bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal variation of β-diversity and assembly mechanisms in a bacterial metacommunity
Authors: Langenheder Silke , Berga Mercè , Östman Örjan , Székely Anna J
Published: December 2011

The turnover of community composition across space, β-diversity, is influenced by different assembly mechanisms, which place varying weight on local habitat factors, such as environmental conditions and species interactions, and regional factors such as dispersal and history. Several assembly mechanisms may function simultaneously; however, little is known about how their importance changes over time and why. Here, we implemented a field survey where we sampled a bacterial metacommunity consisting of 17 rock pools located at the Swedish Baltic Sea coast at 11 occasions during 1 year. We determined to which extent communities were structured by different assembly mechanisms using variation partitioning and studied changes in β-diversity across environmental gradients over time. β-Diversity was highest at times of high overall productivity and environmental heterogeneity in the metacommunity, at least partly due to species sorting, that is, selection of taxa by the prevailing environmental conditions. In contrast, dispersal-driven assembly mechanisms were primarily detected at times when β-diversity was relatively low. There were no indications for strong and persistent differences in community composition or β-diversity between permanent and temporary pools, indicating that the physical disturbance regime is of relatively minor importance. In summary, our study clearly suggests that there are temporal differences in the relative importance of different assembly mechanisms related to abiotic factors and shows that the temporal variability of those factors is important for a more complete understanding of bacterial metacommunity dynamics.
Enhanced thermal self-focusing of a Gaussian laser beam in a collisionless plasma
Authors: Gupta Devki Nandan , Suk Hyyong
Published: December 2011

Theory given by Wang-Zhou [Phys. Plasmas 18, 043101 (2011)] for the thermal self-focusing of a Gaussian laser beam in a collisionless plasma is revisited by including the effect of a localized upward plasma-density ramp. As the equilibrium electron density is an increasing function of the distance of propagation of the laser beam, the diffraction length decreases rapidly as the beam penetrates deeper into the plasma and the diffraction effect becomes reduced; thus, the laser becomes more focused. A significant enhancement in laser thermal self-focusing in a collisionless plasma is consequently observed if a localized plasma density ramp is introduced.
Rotating-filaments-pairs in a hexagonal superlattice state in dielectric barrier discharge
Authors: Dong Lifang , Yang Yujie , Li Ben , Fan Weili , Song Qian
Published: December 2011

Rotating-filaments-pairs in a hexagonal superlattice state (HSS) are studied in a dielectric barrier discharge system. The evolution and phase diagrams of HSS are given. The wavelength of HSS and the mean diameter of the two rotating filaments all decrease with the increase of applied voltage. The instantaneous orientations of rotating-filaments-pairs are equal probability approximately. There is a larger peak and a smaller one in both the probability density functions of the rotation speed (ω) of rotating filaments and that of the distance (D) between two rotating filaments. According to the fitting curves of lnω2 vs. lnD, ω2 is inversely proportional to D7. The rotation of filaments is discussed theoretically by the force among surface charges.
Effect of passive porous surface on the trailing-edge noise
Authors: Bae Youngmin , Moon Young J.
Published: December 2011

This study numerically investigates the effect of porous surfaces on the turbulent noise generated by a blunt trailing-edge of a flat plate. The three-dimensional turbulent flow over the flat plate (Rec = 1.3 × 105 and M = 0.06) is computed by incompressible large eddy simulation (LES) based on the volume-averaged Navier-Stokes equations, while the acoustic field is calculated by the linearized perturbed compressible equations (LPCEs) coupled with LES. The porous surface is applied to a small, selected area near the trailing-edge where vortex shedding and edge-scattering of convecting eddies generate dipole noise. The computed results show that the trailing-edge with porosity ε=0.25 and permeability (normalized) K* = 0.01 yields a reduction of the tonal peak by 13 dB for the zero angle of attack (α = 0°) case, via breaking not only in the streamwise direction but also in the spanwise direction, the spatial correlation of the wall pressure fluctuations near the trailing-edge. For the separated flow case (α = 5°), the porous surface is found to weaken the pressure fluctuations at the trailing-edge and results in 3 ∼ 10 dB noise reduction over a wide range of frequency, via interrupting the edge-scattering and reducing the separated flow region over the upper surface of the plate.
Relaminarisation of Reτ = 100 channel flow with globally stabilising linear feedback control
Authors: Sharma A. S. , Morrison J. F. , McKeon B. J. , Limebeer D. J. N. , Koberg W. H. , Sherwin S. J.
Published: December 2011

The problems of nonlinearity and high dimension have so far prevented a complete solution of the control of turbulent flow. Addressing the problem of nonlinearity, we propose a flow control strategy which ensures that the energy of any perturbation to the target profile decays monotonically. The controller’s estimate of the flow state is similarly guaranteed to converge to the true value. We present a one-time off-line synthesis procedure, which generalises to accommodate more restrictive actuation and sensing arrangements, with conditions for existence for the controller given in this case. The control is tested in turbulent channel flow (Reτ = 100) using full-domain sensing and actuation on the wall-normal velocity. Concentrated at the point of maximum inflection in the mean profile, the control directly counters the supply of turbulence energy arising from the interaction of the wall-normal perturbations with the flow shear. It is found that the control is only required for the larger-scale motions, specifically those above the scale of the mean streak spacing. Minimal control effort is required once laminar flow is achieved. The response of the near-wall flow is examined in detail, with particular emphasis on the pressure and wall-normal velocity fields, in the context of Landahl’s theory of sheared turbulence.
Quantum Hall effect on centimeter scale chemical vapor deposited graphene films
Authors: Shen Tian , Wu Wei , Yu Qingkai , Richter Curt A. , Elmquist Randolph , Newell David , Chen Yong P.
Published: December 2011

We report observations of well developed half integer quantum Hall effect on mono layer graphene films of 7 mm × 7 mm in size. The graphene films are grown by chemical vapor deposition on copper, then transferred to SiO2/Si substrates, with typical carrier mobilities ≈4000 cm2/Vs. The large size graphene with excellent quality and electronic homogeneity demonstrated in this work is promising for graphene-based quantum Hall resistance standards and can also facilitate a wide range of experiments on quantum Hall physics of graphene and practical applications exploiting the exceptional properties of graphene.
Prediction of atomic force microscope probe dynamics through the receptance coupling method
Authors: Mehrpouya M. , Park S. S.
Published: December 2011

The increased growth in the use of tip-based sensing, manipulations, and fabrication of devices in atomic force microscopy (AFM) necessitates the accurate prediction of the dynamic behavior of the AFM probe. The chip holder, to which the micro-sensing device is attached, and the rest of the AFM system can affect the overall dynamics of the probe. In order to consider these boundary effects, we propose a novel receptance coupling method to mathematically combine the dynamics of the AFM setup and probe, based on the equilibrium and compatibility conditions at the joint. Once the frequency response functions of displacement over force at the tool tip are obtained, the dynamic interaction forces between the tip and the sample in nanoscale can be determined by measuring the probe tip displacement.
Vibrational dynamics of the bending mode of water interacting with ions
Authors: Piatkowski L. , Bakker H. J.
Published: December 2011

We studied the vibrational relaxation dynamics of the bending mode (ν2) of the H2O water molecules in the presence of different salts (LiCl, LiBr, LiI, NaI, CsI, NaClO4, and NaBF4). The linear and nonlinear spectra of the bending mode show distinct responses of water molecules hydrating the anions. We observe that the bending mode of water molecules that are hydrogen-bonded to an anion exhibits much slower relaxation rates (\documentclass[12pt]{minimal}\begin{document}${\rm T}_{1}\sim 1 \text{ps}$\end{document}T1∼1ps) than water molecules that are hydrogen-bonded to other water molecules (\documentclass[12pt]{minimal}\begin{document}${\rm T}_{1}=400\; \text{fs}$\end{document}T1=400fs). We find that the effect of the anion on the absorption spectrum and relaxation time constant of the water bending mode is not only determined by the strength of the hydrogen-bond interaction but also by the shape of the anion.
A novel multi-component generalization of the short pulse equation and its multisoliton solutions
Authors: Matsuno Yoshimasa
Published: December 2011

We propose a novel multi-component system of nonlinear equations that generalizes the short pulse (SP) equation describing the propagation of ultra-short pulses in optical fibers. By means of the bilinear formalism combined with a hodograph transformation, we obtain its multisoliton solutions in the form of a parametric representation. Notably, unlike the determinantal solutions of the SP equation, the proposed system is found to exhibit solutions expressed in terms of pfaffians. The proof of the solutions is performed within the framework of an elementary theory of determinants. The reduced 2-component system deserves a special consideration. In particular, we show by establishing a Lax pair that the system is completely integrable. The properties of solutions such as loop solitons and breathers are investigated in detail, confirming their solitonic behavior. A variant of the 2-component system is also discussed with its multisoliton solutions.
Electron density measurements in a pulse-repetitive microwave discharge in air
Authors: Nikolić M. , Popović S. , Vušković L. , Herring G. C. , Exton R. J.
Published: December 2011

We have developed a technique for absolute measurements of electron density in pulse-repetitive microwave discharges in air. The technique is based on the time-resolved absolute intensity of a nitrogen spectral band belonging to the Second Positive System, the kinetic model and the detailed particle balance of the N2C3Πu (ν = 0) state. This new approach bridges the gap between two existing electron density measurement methods (Langmuir probe and Stark broadening). The electron density is obtained from the time-dependent rate equation for the population of N2C3Πu (ν = 0) using recorded waveforms of the absolute C3Πu → B3Πg (0-0) band intensity, the forward and reflected microwave power density. Measured electron density waveforms using numerical and approximated analytical methods are presented for the case of pulse repetitive planar surface microwave discharge at the aperture of a horn antenna covered with alumina ceramic plate. The discharge was generated in air at 11.8 Torr with a X-band microwave generator using 3.5 μs microwave pulses at peak power of 210 kW. In this case, we were able to time resolve the electron density within a single 3.5 μs pulse. We obtained (9.0 ± 0.6) × 1013 cm–3 for the peak and (5.0 ± 0.6) × 1013 cm–3 for the pulse-average electron density. The technique presents a convenient, non-intrusive diagnostic method for local, time-defined measurements of electron density in short duration discharges near atmospheric pressures.
Simulated Short-Term Impacts of the Atlantic Menhaden Reduction Fishery on Chesapeake Bay Water Quality
Authors: Lynch Patrick D. , Brush Mark J. , Latour Robert J.
Published: December 2011

Atlantic menhaden Brevoortia tyrannus support an intense fishery in Chesapeake Bay, an estuary that is impaired by eutrophication and excess phytoplankton biomass. Since Atlantic menhaden are filter-feeding fish that consume plankton, including phytoplankton, fishery removals may negatively affect water quality and may therefore hinder bay restoration efforts. We performed a simulation to estimate the short-term (monthly and annual) water quality impacts caused by the reduction fishery harvesting its current total allowable catch of Atlantic menhaden in Chesapeake Bay (109,020 metric tons/year). A theoretical loss in net nitrogen removal (Nt) due to the fishery was estimated for each month, and the simulation was repeated for several scenarios to account for uncertainties associated with Atlantic menhaden feeding behavior. The largest potential impact of the fishery (i.e., absolute value of Nt) occurred in August for all scenarios, but depending on the value assumed for average feeding rate the fishery was estimated to have either a positive impact or a negative impact on water quality. The sum of Nt across months ranged from −5.78 × 105 to 1.85 × 107 kg of N/year, indicating that the harvested Atlantic menhaden could have contributed up to 0.38% or removed up to 12.19% of the estimated total nitrogen load for Chesapeake Bay. This large range probably captures all possible scenarios of Atlantic menhaden feeding intensity; however, the current understanding of their feeding rates as related to phytoplankton composition in Chesapeake Bay suggests that average feeding rates are relatively low and that the probable impact of the fishery on water quality is negligible.

Received July 13, 2010; accepted December 24, 2010
An Evaluation of Underwater Epoxies to Permanently Install Temperature Sensors in Mountain Streams
Authors: Isaak Daniel J. , Horan Dona L.
Published: December 2011

Stream temperature regimes are of fundamental importance in understanding the patterns and processes in aquatic ecosystems, and inexpensive digital sensors provide accurate and repeated measurements of temperature. Most temperature measurements in mountain streams are made only during summer months because of logistical constraints associated with stream access and concerns that large annual floods will destroy sensor installations. We assessed six underwater epoxies to determine whether sensors could be attached to large rocks already in streams to provide durable installations and whether temperature measurements would be biased by heat conduction through the rocks. Only one of the six test epoxies bonded the sensors firmly to rock surfaces in laboratory trials. In subsequent field trials, 9 of 11 sensors attached to rocks with this epoxy successfully weathered above-average floods in four Idaho and Nevada streams in 2010. Comparisons of daily maximum, minimum, and mean temperatures between rock-mounted sensors and control sensors at 10 rocks suggested temperature measurements were not biased by attachment to rocks. We also assessed the effect of direct sunlight on sensors by removing solar shields from some sensors and noted rapid and statistically significant increases in daily means (+0.21°C) and maxima (+0.54°C), but not minima (−0.01°C). Use of underwater epoxy for permanent installation of temperature sensors in mountain streams is a viable technique if an appropriate epoxy is chosen, sensors are shielded from direct sunlight, and rocks large enough to withstand floods are used. Moreover, installations using epoxy are rapid (approximately 20 min), and firm attachments to rock surfaces over a range of stream temperatures (5–20°C) are possible.

Received September 16, 2010; accepted November 12, 2010
Spatiotemporal Distribution and Population Characteristics of a Nonnative Lake Trout Population, with Implications for Suppression
Authors: Dux Andrew M. , Guy Christopher S. , Fredenberg Wade A.
Published: December 2011

We evaluated the distribution and population characteristics of nonnative lake trout Salvelinus namaycush in Lake McDonald, Glacier National Park, Montana, to provide biological data in support of a potential suppression program. Using ultrasonic telemetry, we identified spatial and temporal distribution patterns by tracking 36 adult lake trout (1,137 relocations). Lake trout rarely occupied depths greater than 30 m and were commonly located in the upper hypolimnion directly below the metalimnion during thermal stratification. After breakdown of the metalimnion in the fall, lake trout primarily aggregated at two spawning sites. Lake trout population characteristics were similar to those of populations within the species’ native range. However, lake trout in Lake McDonald exhibited lower total annual mortality (13.2%), later maturity (age 12 for males, age 15 for females), lower body condition, and slower growth than are typically observed in the southern extent of their range. These results will be useful in determining where to target suppression activities (e.g., gillnetting, trap-netting, or electrofishing) and in evaluating responses to suppression efforts. Similar evaluations of lake trout distribution patterns and population characteristics are recommended to increase the likelihood that suppression programs will succeed.

Received March 24, 2009; accepted November 23, 2010
Movement Patterns of American Shad Transported Upstream of Dams on the Roanoke River, North Carolina and Virginia
Authors: Harris Julianne E. , Hightower Joseph E.
Published: December 2011

American shad Alosa sapidissima are in decline throughout much of their native range as a result of overfishing, pollution, and habitat alteration in coastal rivers where they spawn. One approach to restoration in regulated rivers is to provide access to historical spawning habitat above dams through a trap-and-transport program. We examined the initial survival, movement patterns, spawning, and downstream passage of sonic-tagged adult American shad transported to reservoir and riverine habitats upstream of hydroelectric dams on the Roanoke River, North Carolina and Virginia, during 2007–2009. Average survival to release in 2007–2008 was 85%, but survival decreased with increasing water temperature. Some tagged fish released in reservoirs migrated upstream to rivers; however, most meandered back and forth within the reservoir. A higher percentage of fish migrated through a smaller (8,215-ha) than a larger (20,234-ha) reservoir, suggesting that the population-level effects of transport may depend on upper basin characteristics. Transported American shad spent little time in upper basin rivers but were there when temperatures were appropriate for spawning. No American shad eggs were collected during weekly plankton sampling in upper basin rivers. The estimated initial survival of sonic-tagged American shad after downstream passage through each dam was 71–100%; however, only 1% of the detected fish migrated downstream through all three dams and many were relocated just upstream of a dam late in the season. Although adult American shad were successfully transported to upstream habitats in the Roanoke River basin, under present conditions transported individuals may have reduced effective fecundity and postspawning survival compared with nontransported fish that spawn in the lower Roanoke River.

Received August 8, 2010; accepted December 30, 2010
Evaluation of Hypotheses for Describing Temporal Trends in Atlantic Salmon Parr Densities in Northeast U.S. Rivers
Authors: Wagner Tyler , Sweka John A.
Published: December 2011

Atlantic salmon Salmo salar in the USA have declined dramatically and their persistence is heavily dependent on stocking juvenile fish, predominantly fry. The success of stocking hatchery fry is evaluated annually throughout New England by electrofishing surveys targeting age-1 parr. The objective of this study was to examine temporal trends in Atlantic salmon parr densities throughout New England and determine how trends vary among river basins. We fit generalized additive mixed models to investigate potential linear and nonlinear temporal trends in parr density. Akaike's information criterion was used to evaluate competing hypotheses about how temporal trends vary regionally. The top-ranked model suggested two types of trends. The first type (the Penobscot River) showed a nonlinear trend in which parr densities increased until the 1990s and then rapidly decreased through 2008. The second type (all other rivers) showed a linear decrease throughout the time series. Parr density trends reflected trends in spawning escapement for each river group. We conclude that fry stocking has not been able to overcome the decrease in spawning escapement in altered stream ecosystems in New England and that additional management strategies should be considered.

Received July 2, 2010; accepted January 9, 2011
Gill-Net Saturation in Lake Erie: Effects of Soak Time and Fish Accumulation on Catch per Unit Effort of Walleye and Yellow Perch
Authors: Li Yan , Jiao Yan , Reid Kevin
Published: December 2011

Gill-net saturation was analyzed through a delta model (i.e., two-stage model) by examining the effects of soak time and fish accumulation (number of fish of all species enmeshed per square meter of a given gill net, including the species of interest) on catch per unit effort (CPUE) of walleyes Sander vitreus and yellow perch Perca flavescens in Lake Erie. The analysis was based on fishery-independent survey data for 1989–2003. In the delta model, the positive values of CPUE were estimated by a generalized additive model (GAM) assuming a log-gamma distribution, and the probability of obtaining nonzero values of CPUE was estimated by a GAM assuming a binomial distribution. Soak time and fish accumulation had significant effects on CPUE. The CPUE of walleyes decreased in gill nets soaked for 10 h and started to decline when fish accumulation was around 2 fish/m2. We did not observe a substantial decline in the CPUE of yellow perch within the soak time interval we examined, but we did observe a decline when fish accumulation was 6–8 fish/m2. The decline in CPUE with increasing soak time for walleyes and with increasing fish accumulation levels for both walleyes and yellow perch indicates that gill-net saturation did exist in Lake Erie gill-net surveys for these two species and that the gill nets were saturated faster by walleyes than by yellow perch. We suggest that gill-net saturation be considered when applying CPUE from gill-net surveys to stock assessment and that the generalized linear additive-based modeling approach be considered as an alternative in gill-net saturation analyses.

Received March 11, 2010; accepted January 6, 2011
Movement and Survival of Brown Trout and Rainbow Trout in an Ozark Tailwater River
Authors: Quinn Jeffrey W. , Kwak Thomas J.
Published: December 2011

We evaluated the movement of adult brown trout Salmo trutta and rainbow trout Oncorhynchus mykiss in relation to a catch-and-release area in the White River downstream from Beaver Dam, Arkansas. Nine fish of each species were implanted with radio transmitters and monitored from July 1996 to July 1997. The 1.5-km river length of a catch-and-release area (closed to angler harvest) was greater than the total linear range of 72% of the trout (13 of 18 fish), but it did not include two brown trout spawning riffles, suggesting that it effectively protects resident fish within the catch-and-release area except during spawning. The total detected linear range of movement varied from 172 to 3,559 m for brown trout and from 205 to 3,023 m for rainbow trout. The movements of both species appeared to be generally similar to that in unregulated river systems. The annual apparent survival of both trout species was less than 0.40, and exploitation was 44%. Management to protect fish on spawning riffles may be considered if management for wild brown trout becomes a priority.

Received August 31, 2010; accepted January 20, 2011
Verifying Identification of Salmon and Trout by Boat Anglers in Lake Ontario
Authors: Bowlby James N. , Savoie Paul J.
Published: December 2011

We estimated how well anglers with varying levels of fishing experience identified six salmonid species during creel surveys of the boat angler fishery in Canadian waters of Lake Ontario (1995 and 1996). Anglers were asked to identify the species of their harvested salmon and trout. Angler identifications were compared with identifications made by creel survey technicians. In total, 583 noncharter anglers and 92 charter boat captains identified 1,098 and 271 fish, respectively. Chinook salmon Oncorhynchus tshawytscha, rainbow trout O. mykiss, and lake trout Salvelinus namaycush dominated the observations. The greatest accuracy in identification by noncharter anglers was for lake trout (96%), followed by Chinook salmon (93%), rainbow trout (88%), brown trout Salmo trutta (85%), Atlantic salmon Salmo salar (67%), and coho salmon O. kisutch (60%). Identifications by charter captains were closer to identifications made by the creel survey technicians: accuracy for coho salmon and rainbow trout was 100%, followed by Chinook salmon (97%), lake trout (96%), and brown trout (86%). Noncharter anglers with over 8 years of salmonid angling experience on Lake Ontario identified coho salmon more accurately (79%) than anglers with fewer years of experience (18%). Noncharter anglers’ fishing experience had no relationship with identification accuracy for species other than coho salmon; angling experience among charter captains had no effect on identification accuracy for any species. Among Chinook salmon, accurately identified individuals were significantly larger than misidentified fish. Size probably plays a role in identification of Chinook salmon as they are the largest salmonids in the fishery. Accurate identification of salmonids in Lake Ontario allows Ontario fisheries biologists to use catch rates with confidence, and these results may be applicable on a widespread basis throughout the Great Lakes.

Received April 7, 2010; accepted January 1, 2011
Site Fidelity and Movement of Eight Species of Pacific Rockfish at a High-Relief Rocky Reef on the Oregon Coast
Authors: Hannah Robert W. , Rankin Polly S.
Published: December 2011

We used acoustic telemetry techniques to study the movements of eight species of Pacific rockfish (genus Sebastes) inhabiting Siletz Reef, a high-relief rocky reef complex on the Oregon coast. Our primary interest was evaluating potential residence times for rockfish species in small, no-take marine protected areas (MPAs) like those recently designated for Oregon waters (337–1,502 ha). We tagged 6 black rockfish S. melanops, 31 canary rockfish S. pinniger, 9 yelloweye rockfish S. ruberrimus, 5 quillback rockfish S. maliger, and 2 copper rockfish S. caurinus, along with single specimens of china rockfish S. nebulosus, vermilion rockfish S. miniatus, and tiger rockfish S. nigrocinctus, and monitored their movements with a large (about 5,200-ha) receiver grid for over a year. Canary rockfish showed low site fidelity and wide-ranging movements that exceeded the scale of our detection grid and a wide range of vertical movements (up to 27 m). Quillback, vermilion, tiger, china, and some yelloweye rockfish showed high site fidelity, being detected only at one or two nearby receivers for a full year. The range of vertical movements of yelloweye, quillback, vermilion, and tiger rockfish was small, ranging from only 2–3 m for the single tiger rockfish to 3–13 m for four of the quillback rockfish. Black and copper rockfish showed site fidelity that was intermediate between that of canary rockfish and the other species. Black and copper rockfish showed a wide range in vertical movements (10–35 m and 2–33 m, respectively) within a month. Our results suggest that small, no-take MPAs located on high-relief rocky reefs would provide minimal protection for canary rockfish, some protection for black and copper rockfish, and greater protection for quillback, vermilion, tiger, and some yelloweye rockfish.

Received April 2, 2010; accepted February 21, 2011
Long-Term PIT and T-Bar Anchor Tag Retention Rates in Adult Muskellunge
Authors: Rude Neil P. , Whitledge Gregory W. , Phelps Quinton E. , Hirst Shawn
Published: December 2011

Mark–recapture studies require knowledge of tag retention rates specific to the tag types, fish species and size, and study duration. We determined the probability of tag loss for passive integrated transponder (PIT) tags implanted into dorsal musculature, T-bar anchor tags attached to dorsal pterygiophores, and both tags in relation to years posttagging for double-marked adult muskellunge Esox masquinongy over a 10-year period. We also used PIT tags as a benchmark to assess the interactive effects of fish length at tagging, sex, and years posttagging on T-bar anchor tag loss rates. Only five instances of PIT tag loss were identified; the calculated probability of a fish's losing its PIT tag was consistently less than 1.0% for up to 10 years posttagging. The probability of T-bar anchor tag loss by muskellunge was related to both the number of years posttagging and the total length (TL) of the fish at tagging. The T-bar anchor tag loss rate 1 year after tagging was 6.5%. Individuals of less than 750 mm TL at tagging had anchor tag loss rates less than 10% for up to 6 years after tagging. However, the proportion of fish losing T-bar anchor tags steadily increased with increasing years posttagging (∼30% after 6 years) for larger muskellunge. Fish gender did not influence the probability of T-bar anchor tag loss. Our results indicate that T-bar anchor tags are best suited for short-term applications (≤1 year) involving adult muskellunge. We recommend use of PIT tags for longer-term tagging studies, particularly for muskellunge larger than 750 mm TL.

Received November 19, 2010; accepted March 28, 2011
Predicting Fish Assemblages from Substrate Variation in a Turbid River: Grab Samples Compared with Pole Probing
Authors: Pritchett Jennifer , Pyron Mark
Published: December 2011

We tested two substrate quantification methods at 28 500-m-long sites in the Wabash River in 2008. We predicted boat electrofishing collections of fish using substrate characterization based on grab samples and pole probing. Our approach was to compare discrete scores with a nonparametric approach and use canonical correspondence analyses to analyze alternative substrate quantification methods to predict fish assemblage structure. There was no difference in the ranks of grab and pole samples. Both substrate quantification approaches provided reasonable predictions of fish assemblage variation. Mantel tests were used as an additional method of comparing the two substrate methods for concordance with fish assemblages. We suggest that the pole method is most cost effective because it does not require additional time for laboratory processing.

Received August 6, 2010; accepted April 21, 2011
Relative Performance of Diploid and Triploid Catchable Rainbow Trout Stocked in Idaho Lakes and Reservoirs
Authors: Koenig Martin K. , Meyer Kevin A.
Published: December 2011

Idaho Department of Fish and Game hatcheries stock predominantly sterile triploid (3n) rainbow trout Oncorhynchus mykiss to provide sportfishing opportunities while minimizing the genetic risks to wild stocks. Triploid catchable-sized rainbow trout are stocked in over 500 water bodies across Idaho annually, but there remains some uncertainty regarding the performance of triploid rainbow trout relative to their diploid (2n) counterparts. We examined the relative survival, growth, and returns of diploid and triploid all-female catchable rainbow trout across 13 lakes and reservoirs. Most reservoirs showed higher returns of 2n rainbow trout to anglers. In 2008, 3n rainbow trout returned on average at only 72% and 81% of the rates of 2n trout in gill nets and snout collection boxes, respectively, and the difference for both methods was statistically significant. Carryover of marked rainbow trout from 2008 was low or zero in most reservoirs. Where there was carryover, snout collection boxes suggested that 3n rainbow trout returned to anglers at 71% of the rate of 2n rainbow trout in the second year after planting, but the difference was not statistically significant. Triploid rainbow trout did not show any growth advantages over 2n rainbow trout but were similar in length, weight, and dressed weight. The disparity in returns between 2n and 3n trout varied across reservoirs but was more pronounced in locations subjected to greater drawdown and with greater species diversity. While 2n rainbow trout may grow and survive better in reservoirs subject to low water levels, triploid rainbow trout may perform equally well under good habitat conditions while not having genetic impacts on native stocks. These findings are rather fortuitous for fisheries managers, as triploids probably perform better in higher-quality habitats where native trout often exist, whereas diploids are better suited to reservoirs with degraded habitats where native stocks have usually been extirpated.

Received September 14, 2010; accepted May 18, 2011
Biology, Status, and Management of the Yellowstone Cutthroat Trout
Authors: Gresswell Robert E.
Published: December 2011

Yellowstone cutthroat trout Oncorhynchus clarkii bouvieri were historically distributed in the Yellowstone River drainage (Montana and Wyoming) and the Snake River drainage (Wyoming, Idaho, Utah, Nevada, and probably Washington). Individual populations evolved distinct life history characteristics in response to the diverse environments in which they were isolated after the last glaciation. Anthropogenic activities have resulted in a substantial decline (42% of the historical range is currently occupied; 28% is occupied by core [genetically unaltered] populations), but the number of extant populations, especially in headwater streams, has precluded listing of this taxon under the Endangered Species Act. Primary threats to persistence of Yellowstone cutthroat trout include (1) invasive species, resulting in hybridization, predation, disease, and interspecific competition; (2) habitat degradation from human activities such as agricultural practices, water diversions, grazing, dam construction, mineral extraction, grazing, timber harvest, and road construction; and (3) climate change, including an escalating risk of drought, wildfire, winter flooding, and rising temperatures. Extirpation of individual populations or assemblages has led to increasing isolation and fragmentation of remaining groups, which in turn raises susceptibility to the demographic influences of disturbance (both human and stochastic) and genetic factors. Primary conservation strategies include (1) preventing risks associated with invasive species by isolating populations of Yellowstone cutthroat trout and (2) connecting occupied habitats (where possible) to preserve metapopulation function and the expression of multiple life histories. Because persistence of isolated populations may be greater in the short term, current management is focused on isolating individual populations and restoring habitats; however, this approach implies that humans will act as dispersal agents if a population is extirpated because of stochastic events.

Received August 19, 2010; accepted April 28, 2011
Coarse Woody Habitat, Lakeshore Residential Development, and Largemouth Bass Nesting Behavior
Authors: Lawson Zach J. , Gaeta Jereme W. , Carpenter Stephen R.
Published: December 2011

Lakeshore residential development (LRD) is associated with both low riparian tree density and reduced structural complexity of the littoral zone. Fallen trees from riparian zones (coarse woody habitat [CWH]) provide littoral structure for fish refuge, substrate for invertebrate production, and habitat for nesting fish. We performed a subsurface viewing and snorkel survey comparing the spawning behavior of largemouth bass Micropterus salmoides in six lakes that span the known regional gradients of CWH and LRD in Wisconsin's Northern Highlands Lake District. We tested for differences in the water depth at nest sites and the nest distance to littoral structures (including every dock encountered) among lakes with contrasting CWH or LRD density. Largemouth bass nested under or near CWH in lakes with high CWH density. In lakes with low CWH, many males nested near CWH; however, nests contained smaller pieces of wood and were established in deeper water within low-CWH lakes than within high-CWH lakes. No nests were closer to a dock than to CWH, which suggested that docks do not act as surrogates for CWH. Habitat alterations associated with LRD significantly affect largemouth bass nest site location, and an understanding of these impacts will be important for maintaining viable populations of this prized game fish as LRD pressures expand.

Received November 16, 2010; accepted May 11, 2011
Habitat Use by Juvenile Chinook Salmon in the Nearshore Areas of Lake Washington: Effects of Depth, Lakeshore Development, Substrate, and Vegetation
Authors: Tabor Roger A. , Fresh Kurt L. , Piaskowski Richard M. , Gearns Howard A. , Hayes Daniel B.
Published: December 2011

Juvenile Chinook salmon Oncorhynchus tshawytscha in nearshore areas of Lake Washington, Washington, were studied to determine their depth distribution, substrate associations, and use of overhanging vegetation (OHV) and shoreline armoring. From March to May, juvenile Chinook salmon progressively shifted to deeper waters as they increased in size. At night, they were associated with small substrates, whereas no association with a particular substrate type was detected during daytime. Juveniles were commonly found in open areas or within 5 m of overwater structures (e.g., piers and docks) but were rarely found directly under such structures. The number of juveniles associated with armored shorelines was lower than expected given the availability of this habitat type. Large numbers of small juveniles often used OHV during the day; however, at night they moved away from cover and occupied open areas with no structure. Larger juveniles did not show a strong affinity to overhead cover. Our results suggest that continued development of the Lake Washington shoreline has the potential to restrict the amount of habitat that is useable by the Chinook salmon. They used shallow shoreline areas with fine substrates (sands and gravels), including both open beaches and areas with riparian vegetation for providing woody debris and OHV. These types of habitat features tend to be reduced as a result of lakeshore development. We hypothesize that habitat use by juvenile Chinook salmon was most likely being driven by predation risk. Habitat changes resulting from shoreline development could therefore potentially increase their vulnerability to predators.

Received November 30, 2010; accepted June 1, 2011
A Proposed Change to Palmetto Bass Proportional Size Distribution Length Categories
Authors: Dumont Spencer C. , Neely Ben C.
Published: December 2011

Palmetto bass (female striped bass Morone saxatilis × male white bass M. chrysops) are an important sport fish in the Southeast and Midwest regions of the United States. Because palmetto bass populations must be established and maintained by regular stocking, population assessments are necessary to evaluate and refine stocking plans. A commonly used metric for fish population assessment is the proportional size distribution (PSD). However, the value of this metric is limited for palmetto bass because the original lengths designated for the stock (8 in), quality (12 in), preferred (15 in), memorable (20 in), and trophy length categories (25 in) were based on the old world-record length of 31 in, which is much shorter than the current length of 39 in. Thus, new lengths of 10, 16, 20, 24, and 28 in are proposed for assessing palmetto bass populations via PSD indices. These proposed lengths more accurately reflect the maximal length and life history characteristics (i.e., fast growing, short lived, and seldom stunting) of palmetto bass than the current PSD length categories. With the proposed length categories, PSD estimates are likely to provide a more useful index of the growth, mortality, and recruitment of palmetto bass and improve communication among fisheries managers.

Received February 21, 2011; accepted May 8, 2011
Populations on the Brink: Low Abundance of Southern Upland Atlantic Salmon in Nova Scotia, Canada
Authors: Gibson A. Jamie F. , Bowlby Heather D. , Hardie David C. , O'Reilly Patrick T.
Published: December 2011

Populations of Atlantic salmon Salmo salar in the Southern Upland region of Nova Scotia, Canada, have declined to very low abundances. Sixty-three rivers in this region—9% of the total number of Canadian rivers that contain Atlantic salmon—are known to have supported populations in the recent past. Annual adult abundance data from four rivers show declines of 83–99% from peak levels in the 1980s; this pattern is consistent with trends in recreational catch within the region. Regionwide comparisons of juvenile density data from more than 50 other rivers indicate significant ongoing declines and provide evidence for river-specific extirpations. Based on surveys conducted in 2000 and again in 2008–2009, total juvenile density decreased substantially at the majority of locations; during the 2008–2009 survey, juveniles were not found at nine sites (four rivers) where they were present in 2000. Although river acidification has significantly contributed to the deterioration or extirpation of Atlantic salmon populations from many Southern Upland rivers during the last century, contemporary declines occurring in nonacidified rivers indicate that other factors are now affecting these populations. Several lines of evidence demonstrate that Southern Upland Atlantic salmon are biologically unique and that their extinction would constitute an irreplaceable loss of Atlantic salmon biodiversity.

Received November 2, 2010; accepted June 2, 2011
Determining Mark Success of 15 Combinations of Enriched Stable Isotopes for the Batch Marking of Larval Otoliths
Authors: Woodcock Skye H. , Gillanders Bronwyn M. , Munro Andrew R. , Crook David A. , Sanger Andrew C.
Published: December 2011

Chemical marking of otoliths via immersion in solutions of enriched stable isotopes provides a means of distinctively marking large batches of hatchery-produced fish. Four enriched stable isotopes (barium: 137Ba and 138Ba; strontium: 88Sr; magnesium: 24Mg) were used individually and in combination to determine mark success and the ability to correctly classify 15 unique batch marks in the otoliths of larval Murray cod Maccullochella peelii. Marking with the enriched stable isotopes 137Ba, 138Ba, and 88Sr (individually or in combination) produced clear and distinctive marks (98% mark success) with 93% of fish correctly classified to their respective isotope mark. Despite exposure of the fish to an altered Mg isotope ratio in the water, a corresponding shift in the otoliths was not observed (8% mark success), and many 24Mg-enriched fish were misclassified. Due to the low cost and minimal effects on hatchery protocols, the use of Sr and Ba isotopes to mark hatchery-reared fish at the larval stage has the potential to be a powerful tool in the production and management of a wide range of fish species.

Received February 25, 2011; accepted May 22, 2011
Ecological Impacts of Non-native Freshwater Fishes
Authors: Cucherousset Julien , Olden Julian D
Published: December 2011

There is a long history of introduction of non-native fishes in fresh waters and the introduction rate has accelerated greatly over time. Although not all introduced fishes have appreciable effects on their new ecosystems, many exert significant ecological, evolutionary, and economic impacts. For researchers, managers, and policy makers interested in conserving freshwater diversity, understanding the magnitude and array of potential impacts of non-native fish species is of utmost importance. The present study provides an illustrative conspectus of the most recent literature reporting ecological impacts of non-native freshwater fishes from a wide range of species and geographic locations and concludes with a prospectus of needed areas of scientific inquiry. Both directly and indirectly, invasive fishes affect a wide range of native organisms from zooplankton to mammals across multiple levels of biological organizations ranging from the genome to the ecosystem. Although a great deal of knowledge has been recently accumulated, this body of knowledge dwarfs in comparison to what we still need to learn. Specifically, we cite the need for additional scientific inquiry to fill knowledge gaps that are principally caused by taxonomically, geographically, disciplinarily, and methodologically unbalanced approaches.
Native Fish Conservation Areas: A Vision for Large-Scale Conservation of Native Fish Communities
Authors: Williams Jack E , Williams Richard N , Thurow Russell F , Elwell Leah , Philipp David P , Harris Fred A , Kershner Jeffrey L , Martinez Patrick J , Miller Dirk , Reeves Gordon H , Frissell Christopher A , Sedell James R
Published: December 2011

The status of freshwater fishes continues to decline despite substantial conservation efforts to reverse this trend and recover threatened and endangered aquatic species. Lack of success is partially due to working at smaller spatial scales and focusing on habitats and species that are already degraded. Protecting entire watersheds and aquatic communities, which we term “native fish conservation areas” (NFCAs), would complement existing conservation efforts by protecting intact aquatic communities while allowing compatible uses. Four critical elements need to be met within a NFCA: (1) maintain processes that create habitat complexity, diversity, and connectivity; (2) nurture all of the life history stages of the fishes being protected; (3) include a long-term enough watershed to provide long-term persistence of native fish populations; and (4) provide management that is sustainable over time. We describe how a network of protected watersheds could be created that would anchor aquatic conservation needs in river basins across the country.
Potential Impact of the Deepwater Horizon Oil Spill on Commercial Fisheries in the Gulf of Mexico
Authors: McCrea-Strub A , Kleisner K , Sumaila U R , Swartz W , Watson R , Zeller D , Pauly D
Published: December 2011

Given the economic and social importance of fisheries in the Gulf of Mexico large marine ecosystem (LME), it is imperative to quantify the potential impacts of the Deepwater Horizon oil spill. To provide a preliminary perspective of the consequences of this disaster, spatial databases of annual reported commercial catch and landed value prior to the spill were investigated relative to the location of the fisheries closures during July 2010. Recent trends illustrated by this study suggest that more than 20% of the average annual U.S. commercial catch in the Gulf has been affected by postspill fisheries closures, indicating a potential minimum loss in annual landed value of US$247 million. Lucrative shrimp, blue crab, menhaden, and oyster fisheries may be at greatest risk of economic losses. Overall, it is evident that the oil spill has impacted a highly productive area of crucial economic significance within the Gulf of Mexico LME. This study draws attention to the need for ongoing and thorough investigations into the economic impacts of the oil spill on Gulf fisheries.