Historically, yellow perch, Perca flavescens Mitchill held great recreational and commercial importance to the Lake Michigan fishery. Unfortunately, fluctuations in lake‐wide abundances in the past four decades created inconsistencies in catch. As adults, yellow perch have been commonly observed to swim great distances suggesting there is likely to be partitioning of the population within the lake. The objective was to determine whether population demographics of yellow perch in the Indiana waters of Lake Michigan were consistent with a single population. Seasonal population demographics of yellow perch collected from the Indiana waters of Lake Michigan in 2009, 2011 and 2012 were compared. Catch‐per‐unit‐effort of female yellow perch increased during later sampling periods across years. Similarly, total length of females and males increased 10% throughout the year. The proportion of females increased from 20% at the beginning of the survey period to 95% at the end. A few larval yellow perch were collected. These data suggest that Indiana waters of Lake Michigan are not a primary spawning area, rather these waters serve as a feeding or recovery area for post‐spawned yellow perch, particularly females.

Walleye Sander vitreus and hybrid striped bass Morone chrysops x M. saxatilis fisheries are supported by annual stockings in many US midwestern reservoirs. To maximize return to the angler, yield-per-recruit models are often used to evaluate expected yield and assist managers to determine which regulation to implement, generally length or bag limits. However, yield-per-recruit models are typically formulated with point estimates of life history parameters, which ignore uncertainty. Our objective was to estimate yield from yield-per-recruit models of walleye and hybrid striped bass under various harvest strategies (e.g., alternative minimum length limits and conditional fishing mortality rates) while incorporating uncertainty about the input model parameters. We estimated parameters of age and growth and weight length models simultaneously using Bayesian inference. The full posterior distribution of these model parameter estimates were then used to estimate yield. We found that yield differed among length limits for both species at high conditional fishing mortality. We also found yield decreased for both species as minimum length limits increased for low conditional fishing mortality. Finally, we presented a probabilistic framework to determine how changing minimum length limits and conditional fishing mortality affects the probability of achieving 70-90% of the maximum yield. Our results provide insight on the expected yield under different minimum length limits and bag limits, while incorporating uncertainty in the model inputs, and add to the sparse literature on hybrid striped bass population dynamics. (C) 2017 Elsevier B.V. All rights reserved.

Trade-offs among growth, mortality, and reproduction form the basis of life history theory but may vary among populations owing to local ecological conditions. We examined life history trade-offs driving variation in maturation among 13 yellow perch (Perca flavescens) stocks in the Great Lakes using sex-specific age and length at 50% maturity (A(50) and L-50, respectively) and probabilistic maturation reaction norm midpoints (Lp(50,a)). Both sexes exhibited positive correlations between growth and mortality, and faster-growing stocks were mature at younger ages but larger sizes. Male and female A(50) and L-50 were positively correlated among stocks, but Lp(50,a) estimates were negatively correlated among stocks, indicating stocks that matured at large sizes for a given age in females matured at smaller age-specific sizes in males. Female Lp(50,a) estimates were negatively related to growth and mortality, while male Lp(50,a) estimates were positively related to growth. These results suggest that (i) sex-based life history trade-offs sometimes act to differentially structure maturation schedules in males and females and (ii) males may be less responsive to changes in mortality than females.

Fishes were sampled in the Mississinewa, Salamonie, Wabash, and White rivers, Indiana to determine whether fish depth ratio (maximum depth/total length) varied between pool and riffle habitats. Fish collections were made using a backpack electrofisher and water velocity measurements were made using a flow meter. Our results indicated median depth ratio differed between fishes located in pool habitats (0.28) compared to fishes in riffle habitats (0.17). These depth ratio findings were consistent among all four rivers, showing fish morphology is related to habitat selection and use. Changes in fish community structure would be expected with habitat changes in flow regimes, either through natural or anthropogenic (e.g., channelization) alterations.

We collaborated with 26 groups from universities across the United States to sample 42 sites for 33 trace organic compounds (TOCs) in water and sediments of lotic ecosystems. Our goals were 1) to further develop a national database of TOC abundance in United States lotic ecosystems that can be a foundation for future research and management, and 2) to identify factors related to compound abundance. Trace organic compounds were found in 93% of water samples and 56% of sediment samples. Dissolved concentrations were 10–1000 × higher relative to sediment concentrations. The ten most common compounds in water samples with detection frequency and maximum concentration were sucralose (87.5%, 12,000 ng/L), caffeine (77.5%, 420 ng/L), sulfamethoxazole (70%, 340 ng/L), cotinine (65%, 130 ng/L), venlafaxine (65%, 1800 ng/L), carbamazepine (62.5%, 320 ng/L), triclosan (55%, 6800 ng/L), azithromycin (15%, 970 ng/L), diphenylhydramine (40%, 350 ng/L), and desvenlafaxine (35%, 4600 ng/L). In sediment, the most common compounds were venlafaxine (32.5%, 19 ng/g), diphenhydramine (25%, 41 ng/g), azithromycin (15%, 11 ng/g), fluoxetine (12.5%, 29 ng/g) and sucralose (12.5%, 16 ng/g). Refractory compounds such as sucralose may be good indicators of TOC contamination in lotic ecosystems, as there was a correlation between dissolved sucralose concentrations and with the total number of compounds detected in water. Discharge and human demographic (population size) characteristics were not good predictors of compound abundance in water samples. This study further confirms the ubiquity of TOCs in lotic ecosystems. Although concentrations measured rarely approached acute aquatic-life criteria, the chronic effects, bioaccumulative potential, or potential mixture effects of multiple compounds are relatively unknown.

Freshwater fisheries in the United States are structured from three driving influences: fish diversity, habitats and human users. The United States has over 1200 species of fishes, many of which are endemic to North America, such as members of the Centrarchidae (black basses and sunfish) family, while other classifications (e.g. Salmonidae) transcend political and geographical boundaries and are more ubiquitous. The specific diversity of fishes in the United States varies by geographical region, typically related to physical habitat, including rivers, streams, ponds, lakes and reservoirs. Cool-and coldwater fisheries are found along the northern states and mountain areas, while warmwater fisheries encompass much of the rest of the country. Historical use of these fishes was for consumption, with harvest coming from subsistence and commercial fishing activities. Increases in the demand for fishes and a denigration of water quality readily apparent in the beginning of the 20th century threatened the sustaining fisheries benefit. In the past 100 years, a scientific approach towards this resource has provided stewardship, particularly as recreational fishing has become popular. Contemporary management tenets are multidimensional and take on the holistic ecosystem approaches needed for successful management of these diverse fisheries resources.

The Laurentian Great Lakes in North America compose the single largest freshwater system in the world, providing an expansive and heterogeneous mix of environments. Their size and complexity have resulted in the development of cold-, cool- and warmwater fishes that have been continually harvested for both commercial and recreational uses. Beginning in the early 1800s, overexploitation, pollution and non-indigenous species dramatically changed the fish assemblage, ultimately reaching a configuration by the 1950s that was, by many accounts, unacceptable. Control of the sea lamprey Petromyzon marinus, creation of extensive salmonid stocking programmes and pollution abatement mitigated much of the problem. Most recently, Canada and the United States have developed united and comprehensive management approaches that will protect, enhance and provide sustainable use of the Great Lakes fishery and its environment for years to come.

Walleye Sander vitreus are native to central North American freshwater habitats. Introductions within and outside their native range have occurred in all of the lower 48 states. These stockings have occurred due to the increasing popularity of this species, leading to the demand surpassing the supply. Despite the popularity of this species for anglers, and extensive research on the distribution, life history, population dynamics, culture, and stocking strategies, there is disparate information on first year survival of stocked populations. The objective of this study was to test for associations between biotic and abiotic variables for recruitment of age-0 fish in the fall. We tested for the influence of the number of stocking events, moronid stocking density, spring/summer warming rate, and spring/summer maximum discharge on electrofishing catch rates in the fall of age-0 walleye. We used a hierarchical generalized linear model with the Poisson distribution to evaluate these relationships. Parameters of the model were estimated using Bayesian inference. Our model suggested the number of stocking events, moronid stocking density, and maximum discharge/rainfall were the most important factors influencing walleye recruitment. Fall catch rates of age-0 walleye were positively related to stocking events, negatively related to moronid stocking density, and negatively related to maximum discharge/rainfall. However, these relationships were not concordant across all reservoirs. Further, variability we observed across reservoirs support the conclusion that walleye populations must be managed at individual reservoirs. This study will assist managers locally and regionally to determine stocking strategies for walleye to improve recruitment in midwestem reservoirs. (C) 2015 Elsevier B.V. All rights reserved.

Adult yellow perch were collected from the Indiana waters of Lake Michigan during 2009, 2011, and 2012 to estimate the length and timing of the yellow perch spawning season. Sampling was conducted using gill nets at three zones near East Chicago, Burns Harbor, and Michigan City from May to August in 2009 and 2011; however, sampling was conducted twice in April before continuing from May to August in 2012. After collection, yellow perch were measured, counted, and sexed and then the maturity state was determined. Logistic regression was used to model the proportion of post-spawn (spent) fish over time for each year. The resulting models estimated the timing and duration of yellow perch spawning and allowed the determination of peak spawn (50% spent) for each year. We found that yellow perch spawning started when mean daily water temperatures at the sample sites reached approximately 11 °C and lasted two to four weeks with cessation occurring when water temperatures exceeded 13 °C. In 2009 and 2011, spawning began in mid-May and was finished in early June, while in 2012 spawning started in early May and finished before June. These differences were likely in response to unseasonably warm lake temperatures caused by record high springtime air temperatures in the Great Lakes region. These findings suggest global climate change will alter yellow perch reproductive cycles.

Size-selective harvest of fish stocks can lead to maturation at smaller sizes and younger ages, which may depress stock productivity and recovery. Such changes in maturation may be very slow to reverse, even following complete fisheries closures. We evaluated temporal trends in maturation of five Great Lakes stocks of yellow perch (Perca flavescens Mitchill) using indices that attempt to disentangle plastic and evolutionary changes in maturation: age at 50% maturity and probabilistic maturation reaction norms (PMRNs). Four populations were fished commercially throughout the time series, while the Lake Michigan fishery was closed following a stock collapse. We documented rapid increases in PMRNs of the Lake Michigan stock coincident with the commercial fishery closure. Saginaw Bay and Lake Huron PMRNs also increased following reduced harvest, while Lake Erie populations were continuously fished and showed little change. The rapid response of maturation may have been enhanced by the short generation time of yellow perch and potential gene flow between northern and southern Lake Michigan, in addition to potential reverse adaptation following the fishing moratorium. These results suggest that some fish stocks may retain the ability to recover from fisheries-induced life history shifts following fishing moratoria.

Bayesian inference is an emerging statistical paradigm and is becoming an increasingly used alternative to frequentist inference. Unfortunately, little is known about the efficacy of Bayesian inference and how it relates to the historical methodology of evaluating fisheries related models. Mortality information is routinely used in fisheries management to describe fish population abundance over time and has been historically estimated using catch curves and frequentist inference (i.e., maximum likelihood estimation). The objective of this study was to compare frequentist and Bayesian inference approaches to estimate instantaneous mortality (Z) from a hierarchical catch curve model. The data used in the comparison were from a long term monitoring program of yellow perch Perca flavescens from southern Lake Michigan in addition to a simulated dataset where parameter estimates were compared to known values. Point estimates of Z were similar among both methods. Similarly, Bayesian inference 95% credible intervals were concordant with frequentist 95% confidence intervals. However, the root mean squared error of frequentist inference increased at a higher rate than Bayesian inference with increasing variability in the simulated dataset. Our study builds on the literature that seeks to compare results between these two paradigms to assist managers to make the best decision possible when deciding what statistical paradigm to employ.

Yellow perch Perca flavescens (Mitchill) are typically collected using multi-mesh gill nets; however, gear selectivity information for this species is sparse. Selectivity using experimental gill nets was determined for yellow perch using data collected from southern Lake Michigan from 2007 to 2012 using stretch mesh sizes of 12.5, 16, 20, 25, 32, 38, 46, 51, 64, and 76mm. Female selectivity was best described by a model with a skewed (log-normal) distribution while males were best described by a normal distribution. When sex data were combined, the skewed (log-normal) distribution provided the best model. Differences in selectivity between sexes were minimal, but likely due to the variant size structure of the local population sampled, with females the larger sex. These findings suggest that bias in individual gill net selectivity can be used to target specific yellow perch size groups or to replace other gear types with unknown selectivity.

Pharmaceuticals and personal care products (PPCPs) have been documented throughout the United States freshwaters but research has focused largely on lotic systems. Because PPCPs are designed to have a physiological effect, it is likely that they may also influence aquatic organisms. Thus, PPCPs may negatively impact aquatic ecosystems. The objectives of this research were to quantify PPCP abundance in near-shore habitats of southern Lake Michigan and identify factors related to PPCP abundance. Stratified sampling was conducted seasonally at four southern Lake Michigan sites. All sites and depths had measurable PPCP concentrations, with mean individual compound concentrations of acetaminophen (5.36 ng/L), caffeine (31.0 ng/L), carbamazepine (2.23 ng/L), cotinine (4.03 ng/L), gemfibrozil (7.03 ng/L), ibuprofen (7.88 ng/L), lincomycin (4.28 ng/L), naproxen (6.32 ng/L), paraxanthine (1,7-dimethylxanthine; 46.2 ng/L), sulfadimethoxine (0.94 ng/L), sulfamerazine (0.92 ng/L), sulfamethazine (0.92 ng/L), sulfamethoxazole (26.0 ng/L), sulfathiazole (0.92 ng/L), triclocarban (5.72 ng/L), trimethoprim (5.15 ng/L), and tylosin (3.75 ng/L). Concentrations of PPCPs varied significantly among sampling times and locations (river mouth vs offshore), with statistical interactions between the main effects of site and time as well as time and location. Concentrations of PPCPs did not differ with site or depth. Temperature, total carbon, total dissolved solids, dissolved oxygen, and ammonium concentrations were related to total pharmaceutical concentrations. These data indicate that PPCPs are ubiquitous and persistent in southern Lake Michigan, potentially posing harmful effects to aquatic organisms.

Fish age and length at 50% maturity are used extensively in the management of exploited fish populations. These parameters are historically estimated using logistic regression models (e.g., frequentist inference) for individual year-classes and often fail to converge or result in insignificant results when a small sample size is used. The sample-size problem motivated us to evaluate whether a hierarchical logistic regression model fit using frequentist inference or Bayesian inference, could improve our ability to fit these models. Our objective was to compare Bayesian and frequentist inference for estimating age and length at 50% maturity to determine whether the models produced similar values. To make this evaluation, we used a long-term data set of Yellow Perch Perca flavescens from southern Lake Michigan. Frequentist inference of the year-class-specific models resulted in significant results when sample size was sufficiently large, a result that occurred in 76% of the models. The hierarchical model produces estimates of age (or length) at 50% maturity for all year-classes using both frequentist and Bayesian inference. However, Bayesian inference of the hierarchical model resulted in more precise parameter estimates and provided the complete posterior distribution in one seamless and easy approach, and the computation time was 78% to 83% faster. We suggest that a hierarchical model fit using Bayesian inference of age (or length) at 50% maturity is an improvement over frequentist interference methods by providing more information about the population of interest, particularly when sample sizes are limited. Received December 11, 2012; accepted March 28, 2013

Background. The wide availability of specimen-based museum collections allows scientists to address a variety of ecological and systematic hypotheses from a broad timeframe and extensive spatial scale. However, techniques employed to preserve and maintain these collections affect morphology, potentially altering or skewing any morphological comparisons inherent in research study questions. The purpose of this study was to better understand and describe the effects that preservation techniques may have on fish specimens. Materials and methods. Bluegill, Lepomis macrochirus Rafinesque, 1819, and green sunfish, Lepomis cyanellus Rafinesque, 1819, were initially preserved for six weeks in a 10% formalin solution and then transferred to 70% ethyl alcohol for 46 additional weeks to determine how the commonly used preservation methods influence morphology. Fish were photographed at 0, 3, 6, 12, 24, 39, and 52 weeks of preservation to assess changes in shape. Standard length and maximum depth were measured on all fish images using Sigma Scan Pro. These measurements were then used to generate aspect ratios (maximum depth vs. standard length) for each fish. Additionally, geometric morphometric techniques (relative warp analysis) using 10 digital landmarks, were also used to evaluate overall morphological change. Results. During the 52-week period of preservation, fish standard length was reduced, but this dimension shrank proportionally with body depth. This finding was confirmed along the major gradients elicited from relative warp axis scores tested using repeated measures ANOVA. However, with both species, morphological contortions were observed immediately after the fish were placed in formalin and again when this fixative was replaced with ethyl alcohol. Conclusion. Ultimately, shape stabilized after a period of acclimatization of up to 39 weeks. This stabilization phenomenon provides evidence that long term museum collections do plateau in shape change and may be compared to address a variety of ecological and evolutionary hypotheses.

Five darter species (Greenside Darter Etheostoma blennioides, Rainbow Darter E. caeruleum, Fantail Darter E. flabellare, Johnny Darter E. nigrum, and Orangethroat Darter E. spectabile) were collected from seven streams and rivers in two Indiana watersheds to determine patterns of microhabitat selection with respect to depth, water velocity (flow), and substrate size. Heterogeneous habitats create a variety of niche dimensions, promoting the coexistence of congeneric species. Greenside and Rainbow darters were most commonly found among intermediate substrate sizes (cobble + boulder) and in locations with higher velocities and deeper water. Fantail and Orangethroat darters associated with intermediate to large substrate sizes (cobble + bedrock) were found in shallower water with lower velocities. Fantail Darters were only observed in the Whitewater River watershed. In contrast, Johnny Darters were observed only within the White River watershed among small substrate sizes (silt + sand), moderate velocities, and deeper water. Based on nonmetric multidimensional scaling and multinomial logistic regression, substrate size was the most important variable in characterizing microhabitat selection. Ultimately, habitats produced patterns of segregation and coexistence among these five darters in Indiana streams. Although ecological patterns of microhabitat use are additionally influenced by competition, morphology, and life history traits, heterogeneous habitat features within ecosystems appear to be structuring fish assemblages. Received January 16, 2012; accepted November 25, 2012

ABSTRACT The objective of this article is to describe the theory and types of commonly used assessments and how they relate to course objectives and the learning process in higher education. Using a fisheries course example, I argue that quality assessment techniques occur continuously, are aimed at both instructor and student, are not always used to assign grades, and improve the quality of instruction in the classroom. Properly used, assessments can transform institutions of higher education from a place where instruction is given to one where learning takes place.