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With publication of Standard Methods for Sampling North American Freshwater Fishes in 2009, the American Fisheries Society (AFS) recommended standard procedures for North America. To explore interest in standardizing at intercontinental scales, a symposium attended by international specialists in freshwater fish sampling was convened at the 145th Annual AFS Meeting in Portland, Oregon, in August 2015. Participants represented all continents except Australia and Antarctica and were employed by state and federal agencies, universities, nongovernmental organizations, and consulting businesses. Currently, standardization is practiced mostly in North America and Europe. Participants described how standardization has been important for management of long-term data sets, promoting fundamental scientific understanding, and assessing efficacy of large spatial scale management strategies. Academics indicated that standardization has been useful in fisheries education because time previously used to teach how sampling methods are developed is now more devoted to diagnosis and treatment of problem fish communities. Researchers reported that standardization allowed increased sample size for method validation and calibration. Group consensus was to retain continental standards where they currently exist but to further explore international and intercontinental standardization, specifically identifying where synergies and bridges exist, and identify means to collaborate with scientists where standardization is limited but interest and need occur.

Lakes and reservoirs progress through an aging process often accelerated by human activities, resulting in degradation or loss of ecosystem services. Resource managers thus attempt to slow or reverse the negative effects of aging using a myriad of rehabilitation strategies. Sustained monitoring programs to assess the efficacy of rehabilitation strategies are often limited; however, long-term standardized fishery surveys may be a valuable data source from which to begin evaluation. We present 3 case studies using standardized fishery survey data to assess rehabilitation efforts stemming from the Nebraska Aquatic Habitat Plan, a large-scale program with the mission to rehabilitate waterbodies within the state. The case studies highlight that biotic responses to rehabilitation efforts can be assessed, to an extent, using standardized fishery data; however, there were specific areas where minor increases in effort would clarify the effectiveness of rehabilitation techniques. Management of lakes and re...

Aging of reservoirs alters the functions, and associated services, of these systems through time. The goal of habitat rehabilitation is often to alter the trajectory of the aging process such that the duration of the desired state is prolonged. There are two important characteristics in alteration of the trajectory—the amplitude relative to current state and the subsequent rate of change, or aging—that ultimately determine the duration of extension for the desired state. Rehabilitation processes largely fall into three main categories: fish community manipulation, water quality manipulation, and physical habitat manipulation. We can slow aging of reservoirs through carefully implemented management actions, perhaps even turning back the hands of time, but we cannot stop aging. We call for new, innovative perspectives that incorporate an understanding of aging processes in all steps of rehabilitation of reservoirs, especially in planning and assessing.

We used quantile regression to compare the body condition of walleye Sander vitreus and white bass Morone chrysops before (1980–1988) and after (1989–2004) the establishment of alewives Alosa pseudoharengus in Lake McConaughy, Nebraska. Higher quantiles (percentiles = 100% × quantiles (0, 1)) of weight (W) at the same total length (TL) were indicative of better body condition in an allometric growth model that included separate slopes and intercepts for the before and after groups. All quantiles of walleye weights by TL increased in the years after alewife introduction, ranging from 1.01 to 1.12 times weights in the years before alewife introduction, with greatest increases for the lower (

Managers have conducted a number of activities to improve the growth rates of bluegill Lepomis macrochirus. However, attempts to compare the effectiveness of management actions often ignore basic differences in growth related to the type of water body in which populations reside. Bluegill age and growth data were collected from four different water body types in Nebraska between 1994 and 2001. Model analysis detected significant differences in the previous year's growth increments by water body type. When compared with other water body types, growth increments were greater in Sandhill lakes for age-2 and age-3 bluegills and mean length at capture was greater for age −6 and −7 bluegills. Several significant age × management activity interactions were detected within water body types. The application of supplemental feed and the absence of gizzard shad Dorosoma cepedianum increased bluegill growth increments in borrow and sand– gravel mining pits, while in flood control reservoirs, the presence of ...

Flathead catfish (Pylodictis olivaris) were stocked for recreational angling in Branched Oak Reservoir, Nebraska in 1981 and subsequently in 1994 through 1996. During 1999 and 2000, additional fish were stocked to act as predators on an abundant white perch (Morone americana) population. We studied food habits and habitat use of flathead catfish to evaluate their utilization of white perch. Flathead catfish were sampled by electrofishing every other week from May through September of 2001. Flathead catfish were separated into five size classes and pulsed gastric lavage was performed on up to six individuals per size class. One flathead catfish per 250 mm size class and ten white perch (150–175 mm) were placed in each of eight experimental feeding enclosures to establish baseline consumption rates. Seventy four percent of all captured flathead catfish were found near rocky habitat, which comprised only 25% of the reservoir shoreline. Flathead catfish consumed mostly white perch and crayfish. Flath...

Mechanical fish feeders were placed throughout the littoral zone of a flood control reservoir and operated for four growing seasons to improve growth rates of bluegill. Analysis of previous year growth increments suggested that only age 5 bluegill benefited from the supplemental feeding program. To validate utilization by the target species, toxic fish bait was applied through the feeders. Gizzard shad were the only species captured through this method. These results suggest that the presence of gizzard shad may reduce the effectiveness of supplemental feeding programs for bluegill.

We examined relative weight (W r) relationships of walleye Stizostedion vitreum and white bass Morone chrysops before and after the addition of alewife Alosa pseudoharengus in Lake McConaughy, Nebraska, where gizzard shad Dorosoma cepedianum had been the primary prey. Walleyes and white bass were collected in fall gillnetting surveys from 1980 to 1995. A general linear model was constructed to determine the least-squares means of walleye and white bass W rs by length category and year. Contrast statements were used to test for significant differences in the annual W rs of walleye and white bass population length categories before and after the establishment of alewives. The annual mean W rs of walleyes of stock to quality (S-Q), quality to preferred (Q-P), and preferred to memorable (P-M) lengths and Q-P-length white bass increased significantly, whereas that of S-Q-length and P-M-length white bass decreased significantly after 1988. The introduction of alewives changed the body condition of wall...

The high-elevation headwater streams of the Pinaleno Mountains support small populations of threatened Apache trout Oncorhynchus apache that were stocked following the chemical removal of nonnative salmonids in the 1960s. A fisheries survey to assess population composition, growth, and size structure confirmed angler reports of infrequent occurrences of Oncorhynchus spp. exhibiting the external morphological characteristics of both Apache trout and rainbow trout O. mykiss. Nonlethal tissue samples were collected from 50 individuals in the headwaters of each stream. Mitochondrial DNA (mtDNA) sequencing and amplification of nuclear microsatellite loci were used to determine the levels of genetic introgression by rainbow trout in Apache trout populations at these locations. Sexually dimorphic introgression from the spawning of male rainbow trout with female Apache trout was detected using mtDNA and microsatellites. Estimates of the degree of hybridization based on three microsatellite loci were 10–8...

We investigated walleye (Stizostedion vitreum) prey selection by comparing results from feeding experiments and stomach content analysis. Walleye captured from Lake McConaughy, Nebraska in June through September, 1995, were presented treatments of three prey species-yellow perch (Perca flavescens), white sucker (Catostomus commersoni) and either alewife (Alosa pseudoharengus) or gizzard shad (Dorsoma cepedianum). In the feeding experiments, walleye selected white sucker and yellow perch over alewife and gizzard shad. However, alewife were the most abundant prey species in walleye stomachs and not significantly different from their proportion in the natural prey fish assemblage. Differences in prey selection between experiments and field studies suggest that walleye altered their foraging behavior to take advantage of vulnerable or more accessible prey.

We investigated the effects of prey availability on relative weights (Wr ; the ratio of fish weight to the weight of a standard fish of the same length) in populations of walleye Stizostedion vitreum from two reservoirs, Lake Ogallala and Lake McConaughy, in western Nebraska. Partitioned by season of capture and 50-mm length-classes, walleye Wr was compared with the abundance of prey fish by length-class. Walleye Wr changed seasonally and was heavily influenced by prey size availability. In Lake Ogallala, where smaller prey were abundant, there was no significant difference in Wr across length-classes by fall. In Lake McConaughy, where more than 90% of all prey fish were over 170 mm, there was a distinct trend by fall. Small walleyes (250–400 mm) exhibited the lowest Wr (92.0 ± 0.84); and large walleyes (550–700 mm) had the highest Wr (104.0 ± 1.57). Examining changes in walleye Wr among length-classes across seasons was more informative than using a mean population Wr because it was sensitive to...