您当前的位置: 首页 > 网页快照
Canadian Science Publishing
Just-IN Discrimination between schools and submerged trees in reservoirs: A preliminary approach using narrowband and broadband acoustics . Arthur Blanluet . , Sven Gastauer . , Franck Cattanéo . , Chloé Goulon . , David Grimardias . , and Jean Guillard . Just-IN With a growing demand for hydroelectric energy, the number of reservoirs is dramatically increasing worldwide. These new water bodies also present an opportunity for the development of fishing activities. However, these reservoirs are commonly impounded on uncut forests, resulting in many immersed trees. These trees hinder fish assessments by disrupting both gill netting and acoustic sampling. Immersed trees can easily be confused with fish schools on echograms. To overcome this issue, we developed a method to discriminate fish schools from immersed trees. A random forest algorithm was used to classify echo-traces at 120 and 200 kHz, recorded by an EK80 (SIMRAD) in narrowband (Continuous Wave) and in broadband mode (Frequency Modulated). We obtained a good discrimination rate between trees and schools, especially in broadband (90 % ratio of good classification). We demonstrate that it is possible to discriminate fish schools from immersed trees and thus facilitate the use of fisheries acoustics in reservoirs. Get Access Patterns and drivers of native, non-native, and at-risk freshwater fish richness in Canada . M.U. Mohamed Anas PhD . and Nicholas E. Mandrak . Just-IN Understanding the relative roles of the historical, environmental, and anthropogenic processes underlying spatial biodiversity patterns is crucial to predict the impacts of global environmental changes. We quantified the relative roles of these factors in influencing species richness of total, native, non-native, and at-risk freshwater fishes in 985 tertiary watersheds across Canada, while accounting for correlations among descriptors and spatial autocorrelation. Our findings indicate differences in factors influencing richness patterns among species categories. Environmental factors related to energy availability and historical factors related to post-glacial recolonization both played roles in shaping spatial variation in native species richness. In contrast, variation in non-native species richness was largely related to human activities increasing propagule pressure and habitat disturbance, which were greater for foreign species (i.e. not native to Canada) than for translocated native species. Anthropogenic processes and environmental conditions were both important determinants of at-risk species richness. Our study emphasizes the importance of an integrated approach that simultaneously considers natural and anthropogenic processes to better predict the fish biodiversity change at the landscape scale. Get Access Unveiling the recovery dynamics of Walleye after the invisible collapse . Christopher L. Cahill . , Carl J. Walters . , Andrew J. Paul . , Michael G. Sullivan . , and John R. Post . Just-IN Walleye (Sander vitreus) populations in Alberta, Canada collapsed by the mid-1990s and were a case study in the paper Canada’s Recreational Fisheries: The Invisible Collapse? Here we fit age-structured population dynamics models to data from a landscape-scale monitoring program to assess Walleye population status and reconstruct recruitment dynamics following the invisible collapse. Assessments indicated that populations featured low F_msy values of approximately 0.2-0.3 under conservative assumptions for the stock-recruitment relationship but that many populations were lightly exploited during 2000-2018. Recruitment reconstructions showed that recovery from collapse in 33/55 lakes was driven in part by large positive recruitment anomalies that occurred during 1998-2002. Additionally, 15/55 lakes demonstrated cyclic recruitment dynamics. Both the recruitment anomalies and cyclic fluctuations could be due to environmental effect(s) and(or) cannibalism, and experimentation may be necessary to resolve this uncertainty. These findings contribute new information on the recovery dynamics of Walleye following the invisible collapse, and demonstrate the effectiveness of coupling traditional fisheries science models with broad-scale monitoring data to improve understanding of population dynamics and sustainability across landscapes. Get Access Mixed stock analysis of genetic compositions of lake sturgeon (Acipenser fulvescens) mixtures in Lake Michigan: hierarchical spatial heterogeneity and evidence of improving recruitment in Wisconsin spawning populations . Kim T Scribner . , Travis O. Brenden . , Rob Elliot . , Michael Donofrio . , Kristin Bott . , Jeannette Kanefsky . , Jared J Homola . , Iyob Tsehaye . , James R Bence . , Edward A. Baker . , and Nancy A Auer . Just-IN Information regarding site occupancy of fish that migrate long distances during non-spawning periods together with estimates of recruitment trends for individual populations can be informative for management, especially when individuals from different spawning populations intermix and are sampled/harvested together. Tendencies for individuals from different populations to preferentially occupy specific regions increases vulnerability to anthropogenic and natural disturbances. Using mixed stock analysis (MSA), we estimated population-specific occupancy of lake sturgeon in open-water and nearshore regions of Lake Michigan across a hierarchy of spatial scales. Open-water mixture composition differed between Lake Michigan’s eastern and western basins. Significant heterogeneity in habitat occupancy was also observed at microgeographic scales throughout open-water regions of Green Bay, indicating non-random occupancy to regions proximal to natal streams. Estimates of relative recruitment levels determined from MSA extensions indicated increasing recruitment trends for spawning populations associated with Wisconsin tributaries (Oconto/Peshtigo, Fox, and Menominee Rivers). Our lake sturgeon results demonstrate the utility of genetic data for informing management efforts for spatially-structured, highly migratory species. Similar analyses could prove beneficial for species with similar characteristics. Get Access Somatic growth of Atlantic bluefin tuna Thunnus thynnus under global climate variability: Evidence from over 60 years of daily resolved growth increments with a simulation study . Can Zhou . Just-IN Somatic growth is integral to fishery stock productivity. Under climate variability, omitting growth variability renders fishery management strategies non-optimal. Based on a multidecadal tag-recapture database, a case study is presented to investigate the potential growth response of the Atlantic bluefin tuna to three regionally relevant large-scale climate patterns, i.e., the North Atlantic Oscillation, Arctic Oscillation, and Pacific North America pattern. An additional simulation study is conducted to explore the effect of the overall scale and the distribution of measurement error on the detection probability of extrinsic effects and the estimation of growth parameters. Results indicate significant growth response at an intra-annual scale to all three climate indices examined. Identified growth responses to climate variations are highly nonlinear. The projected growth shows increased growth in recent decades under climate variability with respect to the historical mean. Simulation results show a higher probability to detect climate signals when the overall measurement error is low. Substantial bias is expected when the measurement error at tag release is high, cautioning against careless integration of different types of growth data. Get Access M. cerebralis establishment and spread: A graphical synthesis . Pouria Ramazi . , Samuel Matthias Fischer . , Julie Alexander . , Clayton James . , Andrew J. Paul . , Russell Greiner . , and Mark A Lewis . Just-IN M. cerebralis is the parasite causing whirling disease, which has dramatic ecological impacts due to its potential to cause high mortality in salmonids. The large-scale e?orts, necessary to underpin an e?ective surveillance program, have practical and economic constraints. There is, hence, a clear need for models that can predict the parasite spread. Model development, however, often heavily depends on knowing in?uential variables and governing mechanisms. We have developed a graphical model for the establishment and spread of M. cerebralis by synthesizing experts’ opinion and empirical studies. First, we conducted a series of workshops with experts to identify variables believed to impact the establishment and spread of the parasite M. cerebralis and visualized their interactions via a directed acyclic graph. Then we re?ned the graph by incorporating empirical ?ndings from the literature. The ?nal graph’s nodes correspond to variables whose considerable impact on M. cerebralis establishment and spread is either supported by empirical data or con?rmed by experts, and the graph’s directed edges represent direct causality or strong correlation. This graphical model facilitates communication and education of whirling disease and provides an empirically driven framework for constructing future models, especially Bayesian networks. Get Access Life history contrasts in nutritional state and return probability of post-spawned Atlantic salmon . Kristin B?e PhD . , Michael Power . , Martha J Robertson . , J. Brian Dempson . , and Ian A Fleming . Just-IN Using non-lethal tissue biopsies, we investigated somatic energy, lipid composition, and condition in post-spawned Atlantic salmon (kelts, n = 69) returning to sea in the spring and explored contrasts as a function of previous migration- and spawning history, length and sex. Using mark-recapture analysis, we also explored linkages between spawning history and probability of future repeat spawning. Lipid density was significantly higher in previously spawned individuals compared to first time spawned fish, and in females compared to males. Fatty acid composition differed significantly among spawning histories. Return rates to consecutive spawning the following year were consistent with spawning history dependent differences in lipid density, as first time spawned kelts had lower return rates compared to consecutive repeat spawned kelts. We suggest that spawning history related contrasts in nutritional state in post-spawned Atlantic salmon may be a carry-over effect of differences in the feeding habitat as affected by spawning-history dependent migration strategies. Alternatively, it may represent an adaptive response to increased survival and recovery potential with age. Get Access Long-term interplay between harvest regimes and biophysical conditions may lead to persistent changes in age-at-sexual maturity of Northeast Arctic cod (Gadus morhua) . Carl Jakob R?rvik Cand.real. . , Bjarte Bogstad . , Geir Ottersen . , and Olav Sigurd Kjesbu . Just-IN This investigation commenced by constructing principal maturation schedule equations as a function of fishing mortality (F), key biophysical factors and a term attributed to fisheries-induced adaptive change (FIAC). Following the onset of industrial trawl fishery on the model stock, Northeast Arctic cod (NEAC) (1934-2020), F on immature age groups 5-8 years (F5-8) increased and mean age at 50% maturity (A50) decreased from ≈10 years in the late 1940s to ≈7 years today. Large annual fluctuations in total stock biomass (TSB), sea temperature (KolaT) and F5-8 were used to better understand A50 responses. In the model, the annual accumulation of F5-8 drives FIAC. The model includes the option that NEAC may sustain F5 8 up to a certain level (F_bal) before FIAC becomes statistically evident, with F_bal falling between 0.00 and 0.40 for A50. This dynamic range in F_bal indicates a sophisticated, underlying adaptive response. Independent of F_bal, our analysis clarifies that FIAC is necessary to explain the observed changes in A50. Get Access Paleolimnological evidence reveals climate-related preeminence of cyanobacteria in a temperate meromictic lake . Kevin Erratt . , Irena F. Creed . , Elizabeth J. Favot . , Irina Todoran . , Vera Tai . , John P Smol . , and Charles G. Trick . Just-IN Meromictic lakes provide a physically stable environment in which proxies for potentially harmful cyanobacteria are exceptionally well-preserved in the sediments. In Sunfish Lake, a meromictic lake that has recently become the focus of citizen concern due to the apparent rise in cyanobacteria blooms, we used a multi-proxy paleolimnological approach pairing novel spectral (i.e., VNIRS) and molecular (i.e., qPCR) assessment tools to explore long-term cyanobacteria trends. We hypothesized that climate change over the past 50 years altered the Sunfish Lake environment to favour cyanobacteria dominance, resulting in an increased incidence of bloom events. Spectral and genetic results aligned to reveal an unprecedented abundance of cyanobacteria in modern times and coincided with warmer and wetter climatic conditions in the region. Our findings offer evidence for climate-driven shifts in cyanobacteria abundance and suggest that a shift towards warmer and wetter conditions supports the rise of cyanobacteria in lakes. Get Access Microlitter in the water, sediments, and mussels of the Saint John River (Wolastoq) watershed, Atlantic Canada . Andrew L. Labaj . , Amber D. LeBlanc . , Casey V. Doucet . , Christina E. Tardif . , and Joshua Kurek . Just-IN Microlitter is a widespread contaminant with implications for aquatic health; however, knowledge of its distribution in freshwaters is limited. We examined microlitter in surface water, sediment, and mussels within the Saint John River and four major tributaries. Microlitter was present at all 89 sites, with concentrations in water equivalent to other Canadian watersheds. Microlitter concentrations likely reflected differences in land use and development. Comparisons between rivers generally revealed distinct water microlitter particle compositions, suggesting that input sources were specific to each river, while microlitter in sediments and mussels was largely homogenous among rivers. There was little similarity in concentration and composition of microlitter between the three matrices sampled. Microlitter in sediments and mussels may not reliably track concentration and composition in aquatic environments. Microlitter concentration was not significantly greater downstream of wastewater treatment plants. Airborne microlitter transportation was evident, as remote sites in two tributary rivers demonstrated the highest concentrations of microlitter. Our data highlights the prevalence of microlitter in rural rivers, underscoring the ubiquity of this emerging contaminant and its integration into food webs. Get Access Estimating catch curve mortality based on relative return rates of coded wire tagged lake trout in US waters of Lake Huron . Ji X. He . , Mark P. Ebener . , Richard D. Clark . , James R Bence . , Charles P Madenjian . , Kevin N. McDonnell . , Matthew S. Kornis . , and Charles R. Bronte . Just-IN We estimated total mortality using catch curves based on relative return rates (RRs) of coded wire tagged lake trout in US waters of Lake Huron. RR was calculated as age specific CPUE per million of fish stocked. Annual mortality for the late 1990s through early 2000s was estimated as 38% from the 1991-1995 year-classes with an effective age range of 5-10 years, and then was estimated as 24% for the post-2000 period from the 1996-2009 year-classes. The two estimates from simple catch curve regressions based on average RR at age values were the same as from a mixed model with individual RR values from all stocking events. These two estimates were also comparable to the findings from statistical catch-at-age assessments with fundamentally different assumptions. Our approach is not constrained by the assumption that the expected recruitment is a constant over time and thus has the advantage to use multiple observations on each age from multiple cohorts. Our approach has broad applicability to aquatic ecosystems in which multiple mark-and-release events of fish stocking have been implemented. Get Access Oxythermal habitat as a primary driver of ecological niche and genetic diversity in cisco (Coregonus artedi) . Ryan C Grow . , Kyle D Zimmer . , Jennifer L Cruise . , Simon K Emms . , Loren M Miller . , Brian R Herwig . , David F Staples . , Angela R Tipp MN . , Greta M Gerdes . , and Peter C Jacobson . Just-IN Cisco (Coregonus artedi) are threatened by climate change and lake eutrophication, and their oxythermal habitat can be assessed with TDO3, the water temperature at which dissolved oxygen equals 3 mg L-1. We assessed the influence of TDO3 on cisco habitat use, genetic diversity, diets, and isotopic niche in 32 lakes ranging from oligotrophic to eutrophic. Results showed that as TDO3 increased cisco were captured higher in the water column, in a narrower band, with higher minimum temperatures and lower minimum dissolved oxygen. TDO3 was also negatively related to cisco allelic richness and expected heterozygosity, likely driven by summer kill events. Moreover, TDO3 influenced the isotopic niche of cisco, as fish captured deeper were more depleted in δ13C and more enriched in δ15N compared to epilimnetic baselines. Lastly, cisco in high TDO3 lakes consumed more Daphnia, had fewer empty stomachs, and achieved larger body size. Our work identifies specific characteristics of cisco populations that respond to climate change and eutrophication effects, and provides a framework for understanding responses of other cold-water species at the global scale. Get Access Temporal Variation in the Niche Partitioning of Lake Michigan Salmonines as it Relates to Alewife Abundance and Size Structure. . Benjamin A. Turschak . , Charles R. Bronte . , Sergiusz J. Czesny . , Brandon S. Gerig . , Austin Happel . , Tomas O. H??k . , Matthew S. Kornis . , Benjamin S. Leonhardt . , Bryan G. Matthias . , Jacques Rinchard . , and Harvey A Bootsma . Just-IN Stable isotope analyses offer a useful means for quantifying ecological niche dimensions, though few studies have examined isotopic response of an ecological community with respect to resource gradients such as fluctuations in prey availability. Stable carbon and nitrogen isotopes were measured for Lake Michigan salmonines and their prey collected from 2014 to 2016. Bayesian ellipse and mixing model analyses were used to quantify isotopic niche characteristics and diets, respectively, among species and years. During the three-year study period, abundance and size structure of preferred alewife prey changed substantially and offered an opportunity to explore predator isotopic niche response and diet shifts along a prey resource gradient. Results suggested increased reliance on alewives, especially small alewives, over the study period and were consistent with greater availability of this prey. However, differential use of alewife size classes and alternative prey sources by salmonine predators was apparent, which suggested possible resource partitioning. Characterization of ecological niche overlap using stable isotopes likely requires consideration of shared resource availability as well as specific prey and habitat preferences. Get Access Physiological and nutritional constraints on zooplankton productivity due to eutrophication and climate change predicted using a resource-based modeling approach . Chen Zhang PhD . , Michael T. Brett . , Jens M. Nielsen . , George B. Arhonditsis . , Ashley P. Ballantyne . , Jackie L. Carter . , Jacob Kann . , D?rthe C Müller-Navarra . , Daniel E. Schindler . , Jason D. Stockwell . , Monika Winder . , and David A. Beauchamp Ph.D. . Just-IN Emerging evidence suggests that zooplankton production is affected by physiological and nutritional constraints due to climate change and eutrophication, which in turn could have broad implications for food-web dynamics and fisheries production. In this study, we developed a resource-based zooplankton production dynamics model that causally links freshwater cladoceran and copepod daily production-to-biomass (P/B) ratios with water temperature, phytoplankton biomass and community composition, and zooplankton feeding selectivity. This model was used to evaluate constraints on zooplankton growth under four hypothetical scenarios: involving natural plankton community seasonal succession; lake fertilization to enhance fisheries production; eutrophication; and climatic warming. Our novel modeling approach predicts zooplankton production is strongly dependent on seasonal variation in resource availability and quality, which results in more complex zooplankton dynamics than predicted by simpler temperature dependent models. For mesotrophic and hypereutrophic lakes, our study suggests that the ultimate control over zooplankton P/B ratios shifts from physiological control during colder periods to strong resource control during warmer periods. Our resource-based model provided important insights into the nature of biophysical control of zooplankton under a changing climate that has crucial implications for food web energy transfer and fisheries production. Get Access Incorporating antenna detections into abundance estimates of fish . Maria C. Dzul . , Charles B. Yackulic . , William Louis Kendall . , Dana L Winkelman . , Mary M. Conner . , and Micheal D. Yard . Just-IN Autonomous passive integrated transponder (PIT) tag antennas are commonly used to detect fish marked with PIT tags but cannot detect unmarked fish, creating challenges for abundance estimation. Here we describe an approach to estimate abundance from paired physical capture and antenna detection data in closed and open mark-recapture models. Additionally, for open models, we develop an approach that incorporates uncertainty in fish size, because fish size changes through time (as fish grow bigger) but is unknown if fish are not physically captured (e.g., only detected on antennas). Incorporation of size uncertainty allows for estimation of size-specific abundances and demonstrates a generally useful method for obtaining state-specific abundances estimates under state uncertainty. Simulation studies comparing models with and without antenna detections illustrate that the benefit of our approach increases as a larger proportion of the population is marked. When applied to two field data sets, our approach to incorporating antenna detections reduced uncertainty in abundance substantially. We conclude that PIT antennas hold great potential for improving abundance estimation, despite the challenges they present. Get Access From drought to deluge: spatiotemporal variation in migration routing, survival, travel time and floodplain use of an endangered migratory fish . Dalton J Hance . , Russell W Perry PhD . , Adam C Pope . , Arnold J Ammann . , Jason L. Hassrick . , and Gabriel Hansen . Just-IN We developed a novel statistical model to relate the daily survival and migration dynamics of an endangered anadromous fish to river flow and water temperature during both extreme drought and severe flooding in an intensively managed river system. Our Bayesian temporally stratified multistate mark recapture model integrates over unobserved travel times and route transitions to efficiently estimate covariate relationships and includes an adjustment for telemetry tag battery failure. We applied the model to acoustic-tagged juvenile Sacramento river winter-run Chinook salmon (Oncorhynchus tshawytscha) and found that survival decreased with decreasing river flows and increased water temperatures. We found that fish were likely to enter at a large floodplain during flood conditions and that survival in floodplain was comparable to the mainstem Sacramento river. Our study demonstrates the response of an endangered anadromous fish population to extreme spatial and temporal variability in habitat accessibility and quality. The general model framework we introduce here can be applied to telemetry of migratory fish through systems with multiple routes to efficiently estimate spatiotemporal variation in survival, travel time, and routing. Get Access Efficiency is Doing Things Right: High Throughput, Automated, 3D Methods in the Modern Era of Otolith Morphometrics . Micah James Quindazzi BSc . , Adam Summers . , and Francis Juanes . Just-IN The morphometrics of fish otoliths have been commonly used to investigate population structures and the environmental impacts on ontogeny. These studies can require hundreds if not thousands of otoliths to be collected and processed. Processing these otoliths takes up valuable time, money, and resources that can be saved by automation. These structures also contain relevant information in three dimensions that is lost with 2D morphometric methods from photographic analysis. In this study, the otoliths of three populations of Coho Salmon (Oncorhynchus kisutch) were examined with manual 2D, automated 2D, and automated 3D otolith measurement methods. The automated 3D method was able to detect an 8% difference in average otolith density, while 2D methods could not. Due to the loss of information in the z-axis, and the longer processing time, 2D methods can take up to 100 times longer to reach the same statistical power as automated 3D methods. Automated 3D methods are faster, can answer a wider range of questions, and allow fisheries scientists to automate rather monotonous tasks. Get Access Bycatch reduction in the deep-water shrimp (Pandalus borealis) trawl fishery by increasing codend mesh openness . Nadine Jacques . , Hermann Pettersen . , Kristine Cerbule . , Bent Herrmann . , ?lafur A. Ingólfsson . , Manu Sistiaga . , Roger B. Larsen . , Jesse Brinkhof PhD . , Eduardo Grimaldo . , Jure Br?i? . , and Dagfinn Lilleng . Just-IN In most trawl fisheries, drag forces tend to close the meshes in large areas of diamond mesh codends, negatively affecting their selective potential. In the Barents Sea deep-water shrimp (Pandalus borealis) trawl fishery, selectivity is based on a sorting grid followed by a diamond mesh codend. However, the retention of juvenile fish as well as undersized shrimp is still a problem. In this study, we estimated the effect of applying different codend modifications, each aimed at affecting codend mesh openness and thereby selectivity. Changing from a 4-panel to a 2-panel construction of the codend did not affect size selectivity. Shortening the lastridge ropes of a 4-panel codend by 20% resulted in minor reductions for juvenile fish bycatch, but a 45% reduction of undersized shrimp was observed. Target-size catches of shrimp were nearly unaffected. When the codend mesh circumference was reduced while simultaneously shortening the lastridge ropes, the effect on catch efficiency for shrimp or juvenile fish bycatch was marginal compared to a 4-panel codend design with shortened lastridge ropes. Get Access OPEN ACCESS Quantification of land-sea nutrient fluxes supplied by allis shad across the species' range . Camille Poulet . , Betsy L. Barber-O'Malley . , Géraldine Lassalle . , and Patrick Lambert . Just-IN Diadromous species act as nutrient vectors between their marine and freshwater habitats. Few valuations of this regulating service exist and none at the scale of species distribution ranges. This large-scale approach seems particularly relevant for species moving and exchanging individuals across borders and territories as these populations may strongly depend upon each other in terms of population viability and provision of ecosystem services. The development of a new nutrient routine within an existing mechanistic species distribution model provided estimates of the 'maximum potential' of the anadromous allis shad (Alosa alosa) to provide nitrogen and phosphorous subsidies throughout Western Europe. During their seasonal reproductive migration, shad provided low amounts of nutrient subsidies when compared to North-American anadromous species and annual riverine nutrient loads. However, these subsidies are delivered as pulses concentrated in space and time, suggesting that more work is needed to figure out the significance of these shad-derived nutrients in terms of riverine ecosystem functioning. The evidence of a substantial flow of strayers delivering nutrient subsidies in several rivers confirmed the need for large-scale management of migratory species to ensure a sustainable provision of ecosystem services. PDF . High-resolution remote sensing and multistate occupancy estimation identify drivers of spawning site selection in fall chum salmon (Oncorhynchus keta) across a sub-Arctic riverscape . Chelsea M. Clawson . , Jeffrey A. Falke . , Larissa L. Bailey . , Joshua Rose . , Anupma Prakash . , and Aaron E. Martin . Just-IN Groundwater upwellings provide warmer, stable overwinter temperatures for developing salmon embryos, which may be particularly important in cold, braided, gravel-bed sub-Arctic rivers. We used a three-year time series of aerial counts and remote sensing to estimate the distribution of low and high aggregations of spawning fall chum salmon, classify approximately 0.5-km long river segments by geomorphic channel type, and map thermal variability along a 25.4 km stretch of the Teedriinjik River, Alaska. We used a dynamic multistate occupancy model to estimate detectability, occupancy, and the dynamics of spawning aggregations among river segments. Detectability was higher for large (>150) relative to smaller aggregations. Unoccupied segments were likely to remain so from year to year, low abundance spawning segments were dynamic and rarely remained in that state for multiple years, while ~20-35% of high abundance segments remained stable, indicating the presence of high-quality spawning habitat. Spawning habitat use was associated with warmer water temperatures likely caused by groundwater upwellings. We identified spawning habitat characteristics and trends in usage by fall chum salmon, which will inform land management decisions and assist in evaluating impacts of shifting climate conditions and resource management on Arctic salmon populations. Get Access OPEN ACCESS The truncate soft-shell clam, Mya truncata, as a biomonitor of municipal wastewater exposure and historical anthropogenic impacts in the Canadian Arctic. . Christina Mae Schaefer M.Sc. . , David Deslauriers . , and Ken M Jeffries . Just-IN Municipal wastewater is a large source of pollution to Canadian waters, yet its effects on Arctic marine ecosystems remains relatively unknown. We characterized the impacts of municipal wastewater from a growing northern community, Iqaluit, Nunavut on the Arctic truncate soft-shell clam,Mya truncata. Clams were sampled from six locations that varied in proximity to the wastewater treatment plant and shell biogeochemical analysis revealed that clams nearest the wastewater treatment plant had slower growth rates, lower carbon and oxygen stable isotope ratios, and elevated concentrations of copper and lead. A parallel analysis on mRNA expression profiles characterized M. truncata’s physiological response to wastewater effluent. Clams nearest the wastewater treatment plant had significantly lower mRNA expression of genes associated with metabolism, antioxidants, molecular chaperones, and phase I and II detoxification, but had heightened mRNA expression in genes coding for enzymes that bind and remove contaminants. These results demonstrated a biological response to Iqaluit’s wastewater effluent and highlight M. truncata’s potential to act as a biomonitor of municipal wastewater along Arctic coastlines in Canada. PDF . Temporal dynamics of dissolved organic matter (DOM) in mountain lakes: the role of catchment characteristics . Mark H Olson . , Janet M Fischer . , and Masaki Hayashi . Just-IN Climate change is affecting mountain ecosystems by increasing vegetation coverage and altering meteorological conditions. These changes are likely to impact the timing and magnitude of dissolved organic matter (DOM) inputs to lakes from the surrounding catchment. We examined temporal dynamics of DOM using in situ optical sensors that measured DOM fluorescence (fDOM) through the ice-free season in five lakes with differing catchment characteristics. We also measured changes in lake level and compiled daily meteorological data from nearby weather stations. At a seasonal timescale, fDOM dynamics occurred in two phases. fDOM declined in the first phase, which lasted until late July/mid-August, and corresponded to a decline in lake level following spring snowmelt. This decline was more pronounced in lakes with more vegetated catchments. At a shorter timescale, fDOM increased following precipitation events with a 0-1 day lag. Rates of fDOM increase per cm change in lake level were greater in lakes with vegetated catchments. As climate change increases vegetation coverage, DOM will likely become more dynamic at daily and seasonal timescales and impact water transparency and productivity of mountain lakes. Get Access OPEN ACCESS Ecological responses to elevated water temperatures across invasive populations of the round goby (Neogobius melanostomus) in the Great Lakes basin . Heather Bauer Reid . and Anthony Ricciardi . Just-IN Climate warming is expected to alter the distribution, abundance, and impact of non-native species in aquatic ecosystems. In laboratory experiments, we measured the maximum feeding rate and critical thermal maximum (CTmax) of an invasive Eurasian fish, the round goby (Neogobius melanostomus), acclimated to a range of temperatures (18–28°C) reflecting current and projected future thermal conditions for the nearshore Great Lakes. Fish were collected from four distinct populations along a latitudinal gradient from the western basin of Lake Erie to Hamilton Harbour (Lake Ontario) and the upper St. Lawrence River. Thermal tolerance increased with acclimation temperature for populations in lakes Erie and Ontario. However, the St. Lawrence River populations had lower acclimation capacity and exhibited an unexpected decline in CTmax at the highest acclimation temperature. Maximum feeding rates peaked at 18–24°C and declined with temperatures above 24°C. Northern populations in the basin appear poorly adapted to elevated temperatures such that their performance and impact could be reduced by climate warming. Thermal response data from latitudinally distributed populations are needed to inform invasive species risk assessment. PDF . OPEN ACCESS Simulated Pre-Spawning Catch & Release of Wild Atlantic Salmon (Salmo salar) Results in Faster Fungal Spread and Opposing Effects on Female and Male Proxies of Fecundity . MAGDALENE PAPATHEODOULOU . , Libor Závorka . , Barbara Koeck . , Neil B Metcalfe . , and Shaun S Killen . Just-IN Atlantic salmon are increasingly being released after capture by anglers. Yet, there are still unknown effects on the fish being subjected to the process of catch and release. Capture too close to spawning could have adverse effects on fish, and such data are important for setting appropriate closed seasons. This study examines how stressors related to catch and release experienced shortly before spawning affects adult mortality, vulnerability to Saprolegnia spp., and reproductive traits. Adult salmon were collected from the river Blackwater, Scotland, towards the end of their migration and were exposed to one of four protocols comprising exercise and air exposure of different durations. The experimental stressors increased the growth rate of the fungus Saprolegnia spp. over the body of the fish. Moreover, male salmon from the most disturbed group exhibited an increase in the maximum duration of their sperm motility. Lastly, females that experienced exercise and/or air exposure spawned at the usual time but with fewer eggs. These suggest that there may be benefits from preventing angling close to the time of spawning. PDF . Where do you come from, where do you go: Early life stage drift and migrations of cod inferred from otolith microchemistry and genetic population assignment . Karin Hüssy . , Christoffer Moesgaard Albertsen . , Jakob Hemmer-Hansen . , Morten Vinther . , Simon Hansen Serre . , Tonny Bernt Thomsen . , and Margit Eero PhD . Just-IN This study investigates stock mixing of genetically distinct Atlantic cod (Gadus morhua) stocks in the Kattegat, an area geographically located between the North Sea and the Baltic Sea, by combining genetic population identification with habitat assignments from hatch to capture from otolith microchemistry. Cod captured in Kattegat were genetically assigned to either the North Sea or the endemic Kattegat population. Otolith chemical fingerprints differed significantly between populations during the larval and pelagic juvenile stage with higher strontium and lower barium and manganese concentrations in the North Sea population than the Kattegat population, indicating that North Sea cod are spawned in the North Sea or Skagerrak and drift into the Kattegat during the early life stages. Individual cod of both populations undertook frequent migrations to other areas, with < 25 % of individuals remaining resident within the Kattegat throughout their life. Across seasons and age classes, the two populations were most frequently distributed in the Kattegat (67 %), with approximately 25 % distributed in the western Baltic Sea and < 10 % in the Skagerrak/North Sea. Get Access Seasonal residency, activity space, and use of deep-water channels by Greenland sharks (Somnious microcephalus) in an Arctic fjord system . Jena Elizabeth Edwards Master of Science . , Kevin J. Hedges . , and Nigel E. Hussey . Just-IN As Arctic ecosystems become increasingly vulnerable to climate- and human-induced stressors, effective marine management will rely on the characterization of fish movements. Over a six-year study period, the movements of 65 Greenland sharks (Somniosus microcephalus) (41 males, 24 females [mean LT = 2.48 ± 0.50 m]) were monitored using static acoustic telemetry. Shark presence in a typical deep-water fjord was restricted to the summer open-water period. Residency duration varied based on age-class (juvenile [n=17] vs. subadult [n=48]), however, activity space size and extent were comparable. A quarter of tagged sharks (n=16) returned to the system in subsequent years after tagging, with individuals re-detected for a maximum of 4 y. Movements between coastal and offshore waters occurred primarily via a deep-water channel with sharks detected along the channel banks. These multi-year data depict how a potentially vulnerable Arctic predator utilizes a deep-water fjord in the context of the regional development of community inshore and offshore commercial fisheries. Get Access Early lessons in deploying cameras and artificial intelligence technology for fisheries catch monitoring: where machine learning meets commercial fishing . Muhammad Rizwan Khokher Doctor of Philosophy . , L. Richard Little . , Geoffrey N Tuck . , Daniel V. Smith . , Maoying Qiao . , Carlie Devine . , Helen O'Neill . , John Pogonoski . , Rhys Arangio . , and Dadong Wang . Just-IN Electronic monitoring (EM) is increasingly used to monitor catch and bycatch in wild capture fisheries. EM video data is still manually reviewed and adds to on-going management costs. Computer vision, machine learning, and artificial intelligence-based systems are seen to be the next step in automating EM data workflows. Here we show some of the obstacles we have confronted, and approaches taken as we develop a system to automatically identify and count target and bycatch species using cameras deployed to an industry vessel. A Convolutional Neural Network was trained to detect and classify target and bycatch species groups, and a visual tracking system was developed to produce counts. The multiclass detector achieved a mean Average Precision of 53.42%. Based on the detection results, the visual tracking system provided automatic fish counts for the test video data. Automatic counts were within two standard deviations of the manual counts for the target species, and most times for the bycatch species. Unlike other recent attempts, weather and lighting conditions were largely controlled by mounting cameras under cover. Get Access The effect of total dissolved gas supersaturation on gas bubble trauma in juvenile rainbow trout (Oncorhynchus mykiss), juvenile kokanee (Oncorhynchus nerka) and two age classes of white sturgeon (Acipenser transmontanus). . Anthony Kovac . , Naomi K. Pleizier . , and Colin J Brauner . Just-IN Hydroelectric dams are an important source of electricity globally, but they can also cause total dissolved gas (TDG) supersaturation in rivers. Total dissolved gas supersaturation can harm fish through a condition called gas bubble trauma (GBT). Gas bubble trauma has been studied primarily in salmonids, such as rainbow trout and steelhead salmon (Oncorhynchus mykiss), but seldomly in non-salmonids like white sturgeon (Acipenser transmontanus). We assessed the vulnerability of juvenile rainbow trout (<1 year old), juvenile kokanee (Oncorhynchus nerka) (<1 year old), and two ages of white sturgeon (<1 year old and 3+ year old) to GBT. Bubble formation and the time to 50% loss of equilibrium (LOE) was quantified during exposure to nominal levels of 100, 115, 120 and 130% TDG. We predicted that all three species would show similar times to 50% LOE at a given TDG level. However, time to LOE was longer, the proportion of fish with external symptoms of GBT was lower and the proportion of fish with bubbles in the gills was higher or lower (dependant on age) in white sturgeon relative to rainbow trout and kokanee at a given TDG. The physiological basis for the difference is not known. However, it is important to consider species specific differences in TDG sensitivity in the conservation of vulnerable species Get Access Fine-scale behavior of red snapper (Lutjanus campechanus) around bait: approach distances, bait plume dynamics, and effective fishing area . Nathan M. Bacheler Ph.D. . , Brendan J. Runde . , Kyle W. Shertzer . , Jeffrey A Buckel . , and Paul J. Rudershausen . Just-IN The behavior of fish around bait is poorly understood despite it being important for the fish catching process and estimating relative abundance. We used a fine-scale acoustic positioning system to quantify the movements of 26 red snapper (Lutjanus campechanus) around 120 bait deployments in 2019 at a natural reef site (~37-m deep) in North Carolina, USA. There were 39 instances of tagged red snapper approaching bait during four baiting days, some of which approached due to apparent sensory cues (28%) while most approached incidentally (72%). Tagged red snapper approached bait from initial distances of 1 to 1 147 m (median = 27 m; mean = 86 m), and took 0 – 77 min (mean = 22 min) to approach. Fish were more likely to approach bait if they were located close to, and down-current of, the bait at deployment. Our estimated effective fishing area of 2 290 m2 (within which >50% of red snapper responded to bait) could be used along with video counts and other information to estimate densities of red snapper. Get Access Ecological considerations for species distribution modelling of euphausiids in the north east Pacific Ocean . Rhian Evans PhD . , Stéphane Gauthier . , and Clifford LK Robinson . Just-IN Euphausiids are a keystone species in marine food webs of the north-east Pacific Ocean, important for forage fish, commercial fish species and marine predators such as seabirds and whales. Ecosystem-based fisheries management relies on realistic lower-trophic level information for forecasting under future changing climate scenarios. We synthesised information from quantitative modelling studies analysing the relationship between euphausiids and their environment for two species of euphausiids which dominate assemblages in this region – Euphausia pacifica and Thysanoessa spinifera. Studies analysed suggest that variables reflecting the physical and biological environment in situ, features reflecting the geomorphic marine landscape, and large-scale climate indices all significantly affect euphausiid biomass and distribution. Temperature was the most tested predictor variable in the euphausiid models reviewed, however it was significant in fewer models than other variables tested. We review and compare model structures, predictor variable selection and temporal lag phases, to develop recommendations for species distribution modelling of euphausiids in the north-east Pacific Ocean. We believe the results from this review will be applicable globally across regions with similar climates where euphausiids are numerous, and can be adapted for different species and environments. Get Access OPEN ACCESS Kootenay Lake kokanee (Oncorhynchus nerka) collapse into a predator pit . Will G. Warnock . , Joseph L Thorley PhD . , Steven K Arndt . , Tyler J Weir . , Matthew D Neufeld . , Jeff A Burrows M.Sc. . , and Greg F Andrusak . Just-IN Kootenay Lake is a large, oligotrophic waterbody in southern British Columbia renowned for recreational fisheries for piscivorous rainbow trout (Oncorhynchus mykiss) and bull trout (Salvelinus confluentus). Long-term datasets showed a build-up of large-bodied (>2 kg) piscivore abundance followed by a collapse of the kokanee (Oncorhynchus nerka) prey population in 2013 and subsequent decline of large-bodied piscivores. An unprecedented post-collapse state formed in 2015-2018, characterized by low kokanee spawner abundance and biomass and high catch rates for small-bodied (<2 kg), slow growing piscivores. Bioenergetics model estimates of average historic (1961-2008) piscivore consumption was 29.3% of the average historic (1993-2008) kokanee prey supply (biomass and production), but increased to 78.7% in 2011, immediately preceding kokanee collapse. From 2015-2018, kokanee did not recover due to persistently poor juvenile survival; estimated piscivore consumption relative to prey supply remained high (73.0%), suggesting that kokanee were trapped in a predator pit. Although the ultimate and interacting causes of the initial predator build-up remain uncertain, overcoming current depensatory dynamics may be aided by kokanee stocking or increasing harvest on still-abundant, unsatiated piscivores. PDF . On the alarming state of freshwater biodiversity in Canada . Jessica Emilie Desforges . , Julia Clarke . , Evaline J. Harmsen . , Alex M. Jardine . , Jessica A. Robichaud . , Serina Serré . , Prosanta Chakrabarty . , Joseph R. Bennett . , Dalal E. L. Hanna . , John P Smol . , Trina Rytwinski . , Jessica J Taylor . , André L Martel . , Amanda K. Winegardner . , Jér?me Marty . , Mark K Taylor . , Constance M O'Connor . , Stacey A. Robinson PhD . , Andrea J. Reid . , Irena F. Creed . , Irene Gregory-Eaves . , Nicolas W.R. Lapointe . , and Steven J Cooke . Just-IN Little is known about the current state of freshwater biodiversity in Canada, one of the countries with the greatest amount of surface waters in the world. To address this knowledge gap, we compiled a list of all available assessments of conservation status for freshwater species (over 3,000 taxa) and further evaluated the overall status of six distinct taxonomic groups, focusing on organisms reliant on freshwaters [i.e., aquatic plants, invertebrates (with a focus on freshwater mussels), fishes, herpetofauna (reptiles and amphibians), birds, and mammals]. Overall, 11.7% of all freshwater species of plants and animals assessed were found to be ‘at risk’ (i.e., listed as ‘Threatened’, ‘Endangered’, or ‘Extirpated’) and 17.9% identified as ‘Special Concern’. We found that 37.9% of species lacked sufficient data to enable their status to be assessed. Data gaps in Canada’s assessment of its freshwater species were most prevalent in invertebrates (excluding freshwater mussels). Given the alarming state of freshwater biodiversity in Canada, we conclude by providing recommendations that focus on evaluating temporal trends and informing conservation actions. Get Access Spatially integrated modelling of data-limited orange roughy (Hoplostethus atlanticus) using environmental covariates . Charles Thomas Thesen Edwards . , Marie-Julie Roux . , and Malcolm Ross Clark . Just-IN Spatial stock assessment models are recognised as increasingly important for estimation of stock status and a sustainable exploitation rate. The inclusion of movement between spatial units within a model is difficult, because the data requirements are high. However for populations with low levels of spatial exchange it is possible to reduce the data requirements by distributing information on biological parameters between neighbouring units, or units with shared environmental conditions. This can allow spatial modelling to be applied even in data-limited situations. We develop this approach here through application to orange roughy (Hoplostethus atlanticus) sub-populations inhabiting neighbouring seamounts in the South Pacific. Despite limited data for each seamount, we were able to simultaneously fit multiple, localised, process-based models of the depletion dynamics. This was achieved by sharing information on the unexploited population size via known environmental covariates, with the relationship estimated in a hierarchical and integrated manner during the model fit. Cross-validation demonstrated that this approach can compensate for a lack of seamount-specific abundance data and improve ability of the model to estimate localised depletions. Get Access Diel patterns of foraging and microhabitat use by sympatric rainbow trout and bull trout: implications for adaptive differentiation and instream flow assessment . Sean M. Naman . , Jordan S Rosenfeld . , and Alecia S. Lannan . Just-IN Salmonids make flexible and adaptive trade-offs between foraging efficiency and predation risk that result in variable patterns of diel activity and habitat use. However, it remains unclear: (1) how patterns differ among salmonid species; and (2) how this affects the interpretation of habitat suitability models that inform instream flow management. We combined snorkel observations with experimental additions of cover to investigate how predation risk, cover, and bioenergetics affect diel activity and habitat use patterns by sympatric rainbow trout and bull trout in the Skagit River, BC, Canada. Both species foraged primarily at dusk, supporting the well-described trade-off between foraging efficiency and predation risk. However, only rainbow trout responded to cover additions, suggesting that risk tolerance and the nature of foraging-predation risk trade-offs differ between species. Diel shifts in activity and habitat use also substantially altered predictions of habitat suitability models, with potentially large consequences for flow management. Get Access A Bayesian multistate approach to evaluate movements of an invasive freshwater estuarine-opportunist . Aaron J Bunch . , Henry Hershey . , Gregory R Reger . , Frederick J Hoogakker . , Brady P Donovan . , and Troy M Farmer . Just-IN Coastal rivers and estuaries provide habitat and migratory corridors for freshwater estuarine-opportunists. We evaluated movement patterns of 61 blue catfish Ictalurus furcatus in the tidal York and Rappahannock rivers in Virginia, USA with acoustic telemetry from July 2015 to June 2016. To evaluate river-specific movements, we utilized a multistate Cormack-Jolly-Seber (CJS) model within a Bayesian framework to estimate probabilities of detection and transition (movement) among established salinity zones (i.e., tidal-fresh [0-0.5 ‰], oligohaline [>0.5-5 ‰], mesohaline [>5-18 ‰]). We considered flow as an environmental covariate. Despite high site fidelity in tidal-fresh zones, some individuals displayed movements into oligohaline and mesohaline habitats indicative of partial migration. Once downstream movement occurred, the probability of staying in the new salinity zone was higher than the probability of movements to other salinity zones. In the Rappahannock River only, movement upstream from mesohaline habitats was associated with below average flow. As flow increased, the probability of remaining in oligohaline and mesohaline zones increased. Our study shows blue catfish can move into downstream areas of tidal rivers with elevated salinities and that increased freshwater flow may allow them to remain in these habitats for extended durations. Get Access Induced triploidy reduces mercury bioaccumulation in a piscivorous fish . Collin James Farrell . , Brett M Johnson PhD . , Adam G Hansen . , and Christopher A Myrick . Just-IN We compared mercury bioaccumulation in triploid and diploid walleye (Stizostedion vitreum) in Narraguinnep Reservoir, Colorado, USA, and made several hypotheses that sex- and ploidy-specific differences in the allocation of energy towards reproductive development would affect mercury bioaccumulation. We tested our hypotheses with linear regression and a bioenergetics model informed by field data. We found diploid walleye had 28-31% higher mercury concentrations on average than triploids, but there were no differences between sexes of the same ploidy. Triploids of mature age exhibited minimal gonadal development when compared to diploids. After accounting for reproductive investment, the bioenergetics model accounted for most of the observed difference in average mercury concentration between ploidies for females. Conversely, the energetic cost of producing testes was low, and gonadal development could not explain observed patterns for males. Costs associated with elevated swimming activity and metabolism by diploid males relative to other groups could explain the difference but requires further investigation. The use of triploid fish in stocking programs could prove useful for reducing mercury in fish destined for human consumption. Get Access OPEN ACCESS Size spectra analysis of a decade of Laurentian Great Lakes data . Thomas M Evans PhD . , Zachary S Feiner PhD . , Lars G Rudstam . , Doran M. Mason . , James M Watkins . , Euan D. Reavie . , Anne E Scofield . , Lyubov E Burlakova . , Alexander Y Karatayev . , and W. Gary Sprules . Just-IN Size spectra analysis (SSA) is used to detect changes in food webs by simplifying complex community structures through abundance-versus-biomass considerations. We applied SSA to 10 years (2006-2015) of data on Great Lakes organisms ranging in size from picoplankton to macrozooplankton. Summer pelagic size spectra slopes were near the theoretical value of -1.0, but spring slopes were steeper, reflecting seasonal differences in abundance of small and large individuals. Pelagic size spectra slopes were relatively stable over the time period we examined. Height (the predicted number of organisms at the spectra midpoint) varied among lakes and was slightly higher in summer than spring in more productive basins. Including benthic data led to shallower slopes when combined with pelagic data, suggesting benthic organisms may increase food web efficiency; height was less affected by benthic data. Benthic data are not routinely included in SSA, but our results suggest they affect slopes and therefore SSA-based predictions of fish abundance. The ability of SSA to track changes in trophic energy transfer makes it a valuable ecosystem monitoring tool. PDF . Stock specific variation in the probability of precocious male maturation in hatchery Chinook Salmon (Oncorhynchus tshawytscha) . Donald A Larsen . , Abby E. Fuhrman . , Deborah L. Harstad . , David A Venditti . , and Brian R Beckman . Just-IN Age of maturation in many salmonid species is phenotypically plastic and dependent on exceeding a genetically set threshold in growth, often described as a probabilistic maturation reaction norm (PMRN). Hatchery supplementation programs for Chinook salmon in the Pacific Northwest US have been developed to minimize differences between hatchery and wild fish by integrating natural-origin adults into broodstock, potentially affecting PMRNs. We raised fish from 10 Chinook salmon stocks with variable levels of natural-origin integration in a common garden environment to explore potential genetic variation in PMRNs for precocious male maturation as age 2 minijacks. Proportion minijacks varied ≈10-fold (0.043 to 0.443) and the PMRN WP50 (predicted weight at 50% maturation) varied by ≈18 g (24.1 to 41.7g). The propensity for minijack maturation was generally higher in stocks with higher levels of natural origin integration. These findings demonstrate the effect of genotype by environment interactions on life history of salmonids and the need for stock specific tailoring of rearing regimes to regulate differences between hatchery and wild fish, when wild fish are used in broodstocks. Get Access OPEN ACCESS Spatiotemporal Modeling of Bycatch Data: Methods and a Practical Guide through a Case Study in a Canadian Arctic Fishery . Yuan Yan . , Eva Cantoni . , Chris Field . , Margaret A Treble . , and Joanna Mills Flemming . Just-IN Excess bycatch of marine species during commercial fishing trips is a challenging problem in fishery management worldwide. The aims of this paper are twofold: to introduce methods and provide a practical guide for spatio-temporal modelling of bycatch data, as well as to apply these methods and present a thorough examination of Greenland shark bycatch weight in a Canadian Arctic fishery. We introduce the spatially explicit two-part model and offer a step by step guide for applying the model to any form of bycatch data, from data cleaning, exploratory data analysis, variable and model selection, model checking, to results interpretation. We address various problems encountered in decision making and suggest that researchers proceed cautiously and always keep in mind the aims of the analysis when fitting a spatio-temporal model. Results identified spatio-temporal hotspots and indicated month and gear type were key drivers of high bycatch. The importance of onboard observers in providing robust bycatch data was also evident. These findings will help to inform conservation strategies and management decisions, such as limiting access to spatial hotspots, seasonal closures and gear restrictions. PDF . Cohort strength and body size in co-occurring salmonids in a small stream network: variation in space and time . Benjamin H. Letcher . , Keith H. Nislow . , Matthew J O'Donnell . , Andrew R. Whiteley . , Jason A. Coombs . , and Todd L Dubreuil . Just-IN Trout and salmon commonly coexist in stream networks. Exploring similarities and differences among species can help explain coexistence and invasive ability. Here, we describe spatial distribution, cohort strengths and size-at-age of three co-occurring species in a small stream network. Spatial distributions varied dramatically among species; native brook trout occupied all stream reaches, naturalized brown trout were found in the mainstem and lower portions of tributaries and fry-stocked Atlantic salmon were limited to the mainstem. Size-at-age also differed among species, Atlantic salmon were consistently the smallest, brook trout were intermediate in size and brown trout were the largest. Despite size differences, mean lengths of brook trout and brown trout were highly correlated among years. Cohort strengths varied considerably across years but were also highly correlated for the two trout species, suggesting strong environmental control on cohort strength and a reduced role for species interactions. At low densities, we observed strong negative effects of density on body sizes and weaker effects otherwise. Overall, these results suggest differences in spatial distribution combined with similarities in response to environmental variation contribute to species coexistence in this small steam network. Get Access Fitting growth models to otolith increments to reveal time-varying growth . Timothy E. Essington . , Mary Elizabeth Matta . , Bryan A. Black . , Thomas E Helser . , and Paul D. Spencer . Just-IN Identifying changes in fish growth is important for accurate scientific advice used for fisheries management, because environmental change is affecting fish growth and size-at-age is a critical component of contemporary stock assessment methods. Growth-increment biochronologies are time series of growth-increments derived from hard parts of marine organisms that may reveal dynamics of somatic fish growth. Here we use time series of otolith increments of two fish stocks to fit and compare a biologically-derived growth model and a generalized statistical model. Both models produced similar trajectories of annual growth trends, but the biologically-based one was more precise and predicted smaller inter-annual fluctuations than the statistical model. The biologically-based model strongly indicated covariance between anabolic and catabolic rate among individuals. Otolith size-at-age did not closely match fish length-at-age, and consequently the growth model could not accurately hindcast observed fish length-at-age. For these reasons, fitted growth dynamics from otolith biochronologies may best suited to identify growth rate fluctuations, to understand past drivers of growth dynamics, and improve ecological forecast in the face of rapid environmental change. Get Access A management-scale investigation of consistent individual differences in behaviour and trapping bias in Sea Lamprey (Petromyzon marinus) . Rachel R. Holub . , Gale A. Bravener Masters . , and Robert L. McLaughlin . Just-IN The Sea Lamprey (Petromyzon marinus) is invasive in the Laurentian Great Lakes. Trapping in large rivers could suppress Sea Lamprey recruitment by removing migrating adults prior to spawning. Currently, the proportion of Sea Lamprey trapped (efficiency) is too low for control purposes, possibly because trapping is biased toward certain behavioural types. We tested if individual differences in time to enter a novel environment (risk-taking) and proportion of time moving (activity) under standardized laboratory conditions were correlated with time to encounter and enter a trap in the field. 638 Sea Lamprey were tagged, assessed for risk-taking and activity in sequential trials, and released in the river to be trapped. In the laboratory, individuals differed consistently in risk-taking and activity behaviours, and more active individuals entered a simulated trap sooner than less active individuals. In the field, however, the times to first trap encounter, and capture in a trap, were not correlated with risk-taking or activity. Our study provides a novel demonstration of how patterns from small-scale behavioural studies may not extend to management-scale applications. Get Access Individual assignment of Atlantic bluefin tuna in the northwestern Atlantic Ocean using single nucleotide polymorphisms reveals an increasing proportion of migrants from the eastern Atlantic Ocean. . Gregory Neils Puncher PhD . , Alex Hanke . , Dheeraj Busawon . , Emma Sylvester . , Walter Golet . , Lorraine C Hamilton . , and Scott A. Pavey . Just-IN Identifying the origin of fish contained in a mixed fishery is critical for accurate stock assessments and the subsequent development of appropriate management strategies. Using a panel of 92 SNPs developed to differentiate Atlantic bluefin tuna (Thunnus thynnus) from the two main spawning areas (Gulf of Mexico and Mediterranean Sea), we used individual assignment to determine composition of feeding aggregations in the northwestern Atlantic Ocean (Gulf of Maine, Bay of Fundy, Scotian Shelf, Gulf of St. Lawrence, coastal Newfoundland). Among the 3,163 individuals collected between 2004 and 2018, we found that among lower age groups (<15 years) the spawning stock providing the most recruits to the Canadian fishery transitioned from Western Atlantic to Mediterranean origin over time. While the majority of older adults (>15 years) have consistently been of Western Atlantic origin, the disparity in the proportional contribution of western and eastern spawning groups narrowed significantly over the 14-year study period. Our results can be used to inform population-specific exploitation rates, improve stock assessments, identify age-dependent habitat use and areas suitable for additional conservation efforts. Get Access OPEN ACCESS Swimming capability of target fish from eight hydropower stations in China relative to fishway design . Xiaotao Shi . , Senfan Ke . , Zhiying Tu . , Yongmeng Wang . , Junjun Tan . , and Wentao Guo . Just-IN The four major Chinese carp (MC), Schizothorax fish species (SF), and Cobitidae fish species (CF) are the most important target fish species in China. The swimming behaviour study of three target fish groups is the key to Chinese fishway designs. The 20-min critical swimming speed (Ucrit-20 min) and endurance of the target fish species in relation to body length, swimming speed, and water temperature were estimated using multiple linear regression. The results indicated that both fish body length and water temperature had a significant effect on swimming capability. Performance comparisons indicated that SF were remarkably strong swimmer. CF possess slightly greater swimming capability than MC. The entrance velocity of the upstream fishway should be greater than Ucrit-20 min, but less than maximum swimming speed to make the flow out of the fishway noticeable. The maximum swimming distance could be estimated using endurance model at flow velocity of 1.2 m/s. For the downstream-migrating juvenile fish, it was suggested that the flow velocity of turbine intake should be less than maximum sustained speed avoiding entering turbine. PDF . Bioeconomic analysis accounting for environmental effects in data-poor fisheries: The Northern Labrador Arctic Charr . Melina Kourantidou PhD . , Di Jin . , and Andrew R Solow . Just-IN Fisheries managers call for more nuanced understandings of complex interactions between exploitation and environmental variability, especially in data poor settings. We develop a bioeconomic model for the Arctic Charr out of Nain, Northern Labrador, incorporating climate variability into growth. We derive parameters necessary for the bioeconomic analysis through optimization and identify optimal equilibrium conditions for the model with and without climate variability. Accounting for variability results in a slightly higher optimal harvest, fishing effort and stock. We find an optimal effort of 591 fishing weeks and harvest of 156,920kg for 2014, suggesting that both were below optimal. We further find that increased temperature leads to higher optimal effort and net benefits at steady state. Despite numerous uncertainties, data and knowledge gaps limiting the accuracy of our estimates, this is the first effort to identify the equilibrium harvesting conditions for this, currently uneconomic, yet socially and culturally important fishery. The methodology can be applicable to other data-deficient fisheries with similar challenges and unknowns, to advance the understanding of socially optimal harvesting and interactions with environmental variability. Get Access Space use of juvenile and subadult yellow perch (Perca flavescens) in the Detroit River using acoustic telemetry: incorporating variable detection ranges in vegetated areas . Jordan K. Matley . , Natalie V. Klinard M.Sc . , Sarah M. Larocque . , Amy A. Weinz . , and Scott F Colborne Ph.D. . Just-IN Understanding the space use of fishes in early life stages provides information that can contribute to effective fisheries management; however, it can be difficult to track fish in shallow, densely vegetated areas. Using acoustic telemetry, 60 subadult yellow perch (Perca flavescens) were tagged and monitored in a vegetated area of the Detroit River (May-Nov 2018). Variable detection range from submerged aquatic vegetation (SAV) was incorporated in estimates by applying a spatio-temporal correction to aid with interpretation of seasonal changes in activity space. Although subadult yellow perch were commonly detected in the array, demonstrating the importance of SAV habitat (mean detection residency index: 0.85), 60% of individuals were not detected following August, the period with highest activity space estimates, likely due to seasonal movements and predation. Individuals were more commonly detected during the daylight hours compared to night, but activity peaked at crepuscular periods. This study provided spatial information about the often-overlooked early life history of yellow perch, increasing the ecological information available for a species of management and conservation interest in the Great Lakes. Get Access OPEN ACCESS Artificial light improves size selection for northern shrimp (Pandalus borealis) in trawls . ?lafur Arnar Ingólfsson . , Terje J?rgensen . , Manu Sistiaga . , and Liz Kvalvik . Just-IN Size selection in the northern shrimp (Pandalus borealis) trawl fisheries is a widely studied topic. While the focus has largely been on codend and grid selectivity, studies have shown the importance of other design changes and the application of artificial light to evoke behavioural responses. LED lights of three different colours; green (~470–580 nm), white (~425–750 nm) and red (~580–670 nm), were mounted in the belly section of a shrimp trawl to investigate their influence on the overall selectivity of the trawl. The study was conducted using a twin-trawl setup, one with light and the other without light. For catch-comparison analysis, a polynomial regression with random effects was applied. The number of valid hauls with green, white and red lights were eleven, eight, and nine, respectively. All lights tested significantly affected the length-dependent retention of shrimp. Green light had the greatest effect, red the least. Significant loss was observed for shrimp below 17.5 mm carapace length (CL) for green light, 19.5 mm CL for white and 20.8 mm CL for red light. PDF . Bottom-up conservation: Using translational ecology to inform conservation priorities for a recreational fishery . Carissa Lynn Gervasi . , Rolando O. Santos . , Ryan J. Rezek . , W. Ryan James . , Ross E. Boucek . , Christopher Bradshaw . , Christopher Kavanagh . , Jason Osborne . , and Jennifer S. Rehage . Just-IN Translational ecology defines a collaborative effort among scientists and stakeholders to rapidly translate environmental problems into action. This approach can be applied in a fisheries management context when information needed to inform regulations is unavailable, yet conservation concerns exist. Our research uses a translational ecology framework to assess the stock status and develop research priorities for the Crevalle Jack (Caranx hippos) in the Florida Keys, U.S.A., a currently unregulated species. Interview data that compiled expert fishing guide knowledge were used to develop hypotheses tested using existing fisheries-dependent datasets to check for agreement among sources and assess the consistency of observed patterns. Six hypotheses were developed concerning the status and trends of the Crevalle Jack population in the Florida Keys, and four of these hypotheses received clear support, with agreement between guide observations and one or more of the fisheries-dependent datasets. The results of our study outline an effective translational ecology approach for recreational fisheries management designed to rapidly recognize potential management needs as identified by fishing guides, which allows for actionable science and proactive management. Get Access Comparative analyses with conventional surveys reveal the potential for an angler app to contribute to recreational fisheries monitoring . Fiona D Johnston . , Sean Simmons . , Brett T van Poorten . , and Paul A Venturelli . Just-IN Growing interest in apps to collect recreational-fisheries data requires that relationships between self-reported data and other fisheries data are evaluated, and that potential biases are assessed. This study compared results from a mobile-phone application and website for anglers (MyCatch) to results from three types of fisheries surveys – 1 provincial-level mail survey, 2 creel, and 17 gillnet surveys. Results suggest that an app/website can (i) recruit users that have a broad spatial distribution that is similar to conventional surveys, (ii) generate data that capture regional fishing patterns (2218 trips on 289 lakes and 90 streams/rivers), and (iii) provide catch rate estimates that are similar to those from other fisheries-dependent surveys. Some potential biases in app users (e.g., urban bias) and in the relative composition of species caught provincially were identified. The app was not a suitable tool for estimating fish abundance and relative community composition. Our study demonstrates how apps can/cannot provide a complementary data-collection tool for recreational-fisheries monitoring, but further research is needed to determine the applicability of our findings to other fisheries contexts. Get Access OPEN ACCESS Using decades of spawning data and hydraulic models to construct a temperature dependent resource selection function for management of an endangered salmonid . Peter N Dudley . , Sara N John . , Miles E Daniels . , and Eric M. Danner . Just-IN In North America, impassable, man-made barriers block access to salmonid spawning habitat and require costly restoration efforts in the remaining habitats. Evaluating restored spawning habitat quality requires information on salmon water velocity and depth preferences, which may vary in relation to other variables (e.g. water temperature). We demonstrate a generalizable, low cost method to gather and analyze this data by combining aerial redd surveys of winter-run Chinook salmon (Oncorhynchus tshawytscha), 2D hydraulic modeling, and generalized linear models to calculate spawning resource selection functions (RSFs). Our method permits the examination of interactions between environmental variables on habitat selection, which are frequently treated as independent. Our methods resulted in a RSF that shows interactions between both velocity and depth preference with changing temperature. Preferred depth increased and preferred velocity decreased with increasing temperature. Spawning RSFs for environmental variables may change as other environmental conditions (i.e. water temperature) change, thus it is importance to account for potential interactions when using or producing RSFs. PDF . Interannual variability in life-stage specific survival and life history diversity of coho salmon in a coastal Oregon basin . Kim K Jones MS . , Trevan J Cornwell . , Daniel L. Bottom . , Staci Stein . , and Steven Starcevich . Just-IN We quantified the population dynamics and life history diversity of seven brood years of coho salmon using a life-cycle approach. Four life history patterns, composed of fry, fry–nomad, parr, and yearling migrants indicated the importance of connectivity and access to a full range of freshwater and estuarine rearing environments through the year. Survival of each life history type varied annually with the yearling migrants contributing an average of 70% to the spawners in all but one return year. Fifty eight percent of the spawners of the 2013 return year had an estuarine rearing strategy, primarily parr migrants that overwintered in the estuary. Fry migrants, thought to be surplus production, were consistently observed in the estuary and represented in the returning spawners. The annual contribution of alternative rearing strategies to the spawners may support the resilience and viability of the population. We recommend that life cycle models of coho salmon account for the contribution of estuary migrants to the productivity and persistence of coho salmon in support of management and restoration of populations. Get Access OPEN ACCESS Eye lenses reveal ontogenetic trophic and habitat shifts in an imperiled fish, Clear Lake Hitch Lavinia exilicauda chi . Matthew J. Young . , Veronica Larwood . , Justin K. Clause . , Miranda Bell-Tilcock M.S. . , George Whitman . , Rachel C Johnson . , and Frederick Feyrer . Just-IN Stable isotopes recorded in fish eye lenses are an emerging tool to track dietary shifts coincident with use of diverse habitats over the lifetime of individuals. Eye lenses are metabolically inert, sequentially deposited, archival tissues that can open avenues to chronicle contaminant exposures, diet histories, trophic dynamics and migratory histories of individual fishes. In this study, we demonstrated that trophic histories reconstructed using eye lenses can resolve key uncertainties regarding diet and trophic habitat shifts. Clear Lake Hitch Lavinia exilicauda chi, a threatened cyprinid, inhabits a single lake (Clear Lake, Lake County, California) and utilizes tributary streams for reproduction. Bayesian mixing models applied to δ13C and δ15N recorded in eye lenses uncovered ontogenetic diet shifts that corresponded with shifts in occupation of habitats providing spawning (tributary streams), rearing (littoral lake), and growth (pelagic lake) functions. The reconstruction of size-structured trophic and habitat information can provide vital information needed to manage and conserve imperiled species such as the Clear Lake Hitch. PDF . OPEN ACCESS Predicting warming-induced hypoxic stress for fish in a fragmented river channel using ecosystem metabolism models . Jacob P. Ziegler . , James W. Roy . , Matthew J. Bogard . , and D. Andrew R. Drake . Just-IN Aquatic biota often face multiple anthropogenic threats such as river fragmentation and climate change that can contribute to high rates of aquatic species imperilment world-wide. Temperature-induced hypoxia is one under-explored mechanism that can threaten aquatic species in fragmented rivers with reduced flows. We applied ecosystem metabolism models to define the effect of water temperature on net ecosystem production (NEP) of oxygen at 12 sites of a fragmented river channel that supports three fish species at risk and experiences hypoxia. We found that water temperature and precipitation events at 75% of our sites were significantly and negatively correlated to NEP estimates and explained 28% of the variation in NEP within sites. Temperature-induced reductions in NEP at these sites likely contributed to hypoxic conditions threatening the three species at risk as NEP explained 41% of the variation in dissolved oxygen near all sites. Our results have applications for understanding drivers of hypoxic stress in fragmented watercourses, integrating water temperature-NEP effects with oxygen demands of sensitive fish species, and modeling future effects of climate change on aquatic species. PDF . OPEN ACCESS Outmigration Survival of a Threatened Steelhead Population through a Tidal Estuary . Rebecca A. Buchanan . , Elissa Buttermore . , and Joshua Israel . Just-IN Juvenile steelhead are exposed to numerous threats in heterogeneous, estuarine environments, yet understanding of survival patterns and processes during this migratory stage is often limited by studies that use surrogate species or are restricted in duration and spatial specificity. Lack of detailed survival information in this critical migratory stage limits the effectiveness of management to maintain juvenile life history diversity in threatened populations. We used acoustic telemetry with multistate release-recapture models to investigate survival patterns during a key stage of the juvenile emigration of anadromous steelhead through the Sacramento-San Joaquin River Delta of California, United States, over multiple years, including three drought years. Survival was highly variable both within and among the six years of the study; estimated total survival through the Delta ranged from 0.06 (May 2014) to 0.69 (March 2011). Survival in the upstream reaches was associated with river discharge into the Delta, while survival through the lower reaches was associated with migration route. The lack of a single factor associated with survival in all reaches counteracts preconceived ideas of survival processes. Hydrodynamic manipulation and habitat improvements are recommended to support this anadromous population in a changing climate. PDF . Effects of selective fishing on a small scale multi-species and multi-gear freshwater fishery in the Magdalena River Basin (Colombia) . Sandra Jeannette Hernández Barrero MSc . , Mauricio Valderrama Barco . , Carlos Guillermo Barreto Reyes . , and Wolfgang B Stotz . Just-IN Classical management has not been able to stop the 65% decrease in fishery production during the last 40 years in the Magdalena-Cauca River Basin. To analyze the effects of selective fishing of multiple species and small scale fisheries we addressed temporal changes at fishing level and the response of fishermen. The fishery reduced production and CPUE (catch per unit effort standardized), decreased the large sizes and growth rates of Prochilodus magdalenae and Pseudoplatystoma magdaleniatum, changed the abundance of trophic levels (decreased carnivores and increase of detritivores, omnivores), and increased exploitation rates. The fishermen have responded by implementing self-control measures, diversifying fishing gear and mesh size, including new species and sizes in the catch with a higher cpue (catch per unit effort) of small sized fish, adjusting the fishing effort to the abundance. We conclude that selective fishing has had ecological effects and fishermen have empirically self-regulated to optimize the cost-benefit ratio of their activity, developing a fishery that is more in line with ecosystemic structures. We address the balanced harvest strategy as a management alternative. Get Access OPEN ACCESS Genome-wide analysis reveals regional patterns of drift, structure, and gene flow in longfin smelt (Spirinchus thaleichthys) in the northeastern Pacific . Ismail Kudret Saglam . , James A. Hobbs . , Randall Baxter . , Levi S. Lewis . , Alyssa Benjamin . , and Amanda J. Finger PhD . Just-IN The southernmost stock of longfin smelt (Spirinchus thaleichthys) is approaching extirpation in the San Francisco Estuary (SFE); however, patterns of genetic structure, diversity and gene flow which are vital for management are poorly understood in this species. Here, we use genome-wide data to evaluate population structure of longfin smelt across a broad latitudinal scale across estuaries ranging from the SFE to Yakutat Bay and Lake Washington, and fine scale within the Fraser River and the SFE. Results indicate high genetic structure between major estuaries, fine-scale structure within the Fraser River, and low levels of structure within the SFE. Genetic structure was more pronounced between northern estuaries whereas southern estuaries showed shared ancestry and ongoing gene flow, most notably unidirectional northward migration out of the SFE. Furthermore, we detected signatures of local adaptation within the Fraser River and the Skeena River estuaries. Taken together, our results identify broad patterns of genetic diversity in longfin smelt shaped by co-ancestry, unidirectional migration and local adaptation. Results also suggest that the SFE population is genetically distinct from northernmost populations and an important source for maintaining nearby populations. PDF . An empirically based simulation model to inform flow management for endangered species conservation . Timothy E. Walsworth . and Phaedra Budy PhD . Just-IN Increasing water demand, water development, and on-going climate change have driven extensive changes to the hydrology, geomorphology and biology of arid-land rivers globally, driving an increasing need to understand how annual hydrologic conditions affect the distribution and abundance of imperiled desert fish populations. We analyzed the relationship between annual hydrologic conditions and the endangered Rio Grande silvery minnow in the Middle Rio Grande, New Mexico, USA, using hurdle models to predict both presence and density as a function of integrated annual hydrologic metrics. Both presence and density were positively related to spring high flow magnitude and duration and negatively related to summer drying, as indicated by an integrated flow metric. Simulations suggest hydrologic conditions near the wettest observed in the data set would be required to meet recovery goals in a single year in all reaches. We demonstrate how the models developed herein can be used to examine alternative water management strategies, including strategies that may currently be socially and logistically infeasible to implement, to identify strategies minimizing trade-offs between conservation and other management goals. Get Access Incorporating demographic information into spawner-recruit analyses alters biological reference point estimates for a western Alaska population . Benjamin A. Staton . , Matthew J. Catalano . , Steven J. Fleischman . , and Jan Ohlberger . Just-IN Changes over time in age, sex, and length-at-age of returning Pacific salmon have been widely observed, suggesting concurrent declines in per capita reproductive output. Thus, assessment models assuming stationary reproductive output may inaccurately estimate biological reference points that inform harvest policies. We extended age-structured state-space spawner-recruit models to accommodate demographic time trends and fishery selectivity to investigate temporal changes in reference points using Kuskokwim River Chinook salmon (Oncorhynchus tshawytscha). We illustrate that observed demographic changes have likely reduced per capita reproductive output in an additive manner, for example, models including changes in both length-at-age or age composition showed larger declines than models incorporating only one time trend. Translated into biological reference points using a yield-per-recruit algorithm, we found escapement needed for maximum sustained catch has likely increased over time, but the magnitude further depended on size-selective harvest (i.e., larger changes for reference points based on larger mesh gillnets). Compared to traditional salmon assessments, our approach that acknowledges demographic time trends allows more complete use of available data and facilitates evaluating trade-offs among gear-specific harvest policies. Get Access Evaluation of a citizen science platform for collecting fisheries data from coastal sea trout anglers . Casper Gundelund . , Paul A Venturelli . , Bruce W. Hartill MSc . , Kieran Hyder . , Hans Jakob Olesen . , and Christian Skov . Just-IN There are often limited data available to support the sustainable management of recreational fisheries. Electronic citizen science platforms (e.g., smartphone applications) offer a cost-effective alternative to traditional survey methods – but these data must be validated. We compared sea trout (Salmo trutta) data from a Danish citizen science platform with three independent traditional surveys: a roving creel survey, an aerial survey, and a recall survey. The comparisons include fisheries data (e.g., catch, release, effort, and size structure) and demographic descriptors (e.g., age) that were collected within the same spatial and temporal frame. We found general alignment between recreational sea trout catch and effort data that were provided by citizen scientists, or collected by more traditional survey methods. Our results demonstrate that citizen science data have the potential to supplement traditional surveys, or act as an alternative source of catch and effort data. However, results were from a highly specialized fishery within a limited spatial and temporal frame, so more research is needed to assess their relevance over time and to a broader set of fisheries. Get Access Temporal patterns and ecosystem correlates of chum salmon (Oncorhynchus keta) migration phenology in the Pacific Northwest . Mickey Agha PhD . , James P. Losee M.S. . , Marisa N. C. Litz . , Craig Smith . , Jason J. Schaffler . , William S Patton Master of Science (Fisheries) . , Aaron M Dufault . , and Gabe M Madel . Just-IN Understanding and quantifying migration phenology of commercially harvested Pacific salmon (Oncorhynchus spp.) is a cornerstone for managing sustainable populations. Here, we use a multi-decadal data timeseries together with a hypothesis driven framework to evaluate migration phenology in adult fall and winter ecotype chum salmon (O. keta) in a poorly studied but highly managed system – the South Puget Sound (SPS) of Washington State, USA. Using generalized additive mixed models that accounted for temporal autoregressive dynamics, we examined the effect of commercial harvest, climate variation, intraspecific density dependence, and predator buffering on migration timing and run duration. SPS chum salmon are migrating earlier over time, especially the winter ecotype that showed the strongest temporal shift from historical timing. Migration timing shifts were closely associated with regional-scale marine climate regimes, local-scale freshwater availability, and statewide pinniped abundance. In conclusion, there is potential for the winter ecotype migration converging with that of the fall ecotype, and that directional change in migration phenology may be driven by a unique combination of ecosystem factors. Get Access .
From:
监测目标主题     
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
系统抽取主题     
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)  
(1)