bluuebunny/crossref_metadata_2025 huggingface dataset:
Selbstkalibrierung von Rasterkraftmikroskopen — Abbildung der PositionsabweichungenSelf Calibration of SPM — Mapping the Errors of the Instrument
Authors: Xu Min , Dziomba Thorsten , Dai Gaoliang , Koenders Ludger
Published: October 2009

Ein Selbstkalibrierungsverfahren zur Abbildung der Positionsabweichungen in der x-y-Ebene und der Rechtwinkligkeitsabweichungen zwischen der z-Achse und der x-y-Ebene von Rasterkraftmikroskopen (engl. Scanning Force Microscopes, SFM) wurde entwickelt und angewendet. Das Verfahren zur Selbstkalibrierung hat Vorteile: einfacher Aufbau, und mit seiner Hilfe können sowohl Unregelmäßigkeiten von Maßverkörperungen als auch Abweichungen vom Idealverhalten von SFMs bestimmt und voneinander getrennt werden. Grenzen sind nur durch die Stabilität des Gerätes und der benutzten Probe gegeben. Zwei handelsübliche SFMs wurden unter Anwendung der vorgeschlagenen Methode untersucht. Die Ergebnisse eines dieser Geräte werden hier zur Illustration der Anwendung gezeigt. Die erzielten Ergebnisse stimmen gut mit denen überein, die klassische Kalibriermethoden mit hochgenauen Transfernormalen und messtechnischen Geräten lieferten. Das Selbstkalibrierungsverfahren bietet sich damit als eine wirkungsvolle Methode zur Abbildung weiterer Fehler von Rasterkraftmikroskopen an.
Einflüsse von Beschleunigungskräften auf einen DrucksensorAcceleration-Induced Effects on a Pressure Sensor
Authors: Gradolph Christian , Friedberger Alois , Müller Gerhard , Wilde Jürgen
Published: October 2009

Drucksensoren für aerodynamische Messungen in Hubschrauber-Rotorblättern müssen hohe Anforderungen an die Druckauflösung erfüllen. Gleichzeitig aber unterliegen sie sehr rauen Umgebungsbedingungen wie den dort herrschenden enormen Fliehkräften und Vibrationen. Die Einflüsse dieser Belastungen auf das Verhalten der Sensorkomponenten und die Querempfindlichkeit des Drucksensors werden analysiert.
Efficient Transposition of Tol2 in the Mouse Germline
Authors: Keng Vincent W , Ryan Barbara J , Wangensteen Kirk J , Balciunas Darius , Schmedt Christian , Ekker Stephen C , Largaespada David A
Published: October 2009

Insertional mutagenesis screens play an integral part in the annotating of functional data for all sequenced genes in the postgenomic era. Chemical mutagenesis screens are highly efficient but identifying the causative gene can be a laborious task. Other mutagenesis platforms, such as transposable elements, have been successfully applied for insertional mutagenesis screens in both the mouse and rat. However, relatively low transposition efficiency has hampered their use as a high-throughput forward genetic mutagenesis screen. Here we report the first evidence of germline activity in the mouse using a naturally active DNA transposon derived from the medaka fish called Tol2, as an alternative system for high-throughput forward genetic mutagenesis screening tool.
The Genetic Basis of Phenotypic Adaptation II: The Distribution of Adaptive Substitutions in the Moving Optimum Model
Authors: Kopp Michael , Hermisson Joachim
Published: October 2009

We consider a population that adapts to a gradually changing environment. Our aim is to describe how ecological and genetic factors combine to determine the genetic basis of adaptation. Specifically, we consider the evolution of a polygenic trait that is under stabilizing selection with a moving optimum. The ecological dynamics are defined by the strength of selection, $\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{{\tilde{{\sigma}}}}\) \end{document}$, and the speed of the optimum, $\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\tilde{v}}\) \end{document}$; the key genetic parameters are the mutation rate Θ and the variance of the effects of new mutations, ω. We develop analytical approximations within an “adaptive-walk” framework and describe how selection acts as a sieve that transforms a given distribution of new mutations into the distribution of adaptive substitutions. Our analytical results are complemented by individual-based simulations. We find that (i) the ecological dynamics have a strong effect on the distribution of adaptive substitutions and their impact depends largely on a single composite measure $\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{{\gamma}}{=}{\tilde{v}}/(\mathrm{{\tilde{{\sigma}}}}{\Theta}\mathrm{{\omega}}^{3})\) \end{document}$, which combines the ecological and genetic parameters; (ii) depending on γ, we can distinguish two distinct adaptive regimes: for large γ the adaptive process is mutation limited and dominated by genetic constraints, whereas for small γ it is environmentally limited and dominated by the external ecological dynamics; (iii) deviations from the adaptive-walk approximation occur for large mutation rates, when different mutant alleles interact via linkage or epistasis; and (iv) in contrast to predictions from previous models assuming constant selection, the distribution of adaptive substitutions is generally not exponential.
Centromere Replication Timing Determines Different Forms of Genomic Instability inSaccharomyces cerevisiaeCheckpoint Mutants During Replication Stress
Authors: Feng Wenyi , Bachant Jeff , Collingwood David , Raghuraman M K , Brewer Bonita J
Published: October 2009

Yeast replication checkpoint mutants lose viability following transient exposure to hydroxyurea, a replication-impeding drug. In an effort to understand the basis for this lethality, we discovered that different events are responsible for inviability in checkpoint-deficient cells harboring mutations in the mec1 and rad53 genes. By monitoring genomewide replication dynamics of cells exposed to hydroxyurea, we show that cells with a checkpoint deficient allele of RAD53, rad53K227A, fail to duplicate centromeres. Following removal of the drug, however, rad53K227A cells recover substantial DNA replication, including replication through centromeres. Despite this recovery, the rad53K227A mutant fails to achieve biorientation of sister centromeres during recovery from hydroxyurea, leading to secondary activation of the spindle assembly checkpoint (SAC), aneuploidy, and lethal chromosome segregation errors. We demonstrate that cell lethality from this segregation defect could be partially remedied by reinforcing bipolar attachment. In contrast, cells with the mec1-1 sml1-1 mutations suffer from severely impaired replication resumption upon removal of hydroxyurea. mec1-1 sml1-1 cells can, however, duplicate at least some of their centromeres and achieve bipolar attachment, leading to abortive segregation and fragmentation of incompletely replicated chromosomes. Our results highlight the importance of replicating yeast centromeres early and reveal different mechanisms of cell death due to differences in replication fork progression.
Deleting the 14-3-3 Protein Bmh1 Extends Life Span inSaccharomyces cerevisiaeby Increasing Stress Response
Authors: Wang Chen , Skinner Craig , Easlon Erin , Lin Su-Ju
Published: October 2009

Enhanced stress response has been suggested to promote longevity in many species. Calorie restriction (CR) and conserved nutrient-sensing target of rapamycin (TOR) and protein kinase A (PKA) pathways have also been suggested to extend life span by increasing stress response, which protects cells from age-dependent accumulation of oxidative damages. Here we show that deleting the yeast 14-3-3 protein, Bmh1, extends chronological life span (CLS) by activating the stress response. 14-3-3 proteins are highly conserved chaperone-like proteins that play important roles in many cellular processes. bmh1Δ-induced heat resistance and CLS extension require the general stress-response transcription factors Msn2, Msn4, and Rim15. The bmh1Δ mutant also displays a decreased reactive oxygen species level and increased heat-shock-element-driven transcription activity. We also show that BMH1 genetically interacts with CR and conserved nutrient-sensing TOR- and PKA-signaling pathways to regulate life span. Interestingly, the level of phosphorylated Ser238 on Bmh1 increases during chronological aging, which is delayed by CR or by reduced TOR activities. In addition, we demonstrate that PKA can directly phosphorylate Ser238 on Bmh1. The status of Bmh1 phosphorylation is therefore likely to play important roles in life-span regulation. Together, our studies suggest that phosphorylated Bmh1 may cause inhibitory effects on downstream longevity factors, including stress-response proteins. Deleting Bmh1 may eliminate the inhibitory effects of Bmh1 on these longevity factors and therefore extends life span.
A Genomewide RNAi Screen for Genes That Affect the Stability, Distribution and Function of P Granules in Caenorhabditis elegans
Authors: Updike Dustin L , Strome Susan
Published: October 2009

P granules are non-membrane-bound organelles found in the germ-line cytoplasm throughout Caenorhabditis elegans development. Like their “germ granule” counterparts in other animals, P granules are thought to act as determinants of the identity and special properties of germ cells, properties that include the unique ability to give rise to all tissues of future generations of an organism. Therefore, understanding how P granules work is critical to understanding how cellular immortality and totipotency are retained, gained, and lost. Here we report on a genomewide RNAi screen in C. elegans, which identified 173 genes that affect the stability, localization, and function of P granules. Many of these genes fall into specific classes with shared P-granule phenotypes, allowing us to better understand how cellular processes such as protein degradation, translation, splicing, nuclear transport, and mRNA homeostasis converge on P-granule assembly and function. One of the more striking phenotypes is caused by the depletion of CSR-1, an Argonaute associated with an endogenous siRNA pathway that functions in the germ line. We show that CSR-1 and two other endo-siRNA pathway members, the RNA-dependent RNA polymerase EGO-1 and the helicase DRH-3, act to antagonize RNA and P-granule accumulation in the germ line. Our findings strengthen the emerging view that germ granules are involved in numerous aspects of RNA metabolism, including an endo-siRNA pathway in germ cells.
Prevalence of Parent-Reported Diagnosis of Autism Spectrum Disorder Among Children in the US, 2007
Authors: Kogan Michael D. , Blumberg Stephen J. , Schieve Laura A. , Boyle Coleen A. , Perrin James M. , Ghandour Reem M. , Singh Gopal K. , Strickland Bonnie B. , Trevathan Edwin , van Dyck Peter C.
Published: October 2009

OBJECTIVES: The reported increasing prevalence of autism spectrum disorder (ASD) and attendant health and family impact make monitoring of ASD prevalence a public health priority.

METHODS: The prevalence of parent-reported diagnosis of ASD among US children aged 3 to 17 years was estimated from the 2007 National Survey of Children's Health (sample size: 78037). A child was considered to have ASD if a parent/guardian reported that a doctor or other health care provider had ever said that the child had ASD and that the child currently had the condition. The point-prevalence for ASD was calculated for those children meeting both criteria. We examined sociodemographic factors associated with current ASD and with a past (but not current) ASD diagnosis. The health care experiences for children in both ASD groups were explored.

RESULTS: The weighted current ASD point-prevalence was 110 per 10,000. We estimate that 673,000 US children have ASD. Odds of having ASD were 4 times as large for boys than girls. Non-Hispanic (NH) black and multiracial children had lower odds of ASD than NH white children. Nearly 40% of those ever diagnosed with ASD did not currently have the condition; NH black children were more likely than NH white children to not have current ASD. Children in both ASD groups were less likely than children without ASD to receive care within a medical home.

CONCLUSIONS: The observed point-prevalence is higher than previous US estimates. More inclusive survey questions, increased population awareness, and improved screening and identification by providers may partly explain this finding.
Life History, Ecology, and Long-term Demographics of Queenfish
Authors: Miller Eric F. , Williams Jonathan P. , Pondella Daniel J. , Herbinson Kevin T.
Published: October 2009

Queenfish Seriphus politus were collected at coastal power plants from San Clemente to Ventura, California. Power functions best described relations between otolith length, width, or weight and either standard length (SL) or total body weight. The length–weight relationship was described by the following equation: weight = 10−5 × SL3.09. Individuals were aged to 12 years by using sagittal otolith sections. Females grew at a significantly faster rate than males. Both sexes reached 50% maturity by 100 mm SL, or shortly after age 1. The total annual instantaneous mortality coefficient was estimated at 0.42. Catalina Harbor (on the windward side of Santa Catalina Island) and Ventura were the most populous sites based on gill-net catch per unit effort from 1995 to 2006. Juvenile and adult queenfish populations have declined since 1980 in a significant relationship with nearshore plankton biomass. Larval queenfish densities recorded in King Harbor (Redondo Beach) have declined since 1987. Long-term recruitment estimates indicated peak recruitment prior to 1976, with three subsequent downward baseline shifts.
Use of a Fishery-Independent Trawl Survey to Evaluate Distribution Patterns of Subadult Sharks in Georgia
Authors: Belcher Carolyn N. , Jennings Cecil A.
Published: October 2009

We investigated the utility of a fishery-independent trawl survey for assessing a potential multispecies shark nursery in Georgia's nearshore and inshore waters. A total of 234 subadult sharks from six species were captured during 85 of 216 trawls. Catch rates and size distributions for subadult sharks and the ratio of neonates to juveniles were consistent among areas. The highest concentrations of subadult sharks occurred in creeks and sounds. Species composition varied among areas. The Atlantic sharpnose shark Rhizoprionodon terraenovae was the most abundant species in sound and nearshore stations, whereas the bonnethead Sphyrna tiburo was the most abundant species in creeks. The aggregate of other species occurred with higher frequency in the sounds and nearshore. Sampling characteristics of the trawl survey were compared with those from a fishery-independent longline survey of subadult sharks to assess the similarity of the two gears. A total of 193 subadult sharks from seven species were captured during 57 of 96 longline sets, whereas 52 subadults from four species were captured during 20 of 48 trawls. Selectivity and efficiency differed between the two gears. The trawl had lower catch rates, caught smaller sharks, and encountered a different suite of species than the longline. General seasonal trends in relative abundance also differed between the two gears; the longline showed an increasing trend in abundance, whereas the trawl showed a stable trend. Although trawls were not found to be efficient for sampling subadult sharks from most species, they can be a useful source of supplemental data.
Overwinter Growth and Mortality of Young-of-the-Year Windowpanes: Cohort-specific Responses
Authors: Neuman Melissa J. , Able Kenneth W.
Published: October 2009

We tested the overwintering capability of young-of-the-year (age-0) windowpanes Scophthalmus aquosus to determine if there are cohort-specific differences in growth and mortality. We conducted a laboratory study at ambient estuarine winter temperatures from 9 November 1995 to 22 April 1996 with two cohorts (spring-spawned cohort: 83–140 mm total length [TL]; fall-spawned cohort: 15–37 mm TL). We hypothesized that (1) among individuals within both cohorts, winter growth rates would be low compared with summer growth rates; and (2) overwinter mortality rates of the smaller, fall-spawned fish would be higher than those of larger, spring-spawned fish due to size-selective mortality. Under ambient winter temperatures (−2.0 to 14.0°C) with daily, ad libitum feeding in the laboratory, growth rates were low but positive for the fall- and spring-spawned fish. Overwinter mortality occurred in both cohorts but was higher for the fall cohort than for the spring cohort (75% and 31%, respectively). Within the fall cohort, mortality was size selective, with reduced survival of individuals smaller than 24 mm TL. Within the spring cohort, there was no evidence of size-selective mortality. We concluded that the first winter of life may be an important mortality bottleneck for both cohorts of age-0 windowpanes in the Middle Atlantic Bight but that mortality patterns are cohort specific and may be determined by different combinations of factors, such as fish size at the start of winter, the magnitude of water temperature decline between fall and winter, and the frequency and duration of extremely cold water temperatures. Thus, overwinter mortality during the first winter of life may influence the population dynamics of the windowpane and other multimodal spawners inhabiting the Middle Atlantic Bight.
Description and Initial Evaluation of a Text Message Based Reporting Method for Marine Recreational Anglers
Authors: Baker M. Scott , Oeschger Ian
Published: October 2009

Despite the large number of marine recreational anglers in the United States, there exist few opportunities for individuals to contribute self-reported effort and catch data directly to fisheries managers. Successfully implemented data collection programs based on self-reported information have been able to provide scientists with additional indices for comparisons with existing fisheries data sets and to increase angler participation and confidence in the fisheries management process. Limitations to self-reported data aside, the lack of a portable, electronic reporting device for the average angler has hindered development of new survey methods. We have developed a simple but fully customizable reporting method by which users can submit basic effort and catch information to an online database via text messages from mobile phones. To evaluate this new approach, we asked captains on behalf of six marine for-hire operations to send a text message to document effort, catch, and disposition of catch by species at the completion of each for-hire trip. Report submission was facilitated by RECTEXT, a compact syntax we developed to allow users to submit information within the technical limitations of a 160-character text message framework. During the course of the 4.5-month evaluation, participants submitted 128 trip-level reports that described 1,957 finfish interactions. Results and feedback from participants indicate that the approach is easy to use, is cost efficient, and allows for real-time reporting of information directly to an online database. In addition to the electronic angler diary application described here, we suggest that future evaluations of this approach be applied to tournament data collection, as the real-time nature of reporting and the organized structure of tournaments may provide a mechanism to both interact with all registered anglers and facilitate design of an unbiased sampling protocol for validating the self-reported data.
Virulence Variation of White Spot Syndrome Virus in Pacific White Shrimp Litopenaeus vannamei
Authors: Laramore S. E. , Scarpa J. , Laramore C. R. , Lin J.
Published: October 2009

The virulence of seven geographic isolates of white spot syndrome virus (WSSV; genus Whispovirus; China (strain CH1995), Nicaragua (strain N2000), Honduras (strain H2000), Ecuador (strains E-L1999 and E-LT2002), and Mexico (strains M-M2001 and M-LP2001)) was compared using a series of challenge experiments, each lasting 10 d. For each isolate, four quantified dilutions (10−6, 10−7, 10−8, and 10−9) of a viral inoculum were prepared from WSSV-infected shrimp tissue. Each viral inoculum was injected into 10 specific pathogen-free juvenile Pacific white shrimp Litopenaeus vannamei (0.25–1.50 g); controls received injections of marine crustacean physiological saline (3.2%). The minimum dose of viral inoculum that killed 50% of injected shrimp (LD50) was calculated for dilution, tissue concentration, and viral DNA amount. The CH1995 and M-M2001 isolates were the least virulent, with LD50 values of 10−6 to 10−7 of viral inoculum. The isolates could be grouped into three virulence clusters (CH1995 and M-M2001; N2000 and E-LT2002; and H2000, E-L1999, and M-LP2001). Virulence clusters were not altered by LD50 values based on viral DNA concentration, although a slight shifting of order in regards to virulence was seen among the three most virulent isolates (E-L1999, H2000, and M-LP2001). Overall, results indicate that there is a measurable virulence difference among WSSV isolates, which may correspond to geographical region.
Tumors in Brown Bullheads in the Chesapeake Bay Watershed: Analysis of Survey Data from 1992 through 2006
Authors: Pinkney Alfred E. , Harshbarger John C. , Rutter Michael A.
Published: October 2009

Liver and skin tumor prevalences in brown bullheads Ameiurus nebulosus have been used in the North American Great Lakes to designate highly contaminated areas of concern and monitor their recovery. Here we interpret the results of six surveys conducted in the Chesapeake Bay watershed between 1992 and 2006, with data for 647 fish. The objective has been to develop an adequate database to critically evaluate the use of tumor prevalence as a habitat quality indicator within the watershed. Surveys featured randomized fish collection; recording of sex, length, weight, and age; and histopathology of all livers and all raised skin lesions. The Bayes information criterion was used to analyze all possible combinations of age, gender, length, and weight as covariates for logistic regression. Length and gender were the covariates that best described liver tumor prevalence. There were no covariates in the model for skin tumor prevalence. In some surveys, biomarkers, such as biliary polynuclear aromatic hydrocarbon (PAH)-like metabolites, hepatic cytochrome P450 activity, and hepatic DNA adducts, were used with sediment and tissue chemistry data to evaluate classes of chemicals as likely contributors to tumor prevalence. We highlight two surveys of the Anacostia River, Washington, D.C. (average = 55% liver tumors, 23% skin tumors), where sediment PAHs, biliary PAH-like metabolites, and hepatic DNA adducts were high, suggesting that PAHs play a major role. We show that logistic regression is an appropriate procedure for comparing “contaminated” versus “reference” locations, and we evaluate the utility of tumor surveys as an environmental indicator for the Chesapeake Bay watershed.
Are All Koi Ulcer Cases Associated with Infection by Atypical Aeromonas salmonicida? Polymerase Chain Reaction Assays of Koi Carp Skin Swabs Submitted by Hobbyists
Authors: Goodwin Andrew E. , Merry Gwenn E.
Published: October 2009

Infection by atypical Aeromonas salmonicida is regarded as the cause of ulcer disease (KUD) in koi carp Cyprinus carpio and goldfish Carassius auratus. However, other causes—including parasites, viral infection, and fungi—have been proposed. In our diagnostic work, we often fail to isolate A. salmonicida even when clear clinical signs of KUD are present. This failure may be because these fastidious and slow-growing bacteria are difficult to isolate in culture or because the bacteria are not actually present in the lesions. In this study, we used polymerase chain reaction (PCR) to detect A. salmonicida in DNA samples swabbed from koi carp ulcers. These alcohol-preserved samples were collected and submitted by hobbyists and included 40 separate cases from 12 different states. We identified atypical A. salmonicida by PCR in 52 of 62 samples submitted and in 33 of 40 unique cases. The negative findings for A. salmonicida by PCR could all be attributed to high water temperatures, prior antibiotic use, poor sample quality, or misdiagnosis of columnaris disease as KUD. Tests for Aphanomyces invadans by PCR were negative in every case. This work confirms that A. salmonicda is still the predominant cause of KUD and that our negative culture results were ost likely due to technical failures rather than an absence of A. salmonicda in the ulcer lesions.
A Comparison of Two Methodologies for Estimating Brook Trout Catch and Harvest Rates using Incomplete and Complete Fishing Trips
Authors: Keefe Donald G. , Perry Robert C. , Luther J. Glenn
Published: October 2009

On the island portion of Newfoundland and Labrador, Canada, the provincial government relies on roving creel surveys to assess the fishery for brook trout Salvelinus fontinalis. The estimation of catch and harvest rates for these surveys requires on-site interview methods that gather information from incomplete fishing trips. When the objective is to determine total catch, the mean-of-ratios estimator is the accepted method for deriving catch rate from incomplete trips, whereas the ratio-of-means estimator is the accepted method for deriving catch rate for completed trips. When we compared the two estimators using incomplete and complete trip catch data measured from the same sample of anglers, we found a persistent bias. Catch and harvest rates derived from the mean-of-ratios estimator were significantly higher than those obtained with the ratio-of-means estimator. Catch rate was higher by 32%, while harvest rate was higher by 39%. When we only used the completed trip data set for both calculations, we found a mean difference of 19% between the two estimators. We also found a second source of error. When we examined individual angler responses for catch and harvest, the estimates revealed a positive bias whereby the incomplete trips showed higher estimates relative to the complete trips (16% and 21%, respectively). These biases appear to be related to the estimation procedure as well as fish and fisher behavior at the individual angler level. We use linear regression analysis to help correct the bias associated with the mean-of-ratios estimator.
Defining and Characterizing Coolwater Streams and Their Fish Assemblages in Michigan and Wisconsin, USA
Authors: Lyons John , Zorn Troy , Stewart Jana , Seelbach Paul , Wehrly Kevin , Wang Lizhu
Published: October 2009

Coolwater streams, which are intermediate in character between coldwater “trout” streams and more diverse warmwater streams, occur widely in temperate regions but are poorly understood. We used modeled water temperature data and fish assemblage samples from 371 stream sites in Michigan and Wisconsin to define, describe, and map coolwater streams and their fish assemblages. We defined coolwater streams as ones having summer water temperatures suitable for both coldwater and warmwater species and used the observed distributions of the 99 fish species at our sites to identify coolwater thermal boundaries. Coolwater streams had June-through-August mean water temperatures of 17.0–20.5°C, July mean temperatures of 17.5–21.0°C, and maximum daily mean temperatures of 20.7–24.6°C. We delineated two subclasses of coolwater streams: “cold transition” (having July mean water temperatures of 17.5–19.5°C) and “warm transition” (having July mean temperatures of 19.5–21.0°C). Fish assemblages in coolwater streams were variable and lacked diagnostic species but were generally intermediate in species richness and overlapped in composition with coldwater and warmwater streams. In cold-transition streams, coldwater (e.g., salmonids and cottids) and transitional species (e.g., creek chub Semotilus atromaculatus, eastern blacknose dace Rhynichthys atratulus, white sucker Catostomus commersonii, and johnny darter Etheostoma nigrum) were common and warmwater species (e.g., ictalurids and centrarchids) were uncommon; in warm-transition streams warmwater and transitional species were common and coldwater species were uncommon. Coolwater was the most widespread and abundant thermal class in Michigan and Wisconsin, comprising 65% of the combined total stream length in the two states (cold-transition streams being more common than warm-transition ones). Our approach can be used to identify and characterize coolwater streams elsewhere in the temperate region, benefiting many aspects of fisheries management and environmental protection.
Using Positional Data from Vessel Monitoring Systems to Validate the Logbook-Reported Area Fished and the Stock Allocation of Commercial Fisheries Landings
Authors: Palmer Michael C. , Wigley Susan E.
Published: October 2009

Stock allocations derived from vessel monitoring system (VMS) positional data from northeastern U.S. fisheries were compared with those obtained from mandatory vessel trip report (VTR) logbooks. A gear-specific speed algorithm was applied to VMS positions collected in 2005 from otter trawl, Atlantic sea scallop Placopecten magellanicus dredge, sink gill-net, and benthic longline fisheries to estimate the locations of fishing activity. Estimated fishing locations were used to reallocate the stock area landings of eight federally managed groundfish species. The accuracy of the VMS method relative to that of the mandatory logbooks was assessed using haul locations and catch data recorded by at-sea observers. The VMS algorithm tended to overestimate the number of statistical areas fished, such that when a trip's fishing activity occurred in a single statistical area, logbooks more accurately reflected the true fishing location. However, when fishing activity occurred in multiple statistical areas, the VMS algorithm showed appreciable gains relative to logbook data. Compared with mandatory logbooks, the VMS method achieved distributions of stock landings closer to observer estimates in 77.8% of the cases examined. The stock allocation percentages from both the VMS- and VTR-based methods were within 1.7% for all stocks, suggesting that the impacts on total stock allocations are relatively minor. However, these small differences represent major relative differences in stock landings for less abundant stocks such as southern New England–Mid-Atlantic yellowtail flounder Limanda ferruginea, where the VTR-based method allocated 61.9% more landings than the VMS-based method. The VMS-based method is not a replacement for the VTR-based method; however, it can and should be used as a tool to identify those vessels for which targeted outreach activities would improve the accuracy of VTR statistical area reporting.
An Assessment of Age Determination Methods for Great Lakes Larval Sea Lampreys
Authors: Dawson Heather A. , Jones Michael L. , Scribner Kim T. , Gilmore Stacy A.
Published: October 2009

Estimating the age composition and recruitment of populations of invasive sea lampreys Petromyzon marinus necessitates the validation and improvement of age assessment methods that rely on statoliths and length-frequency data. Determining age based on length-frequency distributions is subjective because of heterogeneity in the growth rates of larval sea lampreys (ammocoetes) within and across streams and the resulting overlap in lengths between age-classes. Statolith-based age assessment methods have never been validated for more than 1 year. We established “known-age” ammocoete populations in two streams by introducing a single cohort of spawners above barriers and compared estimates of ammocoete age based on statoliths with the true ages. In five additional streams, we used microsatellite data from adults and ammocoetes to assign parents to ammocoetes produced the same year and compared the age determined by statolith-based interpretation with the age based on parentage assignment. We combined length-frequency data with age composition data from streams having known-age populations and evaluated likelihood-based statistical models used to estimate the age composition of the ammocoete population. Multiple independent age readings of statoliths from known-age sea lampreys indicated that the age assessment bias (average percent error) was 24.3–36.2%. Genotype-based ages differed from statolith-based ages in 36.1% of cases across all streams. Bias-corrected statolith ages, when combined with length-frequency data, substantially increased age assessment accuracy in a known-age population stream and increased precision in a randomly selected stream; their use, however, requires knowledge of the magnitude of the bias of statolith-based age assessment in study streams. Further effort is needed to quantify these biases and generalize to different types of streams before a reliable methodology for age assessment will be available for sea lamprey management.
Fishery and Population Characteristics of Blue Catfish and Channel Catfish and Potential Impacts of Minimum Length Limits on the Fishery in Lake Wilson, Alabama
Authors: Holley Michael P. , Marshall Matthew D. , Maceina Michael J.
Published: October 2009

A popular recreational and commercial fishery for blue catfish Ictalurus furcatus and channel catfish I. punctatus exists at Lake Wilson, Alabama (Tennessee River). We examined the fishery, exploitation, angler size selectivity, and population demographics of these two species at Lake Wilson. In addition, we explored management strategies to enhance the fishery of trophy blue catfish. Currently, Alabama has no bag or minimum-length-limit regulations for catfish, except for the harvest of fish over 864 mm total length (TL). From April to October 2006, catfish harvest was high (8 kg/ha), and angler catch and harvest rates averaged 1.5 and 1.2 fish/h, respectively. The majority of fish harvested were between 300 and 600 mm TL, and anglers harvested larger fish in proportion to the sample population. Catfish were collected by low-frequency (15-MHz) DC electrofishing; they were aged with otoliths from 180 and 122 blue catfish and channel catfish, respectively, subsamples of 2,905 blue catfish and 699 channel catfish. Fish over 300 mm TL were tagged with Carlin dangler tags to estimate exploitation. Accounting for tag loss and variations in angler nonreporting rates (20–70%), we estimated that annual exploitation ranged from 8% to 22% for blue catfish and from 4% to 11% for channel catfish. Of the tagged fish harvested, 33% came from seven commercial fishers. Blue catfish and channel catfish displayed different life histories, which pointed to contrasting management strategies for increasing yield. Blue catfish were longer-lived (maximum age = 25 years), expressed slower growth (von Bertalanffy K = 0.081), and had lower natural mortality (M = 0.16) than channel catfish (maximum age = 12 years; von Bertalanffy K = 0.148; M = 0.29). Increasing minimum length limits from 300 to 660 mm for blue catfish would increase yield up to 50%, prevent growth overfishing, and increase the abundance of memorable-length (890-mm) blue catfish over our range of estimated exploitation. However, for channel catfish, minimum length limits greater than 300 mm would result in a lower yield. High length limits could drastically reduce the angler harvest of catfish but increase the abundance of memorable-length and larger blue catfish. Even so, the anglers surveyed preferred to harvest smaller fish. Fishing mortality was probably equal to natural mortality for blue catfish, but for channel catfish fishing mortality was less than natural mortality. On the basis of these observations, angler catches, the lack of angler species recognition, and the abundance of small catfish, we currently do not recommend bag or minimum length limits for this fishery.
Determination of Striped Bass Spawning Locations in the Two Major Tributaries of Lake Texoma
Authors: Baker William P. , Boxrucker Jeff , Kuklinski Kurt E.
Published: October 2009

Even though Lake Texoma is one of only four reservoir systems in the southeastern United States with a reproducing population of striped bass Morone saxatilis, spawning locations have not been determined. Recently proposed water development projects in the watershed make locating and protecting these locations a priority. The objectives of this study were to (1) determine where and when striped bass spawn in the Red and Washita rivers, (2) compare the relative densities of striped bass eggs collected in the two rivers, (3) determine the horizontal distribution of striped bass eggs in the Washita River, and (4) assess water-chemistry-related differences in the size of striped bass eggs between the two rivers. Striped bass eggs were classified into developmental stages and assigned ages (in hours) based on developmental temperature. Spawning areas were predicted from egg age and river current velocity as well as the presence of suitable habitat (verified visually). Striped bass spawning peaks generally followed stage rises in both rivers. Striped bass eggs were collected from 4 April to 18 May, 2001, in the Red River and from 3 April to 19 May, 2001, in the Washita River. Mean egg density peaked at 5 eggs/m3 on 16 April in the Red River and at 34.4 eggs/m3 on 21 April in the Washita River. We found no relationship between spawning distance from the lake and discharge. Direct comparison of egg catches in the two rivers may be misleading due to differences in channel morphology. However, in the Washita River, we found no horizontal difference in egg density across the river channel. Management agencies should exercise caution with respect to the implementation of water development projects within the watershed that could alter river flow or water chemistry, as these are probably key to the continued reproductive success of striped bass in the Lake Texoma system.
Assessment of the Flathead Catfish Population in a Lightly Exploited Fishery in Lake Wilson, Alabama
Authors: Marshall Matthew D. , Holley Michael P. , Maceina Michael J.
Published: October 2009

Population metrics and the fishery for flathead catfish Pylodictis olivaris were examined in Lake Wilson, an impoundment of the Tennessee River in Alabama. We described the recreational and commercial exploitation, angler size selectivity, and population demographics and used modeling to assess the impact of exploitation and minimum length limits on the abundance of memorable (860-mm) and trophy (1,020-mm) fish. A total of 1,113 flathead catfish were collected, and 646 of these fish (≥300 mm) were tagged and released to estimate exploitation. The length distribution indicated that there was a high proportion of larger fish in the population, the relative stock densities of preferred-, memorable-, and trophy-length fish being 21, 8, and 2%, respectively. Ages were estimated from otoliths (N = 198), and it was found that fish were slow growing (von Bertalanffy growth coefficient, 0.066) and long-lived (maximum age, 34 years) and expressed a high annual survival rate (83%) and low instantaneous natural mortality (range, 0.099–0.159). From a liberal tag loss rate (2.617%/month) and range of angler nonreporting (20–70%), estimates of exploitation ranged from 5% to 13%. Commercial angling accounted for 26% of the harvest. However, comparison of the observed and simulated length distributions and the difference between catch-curve survival and natural mortality strongly suggested that exploitation was about 5%. Anglers preferred to harvest larger fish, the highest selection being for fish 600–800 mm long. A reduction in harvest rates would have a larger impact on the maintenance of memorable- and trophy-length fish in the population than 356-, 508-, or 610-mm minimum length limits. At exploitation rates greater than 12%, very few trophy-size flathead catfish would remain in the population even if a high minimum length limit (610 mm) were imposed. Currently, flathead catfish are lightly exploited in this section of the Tennessee River and regulations to maintain the quality size of the population are not necessary at this time. However, this population is slow growing and long-lived with low natural mortality and would be sensitive to overfishing. If exploitation should increase and exceed natural mortality, the abundance of memorable- and trophy-size fish would be greatly reduced.
The Effect of Cull Rings on Catch Rates of Blue Crabs Callinectes sapidus in the North Carolina Trap Fishery
Authors: Rudershausen Paul J. , Turano Marc J.
Published: October 2009

We sampled seven North Carolina estuaries (Currituck, Core, Albemarle, Bogue, and eastern Pamlico sounds and the Cape Fear and Pamlico rivers) to determine the separate and interacting effects of cull ring size and the number of cull rings per trap on the catch rate (catch per trap) of blue crabs Callinectes sapidus. Since a single minimum cull ring size is required in North Carolina and regional differences in blue crab shape may mediate its effectiveness, we also measured subsamples of male and mature female blue crabs to determine whether there were shape differences among estuaries. The cull ring sizes tested in Currituck and Core sounds were 58.7, 60.3, and 61.9 mm. The smallest two sizes were tested in the other five estuaries. We also varied the number of cull rings from two to four per trap. Thus, there were nine treatments in Currituck and Core sounds and six in the other estuaries. Three blue crab types dominated the catches: legal males (≥127 mm), sublegal males, and mature females. Increasing ring size and number did not significantly affect the catch per unit effort (CPUE) of legal males except in Currituck Sound, where they positively affected CPUE. Increasing ring size negatively affected the CPUE of sublegal males in all estuaries except eastern Pamlico Sound, where if had no effect. Increasing ring number negatively affected the CPUE of sublegal males in two estuaries: Currituck and Albemarle sounds. Increasing ring size negatively affected the CPUE of mature females in two pairwise cases in one estuary (Core Sound); ring size and number did not impact the CPUE of mature females in other estuaries. Despite the apparent differences in the shapes of blue crabs among estuaries, the influences of cull ring size and number were consistent. Our data indicate that a 1.6- or 3.2-mm increase in cull ring size would not negatively impact the catch rates of legal blue crabs but would increase the escapement of sublegal blue crabs.
Effect of Temperature on Growth, Condition, and Survival of Juvenile Shovelnose Sturgeon
Authors: Kappenman Kevin M. , Fraser William C. , Toner Matt , Dean Jan , Webb Molly A. H.
Published: October 2009

Water temperature plays a key role in determining the persistence of shovelnose sturgeon Scaphirhynchus platorynchus in the wild and is a primary factor affecting growth both in the hatchery and in natural waters. We exposed juvenile shovelnose sturgeon to temperatures from 8°C to 30°C for 87 d to determine the effect of temperature on growth, condition, feed efficiency, and survival. Growth occurred at temperatures from 12°C to 30°C; the optimal temperature predicted by regression analysis was 22.4°C, and the minimum temperature needed for growth was greater than 10.0°C. The maximum feed efficiency predicted by regression analysis was 24.5% at 21.7°C, and condition factor was highest in the 18°C treatment. Mortality was significantly higher at 28°C and 30°C than at lower temperatures but less than 10% across the thermal regimes tested and 0% at 14‐18°C. Mortality was observed at and below 12°C, suggesting that extended periods of low temperature may deplete energy reserves and lead to higher mortality. Rearing juvenile shovelnose sturgeon at temperatures above 24°C reduced the growth rate and feed efficiency and increased mortality. Temperatures in the range 18‐20°C appeared to maximize the combination of condition, growth, and feed efficiency while not increasing thermal stress. This study corroborates field studies suggesting that altered temperature regimes in the upper Missouri River reduce the growth of shovelnose sturgeon. This information may help protect the thermal habitat critical to the species and guide restoration efforts by delineating temperature regime standards for regulated rivers and those affected by hydroelectric facilities and suggesting new criteria for conservation propagation.
Energy Density of Introduced Round Goby Compared with Four Native Fishes in a Lake Michigan Tributary
Authors: Ruetz Carl R. , Strouse Dana L. , Pothoven Steven A.
Published: October 2009

The round goby Neogobius melanostomus is an invasive species that has changed Great Lakes food webs and become an important prey for many predators. We tested whether the round goby from a Lake Michigan tributary was energetically equivalent to four native fishes: Mottled sculpin Cottus bairdii, johnny darter Etheostoma nigrum, bluntnose minnow Pimephales notatus, and rock bass Ambloplites rupestris. We found positive linear relationships between energy density and the percent dry weight of a fish for each species. We also found evidence of temporal and spatial variation in round goby energy density. Energy density was lower in spring and summer than in fall. The spatial variation in energy density may be linked to the inclusion of the low‐quality prey, dreissenid mussels, in the diets of larger round goby. For a given size, the johnny darter and bluntnose minnow had the highest energy density while mottled sculpin had the lowest. Our results show that the energy density of the round goby is intermediate to those of the four native fishes, suggesting that the round goby is an energetically average prey in a Lake Michigan tributary.
Lethality of Sea Lamprey Parasitism on Lake Sturgeon
Authors: Patrick Holly K. , Sutton Trent M. , Swink William D.
Published: October 2009

Parasitism by sea lampreys Petromyzon marinus may contribute to the delayed recovery of imperiled populations of lake sturgeon Acipenser fulvescens in the Great Lakes. Our study objectives were to examine the survival, growth, and condition of four size‐classes of lake sturgeon following a single sea lamprey attack. Lake sturgeon from one of four size‐groups (I: 470‐570 mm fork length; II: 570‐650 mm; III: 650‐760 mm; and IV: 950‐1,500 mm) were individually subjected to a sea lamprey attack in a series of 55 experimental trials. Direct mortality of lake sturgeon, resulting from acute anemia after an attack, was greatest for smaller lake sturgeon (I: 11%; II: 31%; III: 8%; IV: 0%). Similarly, indirect mortality resulting from secondary fungal infection was also size dependent (I: 11%; II: 19%; III: 8%; IV: 0%). No direct relationship was found between attachment duration and host survival; short intense attachments were as likely to result in host mortality as longer attachments. More than 50% of sea lamprey attacks occurred on the ventral surface of the rostrum or pectoral fin axils, and attachment at these locations resulted in the mortality of the host more often than did attachments at other locations. Declines in lake sturgeon growth and condition after an attack were more pronounced for smaller (size‐classes I‐III) than larger (size‐class IV) lake sturgeon hosts. Although much uncertainty remains about the effects of sea lamprey parasitism on lake sturgeon, the levels of mortality observed in this study suggest that the no‐observable‐effect lampricide treatment protocol, which is designed to protect larval lake sturgeon at the expense of increased production of sea lampreys, may not be the optimal strategy for the concurrent rehabilitation of self‐sustaining lake sturgeon populations and sea lamprey control in the Great Lakes.