bluuebunny/crossref_metadata_2025 huggingface dataset:
Backwater controls of avulsion location on deltas
Authors: Chatanantavet Phairot , Lamb Michael P. , Nittrouer Jeffrey A.
Published: December 2011

River delta complexes are built in part through repeated river‐channel avulsions, which often occur about a persistent spatial node creating delta lobes that form a fan‐like morphology. Predicting the location of avulsions is poorly understood, but it is essential for wetland restoration, hazard mitigation, reservoir characterization, and delta morphodynamics. Following previous work, we show that the upstream distance from the river mouth where avulsions occur is coincident with the backwater length, i.e., the upstream extent of river flow that is affected by hydrodynamic processes in the receiving basin. To explain this observation we formulate a fluvial morphodynamic model that is coupled to an offshore spreading river plume and subject it to a range of river discharges. Results show that avulsion is less likely in the downstream portion of the backwater zone because, during high‐flow events, the water surface is drawn down near the river mouth to match that of the offshore plume, resulting in river‐bed scour and a reduced likelihood of overbank flow. Furthermore, during low‐discharge events, flow deceleration near the upstream extent of backwater causes enhanced deposition locally and a reduced channel‐fill timescale there. Both mechanisms favor preferential avulsion in the upstream part of the backwater zone. These dynamics are fundamentally due to variable river discharges and a coupled offshore river plume, with implications for predicting delta response to climate and sea level change, and fluvio‐deltaic stratigraphy.
Space‐time distribution of afterslip following the 2009 L'Aquila earthquake
Authors: D'Agostino N. , Cheloni D. , Fornaro G. , Giuliani R. , Reale D.
Published: December 2011

The inversion of multitemporal DInSAR and GPS measurements unravels the coseismic and postseismic (afterslip) slip distributions associated with the 2009 MW 6.3 L'Aquila earthquake and provides insights into the rheological properties and long‐term behavior of the responsible structure, the Paganica fault. Well‐resolved patches of high postseismic slip (10–20 cm) appear to surround the main coseismic patch (maximum slip ≈1 m) through the entire seismogenic layer above the hypocenter without any obvious depth‐dependent control. Time series of postseismic displacement are well reproduced by an exponential function with best‐fit decay constants in the range of 20–40 days. A sudden discontinuity in the evolution of released postseismic moment at ≈130 days after the main shock does not correlate with independent seismological and geodetic data and is attributed to residual noise in the InSAR time series. The data are unable to resolve migration of afterslip along the fault probably because of the time interval (six days) between the main shock and the first radar acquisition. Surface fractures observed along the Paganica fault follow the steepest gradients of postseismic line‐of‐sight satellite displacements and are consistent with a sudden and delayed failure of the shallow layer in response to upward tapering of slip. The occurrence of afterslip at various levels through the entire seismogenic layer argues against exclusive depth‐dependent variations of frictional properties on the fault, supporting the hypothesis of significant horizontal frictional heterogeneities and/or geometrical complexities. We support the hypothesis that such heterogeneities and complexities may be at the origin of the long‐term variable behavior suggested by the paleoseismological studies. Rupture of fault patches with dimensions similar to that activated in 2009 appears to have a ≈500 year recurrence time interval documented by paleoseismic and historical studies. In addition to that, paleoseismological evidence of large (>0.5 m) coseismic offsets seems to require seismic events, recurring every 1000–2000 years, characterized by (1) multisegment linkage, (2) surface ruptures larger than in 2009, and (3) complete failure of the 2009 coseismic and postseismic patches.
A simple analytic approximation to the Rayleigh-Bénard stability threshold
Authors: Prosperetti Andrea
Published: December 2011

The Rayleigh-Bénard linear stability problem is solved by means of a Fourier series expansion. It is found that truncating the series to just the first term gives an excellent explicit approximation to the marginal stability relation between the Rayleigh number and the wave number of the perturbation. Where the error can be compared with published exact results, it is found not to exceed a few percent over the entire wave number range. Several cases with no-slip boundaries of equal or unequal thermal conductivities are considered explicitly.
Asymptotic behavior of a retracting two-dimensional fluid sheet
Authors: Gordillo Leonardo , Agbaglah Gilou , Duchemin Laurent , Josserand Christophe
Published: December 2011

Two-dimensional (2D) capillary retraction of a viscous liquid film is studied using numerical and analytical approaches for both diphasic and free surface flows. Full 2D Navier-Stokes equations are integrated numerically for the diphasic case, while one-dimensional (1D) free surface model equations are used for free surface flows. No pinch-off is observed in the film in any of these cases. By means of an asymptotic matching method on the 1D model, we derive an analytical expansion of the film profile for large times. Our analysis shows that three regions with different timescales can be identified during retraction: the rim, the film, and an intermediate domain connecting these two regions. The numerical simulations performed on both models show good agreement with the analytical results. Finally, we report the appearance of an instability in the diphasic retracting film for small Ohnesorge number. We understand this as a Kelvin-Helmholtz instability arising due to the formation of a shear layer in the neck region during the retraction.
Existence of product vectors and their partial conjugates in a pair of spaces
Authors: Kiem Young-Hoon , Kye Seung-Hyeok , Lee Jungseob
Published: December 2011

Let D and E be subspaces of the tensor product of the m- and n-dimensional complex spaces, with co-dimensions k and ℓ, respectively. In order to give upper bounds for ranks of entangled edge states with positive partial transposes, we show that if k + ℓ < m + n − 2, then there must exist a product vector in D whose partial conjugate lies in E. If k + ℓ = m + n − 2, then such a product vector may or may not exist depending on k and ℓ.
Three-by-three bound entanglement with general unextendible product bases
Authors: Skowronek Łukasz
Published: December 2011

We discuss the subject of unextendible product bases with the orthogonality condition dropped and we prove that the lowest rank non-separable positive-partial-transpose states, i.e., states of rank 4 in 3 × 3 systems are always locally equivalent to a projection onto the orthogonal complement of a linear subspace spanned by an orthogonal unextendible product basis. The product vectors in the kernels of the states belong to a non-zero measure subset of all general unextendible product bases, nevertheless, they can always be locally transformed to the orthogonal form. This fully confirms the surprising numerical results recently reported by Leinaas et al. Parts of the paper rely heavily on the use of Bezout's theorem from algebraic geometry.
A data-integrated method for analyzing stochastic biochemical networks
Authors: Chevalier Michael W. , El-Samad Hana
Published: December 2011

Variability and fluctuations among genetically identical cells under uniform experimental conditions stem from the stochastic nature of biochemical reactions. Understanding network function for endogenous biological systems or designing robust synthetic genetic circuits requires accounting for and analyzing this variability. Stochasticity in biological networks is usually represented using a continuous-time discrete-state Markov formalism, where the chemical master equation (CME) and its kinetic Monte Carlo equivalent, the stochastic simulation algorithm (SSA), are used. These two representations are computationally intractable for many realistic biological problems. Fitting parameters in the context of these stochastic models is particularly challenging and has not been accomplished for any but very simple systems. In this work, we propose that moment equations derived from the CME, when treated appropriately in terms of higher order moment contributions, represent a computationally efficient framework for estimating the kinetic rate constants of stochastic network models and subsequent analysis of their dynamics. To do so, we present a practical data-derived moment closure method for these equations. In contrast to previous work, this method does not rely on any assumptions about the shape of the stochastic distributions or a functional relationship among their moments. We use this method to analyze a stochastic model of a biological oscillator and demonstrate its accuracy through excellent agreement with CME/SSA calculations. By coupling this moment-closure method with a parameter search procedure, we further demonstrate how a model's kinetic parameters can be iteratively determined in order to fit measured distribution data.
Electronic transport behavior of off-stoichiometric La and Nb doped SrxTiyO3−δ epitaxial thin films and donor doped single-crystalline SrTiO3
Authors: Baniecki J. D. , Ishii M. , Aso H. , Kobayashi K. , Kurihara K. , Yamanaka K. , Vailionis A. , Schafranek R.
Published: December 2011

Above room temperature electronic transport properties of SrxTiyO3−δ films with cation A/B = (La + Sr/Nb + Ti) ratios of 0.9 to 1.2 are compared to STO single crystals with combined Hall carrier densities of 3 × 1016 cm−3 ≤ nH ≤ 1022 cm−3. In contrast to Hall mobility which is single crystal-like (μH ≈ 6 cm2/Vs) only near A/B = 1, the Seebeck coefficient (S) is single crystal-like over a range of nonstoichiometry. For nH < 1020 cm−3, S is well described by nondegenerate band-like transport with a constant effective mass m∗/mo ≈ 5–8. For nH > 1021 cm−3, S is metallic-like with m∗/mo ∼ 8. No marked increase in m∗ with decreasing nH owing to a carrier filling dependence is observed.
Variability of contact process in complex networks
Authors: Gong Kai , Tang Ming , Yang Hui , Shang Mingsheng
Published: December 2011

We study numerically how the structures of distinct networks influence the epidemic dynamics in contact process. We first find that the variability difference between homogeneous and heterogeneous networks is very narrow, although the heterogeneous structures can induce the lighter prevalence. Contrary to non-community networks, strong community structures can cause the secondary outbreak of prevalence and two peaks of variability appeared. Especially in the local community, the extraordinarily large variability in early stage of the outbreak makes the prediction of epidemic spreading hard. Importantly, the bridgeness plays a significant role in the predictability, meaning the further distance of the initial seed to the bridgeness, the less accurate the predictability is. Also, we investigate the effect of different disease reaction mechanisms on variability, and find that the different reaction mechanisms will result in the distinct variabilities at the end of epidemic spreading.
Thinking outside the box: The uniform electron gas on a hypersphere
Authors: Loos Pierre-François , Gill Peter M. W.
Published: December 2011

We discuss alternative homogeneous electron gas systems in which a finite number n of electrons are confined to a D-dimensional sphere. We derive the first few terms of the high-density (rs → 0, where rs is the Seitz radius) energy expansions for these systems and show that, in the thermodynamic limit (n → ∞), these terms become identical to those of D-dimensional jellium.
Photoacoustic determination of the speed of sound in single crystal cyclotrimethylene trinitramine at acoustic frequencies from 0.5 to 15 GHz
Authors: Johnson Jeremy A. , Manke Kara J. , Veysset David G. , Maznev A. A. , Ramos Kyle J. , Hooks Daniel E. , Nelson Keith A.
Published: December 2011

We report photoacoustic measurements of the quasi-longitudinal speed of sound along different crystallographic directions in the energetic molecular crystal cyclotrimethylene trinitramine (RDX). Measurements in (100)-oriented RDX were made using two complimentary techniques to probe acoustic frequencies from 0.5 to 15 GHz to resolve large discrepancies in reported sound speed values measured using different techniques and frequency ranges. In impulsive stimulated light scattering (ISS), two laser beams were crossed at various angles in a sample to generate coherent acoustic waves with well-defined wavevectors. Picosecond acoustic interferometry (PAI) measurements were conducted in which a laser pulse heated a thin metal transducer layer coated on the sample surface to generate a broadband acoustic wave-packet that propagated into the sample. Time-dependent coherent Brillouin scattering of probe light from the acoustic waves revealed frequencies in the 0.5–3.5 GHz range in ISS measurements and at ∼15 GHz in the PAI measurements, yielding the speed of sound in each case. Our ISS results are in agreement with previous ultrasonic and ISS measurements at kilo- and megahertz frequencies. Our PAI results yielded a 15 GHz sound speed essentially equal to those at megahertz frequencies in contrast to an earlier report based on Brillouin light scattering measurements. The lack of acoustic dispersion over six orders of magnitude in frequency indicates that there is no relaxation process that significantly couples to acoustic waves in RDX at acoustic frequencies up to 15 GHz.
Survey of Pathogens in Hatchery Chinook Salmon with Different Out-Migration Histories through the Snake and Columbia Rivers
Authors: Van Gaest A. L. , Dietrich J. P. , Thompson D. E. , Boylen D. A. , Strickland S. A. , Collier T. K. , Loge F. J. , Arkoosh M. R.
Published: December 2011

The operation of the Federal Columbia River Power System (FCRPS) has negatively affected threatened and endangered salmonid populations in the Pacific Northwest. Barging Snake River spring Chinook salmon Oncorhynchus tshawytscha through the FCRPS is one effort to mitigate the effect of the hydrosystem on juvenile salmon out-migration. However, little is known about the occurrence and transmission of infectious agents in barged juvenile salmon relative to juvenile salmon that remain in-river to navigate to the ocean. We conducted a survey of hatchery-reared spring Chinook salmon at various points along their out-migration path as they left their natal hatcheries and either migrated in-river or were barged through the FCRPS. Salmon kidneys were screened by polymerase chain reaction for nine pathogens and one family of water molds. Eight pathogens were detected; the most prevalent were Renibacterium salmoninarum and infectious hematopoietic necrosis virus. Species in the family Saprolegniaceae were also commonly detected. Pathogen prevalence was significantly greater in fish that were barged through the FCRPS than in fish left to out-migrate in-river. These results suggest that the transmission of infectious agents to susceptible juvenile salmon occurs during the barging process. Therefore, management activities that reduce pathogen exposure during barging may increase the survival of juvenile Chinook salmon after they are released.

Received May 27, 2010; accepted January 17, 2011
Influence of Dreissenid Mussels on Catchability of Benthic Fishes in Bottom Trawls
Authors: Kocovsky Patrick M. , Stapanian Martin A.
Published: December 2011

Inferring trends in true abundance of fish populations from catch per unit effort data requires either the knowledge of capture probability or the assumption that it is constant, both of which are unlikely contingencies. We developed and validated an index of catchability (a proxy measure for capture probability) from a long‐term data set describing nearshore waters of western Lake Erie, and we used the index to test the hypothesis that catchability of four abundant benthic species captured in bottom trawls changed after the invasion of dreissenid mussels. We estimated daytime and nighttime catchability for 1972–1990 (predreissenid period) and 1991–2009 (dreissenid period); we then tested for differences between nighttime and daytime catchability in the predreissenid and dreissenid periods and the nighttime–daytime differential in catchability during the dreissenid period. We also tested relationships between Secchi depth and the catchability index via linear regression. Catchability indices for white perch Morone americana, yellow perch Perca flavescens, and trout‐perch Percopsis omiscomaycus did not differ between daytime and nighttime during the predreissenid period. After establishment of dreissenids, all three of these species had lower daytime catchability than nighttime catchability and had positive nighttime–daytime differentials, indicating a shift toward higher nighttime catchability relative to daytime catchability. Changes in catchability indices for freshwater drum Aplodinotus grunniens were opposite the changes observed for the other three species, possibly because the freshwater drum is the only species that actively feeds on dreissenids. Catchability indices were negatively related to water clarity (Secchi depth) for three of the species. Our results are consistent with the hypothesis that catchability of the four most common benthic fish species captured in bottom trawls within nearshore waters of western Lake Erie changed after the dreissenid invasion because of increased water clarity and increased visibility, which led to greater daytime trawl avoidance.
Factors Affecting Walleye Catch in Short-Term Gill-Net Sets in a Large Minnesota Lake
Authors: Schmalz Patrick J. , Staples David F.
Published: December 2011

Gill nets are a versatile fish sampling gear used for many species and habitats; however, their usefulness may be limited by selectivity patterns and reliance on fish movement, which can be influenced by several factors. We evaluated the effect of net length, time of day, sampling date, surface water temperature, soak time, water depth, and location on the number, length, and initial mortality of walleyes Sander vitreus caught in short-term (mean, 38.8 min; range, 10–200 min) gill nets set in Mille Lacs Lake, Minnesota. The number of walleyes caught was best described by a generalized additive model (GAM) that contained all seven covariates and explained 35% of the variation in catch. The length of walleyes caught was best described by a GAM that contained time of day, sampling date, soak time, and sampling location as covariates and explained 11% of the variation in fish length. The initial mortality of walleyes was best described by a GAM that included surface water temperature and soak time as covariates. Walleye catches were higher from dusk to dawn than at other times, with peak catches occurring around 0500 and 2100 hours, demonstrating the diel activity patterns of walleyes. Catches also increased with surface water temperature and soak time. However, the initial mortality of walleyes also increased with surface water temperature and soak time, with the largest increase in initial mortality at soak times longer than 60 min. Investigators can use these results to assist in designing and planning short-term gill-netting efforts to maximize the catch and minimize the mortality of walleyes.

Received June 23, 2010; accepted October 22, 2010
Development of a Riverine Index Netting Protocol: Comparisons of Net Orientation, Height, Panel Order, and Line Diameter
Authors: Jones Nicholas E. , Yunker Geoffrey B.
Published: December 2011

We developed a gillnetting protocol by sampling 17 nonwadeable rivers across northern Ontario over the course of four summers from 2005 to 2008. The rivers represented a range of habitats; however, all had a coolwater to warmwater fish community characterized by walleyes Sander vitreus, northern pike Esox lucius, white suckers Catostomus commersonii, yellow perch Perca flavescens, and smallmouth bass Micropterus dolomieu. During the study, three net designs were used. Each net had one to four configurations that varied in height, length, monofilament diameter, and sequence of the mesh sizes. We found that most fish (87%) were captured in the lower half of 1.8-m-high gill nets and that there was no difference in catch between gill nets with serial panels (i.e., sequentially increasing mesh sizes) and those with randomly organized panels. Net that were set perpendicular to shore or angled to shore caught approximately twice as many fish as nets that were set parallel to shore. Contrary to expectations, there were no differences in net durability and catch between thick- and thin-diameter monofilament nets. Based on the results of these experiments, we propose an improved net design that we call the large-mesh riverine index net for use in rivers; it is more versatile, reduces net drag, and fishes more effectively than the traditional gill nets that are used in lakes. The large-mesh riverine index net has eight panels (3.1 m long × 0.9 m high) and totals 24.8 m in length. Panel stretch measures (and the random order used) for this design are 127, 76, 178, 25, 102, 203, 51, and 152 mm. The nets are set perpendicular to shore in rivers from July 1 to October 1 and should be fished in areas where water velocity is less than 0.1 m/s.

Received January 12, 2010; accepted November 2, 2010
Sensitivity of Recreational Access to Reservoir Water Level Variation: An Approach to Identify Future Access Needs in Reservoirs
Authors: Daugherty Daniel J. , Buckmeier David L. , Kokkanti Praveen K.
Published: December 2011

Reservoirs support popular sport fisheries and other forms of water recreation. However, access to these systems is often sensitive to variation in water level. Increasing water demands due to population growth and the effects of climate change suggest that maintaining adequate recreational access to reservoirs will become increasingly difficult. Knowledge of the effects of water level variation on boat and shoreline access is required to identify future needs and to aid in prioritizing improvement efforts that promote participation in fishing and aquatic recreation. To address this need, we developed a geographical information systems-based approach to quantify the effects of reservoir water level variation on recreational access and applied the technique to three Colorado River reservoirs in Texas: Lake Buchanan, Lake Travis, and Lyndon B. Johnson Reservoir. The data were used to identify reservoir-specific water levels (m below full pool) at which the availability of access was adversely affected. For the three reservoirs, 33–39% of boat access sites were dewatered with 1–3-m reductions in water level, over 50% of access sites were unusable with an additional 1–2-m loss of water level (i.e., 2–4-m reductions), and over 75% of access sites were lost with 4–8-m reductions in water level. The effect of water level reductions was less for shoreline access than for boat access. Historic water levels in each reservoir were then compared with a regional water availability model to estimate future trends in access for each reservoir. Reservoirs exhibited contrasting trends in future accessibility, ranging from a 92–500% decrease in access for Lake Buchanan to a 5–31% increase for Lake Travis. The techniques developed in this study will assist fisheries managers in working with water authorities and policy makers to minimize, mitigate, or prevent negative effects on recreational access and will aid in identifying and prioritizing reservoirs that require future access improvements.

Received June 25, 2010; accepted December 27, 2010
Performance of Diploid and Triploid Rainbow Trout Stocked in Idaho Alpine Lakes
Authors: Koenig Martin K. , Kozfkay Joseph R. , Meyer Kevin A. , Schill Daniel J.
Published: December 2011

Increased growth, improved survival, and genetic protection of wild stocks have been suggested as benefits of stocking triploid (i.e., sterile) salmonids for recreational fisheries. We examined the return rates and growth of mixed-sex diploid (2N), mixed-sex triploid (3N), and all-female triploid (AF3N) rainbow trout Oncorhynchus mykiss across 28 alpine lakes. Equal numbers of each treatment group were stocked in 2001 and 2003 and sampled 3–4 years later. During 2004 and 2005, a total of 75 2N and 36 3N marked rainbow trout were recaptured. Taken together, the 2N fish accounted for an average of 0.68 of the total marked fish caught, and the combined proportions of test fish (including netting and angling) differed significantly between the test groups and were consistent across survey years. During 2006 and 2007, a total of 60 2N, 31 3N, and 208 AF3N marked rainbow trout were recaptured. The mean length of the test fish was similar between test groups within sampling years. Overall, the return of 3N rainbow trout to alpine lakes in Idaho was low compared with that of 2N trout, whereas AF3N trout appeared to return in higher proportions than both of the other groups. The triploid stocks studied in this evaluation did not show any growth advantages over the duration of the study. Study design limitations may have contributed in part to some of the differences in the number of 2N and 3N rainbow trout captured. However, our results suggest that fisheries managers should consider all-female triploid rainbow trout as a low-risk option for maintaining alpine lake fisheries while minimizing the impact on native stocks.

Received January 27, 2010; accepted November 16, 2010
Recovery of Coded Wire Tags at a Caspian Tern Colony in San Francisco Bay: A Technique to Evaluate Impacts of Avian Predation on Juvenile Salmonids
Authors: Evans Allen F. , Roby Daniel D. , Collis Ken , Cramer Bradley M. , Sheggeby John A. , Adrean Lindsay J. , Battaglia Daniel S. , Lyons Donald E.
Published: December 2011

We recovered coded wire tags (CWTs) from a colony of Caspian terns Hydroprogne caspia on Brooks Island in San Francisco Bay, California, to evaluate predation on juvenile salmonids originating from the Sacramento and San Joaquin rivers. Subsamples of colony substrate representing 11.7% of the nesting habitat used by the terns yielded 2,079 salmonid CWTs from fish released and subsequently consumed by terns in 2008. The estimated number of CWTs deposited on the entire tern colony was 40,143 (ranging from 26,763 to 80,288), once adjustments were made to account for tag loss and the total amount of nesting habitat used by terns. Tags ingested by terns and then egested on the colony were undamaged, and the tags’ complete numeric codes were still identifiable. The CWTs found on the tern colony indicated that hatchery Chinook salmon Oncorhynchus tshawytscha trucked to and released in San Pablo Bay were significantly more likely to be consumed by Caspian terns than Chinook salmon that migrated in-river to the bay; 99.7% of all tags recovered were from bay-released Chinook salmon. Of the CWTs recovered on the tern colony, 98.0% were from fall-run Chinook salmon, indicating a higher susceptibility to tern predation than for the spring run type. None of the approximately 518,000 wild Chinook salmon that were coded-wire-tagged and released in the basin were recovered on the tern colony, suggesting that the impacts on wild, U.S. Endangered Species Act–listed Chinook salmon populations were minimal in 2008. Overall, we estimate that 0.3% of the approximately 12.3 million coded-wire-tagged Chinook salmon released in the basin in 2008 were subsequently consumed by Caspian terns from the Brooks Island colony. These results indicate that CWTs implanted in juvenile salmon can be recovered from a piscivorous waterbird colony and used to evaluate smolt losses for runs that are tagged.

Received January 25, 2010; accepted December 13, 2010
Assessing the Reliability of Fisher Self-Sampling Programs
Authors: Roman Sally , Jacobson Nikki , Cadrin Steven X.
Published: December 2011

The transition to catch share management for groundfish fisheries in the waters off the northeastern USA will require more monitoring than is presently obtained through traditional programs. Other types of at-sea reporting may be necessary to address data gaps and complement other sampling programs like the Northeast Fisheries Observer Program (NEFOP). Validation of fisher self-sampling programs, such as the study fleet program of the School for Marine Science and Technology (University of Massachusetts Dartmouth), provides another monitoring option to be used in conjunction with existing systems. In this paper, data from the study fleet program were compared with other fisheries-dependent data sources in the region. We tested for significant differences in catch at the trip, species, and haul levels by disposition (i.e., kept and discarded). Effort and length measurements for six commercial species were also analyzed. Catch results were mixed but similar for commercial species across comparisons. The study fleet program and NEFOP had consistent reporting in comparison with dealer landings, which are reported to the National Marine Fisheries Service by seafood dealers that are issued a federal permit to sell fish. For comparisons of catch at the haul level, there was a significant difference between NEFOP data and study fleet data; median differences were small, and the study fleet reported less catch. For commercial species, there was no significant difference in catch (except for kept catch) between the study fleet data and NEFOP data. Study fleet catch data were more comprehensive than logbook data (e.g., study fleet data included catch of bycatch species). Effort data from the study fleet were more accurate and precise than logbook data and were similar to NEFOP data. There was no statistical difference in length frequencies based on study fleet data and NEFOP data.

Received April 16, 2010; accepted November 26, 2010
Comparison of Boat Electrofishing, Trawling, and Seining for Sampling Fish Assemblages in Iowa's Nonwadeable Rivers
Authors: Neebling Travis E. , Quist Michael C.
Published: December 2011

The effect of reach length on species richness (estimated with boat-mounted electrofishing, a modified Missouri trawl, and a bag seine) was evaluated in Iowa's nonwadeable river systems. In 2007 and 2008, 21 reaches were sampled on 16 nonwadeable rivers throughout Iowa; reaches were 3 or 5 km in length, depending on stream order. A total of 21,197 fish from 83 species were sampled in this study. Electrofishing produced the highest number of species (65), followed by trawling (60) and seining (54). Forty-seven percent of all the species sampled in this study were captured by all three gears. Four species were captured only by the seine, 8 only by the trawl, and 13 only by electrofishing. Fish sampling data were used to evaluate gears and estimate the number of samples required to observe specified percentages of the total number of species in each reach. The minimum effort necessary to sample 90% of the species in a reach with 95% confidence was determined using a resampling procedure. Sampling with a seine was considered ineffective in nonwadeable rivers and did not substantially reduce the effort necessary to sample 90% of the species in a reach. In 3-km-long reaches, the minimum effort necessary to sample 90% of the species observed was fifteen 100-m electrofishing runs and twenty-four 50-m-long trawls. Twenty-five 100-m electrofishing runs and forty-two 50-m-long trawls were necessary to sample 90% of the species observed in 5-km-long reaches.

Received October 13, 2009; accepted January 27, 2011
A Portable Electronarcosis System for Anesthetizing Salmonids and Other Fish
Authors: Hudson J. Michael , Johnson Jeffrey R. , Kynard Boyd
Published: December 2011

The physiological responses of fish to continuous (nonpulsed) direct current were first described in the 1960s. One of these responses, electronarcosis (anesthesia, accompanied by muscle relaxation, through electrical inhibition), has been used in fisheries research and management as an anesthetic since the 1970s. We provide details on the assembly and operation of a portable electronarcosis unit for fish anesthesia and describe its performance with respect to two species of salmonids. The portability and effectiveness of this approach make electronarcosis a viable alternative to existing anesthetics that can be used for a number of applications.

Received June 8, 2010; accepted January 27, 2011
Postrelease Survival of Sublegal Southern Flounder Captured in a Commercial Gill-Net Fishery
Authors: Smith William E. , Scharf Frederick S.
Published: December 2011

Discards from commercial fisheries may be subject to high rates of mortality that vary over time and space, contributing to inaccuracies in stock assessments. We present the results from a field experiment in the New River estuary, North Carolina, designed to estimate the postrelease survival of commercially gill-netted, sublegal southern flounder Paralichthys lethostigma. Large, replicate field enclosures were used to monitor gill-netted southern flounder for a 3-d period after capture. The survival of observed discards showed significant variation among seasons. During fall and spring, overall survival was estimated to fall between 0.74 and 0.87, while during summer survival was estimated to fall between 0.22 and 0.30 and included fish that were dead when gill nets were retrieved. Logistic regression analysis was used to evaluate the relative effects of individual traits on the postrelease survival of southern flounder in the commercial gill-net fishery. Model selection indicated that season and fish condition were the best characteristics with which to predict postrelease survival and that body size may also influence postrelease survival. Low seasonal estimates of the survival of discarded southern flounder suggest that management measures that mitigate poor discard survival will be most effective during the summer.

Received November 11, 2010; accepted February 17, 2011
Spring Capture Site Fidelity of Adult Muskellunge in Inland Lakes
Authors: Jennings Martin J. , Hatzenbeler Gene R. , Kampa Jeffrey M.
Published: December 2011

Behaviors that affect the distribution of fish within aquatic systems are important considerations in the design of sampling programs. Although movements consistent with reproductive homing have been documented for muskellunge Esox masquinongy in relatively large, complex systems, quantitative data describing their distribution at the restricted spatial scale relevant to small lake fisheries are lacking. We sampled muskellunge by means of fyke netting over 2 years in each of four Wisconsin lakes with surface areas between 110 and 588 ha. Individual capture locations were recorded. Each muskellunge sampled during the first year was injected with a passive integrated transponder to allow identification of the individuals recaptured during the second year. The number of recaptures with functional transponders during the second year ranged from 15 to 43 per lake. Capture site fidelity, defined as the percentage of recaptured fish being found in the same spawning area in two consecutive years, varied from 55% to 93%. The results are relevant to population estimation and broodstock collection for artificial propagation. Population estimates need to include all spawning habitats because marked and unmarked fish are not well mixed throughout the lake during the spawning season. Because repeated netting effort at the same locations among years is likely to resample individuals used for broodstock collection, netting effort should be dispersed among spawning sites.

Received October 21, 2010; accepted February 18, 2011
Impervious Surface, Summer Dissolved Oxygen, and Fish Distribution in Chesapeake Bay Subestuaries: Linking Watershed Development, Habitat Conditions, and Fisheries Management
Authors: Uphoff James H. , McGinty Margaret , Lukacovic Rudolph , Mowrer James , Pyle Bruce
Published: December 2011

We estimated target and limit impervious surface reference points (ISRPs) based on Chesapeake Bay dissolved oxygen (DO) criteria, and we examined associations and relationships among the percentage of watershed in impervious surface (IS), summer DO, and the presence of indicator species (blue crab Callinectes sapidus, white perch Morone americana, striped bass M. saxatilis, and spot Leiostomus xanthurus) in bottom waters of nine brackish subestuaries of Chesapeake Bay. Ideally, a target ISRP represented a level of development that maintained mean bottom DO at 5 mg/L or greater, while an ISRP threshold represented development that degraded mean bottom DO to less than 3 mg/L. The proportion of bottom trawls containing each indicator species rapidly declined from about 0.40 to 0.10 when DO fell below 3 mg/L, whereas the proportion remained at about 0.50 when DO was above 5 mg/L. The IS percentage had a significant negative influence on mean bottom DO and the odds that indicator species were present in midchannel bottom waters (0.8–7.0 m deep). Watersheds at or below a target IS of 5.5% (rural watershed) maintained mean bottom DO above 3 mg/L, but mean DO was only occasionally at or above 5 mg/L. Mean DO seldom exceeded 3 mg/L in watersheds with an IS value above 10% (suburban threshold). Comprehensive watershed management will be needed to offset significant degradation of bottom-water fish habitat in brackish subestuaries if rural lands are converted to suburban areas.

Received July 6, 2010; accepted March 23, 2011
A Comparison of Egg Funnel and Egg Bag Estimates of Egg Deposition in Grand Traverse Bay, Lake Michigan
Authors: Barton Nathan T. , Galarowicz Tracy L. , Claramunt Randall M. , Fitzsimons John D.
Published: December 2011

Reefs are used for spawning by Great Lakes fishes such as the lake trout Salvelinus namaycush, lake whitefish Coregonus clupeaformis, and cisco C. artedi. We designed egg funnels as a new type of sampling gear for quantifying egg deposition while minimizing losses of eggs to physical disturbance and predation. Egg funnels were compared with traditionally used egg bags to quantify egg deposition by spawning fish. In addition, the efficiencies of the egg funnels and egg bags were measured by seeding each gear type with artificial lake trout and lake whitefish eggs in situ. Egg funnels were as efficient as or more efficient than egg bags for capturing artificial eggs and naturally deposited lake trout eggs in both 2008 and 2009. Egg funnels had lower efficiency than egg bags for capture of natural coregonid eggs in 2008, potentially due to avoidance of the gear by spawners; gear avoidance was reduced by burying the egg funnels more deeply in 2009. Accurate estimates of egg deposition will assist fisheries managers in making more-informed decisions for management actions, such as stocking strategies and habitat protection.

Received November 29, 2010; accepted April 26, 2011
Evaluation of Offshore Stocking of Lake Trout in Lake Ontario
Authors: Lantry B. F. , O'Gorman R. , Strang T. G. , Lantry J. R. , Connerton M. J. , Schaner T.
Published: December 2011

Restoration stocking of hatchery-reared lake trout Salvelinus namaycush has occurred in Lake Ontario since 1973. In U.S. waters, fish stocked through 1990 survived well and built a large adult population. Survival of yearlings stocked from shore declined during 1990–1995, and adult numbers fell during 1998–2005. Offshore stocking of lake trout was initiated in the late 1990s in response to its successful mitigation of predation losses to double-crested cormorants Phalacrocorax auritus and the results of earlier studies that suggested it would enhance survival in some cases. The current study was designed to test the relative effectiveness of three stocking methods at a time when poststocking survival for lake trout was quite low and losses due to fish predators was a suspected factor. The stocking methods tested during 2000–2002 included May offshore, May onshore, and June onshore. Visual observations during nearshore stockings and hydroacoustic observations of offshore stockings indicated that release methods were not a direct cause of fish mortality. Experimental stockings were replicated for 3 years at one site in the southwest and for 2 years at one site in the southeast. Offshore releases used a landing craft to transport hatchery trucks from 3 to 6 km offshore out to 55–60-m-deep water. For the southwest site, offshore stocking significantly enhanced poststocking survival. Among the three methods, survival ratios were 1.74 : 1.00 : 1.02 (May offshore : May onshore : June onshore). Although not statistically significant owing to the small samples, the trends were similar for the southeast site, with survival ratios of 1.67 : 1.00 : 0.72. Consistent trends across years and sites indicated that offshore stocking of yearling lake trout during 2000–2002 provided nearly a twofold enhancement in survival; however, this increase does not appear to be great enough to achieve the 12-fold enhancement necessary to return population abundance to restoration targets.

Received November 29, 2010; accepted May 18, 2011
Triploid Grass Carp: Triploid Induction, Sterility, Reversion, and Certification
Authors: Zajicek Paul , Goodwin Andrew E. , Weier Tina
Published: December 2011

Nonnative grass carp Ctenopharyngodon idella have been used in the United States to control aquatic plants for approximately 42 years and are widely dispersed across 45 states, with reproduction occurring in 7 Mississippi River basin states. To prevent grass carp establishment and spread, a functionally sterile version—triploid grass carp—was produced in the early 1980s. However, there is uncertainty today regarding sterility and the efforts associated with triploid grass carp production and distribution. We reviewed relevant literature to summarize biological issues of interest to fishery managers: cell division for sexual reproduction, the induction of triploidy, sterility, reversion from the triploidy to diploidy, and pertinent aspects of the U.S. Fish and Wildlife Service's triploid grass carp certification program.

Received December 13, 2010; accepted May 18, 2011
Summer Use of Side-Channel Thermal Refugia by Salmonids in the North Fork Coeur d'Alene River, Idaho
Authors: Stevens Bryan S. , DuPont Joseph M.
Published: December 2011

We observed aggregations of westslope cutthroat trout Oncorhynchus clarkii lewisi, mountain whitefish Prosopium williamsoni, and to a lesser extent, rainbow trout Oncorhynchus mykiss moving into cold side channels in the North Fork Coeur d'Alene River in northern Idaho during the summer of 2007. The use of cold side channels varied throughout the season, as well as by size-class. Such use was much greater for salmonids 300 mm or more in length, and the movement of salmonids into side channel habitats appeared to be triggered by rising water temperatures in the main river and temperature divergences between the main river and the side channels. Larger salmonids were not evenly distributed among the side channels, and channel physical features varied widely. The probability that a side channel would be used as a thermal refugium by salmonids 300 mm or more appeared to be influenced by channel depth, and salmonids of that size used side channels that were both deep (≥2 m) and cold (≤20°C). Protection of the remaining hyporheic flow paths and thermal refugia may be important for the conservation of summer habitat for westslope cutthroat trout in the lower North Fork Coeur d'Alene River.

Received July 29, 2010; accepted May 25, 2011
Guest Director's Line: AFS Policy Statement Regarding the Need for an Immediate-Release Anesthetic/Sedative for Use in the Fisheries Disciplines
Authors: Bowker Jim , Trushenski Jesse
Published: December 2011

Availability of safe and effective fish sedatives or anesthetics is crucial to fisheries research, management, and culture activities. If fish are sedated prior to handling, the risk to both fish and handler is minimized. Currently, there is no ideal compound that can be legally used on fish without adhering to a lengthy withdrawal period. The absence of a suitable immediate-release sedative jeopardizes fish, fisheries, fish culture, and research, posing a risk to aquatic resources as well as those handling fish. A document, “AFS Policy Statement on the Need for an Immediate-Release Anesthetic/ Sedative for Use in the Fisheries Disciplines,” has been drafted to (1) describe the impediments preventing fisheries professionals from having access to a suitable immediate-release sedative; (2) characterize the constraints that this issue places on aquatic natural resources management, fisheries research, and the private aquaculture industry; and (3) recommend a course of action to facilitate the timely approval of such a sedative, which will minimize risk to fish, fisheries professionals, the general public, and the environment.
Identification and Implementation of Native Fish Conservation Areas in the Upper Colorado River Basin
Authors: Dauwalter Daniel C , Sanderson John S , Williams Jack E , Sedell James R
Published: December 2011

Freshwater fishes continue to decline at a rapid rate despite substantial conservation efforts. Native fish conservation areas (NFCAs) are a management approach emphasizing persistent native fish communities and healthy watersheds while simultaneously allowing for compatible human uses. We identified potential NFCAs in the Upper Colorado River Basin in Wyoming—focusing on Colorado River cutthroat trout (Oncorhynchus clarkii pleuriticus), flannelmouth sucker (Catostomus latipinnis), bluehead sucker (Catostomus discobolus), and roundtail chub (Gila robusta)—through a process that combined known and modeled species distributions, spatial prioritization analysis, and stakeholder discussions. The network of potential NFCAs is intended to serve as a funding framework for a National Fish and Wildlife Foundation (NFWF) Keystone Initiative focused on Colorado River Basin native fishes. We discuss current opportunities for and impediments to implementing the potential NFCAs we identified for the NFWF Initiative over the long term. NFCAs represent a promising approach to fisheries management that complements existing approaches by focusing on persistent native fish communities.
A Hierarchical Spatial Framework and Database for the National River Fish Habitat Condition Assessment
Authors: Wang Lizhu , Infante Dana , Esselman Peter , Cooper Arthur , Wu Dayong , Taylor William , Beard Doug , Whelan Gary , Ostroff Andrea
Published: December 2011

Fisheries management programs, such as the National Fish Habitat Action Plan (NFHAP), urgently need a nationwide spatial framework and database for health assessment and policy development to protect and improve riverine systems. To meet this need, we developed a spatial framework and database using National Hydrography Dataset Plus (I-.100,000-scale); http://www.horizon-systems.com/nhdplus). This framework uses interconfluence river reaches and their local and network catchments as fundamental spatial river units and a series of ecological and political spatial descriptors as hierarchy structures to allow users to extract or analyze information at spatial scales that they define. This database consists of variables describing channel characteristics, network position/connectivity, climate, elevation, gradient, and size. It contains a series of catchment-natural and human-induced factors that are known to influence river characteristics. Our framework and database assembles aü river reaches and their descriptors in one place for the first time for the conterminous United States. This framework and database provides users with the capability of adding data, conducting analyses, developing management scenarios and regulation, and tracking management progresses at a variety of spatial scales. This database provides the essential data needs for achieving the objectives of NFHAP and other management programs. The downloadable beta version database is available at http://ec2-184-73-40-15.compute-1.amazonaws.com/nfhap/main/.