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, 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 intra‐specific density dependence or environmental variability. Fisheries scientists and managers have long sought to understand differences in Largemouth Bass Micropterus salmoides population dynamics

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

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

Juvenile Steelhead Oncorhynchus mykiss enter the northern California Current ecosystem from the Columbia River and other Northwest coastal rivers and include several populations listed under the US 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, called the

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

Spiny Dogfish 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 regards to methylmercury (MeHg) content, the US 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 (wet weight). Because

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

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

Fishes that evolutionarily demonstrated a fluvial life history expression and migrated to spawning and rearing habitat using lotic corridors are increasingly impacted by fragmentation. The overall goal of this study was to identify the contemporary importance of mainstem connectivity and tributaries to maintaining life history expression, population structure, and viability of a large metapopulation

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

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

Analysis of genetic connectivity helps to define stock boundaries and provides information on inter‐population dynamics such as migration and spawning site fidelity. Here we use 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 find that Smallmouth

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

Tautog Tautoga onitis Linnaeus, 1758 supports both recreational and growing commercial fisheries from Virginia to Massachusetts. Tautog, 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 tautog being extremely vulnerable to overexploitation and

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

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

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

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

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

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

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

Studying the reproductive ecology of aggregate broadcast spawning fishes is difficult because it generally is not feasible to sample all potential parents and unambiguously assign their offspring. We used molecular-based parentage analysis to gain insights into the reproductive ecology of the endangered Bonytail, and to evaluate whether protected off-channel habitats could be used as an alternative

Diversity in habitat and life-history strategies promote a species' long-term persistence. However, life-history strategies are most commonly studied at broad spatial and temporal scales. We applied longevity growth models and closed N-mixture models to examine within- versus between stream variability in life-history characteristics of Rio Grande Cutthroat Trout in northern New Mexico streams. We

Mercury (Hg) is a potent toxin that biomagnifies in aquatic food webs. Large fish generally have higher Hg concentrations than small fish of the same species. However, models predict that fish that grow large faster should have lower Hg concentrations than small, slow-growing fish due to somatic growth dilution (SGD). We examined the relationship between Hg concentrations and growth rate in fish using

To estimate the health of the California sheephead Semicossyphus pulcher fishery, a 2004 stock assessment used available biological data that were collected decades prior to an increase in fishing pressure. However, a recent study has found that sex ratios, growth rates, survivorship, and average sizes of females and males have changed in response to size-selective fishing in some California sheephead

The ichthyoplanktonic community of Tamiahua Lagoon, Veracruz, Mexico, was studied throughout an annual cycle. Major concentrations of larvae occurred in the central portion of the lagoon, occasionally along the channels, but never at the inlets. The cycle of larva abundance was correlated with cycles of salinity and temperature. In spite of the greater number of species then, the spring and summer

Floodplain lakes of large river systems contain fish habitats that are not found elsewhere within the river, and these lakes have a diversity of environmental conditions that vary in space and time. Our objective was to examine relationships between floodplain lake fish communities and environmental variables associated with lake morphology, water chemistry, and river-floodplain connectivity in a large

I used cluster analysis to examine associations among 20 fish species to develop a classification scheme for 132 large Texas reservoirs. Five major groups of reservoirs were identified by cluster analysis based on species associations. Of 29 reservoirs surveyed previously, 76% were classified into the same species associations from one survey to the next. When 19 environmental variables were used in