Steven Chipps

• PhD University of Idaho
• Unit Leader, USGS, South Dakota Cooperative Fish & Wildlife Research Unit at South Dakota State University

We evaluated the influence of sex and reproductive condition on seasonal distribution and movement patterns of Lake Sturgeon (Acipenser fulvescens) in Namakan Reservoir, Minnesota–Ontario. Blood samples were collected from 133 Lake Sturgeon prior to spawning and plasma concentrations of testosterone and estradiol-17ß were analyzed using radioimmuno...

The development and application of fish bioenergetics models have flourished in recent years, due in part to the complexity of the issues being faced by fisheries biologists. As with any model, the accuracy of bioenergetics models can be hampered by uncertainty in model parameters. A review of the literature showed that field and laboratory tests o...

We investigated zooplanktivory and nutrient regeneration by the opossum shrimp Mysis relicta and kokanee Oncorhynchus nerka to assess the relative roles of these planktivores in oligotrophic food webs. Using bioenergetic models and clearance rate estimates, we quantified phosphorus (P) excretion rates and consumption of cladoceran prey by Mysis and...

Bluegill sunfish (Lepomis macrochirus) are known to diversify into two forms specialized for foraging on either limnetic or littoral prey. Because juvenile bluegills seek vegetative cover in the presence of largemouth bass (Micropterus salmoides) predators, natural selection should favor the littoral body design at size ranges most vulnerable to pr...

Objective In 2017, we began a 5‐year mark–recapture study to estimate apparent survival of Walleye Sander vitreus and angler exploitation in Lake Sharpe, South Dakota, and inform management strategies for this fishery. The study revealed substantial downstream emigration of Walleye; therefore, we also examined the influence of emigration on apparen...

Bighead Carp, Hypophthalmichthys nobilis, and Silver Carp, Hypophthalmichthys molitrix, have important negative ecological and economic impacts in areas where they have become established. Therefore, preventing the spread of these species is a primary focus throughout much of the US. In recent years, portions of eastern North and South Dakota have...

Metabolic rate is a key parameter in fish energy budgets that strongly influences the output of bioenergetics models. In this study, we tested the hypothesis that metabolic rate varies with growth history of age-1 largemouth bass Micropterus nigricans Cuvier, 1828. Two groups of fish were fed alternating maintenance or ad libitum rations of fathead...

Lyon CA, Davis JL, Fincel MJ, Chipps SR. 2022. Effects of capture depth on walleye hooking mortality during ice fishing. Lake Reserv Manage. XX:XXX–XXX. Length-based regulations are a common tool used to limit fishing mortality by controlling the size of fish harvested. While such regulations are helpful in managing fish populations, mortality asso...

Walleye, Sander vitreus (Mitchill), natural recruitment has declined in northern Wisconsin lakes over time. Age-0 and age-1 walleye relative abundance (catch per unit effort; CPE) data from northern Wisconsin (1986-2019) was used to test for abiotic (i.e., lake characteristics, temperature variables) and biotic (age-0 and age-1 CPE) factors influen...

The freshwater opossum shrimp Mysis diluviana can undergo extensive diel vertical migration (DVM) to feed in shallow, prey rich strata at night. Bright moonlight limits their night-time migration presumably due to predator avoidance. Using a linked, foraging-bioenergetics model, we evaluated the cost of avoiding predators by simulating the effects...

Localized hypoxia can reduce available habitat, restrict movement and limit the abundance of aquatic invertebrates. Although cultural eutrophication, coupled with the effects of climate change, is likely to increase the frequency and extent of hypoxia in aquatic ecosystems, little is known about how oxygen gradients in small reservoirs influence sp...

Age-0 and age-1 Walleye (Sander vitreus) natural recruitment has declined in many populations within the Ceded Territory of Wisconsin (CTWI) over the past 20 years. Using CTWI age-0 and age-1 Walleye relative abundance (CPE) data during 1990-2019, we tested for density-dependent compensatory mortality between age-0 and age-1 Walleye. Age-1 Walleye...

• Landscape homogenization and the removal of riparian areas have altered stream ecosystems worldwide. Numerous conservation programmes attempt to improve water quality and increase instream habitat heterogeneity to elicit desired biological responses. However, the effectiveness of many conservation efforts on isolated stream fragments remains unkn...

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 rec...

Fall electrofishing surveys for age-0 and age-1 Walleye (Sander vitreus) have shown a decline in natural recruitment for many populations in the northern third (Ceded Territory) of Wisconsin over the past 20 years. Our data set spanned from 1985 to 2017 with estimates of age-0/age-1 catch per effort (CPE) and survival/mortality of age-0 and age-1 W...

Density‐dependent growth has been well documented among stream‐dwelling Brown Trout Salmo trutta populations. In Spearfish Creek, South Dakota, biomass of adult Brown Trout (>200 mm) is about three times greater than that reported for similar Black Hills streams, whereas the mean length of adult fish is about 30% less. Here, we evaluate density red...

Natural reproduction of pallid sturgeon Scaphirhynchus albus has been limited for decades and a recruitment bottleneck is hypothesized to occur during the larval stage of development. In this study, we evaluated the effects of water velocity and temperature on the swimming activity, energy use, settling behaviour and mortality of endogenously feedi...

Spawning movements and the factors affecting those movements are often of interest to fisheries managers and biologists. The objective of this study was to examine the influence of environmental factors on the movements of an adfluvial Rainbow Trout Oncorhynchus mykiss population in the Black Hills, South Dakota. Three unique strains of hatchery-re...

We collected Walleye Sander vitreus (May–October) from Bitter and Twin lakes, South Dakota to assess seasonal- and diet-related variation in tissue mercury (Hg) concentration. The average Hg concentration in Walleye was 43–68% higher in the spring for Bitter (p < 0.008) and Twin Lakes (p < 0.017) compared with summer or autumn months. Bioenergetics...

This report examines the effects of summer hypoxia on invertebrate abundance, distribution and assemblages in a southeastern South Dakota impoundment.

Background Alternative protein sources to fishmeal in fish feeds are needed. Objectives Evaluate rearing performance of adult rainbow trout ( Oncorhynchus mykiss ) (initial weight 139.0 ±1.5 g, length 232.9 ± 0.8 mm, mean ± SE) fed one of the two isonitrogenous and isocaloric diets (46% protein, 16% lipid) and reared at one of the two levels of ex...

Lakeshore areas provide important habitat for aquatic invertebrates in shallow lakes. However, these zones are prone to anthropogenic disturbances that include shoreline development, urbanization, nutrient inputs, agricultural and(or) recreational use. Among recreational uses, public access sites are often developed to accommodate boaters and facil...

Pallid Sturgeon Scaphirhynchus albus are a federally endangered species endemic to the Missouri River basin and the lower Mississippi River. Successful natural reproduction has been limited for decades and in addition, a recruitment bottleneck is hypothesized to occur during the endogenous-drift phase of development. Understanding factors that affe...

This 125-day experiment evaluated the growth of adult rainbow trout (Oncorhynchus mykiss) fed one of three isonitrogenous and isocaloric diets (46% protein, 16% lipid). Fish meal was the primary protein source for the reference diet, which was compared to two other diets where bioprocessed soybean meal replaced 60% or 80% of the dietary fish meal....

Purpose Select South Dakota, USA water bodies, including both natural lakes and man-made impoundments, were sampled and analyzed to assess mercury (Hg) dynamics and historical patterns of total Hg deposition. Materials and methods Sediment cores were collected from seven South Dakota lakes. Mercury concentrations and flux profiles were determined...

Pallid Sturgeon Scaphirhynchus albus are a federally endangered species endemic to the Missouri River basin and the lower Mississippi River. Successful natural reproduction has been limited for decades and in addition, a recruitment bottleneck is hypothesized to occur during the endogenous-drift phase of development. Understanding factors that affe...

Context: This 88-day experiment evaluated the rearing performance of juvenile rainbow trout (Oncorhynchus mykiss) fed one of three isonitrogenous and isocaloric diets and reared at velocities of either 2.3 or 18.7 cm s-1. Objective: Evaluate the effects of diet and exercise during rainbow trout rearing. Design: Fishmeal was the primary protein so...

This 121-day experiment evaluated the rearing performance of juvenile brown trout (Salmo trutta; initial weight 56.1±1.6 g, length 167.2±1.4 mm, mean ±SE) fed one of four isonitrogenous and isocaloric diets (46% protein, 16% lipid). Fishmeal, the primary protein source for the reference diet, was compared to diets where bioprocessed soybean meal di...

Geology and hydrology are drivers of water chemistry and thus important considerations for fish otolith chemistry research. However, other factors such as species and habitat identity may have predictive ability, enabling selection of appropriate elemental signatures prior to costly, perhaps unnecessary water/age-0 fish sampling. The goal of this s...

This 121-day experiment evaluated the rearing performance of brown trout Salmo trutta fed one of two isonitrogenous and isocaloric diets and reared at velocities of either 2.8 or 16.1 cm/s. Fishmeal was the primary protein source for the reference diet, and bioprocessed soybean meal replaced approximately 67% of the fishmeal in the experimental die...

Pallid Sturgeon Scaphirhynchus albus are a federally endangered species endemic to the Missouri River basin and the lower Mississippi River. Successful natural reproduction has been limited for decades and in addition, a recruitment bottleneck is hypothesized to occur during the drift phase of endogenous larvae. Understanding factors that affect su...

Bioenergetics modeling is a widely used tool in fisheries management and research. Although popular, currently available software (i.e., Fish Bioenergetics 3.0) has not been updated in over 20 years and is incompatible with newer operating systems (i.e., 64-bit). Moreover, since the release of Fish Bioenergetics 3.0 in 1997, the number of published...

This poster summarizes some of the research findings of a two-year study investigating the movements of an adfluvial Rainbow Trout population in the Black Hills, South Dakota.

We developed a foraging model for young fishes that incorporates handling and digestion rate to estimate daily food consumption. Feeding trials were used to quantify functional feeding response, satiation, and gut evacuation rate. Once parameterized, the foraging model was then applied to evaluate effects of prey type, prey density, water temperatu...

An individual-based model framework was used to evaluate growth potential of the federally endangered pallid sturgeon (Scaphirhynchus albus) in the Missouri River. The model, developed for age-0 sturgeon, combines information on functional feeding response, bioenergetics and swimming ability to regulate consumption and growth within a virtual forag...

We evaluated temperature tolerance in age-0 pallid and shovelnose sturgeon (Scaphirhynchus albus and Scaphirhynchus platorynchus), two species that occur sympatrically in the Missouri and Mississippi Rivers. Fish (0.04-18g) were acclimated to water temperatures of 13, 18 or 24°C to quantify temperatures associated with lethal thermal maxima (LTM)....

Factors affecting feeding and growth of early life stages of the federally endangered pallid sturgeon (Scaphirhynchus albus) are not fully understood, owing to their scarcity in the wild. In this study was we evaluated the performance of a combined foraging-bioenergetics model as a tool for assessing growth of age-0 pallid sturgeon in the Missouri...

Stocking of hatchery-raised fish is an important part of the pallid sturgeon Scaphirhynchus albus recovery program. In the wild, juvenile pallid sturgeon consume primarily aquatic insects, although little is known about specific dietary needs. In hatchery settings, pallid sturgeon are fed commercial diets that are formulated for salmonids. To compa...

We assessed the effect of fin-curl on the swimming and station-holding ability of juvenile shovelnose sturgeon Scaphirhynchus platorynchus (mean fork length = 17 cm; mean weight = 16 g; n = 21) using a critical swimming speed test performed in a small swim chamber (90 L) at 20°C. We quantified fin-curl severity using the pectoral fin index. Results...

Establishment of nonnative Northern Pike Esox lucius in Pactola Reservoir, South Dakota, has prompted concern among biologists about the influence of this species on the lake's intensively managed salmonid fisheries. Ancedotal information suggests that catch rates of Rainbow Trout Oncorhynchus mykiss have declined while mean size and abundance of N...

We surveyed anglers on five community fishing lakes near Brookings, South Dakota to assess angler use and satisfaction. The community lakes attracted younger anglers when compared to statewide and national averages. Overall, satisfaction was generally high (74%) among anglers fishing community lakes. Logistic regression analysis showed that harvest...

Invertebrates are an important food for breeding, migrating, and wintering waterfowl. Sparse study has been devoted to understanding the influence of waterfowl and wetland management on production of invertebrates for waterfowl foods; however, manipulation of hydrology and soils may change or enhance production. Fish can compete with waterfowl for...

We compared diet, stomach fullness, condition, and growth of Brown Trout Salmo trutta among streams with or without blooms of the benthic diatom Didymosphenia geminata in the Black Hills, South Dakota. In Rapid Creek, where D. geminata blooms covered ∼30% of the stream bottom, Brown Trout consumed fewer ephemeropterans (6–8% by weight) than individ...

Much uncertainty exists around how fish communities in shallow lakes will respond to climate change. In this study, we modelled the effects of increased water temperatures on consumption and growth rates of two piscivores (northern pike [Esox lucius] and largemouth bass [Micropterus salmoides]) and examined relative effects of consumption by these...

Blooms of the benthic alga, Didymosphenia geminata [Lyngbye (Schmidt)], were first documented in Rapid Creek, South Dakota, in 2002 and have since been associated with changes to aquatic resources. Low concentration of P has been associated with D. geminata stalk development (i.e., blooms), so we considered elevating P as a possible method to reduc...

We estimated the influence of predation by Smallmouth Bass Micropterus dolomieu on recruitment of age-0 Yellow Perch Perca flavescens in two northeastern South Dakota glacial lakes. We estimated a likely range in consumption of age-0 Yellow Perch using Smallmouth Bass diet information from two time periods when age-0 Yellow Perch constituted high (...

We used stable isotopes of carbon and nitrogen to evaluate trophic similarity between sauger Sander canadensis and walleye S. vitreus in three Missouri River impoundments characterized by unique differences in riverine habitat. Mean δ15N was similar for sauger and walleye in each reservoir ranging from 15.7 to 17.8‰ for sauger and 15.2 to 17.7‰ for...

Habitat requirements for early life stages of the Federally endangered pallid sturgeon are poorly understood. In this study, we developed a growth model that will allow researchers to evaluate habitat quality and survival potential for age-0 pallid sturgeon. To do so, a series of studies were performed to quantify foraging dynamics and energetics o...

Bioenergetics models were applied, along with information on diets, growth, and energy density, for Lake Trout Salvelinus namaycush and Northern Pike Esox lucius in Pactola Reservoir, South Dakota to examine trophic interactions and assess annual predatory demands. Diet, age, and growth data for Lake Trout and Northern Pike were collected during th...

To increase knowledge of larval pallid sturgeon (Scaphirhynchus albus), we developed a bioenergetics model to determine optimal temperature for growth in young-of-year pallid sturgeon. To parameterize the model, we estimated metabolic demands and growth of pallid sturgeon (0.03-10g) subjected to a range of temperatures commonly found in the Missour...

The aquatic nuisance species Didymosphenia geminata was first documented in Rapid Creek of South Dakota’s Black Hills during 2002. Since then, blooms have occurred primarily in a 39-km section of Rapid Creek while blooms were rarely observed in other Black Hills streams. In this study, we evaluated factors related to the presence and development of...

Fincel MJ, Dembkowski DJ, Chipps SR. 2014. Influence of variable rainbow smelt and gizzard shad abundance on walleye diets and growth. Lake Reserv Manage. 30:258-267. Prey availability influences growth and condition of walleye (Sander vitreus) in large systems. In Lake Oahe, South Dakota, rainbow smelt (Osmerus mordax) and gizzard shad (Dorosoma c...

Predation can play an important role in the recruitment dynamics of fishes with intensity regulated by behavioral (i.e., prey selectivity) and/or environmental conditions that may be especially important for rare or endangered fishes. We conducted laboratory experiments to quantify prey selection and capture efficiency by three predators employing...

Diet studies have traditionally been used to determine prey use and food web dynamics, while stable isotope analysis provides for a time-integrated approach to evaluate food web dynamics and characterize energy flow in aquatic systems. Direct comparison of the two techniques is rare and difficult to conduct in large, species rich systems. We compar...

Executive Summary Most traditional fishing opportunities in South Dakota are located in rural areas. However, since more people are moving to urban areas where they have numerous recreational activity options, they are less likely to travel to rural waters to go fishing. One strategy used to address this fisheries management challenge and to increa...

Improving fisheries education is a goal of both educators and employers. However, training students for specialized fisheries jobs is a complex problem. Fisheries-related employment consists of diverse job opportunities that require many different skills. Most fisheries professionals will experience a diversity of jobs, underscoring the need for fi...

Recent sampling surveys in Pactola Reservoir, a coldwater fishery in the Black Hills, South Dakota, and anecdotal information from anglers have reported lowered catch rates of stocked salmonids. Concomitantly, northern pike (Esox lucius) have been illegally introduced into the system. The primary objective of this study was to quantify prey consump...

A 10 year data set was used to evaluate the influence of water levels on population attributes of yellow perch Perca flavescens and walleye Sander vitreus across a range of glacial lakes in northeastern South Dakota, USA. Yellow perch abundance was significantly greater during elevated water levels. Yellow perch size structure, as indexed by the pr...

In Lake Oahe, South Dakota, rainbow smelt are the primary prey of walleye, but their abundance varies substantially from year to year. Recently, gizzard shad have become established in Lake Oahe and their abundance has increased considerably. To evaluate the influence of gizzard shad on walleye diets and growth in Lake Oahe, we compared recent esti...

The influence of water levels on population characteristics of yellow perch, Perca flavescens (Mitchill), and walleye, Sander vitreus (Mitchill), was evaluated across a range of glacial lakes in north-eastern South Dakota, USA. Results showed that natural variation in water levels had an important influence on frequently measured fish population ch...

This study compared patterns of delta N-15 and delta C-13 enrichment of pallid sturgeon Scaphirhynchus albus and shovelnose sturgeon S. platorynchus in the Missouri River, United States, to infer their trophic position in a large river system. We examined enrichment and energy flow for pallid sturgeon in three segments of the Missouri River (Montan...

Gizzard shad, Dorosoma cepedianum, have generally been restricted to the lower Missouri River impoundments in South Dakota. In recent years, gizzard shad numbers have increased in Lake Oahe, marking the northern-most natural population. These increases could potentially affect recreational fishes. Specifically, questions arise about larval gizzard...

http://www.sdstate.edu/nrm/organizations/gpnss/tpn/upload/68-76-Hayer.pdf

We measured growth and oxygen consumption of age-1 yellow perch Perca flavescens subjected to ad libitum (control) or variable feeding cycles of 2 (i.e., 2 d of feed, 2 d of deprivation), 6, or 12 d for a 72-d period. Individual, female yellow perch (initial weight = 51.9 ± 0.9 g [mean ± SE]) were stocked in 110-L aquaria to provide six replicates...

Lesser scaup (Aythya affinis [Eyton]) populations remain below their long-term average despite improved habitat conditions along spring migration routes and at breeding grounds. Scaup are typically associated with large, semipermanent wetlands and exhibit regional preferences along migration routes. Identifying consistently used habitats for conser...

Fishes inhabiting shallow, glacial lakes of the Prairie Pothole Region in the United States and Canada periodically experience hypoxia in severe winters that can lead to extensive fish mortality resulting in high biomasses of dead fish. However, the role of carcass-derived nutrient subsidies in shallow, eutrophic lakes translocated to pelagic prima...

The aquatic nuisance species, Didymosphenia geminata, was first documented in Rapid Creek of South Dakota’s Black Hills during 2002 and since then has been associated with changes to invertebrate and fisheries resources. Because phosphorous (P) has been associated with D. geminata blooms, altering P was considered as a possible method to reduce blo...

The Namakan River and Reservoir system lies on the boundary of Canada and the United States. This system is an important area for lake sturgeon, a species listed as special concern in both countries. A total of 60 adult lake sturgeon were caught and implanted with acoustic transmitters in May of 2007 by the Ontario Ministry of Natural Resources (Ca...

Abstract Stable isotope analysis of fishes is often performed using muscle or organ tissues that require sacrificing animals. Non‐lethal sampling provides an alternative for evaluating isotopic composition for species of concern or individuals of exceptional value. Stable isotope values of white muscle (lethal) were compared with those from fins an...

Fish bioenergetics models based on natural prey items have been widely used to address research and management questions. However, few attempts have been made to evaluate and apply bioenergetics models to hatchery-reared fish receiving commercial feeds that contain substantially higher energy densities than natural prey. In this study, we evaluated...

Quantified were the age, growth, mortality and reproductive structure of lake sturgeon (Acipenser fulvescens) collected in the US and Canadian waters of the Namakan Reservoir. The hypotheses were tested that (i) age and growth of lake sturgeon in the Namakan Reservoir would differ by sex and reproductive stage of maturity, and (ii) that the relativ...

1. When available, Daphnia spp. are often preferred by age‐0 yellow perch and bluegill sunfish because of energetic profitability. We hypothesised that predation by age‐0 yellow perch could lead to a midsummer decline (MSD) of Daphnia spp. and that priority effects may favour yellow perch because they hatch before bluegill, allowing them to capital...

The pallid sturgeon Scaphirhynchus albus is a federally endangered species native to the Missouri and lower Mississippi Rivers, USA. As part of recovery efforts, over 360 000 pallid sturgeon have been stocked into the Missouri River since 1994, and a standardized, long-term monitoring program was initiated in 2003. Understanding the distribution an...

Invertebrate energy density (ED) values are traditionally measured using bomb calorimetry. However, many researchers rely on a few published literature sources to obtain ED values because of time and sampling constraints on measuring ED with bomb calorimetry. Literature values often do not account for spatial or temporal variability associated with...

Stable isotope analysis is a quick and inexpensive method to monitor the effects of food web changes on aquatic communities. Traditionally, whole specimens have been used when determining isotope composition of prey fish or age-0 recreational fishes. However, gut contents of prey fish could potentially alter isotope composition of the specimen, esp...

The purpose of this study was to determine whether water quality parameters commonly associated with primary productivity may be used to predict the susceptibility of a specific water body to exceed proposed fish consumption advisory limitation of 0.3 mg kg−1. South Dakota currently has nine lakes and impoundments that exceed fish tissue mercury ad...

Sauger Sander canadensis populations have declined throughout the Midwest over the past 50 years. One hypothesis to explain this phenomenon relates to competition with walleye S. vitreus, a highly sought after sport fish that is frequently stocked. Examining isotopic overlap and variability provides quantitative insight of energy transfer and diet...

Lake sturgeon (Acipenser fulvescens) are listed as a Threatened Species in Northwest Ontario and Special Concern in Minnesota, with those present within the Namakan River being of management concern for stakeholders on both sides of the international border. Information on the ecology of juvenile sturgeon (i.e., those <60cm in length) is lacking in...

Restoration efforts for the federally endangered pallid sturgeon (Scaphirhynchus albus) have been largely targeted at population augmentation. Recent studies show that pallid sturgeon from the upper Missouri River are genetically distinct from fish found in the middle Missouri and lower Mississippi rivers, but it is not clear if genetic differences...

Transition from endogenous to exogenous feeding is a significant event during early life history of fishes. However early exogenous feeding larvae have functional, anatomical, physiological and behavioral limitations, that affect prey detection, capture, and ingestion. As fish grow, foraging efficiency improves which may ultimately result in diet s...

Establishing a walleye (Sander vitreus) year class in Mina Lake, South Dakota has been a challenge during the past decade. Despite annual fry and fingerling stockings, the number of age-0 walleye sampled during fall night time electrofishing runs is low (range = 0 - 0.2 walleye/hour), indicating poor survival. In addition, fall gill net surveys fro...

Didymosphenia geminata nuisance blooms were first observed in Rapid Creek, South Dakota in 2002. Shortly after its appearance, large declines (>50%) of its naturalized brown trout population were observed. Drought conditions were found to be largely responsible for biomass declines, but size structure differences were observed within D. geminata im...

Stocking of hatchery raised pallid sturgeon (Scaphirhynchus albus) is an important part of the pallid sturgeon recovery program. Little is known about sturgeon dietary needs and hatchery raised pallid sturgeon are currently fed commercial diets that are formulated for salmonids. It is unknown whether these commercial diets are well suited for palli...

Five urban lakes (<11.7 ha) were creeled in South Dakota from April 2009 to October 2010. We evaluated factors influencing angler satisfaction using logistic regression with three models: (1) all ages model, (2) “young” angler model (< age 25), and (3) an “experienced” angler model (>age 40). The global model (χ²=11.15, P=0.13), “young” angler mode...

The range of smallmouth bass (Micropterus dolomieu) is expanding northward, creating new interactions with native predators, including walleye (Sander vitreus). We used a series of experiments to investigate competition between walleye (WAE) and smallmouth bass (SMB) at different life stages and light conditions, identified behaviors that allowed o...

High concentrations of some hepatic elements might be contributing to the decline of the continental lesser scaup (Aythya affinis) population. We evaluated hepatic element concentrations of male and female lesser scaup collected from the upper Midwest (Iowa, Minnesota, North Dakota, and South Dakota) during the 2003 and 2004 spring migrations. We m...

Summary Two-hundred and seven adult shovelnose sturgeon ranging from 450 to 718 mm in length were sampled from June to October 2001 and May to July 2002 to determine diet composition and feeding patterns in the lower Platte River. Shovelnose sturgeon fed primarily upon aquatic insect larvae and nymphs (>99% composition by number). Diptera of the fa...

Elevated mercury concentration has been documented in a variety of fish and is a growing concern for human consumption. Here, we explore the influence of physiochemical and watershed attributes on mercury concentration in walleye (Sander vitreus, M.) from natural, glacial lakes in South Dakota. Regression analysis showed that water quality attribut...

Traditional techniques for stable isotope analysis (SIA) generally require sacrificing animals to collect tissue samples; this can be problematic when studying diets of endangered species such as the pallid sturgeon Scaphirhynchus albus. Our objectives were to (i) determine if pectoral fin tissue (non-lethal) could be a substitute for muscle tissue...