Red Snapper Lutjanus campecheanus is a structure‐associated species occurring across a wide depth range in the northern Gulf of Mexico. We used the random forest machine learning algorithm to understand which habitat and individual fish characteristics could predict reproductive parameters of female Red Snapper. We evaluated fish captured from 2016‐2018 on three artificial reef types with various structure

The management of Snake River spring/summer Chinook Salmon and Snake River steelhead is a major concern for several federal, state, and tribal agencies. A primary issue is the effect of the Federal Columbia River Power System (FCRPS), composed of eight dams and reservoirs in the Snake and Columbia rivers, on adult return rate. Management decisions have been influenced by the hypothesis that the passage

Faulkner et al. (2019) presents data and analyses to support a hypothesis that bypass encounters by juvenile Chinook Salmon and steelhead at hydropower dams are not harmful (e.g., “Our results suggest that after fish leave the hydropower system, bypass passage history has little effect on mortality”), and any difference in life‐cycle survival among bypassed and non‐bypassed fish is largely an artifact

We highlight the uncertainty that exists around estimating productivity and survival for one population of threatened steelhead Oncorhynchus mykiss with the goal of strengthening our understanding of the well documented poor marine survival of Puget Sound steelhead. We evaluated how sensitive estimates of productivity and survival were to the uncertainty associated with smolt trap, redd survey methodology

The Cisco Coregonus artedi is a planktivorous fish that is widely distributed in lakes across glaciated areas of North America. With retreat of Laurentide ice, Cisco dispersed from refugia into a vast network of meltwater (proglacial) lakes that eventually receded, stranding populations in depressions—today’s lakes. Refugial populations also colonized lakes that fell outside of the footprint of a proglacial

Removal of two dams in the Elwha River basin started one of the largest river restoration projects ever attempted in the Pacific Northwest. These dams had eliminated Pacific lamprey populations upstream. After the dam removals, larval production increased in the upper watershed, but the sources and numbers of new adult spawners were unknown. We applied genetic stock identification (GSI), parentage

The introduction of additional forage fish species to enhance sport fisheries is a common management strategy in lakes and reservoirs. However, illegal introductions occur without consideration of all potential ecological consequences. Blueback Herring introduction has been a controversial forage fish enhancement for recreational fisheries with several illegal introductions having occurred in the Southeastern

Hypoxia induced by eutrophication and high summer temperatures is common in most Midwestern reservoirs, with uncertain effects on resident fishes. To evaluate the potential influence of low dissolved oxygen and high temperature conditions on habitat quality for three common sport fishes (Largemouth Bass Micropterus salmoides, saugeye Sander vitreus × S. canadensis, and White Crappie Pomoxis annularis)

In aquatic systems, refuge habitats increase resistance to drying events and maintain populations in disturbed environments. However, reduced water availability and altered flow regimes threaten the function of these habitats. We conducted a capture‐mark‐recapture (CMR) study, integrating angler citizen science. Our objectives were to quantify variation in survival of Florida Largemouth Bass, Micropterus

Delineation of management units across broad spatial scales can help to visualize population structuring and identify conservation opportunities. Geographical information system (GIS) approaches can be useful for developing broad‐scale management units, especially when paired with field data that can validate the GIS‐based delineations. Genetic data can be useful for evaluating whether management units

Pacific salmon spawning and rearing habitats result from dynamic interactions among geomorphic processes, natural disturbances, and hydro‐climatological factors acting across a range of spatial and temporal scales. We used a 21‐year record of redd locations in a wilderness river network in central Idaho, USA, to examine which covariates best predict Chinook salmon (Oncorhynchus tshawytscha) spawning

Environmental changes caused by hydrological shifts between wet and dry seasons in the tropics drive variation in resource availability and feeding interactions for riverine fish assemblages, but studies of trophic structure typically take place over short time scales that do not adequately capture this variation. In this study, we used stable isotope analysis (δ13C and δ15N) to assess seasonal changes

The upper Columbia River in Washington State (main‐stem and tributary habitat between McNary and Chief Joseph dams) is inhabited by two major lineages of Chinook Salmon Oncorhynchus tshawytscha: endangered spring Chinook Salmon and summer Chinook Salmon, which are not Endangered Species Act (ESA) listed. The lineages are highly genetically divergent from one another, and historically, spatial and temporal

Recruitment is one of the driving forces determining the population dynamics of a stock, and knowledge about recruitment is crucial in providing reliable results in modern stock assessment. The population of the American Eel Anguilla rostra is at risk, and the fisheries on the elvers are one threat for its persistence. We applied a generalized depletion model on the catch and effort data of the elver

The Smith River is a popular recreational sport fishery in western Montana, but salmonid abundances there are thought to be artificially limited by riparian land‐use alterations, irrigation water withdrawals, and high summer water temperatures. We used integrated networks of temperature loggers, PIT tag antenna stations, and in situ temperature mapping to investigate the thermal hydrodynamics and associated

Light can modify orientation and locomotory behaviors in fish and has been applied to attract or repel migrant fish by inducing positive or negative phototaxis. Here, recently metamorphosed downstream‐migrating Sea Lamprey Petromyzon marinus were exposed to light cues in several orientations and intensities at night under controlled flowing‐water conditions in a laboratory flume. Behaviors and rates

Recent stock assessments of Atlantic halibut (Hippoglossus hippoglossus) in the United States have been unable to determine stock status. Although there are several fishery‐independent surveys available in the region, few halibut are typically encountered, the survey indices are highly variable, and a reliable index of abundance is not available for this stock. In the absence of reliable fishery‐independent

The St. Louis River estuary is a designated area of concern by the U.S. Environmental Protection Agency due to severe environmental degradation. The spatial ecology of Muskellunge Esox masquinongy, an indicator species, is uncertain within the estuary and the large, connected water body, Lake Superior. We collected genetic samples and used passive acoustic telemetry to track 60 adult Muskellunge in

Lake Sturgeon Acipenser fulvescens, once widespread throughout North America are now considered endangered in much of their natural range. However, recreational catch‐and‐release (C&R) fisheries targeting the Lake Sturgeon have developed in areas with strong populations. Here, we evaluate physiological and behavioural impairment of Lake Sturgeon following C&R angling. Fish were angled from the Winnipeg

It is essential for fish to respond appropriately when faced with a threatening situation. Accordingly, fish are able to reduce predation risk through learning. In addition to privately learned experiences, fish can acquire social information about a threat by observing the response of conspecifics and use such public information to adapt future behavior through learning. It is unclear if social learning

Overwintering Pacific salmon Oncorhynchus spp. are vulnerable to mortality. Ecosystem degradation exacerbates salmonid vulnerability to mortality; thus, knowledge of winter movement dynamics is essential for guiding holistic management and restoration to safeguard population viability. In northeast Oregon, long‐term population performance metrics (e.g., survival) exist for parr of two neighboring Chinook

Despite over 100 years of commercial exploitation for their eggs, there is limited information about the spawning behavior of Atlantic Sturgeon Acipenser oxyrinchus oxyrinchus. Spawning return intervals for males and females have been estimated in the most general of time spans, and researchers have established only in the last 25 years that Atlantic Sturgeon eggs and larvae are freshwater obligates

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

The inclusion of sublethal behavioral effects in population models has predicted lower estimates of cohort abundance and survival. Methylmercury, a persistent contaminant in the Great Lakes, has been shown to alter foraging and predator avoidance behaviors of larval Yellow Perch Perca flavescens, which may have indirect effects on recruitment. Poor recruitment of Yellow Perch in Lake Michigan has been

Razorback Sucker Xyrauchen texanus occur in reservoir and riverine habitats in the Colorado River basin, with some individuals aggregating at river–reservoir inflows. To assess use of inflow areas and potential environmental correlates with fish movement among reservoir and river habitats, we used a passive receiver array to monitor location and movements (n = 69) and depth (n = 19) of acoustic‐ and

Juvenile steelhead Oncorhynchus mykiss enter the northern California Current ecosystem from the Columbia River and other Pacific Northwest coastal rivers and include several populations that are listed under the U.S. Endangered Species Act. However, relatively little is known about the response of these populations to interannual variability in ocean conditions. In 2015 and 2016, anomalous ocean conditions

Spiny Dogfish Squalus acanthias are small sharks that are harvested for seafood, primarily off the Eastern Seaboard of the United States. For the purposes of establishing seafood consumption advisories with regard to methylmercury (MeHg) content, the U.S. Food and Drug Administration (FDA) classifies Spiny Dogfish as “sharks,” an overly broad taxonomic grouping with a mean MeHg content of 0.98 μg/g

Understanding the population dynamics of rare and endangered species can be difficult, particularly when a species has a narrow geographic range. The Spotfin Chub Erimonax monachus is both federally and state (North Carolina) listed as threated and is endemic to the Tennessee River basin in the southeastern United States. The Spotfin Chub was once found throughout the Tennessee River basin, but its

Black Crappie Pomoxis nigromaculatus and White Crappie Pomoxis annularis have contrasting patterns of performance along a gradient of turbidity for reasons that have yet to be elucidated. We examined how distinct, habitat‐linked morphologies of these congeners make Black Crappie more specialized for structurally complex vegetation and White Crappie more specialized for open‐water habitats and tested

Tautog Tautoga onitis supports both recreational and growing commercial fisheries from Virginia to Massachusetts. Tautogs, which aggregate around structured habitats (wrecks, rocks, bridge pilings, etc.), are slow to mature and have a low reproductive rate relative to other teleosts. Slow growth and easy catchability result in Tautogs being extremely vulnerable to overexploitation, and their populations

Analysis of genetic connectivity helps to define stock boundaries and provides information on interpopulation dynamics, such as migration and spawning site fidelity. We used 16 microsatellite loci to describe the genetic population structure of 1,215 Smallmouth Bass Micropterus dolomieu from 32 sites throughout the upper Mississippi River and Lake Michigan watersheds. We found that Smallmouth Bass

The genetic constitution of populations is affected by myriad factors, including both natural and anthropogenic habitat transformations. Previous work on the population structure of Brook Trout Salvelinus fontinalis has suggested that supplemental stocking for fishery enhancement has transformed natural genetic diversity. We utilized microsatellite analysis of 11 loci to examine the genetic structure

Genetic stock assignment is not routinely used when describing the dynamics and demographics of individual stocks supporting mixed‐stock fisheries, and capture location and timing are often used as alternative assignment methods. However, variation in stock demographics and dynamics may not be accounted for if stock assignments based on capture location or timing do not accurately reflect genetic assignments

Reproductive investment, expressed in terms of fecundity and egg quality produced by individual female fish, varies among populations for many species, reflecting plasticity in life history strategies related to intraspecific density dependence or environmental variability. Fisheries scientists and managers have long sought to understand differences in Largemouth Bass Micropterus salmoides population

The effects of lake productivity and late‐summer hypolimnetic oxygen on the size and shape of Cisco Coregonus artedi were examined in 27 Minnesota lakes. Geometric morphometry analyses of specimens captured in vertical gill nets indicated that Cisco in more productive lakes with hypoxic hypolimnia were larger, with deeper bodies, shorter snouts and caudal peduncles, and longer fins. Cisco in unproductive

Tropical rivers across the world are experiencing rapid degradation and loss of fish species due to flow regulation, pollution, and other anthropogenic pressures. Knowledge of how flow alterations at different scales affect tropical fish diversity remains limited, especially in terms of how resulting changes in water chemistry affect fish communities. We investigated fish guild composition and responses

Nonnative Smallmouth Bass Micropterus dolomieu are increasingly sympatric with juvenile spring Chinook Salmon Oncorhynchus tshawytscha in the rivers of western North America. Understanding the potential effects of introduced Smallmouth Bass is essential to efficiently direct salmon management efforts, especially given the potential for upstream range expansion of Smallmouth Bass in response to the

Unsustainably high mortality within the first 2 years of life prevents endangered Lost River Suckers Deltistes luxatus in Upper Klamath Lake, Oregon, from recruiting to spawning populations. Massive blooms of the cyanobacterium Aphanizomenon flos‐aquae and their subsequent death and decay in the lake (bloom‐crashes) are associated with high pH, low percent oxygen saturation, high total ammonia concentrations

We compared 15 blackwater and clearwater streams in coastal drainages of Alabama by quantifying fish assemblages and associated environmental conditions across multiple seasons and characterizing potential relationships using multivariate statistical approaches. Clearwater stream channels tended to be deeper, to have sandier substrates, and to have higher dissolved oxygen concentrations than blackwater

Understanding trends in abundance is important to fisheries conservation, but techniques for estimating streamwide abundance of cryptic fishes with strong habitat–abundance relationships are not well established and need further development. We developed techniques for addressing this need using the Harlequin Darter Etheostoma histrio, a small, cryptic freshwater fish associated with submerged wood

Advances in video technology enable new strategies for stream fish research. We compared juvenile (age‐0) and adult (age 1+) Brook Trout Salvelinus fontinalis abundance estimates from underwater video with backpack electrofishing and dive‐count methods across a series of stream pools in Shenandoah National Park, Virginia (n = 41). Video methods estimated greater mean abundance of adult trout than 1‐pass

Anadromous Pacific salmon are semelparous and resource subsidies from spawning adult salmon (marine‐derived nutrients, or MDN) benefit juvenile salmonids while they rear in fresh water. However, it is unclear if juvenile salmon populations respond predictably to the abundance of spawning salmon at the watershed‐scale. To address whether hypothesized benefits to rearing juveniles scale up to population

Barge transportation of steelhead Oncorhynchus mykiss smolts through the Snake and Columbia rivers can increase the probability of straying by returning adults at the individual scale. However, the effect of barge transportation on a major population group has not been evaluated. We estimated the proportion of hatchery‐origin steelhead spawners present in the John Day River from 2004 to 2018 via observation

Since 2004, seven spawning reefs have been constructed in the St. Clair–Detroit River system to remediate lost spawning habitat and increase recruitment of Lake Sturgeon Acipenser fulvescens. Assessment of management actions by collecting and enumerating eggs and larvae provided evidence of spawning Lake Sturgeon and survival of eggs until larval dispersal at constructed reef sites. However, the number

Nonlethal tools (plasma sex steroid concentrations and ultrasound) for assigning sex and reproductive condition in Burbot Lota lota from Lake Roosevelt, Washington, were assessed. Gonadal tissue, blood plasma, and gonadal sonograms were collected monthly from November 2016 to March 2018. Gametogenesis was described by gonadal histology during an entire reproductive cycle to confirm sex and reproductive

Several species of ciscoes Coregonus, subgenus Leucichthys that are native to the Laurentian Great Lakes are rare or extirpated. The restoration of Coregonus fishes is being actively pursued through stocking, and success may depend on the availability of unoccupied niche space. We described the spring–summer habitat occupancy and diets of three native cisco species (Bloater Coregonus hoyi, Cisco C

The South Fork Snake River supports one of the few remaining robust populations of fluvial Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri in Idaho. Since the early to mid‐2000s, salmonid populations on the South Fork Snake River have been intensively monitored and managed to limit the abundance of introduced Rainbow Trout O. mykiss, which have been increasing in abundance relative to Yellowstone

Forage fishes have a cosmopolitan distribution and constitute key species in marine trophic webs throughout the world. We estimated the energy density of the Argentine Anchovy Engraulis anchoita, a key component of the base of the food web in a large fraction of the southwestern Atlantic Ocean. We also examined the relationships between energy density and different proxies (condition factor, fork length

Physiological condition (hereafter shortened to “condition”) influences survival, spawning schedules, and reproductive effort in salmonids. In iteroparous females, the effects of first spawning on condition could result in trade‐offs with future reproduction, mediated by postspawning survival, repeat spawning schedule (i.e., consecutive or skip spawning), or reproductive effort. However, which aspects

Despite the importance of straying in understanding the ecology of Pacific salmon Oncorhynchus spp. and steelhead O. mykiss, most of what is known about salmon and steelhead straying comes from tagged hatchery fish. We provide estimates of donor straying by natural‐origin spring, summer, and fall Chinook Salmon O. tshawytscha and summer steelhead at three spatial scales in the upper Columbia River

In recreational fisheries it is understood that individual fish that exhibit bolder personality traits have a tendency to be removed from the population (i.e., fishing mortality via harvest or catch‐and‐release mortality), while more timid individuals remain. The use of aquatic protected areas (APAs) has been promoted as a means of offsetting the negative consequences that are associated with fishing

Delineating population structure helps fishery managers to maintain a diverse “portfolio” of local spawning populations (stocks), as well as facilitate stock‐specific management. In Lake Erie, commercial and recreational fisheries for Walleye Sander vitreus exploit numerous local spawning populations, which cannot be easily differentiated using traditional genetic data (e.g., microsatellites). Here

Because of mineral mining threats in the headwaters that drain into Lake Clark National Park, we implemented a baseline ecological survey of the Chulitna River basin through the use of a probability study design. A total of 49 wadeable stream and raftable river sites were sampled for fish assemblages, multiple physical habitat structure variables, and multimeter chemistry (dissolved oxygen, conductivity

Tournament anglers typically possess extensive knowledge of the habitat and seasonal movement of their targeted species. While fish–angler behavioral relationships are critical to understanding fish catchability, few studies have assessed how fish behavior influences their vulnerability to capture by tournament anglers. Our objectives were to determine if Largemouth Bass Micropterus salmoides behavior

The combined effects of conspecific density and climate warming on the vital rates of invasive fish species have not been well studied, but may be important in predicting how successful they will be in the future. We evaluated the effects of temperature and population density on monthly time series of sizes of age‐0 Blue Catfish Ictalurus furcatus in the James, York, and Rappahannock River subestuaries

Lake Sturgeon Acipenser fulvescens populations throughout the Great Lakes have experienced declines. Therefore, Lake Sturgeon have been stocked at several locations, including the Oswegatchie River in New York State, where Lake Sturgeon are listed as threatened. The goal of New York's Lake Sturgeon stocking program has been the establishment of self‐sustaining populations in six out of the seven management

Anadromous Rainbow Smelt Osmerus mordax provide an important nearshore prey base, but they have experienced severe population declines during the last century. Population estimates from spawning run surveys have not been calculated because within‐season repeat spawning, a behavior qualitatively described for this species based on previous studies, has not been quantified. Our objective was to determine

Yellowstone Lake is the site of actions to suppress invasive Lake Trout Salvelinus namaycush and restore native Yellowstone Cutthroat Trout Oncorhynchus clarkii bouvieri and natural ecosystem function. Although gill netting is effective (Lake Trout λ ≤ 0.6 from 2012 through 2018), the effort costs more than US$2 million annually and only targets Lake Trout age 2 and older. To increase suppression efficiency

The adverse effects of invasive species are expected to be proportional to their relative densities. However, interference competition among conspecifics when invasive species are at high densities could limit such effects. These alternative hypotheses inspired us to test the density‐specific effects of red swamp crayfish Procambarus clarkii on experimental populations of the Amargosa Pupfish Cyprinodon

Productive tributary reservoirs can become suboptimal environments for fish during summer because of hypolimnetic hypoxia (≤3 mg O2/L) and high epilimnetic temperatures that reduce access to quality habitat for growth. We conducted a laboratory experiment using a 3 × 3 × 2 (temperature × dissolved oxygen [DO] × fish size) complete factorial design to examine the effect of DO concentration and temperature