A Comparison of Stipends, Health Insurance, and Tuition Remission Policies at Fisheries and Wildlife Graduate Programs throughout the United States

Many factors should be considered before selecting a graduate program to attend. Graduate education can be expensive, so financial and health care benefits offered by a department or college should be considered when selecting a graduate program. A majority of fisheries graduate students recently surveyed believed that financial aspects should be an important consideration in selecting a graduate program. Therefore, our objective was to estimate the range of stipends, tuition remission, and health care benefits provided to students in graduate programs that offer training in wildlife and fisheries disciplines across the United States. Thirty-one out of 70 schools (44%) from across the United States responded to our online survey. Doctoral and master's student stipends were highly variable among programs and appointments (research v. teaching assistants). Over half of the universities offered full tuition remission (67%), and of those that did not, most (97 %) offered at least partial tuition remission. On-campus health care was the most common health care benefit offered to graduate students. Though traditional factors for selecting a graduate school (such as desirability of graduate research topic/question, program reputation, and suitability of the advisor) may override financial considerations, financial benefits may be a critical component when choosing a graduate program

Genetic Structure Among Lake Michigan's Lake Whitefish Spawning Aggregates

Lake whitefish (Coregonus clupeaformis) have comprised an important commercial fishery on Lake Michigan since the early 1800s. Concerns exist regarding the commercial harvest of potentially shared stocks by Michigan and Wisconsin state-licensed and Tribal commercial fishing operations. Previous studies indicated potential stock structure, however, questions still exist regarding the number, identity, distribution, and discreteness of lake whitefish stocks in Lake Michigan. Stocks represent the basic biological unit of focus for fish management efforts and, subsequently, stock delineation is an integral part of sound, science-based, fisheries management programs. The objectives of the study were to determine the usefulness of lake whitefish microsatellite and mitochondrial DNA genetic diversity to discriminate among spawning stocks of lake whitefish and to describe the genetic population structure of spawning lake whitefish aggregates in northern Lake Michigan and Green Bay in terms of genetic stock identification and degree of stock isolation. I assumed that distinct spawning aggregates represented potential stocks and that differences at molecular markers underlie population differentiation. Twelve resolved microsatellite DNA loci exhibited adequate levels of diversity for population differentiation in terms of their allelic richness and heterozygosity, met Hardy-Weinberg equilibrium expectations and, therefore, the utility of the markers was considered sufficient. Two mitochondrial DNA gene regions (D-loop and ND5) exhibited low sequence diversity (π = 0.0002 and 0.0025, respectively) and low numbers of haplotypes (7 and 5, respectively). The observed diversity did not meet a priori levels of genetic diversity deemed necessary for population differentiation and the molecule was abandoned for further use. Genetic stock identification using the twelve microsatellite loci indicated 5-7 potential genetic stocks were present. The resolved stocks corresponded to geographically proximate populations clustering into genetic groups. Analysis of molecular variance suggested six genetic stocks present in the lake as a significant portion of variation was attributable between groups of populations, but not within groups of populations. Within stock analyses (pairwise Fst) suggested all but one stock delineated by AMOVA was a stable grouping (i.e., no between population differences) with the exception being the Hog Island, Traverse Bay grouping (NOE stock). This putative stock showed significant differences between the two populations indicating gene flow between the NOR stock (Naubinway and Epoufette) and Hog Island but not between NOR and Traverse Bay. Elk Rapids was the most genetically divergent population and actually masked the isolation by distance that exists between all other populations within Lake Michigan. Genetic mixture analysis showed mixed stock analysis using the resolved stocks and molecular markers can be accomplished with high accuracy. The coupling of genetic data from this study with current demographic data and a comprehensive mixed-stock analysis will allow for more efficient and effective management of this economically and socially important resource.Great Lakes Fishery Commissio

Survival, Reproduction, and Recruitment of Gizzard Shad (Dorosoma cepedianum) at the Northwestern Edge of its Native Range

South Dakota (SD) represents the northwestern edge of gizzard shad’s (Dorosoma cepedianum) native range. However, with recent climate warming the gizzard shad is experiencing a natural range expansion northward. Little knowledge exists regarding temperatures that are required for overwinter survival, and less is known regarding population dynamics of gizzard shad in these populations. The objectives of this research were to determine the extent of reproduction, recruitment, and overwinter survival after annual introductions of adult gizzard shad in two northeastern SD glacial lakes relative to other SD systems. Prior to spawning, the gizzard shad was introduced into East Krause Lake and Middle Lynn Lake and successfully spawned during 2008 and 2009. Mean (SE) peak larval abundances (number/100 m3 ) were 3.87 (1.87) and 1.72 (0.89) in East Krause Lake and 0.79 (0.22) and 0.17 (0.11) in Middle Lynn Lake in 2008 and 2009, respectively. Larval abundances were lower than those observed in most other SD populations. Survival to fall age-0 was documented in both years in Middle Lynn Lake, but only during 2008 in East Krause Lake. No overwinter survival was documented. Low water temperatures and rapidly cooling water likely caused overwinter mortality of gizzard shad in these systems. Temperature at the sediment–water interface during the winter of 2009–2010 was below 2.2C for 114 and 62 consecutive days in East Krause Lake and Middle Lynn Lake, respectively

Walleye Trophic Position Before and After a Gizzard Shad Extirpation

Walleye (Sander vitreus) are an ecologically and recreationally important sport fish species. Reduced growth and condition in walleye can occur when prey availability is limited. In two Nebraska reservoirs, walleye consumed gizzard shad (Dorosoma cepedianum) as their primary prey until a winterkill extirpated the gizzard shad in 2001. Because of the winterkill, walleye in the two reservoirs had to change to alternative prey items. Our objective was to determine if stable isotope analysis on archived walleye scales can be used to detect a known food web shift in two reservoir food webs. We quantified the changes in walleye trophic position following the loss of gizzard shad using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from archived scales. Walleye δ15N decreased and δ13C increased in both reservoirs after the extirpation of gizzard shad, indicating walleye likely fed at a lower trophic level on more benthic or littoral prey resources post winterkill. A replacement of gizzard shad by white perch (Morone americana) in Pawnee Reservoir may have ameliorated the loss of gizzard shad; in the other system, walleye appeared to feed on a wider variety of prey items as indexed by increased δ13C variability. Our results indicated that walleye were robust to gizzard shad extirpation

Comparing Isotope Signatures of Prey Fish: Does Gut Removal Affect δ13C or δ15N?

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, especially when recent foraging has taken place or when the gut contains non-assimilated material that would normally pass through fishes undigested. To assess the impacts of gut content on prey fish isotope signatures, we examined the differences in isotopic variation of five prey fish species using whole fish, whole fish with the gut contents removed, and dorsal muscle only. We found significant differences in both δ15 and δ13 between the three tissue treatments. In most cases, muscle tissue was enriched compared to whole specimens or gut-removed specimens. Moreover, differences in mean δ15 within a species were up to 2% among treatments. This would result in a change of over half a trophic position (TP) based on a 3.4% increase per trophic level. However, there were no apparent relationships between tissue isotope values in fish with increased gut fullness (more prey tissue present). We suggest that muscle tissue should be used as the standard tissue for determining isotope composition of prey fish or age-0 recreational fishes, especially when determining enrichment for mixing models, calculating TP, or constructing aquatic food webs

Demographic and Life History Characteristics of Black Bullheads <i>Ameiurus melas</i> in a North Temperate USA Lake

Black bullheads Ameiurus melas are an environmentally tolerant omnivorous fish species that are found throughout much of North America and parts of Europe. Despite their prevalence, black bullheads are an infrequently studied species making their biology, ecology, and life history poorly understood. Although limited information has been published on black bullheads, evidence suggests that bullheads can dominate the fish biomass and have profound influences on the fish community in some north temperate USA lakes. The goal of our study was to provide additional information on black bullhead population demographics, growth rates, life history characteristics, and seasonal diet preferences in a northern Wisconsin lake. Using common fish collection gears (fyke netting, electrofishing), fish aging protocols, fecundity assessments, and diet indices, our results suggested that black bullheads exhibited relatively fast growth rates, early ages at maturity, moderate fecundity, and a diverse omnivorous diet. Due to these demographic and life history characteristics, black bullheads have the potential to dominate fish community biomass in their native and introduced range. Results from our study may inform the management of black bullhead as native and invasive species

Genetic Structure of a Disjunct Peripheral Population of Mountain Sucker Pantosteus Jordani in the Black Hills, South Dakota, USA

A peripheral population of mountain sucker, Pantosteus jordani, located in the Black Hills of South Dakota, USA, represents the eastern-most range of the species and is completely isolated from other populations. Over the last 50 years, mountain sucker populations have declined in the Black Hills, and now only occur in 40 % of the historic local range, with densities decreasing by more than 84 %.We used microsatellite DNA markers to estimate genetic diversity and to assess population structure across five streams where mountain suckers persist. We evaluated results in the context of recent ecological surveys to inform decisions about mountain sucker conservation. Significant allele frequency differences existed among sample streams (Global FST = 0.041) but there was no evidence of isolation by distance. Regionally, genetic effective size, Ne, was estimated to be at least 338 breeding individuals, but Ne within streams was expected to be less. Despite almost complete demographic isolation and reduced population size, there appears to be little evidence of inbreeding, but genetic drift and local isolation due to fragmentation probably best explains genetic structure in this peripheral mountain sucker population. Recommended strategies for population enhancement include restoration of stream connectivity and habitat improvement. Moreover, repatriation and assisted movement (i.e., gene flow) of fishes should maximize genetic diversity in stream fragments in the Black Hills region

Demographic and Life History Characteristics of Black Bullheads Ameiurus melas in a North Temperate USA Lake

Black bullheads Ameiurus melas are an environmentally tolerant omnivorous fish species that are found throughout much of North America and parts of Europe. Despite their prevalence, black bullheads are an infrequently studied species making their biology, ecology, and life history poorly understood. Although limited information has been published on black bullheads, evidence suggests that bullheads can dominate the fish biomass and have profound influences on the fish community in some north temperate USA lakes. The goal of our study was to provide additional information on black bullhead population demographics, growth rates, life history characteristics, and seasonal diet preferences in a northern Wisconsin lake. Using common fish collection gears (fyke netting, electrofishing), fish aging protocols, fecundity assessments, and diet indices, our results suggested that black bullheads exhibited relatively fast growth rates, early ages at maturity, moderate fecundity, and a diverse omnivorous diet. Due to these demographic and life history characteristics, black bullheads have the potential to dominate fish community biomass in their native and introduced range. Results from our study may inform the management of black bullhead as native and invasive species

Walleye Trophic Position Before and After a Gizzard Shad Extirpation

Walleye (Sander vitreus) are an ecologically and recreationally important sport fish species. Reduced growth and condition in walleye can occur when prey availability is limited. In two Nebraska reservoirs, walleye consumed gizzard shad (Dorosoma cepedianum) as their primary prey until a winterkill extirpated the gizzard shad in 2001. Because of the winterkill, walleye in the two reservoirs had to change to alternative prey items. Our objective was to determine if stable isotope analysis on archived walleye scales can be used to detect a known food web shift in two reservoir food webs. We quantified the changes in walleye trophic position following the loss of gizzard shad using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N) from archived scales. Walleye δ15N decreased and δ13C increased in both reservoirs after the extirpation of gizzard shad, indicating walleye likely fed at a lower trophic level on more benthic or littoral prey resources post winterkill. A replacement of gizzard shad by white perch (Morone americana) in Pawnee Reservoir may have ameliorated the loss of gizzard shad; in the other system, walleye appeared to feed on a wider variety of prey items as indexed by increased δ13C variability. Our results indicated that walleye were robust to gizzard shad extirpation