of duty cycles represented continuous DC and pulsed-DC frequencies ranging from 15 to 110 Hz and pulse durations of 1 to 6 ms. At each duty cycle, fish were exposed to power densities in excess of those required to immobilize them within 3 s, and we subsequently determined the incidence of hemorrhage, spinal injury, and mortality. Incidence of hemorrhage averaged 3% (range, 0-25%), differed among species, and was not related to duty cycle or fish size. Incidence of spinal injury averaged 3% (range, 0-22%) and mortality averaged 10% (range, 0-75%); both differed among species and were related to duty cycle, fish size, and interactions among these variables. Largemouth bass was the species most vulnerable to hemorrhage, spinal injury, and mortality, channel catfish the least vulnerable; bluegills exhibited effects that were intermediate. Small centrarchids were especially susceptible to mortality. Fish tetanized by the electrical treatment were more likely to experience injury and mortality than fish that were only narcotized. However, mortality was not related to the injuries studied because hemorrhage and spinal injuries were similar in fish that survived electroshock and in those that died. We suggest that electrofishing with intermediate to high duty cycles could reduce electrofishing-induced injury and mortality to warmwater fish. Additionally, the power output and electrode system should be managed to induce narcosis and prevent tetany and to avoid the large peak powers required to immobilize small individuals.

North American Journal of Fisheries Management↗
USGS2005

Distribution and abundance of nonnative fishes in streams of the western United States

This report presents data from one of the largest standardized stream surveys conducted in he western United States, which shows that one of every four individual fish in streams of 12 western states are nonnative. The states surveyed included Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. The most widely distributed and abundant nonnative fishes in the western USA were brook trout Salvelinus fontinalis, brown trout Salmo trutta, rainbow trout Oncorhynchus mykiss, common carp Cyprinus carpio, smallmouth bass Micropterus dolomieu, largemouth bass M. salmoides, green sunfish Lepomis cyanellus, fathead minnow Pimephales promelas, yellow perch Percaflavescens, yellow bullhead Ameiurus natalis, cutthroat trout O. clarkii, western mosquitofish Gambusia affinis, golden shiner Notemigonus crysoleucas, channel catfish Ictalurus punctatus, and red shiner Cyprinella lutrensis. The greatest abundance and distribution of nonnative fishes was in interior states, and the most common nonnatives were introduced for angling. Nonnative fishes were widespread in pristine to highly disturbed streams influenced by all types of land use practices. We present ranges in water temperature, flow, stream order, riparian cover, human disturbance, and other environmental conditions where the 10 most common introduced species were found. Of the total western U.S. stream length bearing fish, 50.1% contained nonnative fishes while 17.9% contained physical environment that was ranked highly or moderately disturbed by humans. Introduced fishes can adversely affect stream communities, and they are much more widespread in western U.S. streams than habitat destruction. The widespread distribution and high relative abundance of nonnative fishes and their documented negative effects suggest their management and control should elicit at least as much attention as habitat preservation in the protection of native western U.S. stream biota. ?? Copyright by the American Fisheries Society 2005.

North American Journal of Fisheries Management↗
USGS2011

Effects of fish size, habitat, flow, and density on capture probabilities of age-0 rainbow trout estimated from electrofishing at discrete sites in a large river

We estimated size-specific capture probabilities of age-0 rainbow trout Oncorhynchus mykiss in the Lee's Ferry Reach of the Colorado River, Arizona, by backpack and boat electrofishing at discrete shoreline sites using both depletion and mark-recapture experiments. Our objectives were to evaluate the feasibility of estimating capture probability for juvenile fish in larger rivers; to determine how it is influenced by fish size, habitat, flow, density, and recovery period; and to test population closure assumptions. There was no mortality among the 351 rainbow trout that were captured by electrofishing, marked, and held for 24 h. Of a total of 2,966 fish that were marked and released, only 0.61% were captured outside of mark-recapture sites, and total emigration from mark-recapture sites was 2.2-2.6%. These data strongly suggest that populations within discrete sites can be treated as effectively closed for the 24-h period between marking and recapture. Eighty percent of capture probability estimates from 66 depletion experiments and 42 mark-recapture experiments ranged from 0.28 to 0.75 and from 0.17 to 0.45, respectively, and the average coefficient of variation of estimates was 0.26. There was strong support for a fish size-capture probability relationship that accounted for the differences in vulnerability across habitat types. Smaller fish were less vulnerable in high-angle shorelines that were sampled by boat electrofishing. There was little support for capture probability models that accounted for within-day and across-month variation in flow. The effects of fish density on capture probability were challenging to discern, variable among habitat types and estimation methodologies, and confounded with the effect of fish size. As capture probability estimates were generally precise and the closure assumption was met, our results demonstrate that electrofishing-based mark-recapture experiments at discrete sites can be used to estimate the abundance of juvenile fish in large rivers.

Arizona↗
USGS2011

Road crossing designs and their impact on fish assemblages of Great Plains streams

A mark-recapture field study was conducted to determine fish passage at 5 concrete box culverts and 5 low-water crossings (concrete slabs vented by culverts) as well as 10 control sites (below a natural riffle) in Flint Hills streams of northeastern Kansas. Additionally, we tested the upstream passage of four fish species native to Great Plains streams (Topeka shiner Notropis topeka , green sunfish Lepomis cyanellus , red shiner Cyprinella lutrensis , and southern redbelly dace Phoxinus erythrogaster ) through three simulated crossing designs (box culverts, round corrugated culverts, and natural rock riffles) at water velocities of 0.1 to 1.1 m/s in an experimental stream. The field study indicated that cyprinids were twice as likely to move upstream of box culverts than low-water crossings and 1.4 times as likely to move upstream of control reaches than any crossing type. The best models indicated that the proportion of cyprinids that moved upstream increased with decreased culvert slope and length, perching, and increased culvert width. Our controlled experiment indicated that fish can move through velocities up to 1.1 m/s in a 1.86-m simulated stream and that the proportion of fish that moved upstream did not differ among crossing designs for southern redbelly dace, green sunfish, or Topeka shiner; however, natural rock riffles had lower proportional movements (mean = 0.19) than the box (0.38) or corrugated culvert designs (0.43) for red shiners. Water velocity did not affect the proportional upstream movement of any species except that of Topeka shiners, which increased with water velocity. Crossing design alone may not determine fish passage, and water velocities up to 1.1 m/s may not affect the passage of many Great Plains fishes. Barriers to fish movement may be the result of other factors (e.g., perching, slope, and crossing length). The use of properly designed and installed crossings has promise in conserving Great Plains stream fishes.

Transactions of the American Fisheries Society↗
USGS2018

Patterns in fish assemblage structure in a small western stream

Knowledge of how patterns in fish assemblages are spatially structured is important for guiding management and conservation actions. However, most studies have taken place in the eastern and midwestern U.S., resulting in a poor understanding of factors influencing western stream fishes. The objectives of this study were to evaluate habitat and species associations of fishes in Deep Creek, a small tributary of the Kootenai River in Idaho. Fishes and habitat were sampled from 58 reaches in Deep Creek. In total, 7,129 individual fishes representing 18 species were sampled. Patterns in species richness were largely a function of channel gradient and associated habitat characteristics. Species richness decreased with increased channel gradient. Species-specific habitat relationships for native and nonnative fishes in Deep Creek provided specific insights into the ecology of each species. Predicted probability of occurrence and relative abundance varied by species and were related to a broad suite of environmental characteristics. This study provides insight on patterns of fish assemblage structure, as well as important information on the ecology of native and nonnative fishes in a western stream system.

Idaho↗
USGS2018

Intensive sampling reveals underreported use of great-river tributaries by large-river fishes in Missouri

Large tributaries may help sustain large-river fish populations by mitigating fish-habitat losses within the highly modified great rivers of the Mississippi River basin. These tributaries are likely most beneficial for fish species specializing on non-degraded large-river habitat for some portion of their life histories. Few great-river tributaries, however, have been surveyed using methods that comprehensively target all fish species, resulting in uncertainty or bias in the reported composition of many tributary fish assemblages. We report important distributional records, including 23 new accounts, for 12 large-river specialist fishes in Missouri —Alosa alabamae (Alabama Shad), Cycleptus elongatus (Blue Sucker), Pimephales vigilax (Bullhead Minnow), Notropis wickliffi (Channel Shiner), Polyodon spathula (Paddlefish), Hybognathus placitus (Plains Minnow), N. blennius (River Shiner), Macrhybopsis hyostoma (Shoal Chub), Scaphirhynchus platorynchus (Shovelnose Sturgeon), M. storeriana (Silver Chub), Ichthyomyzon unicuspis (Silver Lamprey), and Alosa chrysochloris (Skipjack Herring)—following 38 comprehensive fish surveys in tributaries of the Missouri and Mississippi rivers. New accounts collectively demonstrate tributaries support more large-river specialists than historically documented and thus may be currently undervalued sources of habitat for large-river fishes.

Missouri↗