bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rapid Out‐Migration of Lost River and Shortnose Sucker Larvae from In‐River Spawning Beds to In‐Lake Rearing Grounds
Authors: Cooperman Michael , Markle Douglas F. 
Published: June 2004

AbstractWe examined the process of larval out‐migration of endangered Lost River suckers Deltistes luxatus and shortnose suckers Chasmistes brevirostris from spawning grounds in the Williamson and Sprague rivers to rearing grounds in Upper Klamath Lake. Most downstream movement occurred at night, when larvae drifted in surface currents at the center of the channel. During daylight, larvae were absent from the drift and abundant near the periphery of the wetted channel, in areas that lacked current. The ages, sizes, and developmental stages of larvae from spawning grounds and the river mouth were similar, indicating that larval suckers transit from spawning grounds to the lake as soon as 1 d after the beginning of the larval period and that in‐river rearing is rare. The percent of larvae with empty guts declined from upriver towards the river mouth, suggesting that first feeding is an important driver of the out‐migration process. Sucker larvae greater than 13.99 mm standard length were rare in the rivers but abundant in the lake, suggesting out‐migration to Upper Klamath Lake is advantageous. Warmer temperatures and greater food availability may be important attributes of lake nursery grounds that are not found in the river. Most larvae entered the system on the falling river hydrograph, a strategy that does not promote floodplain access. Also, larvae of related species do not use floodplains. Therefore, suggestions that channelization and dredging of the lower Williamson River and severance of river–floodplain connectivity by levee construction have negatively affected larval suckers by slowing the out‐migration process or eliminating preferred habitats were not supported.
Growth and Condition of Alewives in Lake Michigan, 1984–2001
Authors: Madenjian Charles P. , Holuszko Jeffrey D. , Desorcie Timothy J. 
Published: June 2004

AbstractDiets of salmonines in Lake Michigan have been dominated by alewives Alosa pseudoharengus since the 1960s, and information on alewife population dynamics is critical to the management of salmonine fisheries. We monitored alewife size at age and condition (K) at several different locations in Lake Michigan during fall 1984–2001. Alewives were aged by enumerating annuli on otoliths. The results indicated that alewife length at age did not trend upward or downward between 1984 and the late 1990s but decreased from the late 1990s to 2001. Alewife weight at age was relatively constant between 1984 and the mid‐1990s but decreased from the mid‐1990s to 2001. Mean condition for a given alewife age was, on average, 13.7% higher during 1984–1994 than during 1995–2001. This decline in alewife condition was not a density‐dependent response by the alewife population because alewife abundance trended neither upward nor downward during 1984–2001. The decline in alewife condition was possibly due to the lakewide decrease in the abundance of Diporeia spp. during the 1990s. Apparently, the availability of the large‐bodied invertebrates Diporeia and Mysis spp. was an important regulator of adult alewife growth because alewives attained a substantially larger size in Lake Michigan, where these invertebrates were relatively important constituents of the adult alewife diet, than in Lake Ontario, where these invertebrates were not readily eaten by adult alewives. For age‐2 or older females, mean length was 2–9 mm greater than for males. Alewife size at age and condition were slightly higher on the eastern side of Lake Michigan than on the western side.
A General Model of Selectivity for Fish Feeding: A Rank Proportion Algorithm
Authors: Link Jason S. 
Published: June 2004

AbstractGiven that various prey are available to fish in a particular ecosystem, by default fish feed selectively. Studies of fish feeding ecology have provided key insights into the dynamics of aquatic ecosystems, yet prey selectivity is the least addressed component of these studies. This may be due to the higher level of effort associated with examining both the stomach contents and ambient prey abundance, the assumption that a determined diet composition is static, or the lack of a predictive protocol for a priori estimates of prey selectivity and diet composition. Here I present a rank proportion algorithm (RPA) model that predicts prey preference from first principles of predation that, when coupled with ambient prey concentrations, can predict prey utilization (i.e., diet composition). I applied the model to benthivore, planktivore, and piscivore examples from lentic, lotic, estuarine, and marine ecosystems. Compared with observed stomach contents, the RPA model's predictions of diet composition exhibited more than 83% accuracy, and in most of the cases the model predicted the predominant prey item accurately; the entire prey rank order was predicted correctly on the order of 70–80% of the time. Additionally, more than 85% of the prey items were predicted to be within 10% of observed values, and over 70% were within 5%. The results of the RPA model were notably different from those of the null model of no selectivity. The results suggest that the RPA model is a useful tool when prey preference or stomach composition data are limited but required for other applications and that a general knowledge of the predation process is useful in obtaining quantitative information about fish diet.
Influence of External Transmitter Shape and Size on Tag Retention and Growth of Juvenile Lake Sturgeon
Authors: Sutton Trent M. , Benson Angela C. 
Published: June 2004

AbstractFew studies have examined the effects of external radio transmitters on small fish. We evaluated the influence of two shapes (cylindrical and compressed) and three sizes (small, medium, and large [approximately 1.25, 2.00, and 6.00% of body weight, respectively]) of dummy transmitters on the tag retention and growth of juvenile lake sturgeon Acipenser fulvescens in an 8‐week laboratory experiment. Thirty‐five lake sturgeon were contained in each of three tanks, with five fish in each tank assigned to each of the six transmitter treatments. The remaining five fish in each tank, which served as the control group, were handled but did not receive a transmitter. A greater number of compressed transmitters were shed than cylindrical transmitters, and more large transmitters were lost than small or medium transmitters. Fish with medium and large transmitters, regardless of shape, exhibited lower growth than fish with small transmitters or the control group from week 2 through the end of the study. Only fish with small transmitters exhibited growth similar to that of the control group. Our results suggest that external radio transmitters should not exceed 1.25% of body weight and should be cylindrical in shape for telemetry studies involving juvenile lake sturgeon.
Large‐Scale Factors Associated with Sicklefin Chub Distribution in the Missouri and Lower Yellowstone Rivers
Authors: Dieterman Douglas J. , Galat David L. 
Published: June 2004

AbstractThe conservation and management of imperiled fishes requires information on the factors influencing their distribution. The sicklefin chub Macrhybopsis meeki is an imperiled, small‐bodied, riverine fish largely restricted to the main‐stem Missouri, lower Yellowstone, and middle Mississippi rivers. We tested the association of sicklefin chub presence/absence with physical habitat, temperature, turbidity, flow, and piscivore abundance between July and October 1996– 1997 at a riverscape spatial scale encompassing about 48–192‐km‐long segments over nearly 2,000 km of the Missouri and lower Yellowstone rivers. Four of the 64 variables examined were significantly associated with sicklefin chub presence/absence: distance to upstream impoundment, flow constancy (a measure of flow variability), mean turbidity, and percent of total annual flow occurring in August. The frequency of occurrence of sicklefin chub was highest when study segments were over 301 km downstream from an impoundment, flow constancy was 0.56 or lower (indicating variable flow), mean summer–early autumn turbidity was 80 nephelometric turbidity units or greater, and less than 10% of total annual flow occurred in August. Two complimentary models were developed from these results: a univariate model containing only a distance‐to‐upstream‐impoundment term, and a multiple model that included mean turbidity and August flow. Models were evaluated for accuracy with an independent data set from 1998. The univariate model was a more accurate predictor of sicklefin chub presence/absence in 1998, with correct predictions in 79% of the 14 segments sampled, compared with 69% for the multiple model. These results demonstrate, at a riverscape spatial scale, the importance of maintaining or restoring long, free‐flowing reaches containing a natural range of variability in seasonal low flows and turbidity to conserve a small‐bodied, obligate‐riverine fish.
Genetic Diversity of Wild and Hatchery Lake Trout Populations: Relevance for Management and Restoration in the Great Lakes
Authors: Page Kevin S. , Scribner Kim T. , Burnham‐Curtis Mary 
Published: June 2004

AbstractThe biological diversity of lake trout Salvelinus namaycush in the upper Great Lakes was historically high, consisting of many recognizable morphological types and discrete spawning populations. During the 1950s and 1960s, lake trout populations were extirpated from much of the Great Lakes primarily as a result of overfishing and predation by the parasitic sea lamprey Petromyzon marinus. Investigations of how genetic diversity is partitioned among remnant wild lake trout populations and hatchery broodstocks have been advocated to guide lake trout management and conservation planning. Using microsatellite genetic markers, we estimated measures of genetic diversity and the apportionment of genetic variance among 6 hatchery broodstocks and 10 wild populations representing three morphotypes (lean, humper, and siscowet). Analyses revealed that different hatchery broodstocks and wild populations contributed disproportionally to the total levels of genetic diversity. The genetic affinities of hatchery lake trout reflected the lake basins of origin of the wild source populations. The variance in allele frequency over all sampled extant wild populations was apportioned primarily on the basis of morphotype (θMT = 0.029) and secondarily among geographically dispersed populations within each morphotype (θST = 0.024). The findings suggest that the genetic divergence reflected in recognized morphotypes and the associated ecological and physiological specialization occurred prior to the partitioning of large proglacial lakes into the Great Lakes or as a consequence of higher contemporary levels of gene flow within than among morphotypes. Information on the relative contributions of different broodstocks to total gene diversity within the regional hatchery program can be used to prioritize the broodstocks to be retained and to guide future stocking strategies. The findings highlight the importance of ecological and phenotypic diversity in Great Lakes fish communities and emphasize that the management of wild remnant lake trout populations and the restoration of extirpated populations should recognize and make greater use of the genetic diversity that still exists.
Environmental Constraints on Spawning Depth of Yellow Perch: The Roles of Low Temperature and High Solar Ultraviolet Radiation
Authors: Huff David D. , Grad Gabriella , Williamson Craig E. 
Published: June 2004

AbstractThe roles of temperature and ultraviolet radiation (UVR) in determining the spawning success of yellow perch Perca flavescens were investigated in two Pennsylvania lakes with different dissolved organic carbon (DOC) concentrations. In situ incubation experiments were used to manipulate temperature and UVR and to examine hatching time and hatching success. Extensive scuba surveys were used to document actual spawning depths. Differences in the temperature and UVR profiles of the two lakes led to contrasting responses of incubated yellow perch eggs. Higher temperatures in the surface waters of the higher‐DOC lake led to hatching times that were 10–26 d shorter than those in the surface waters of the low‐DOC lake or in the deeper waters of the higher‐DOC lake. The high levels of UVR in the surface waters of the low‐DOC lake killed 100% of the eggs before hatching. Ultraviolet radiation had little effect on survival in the higher‐DOC lake or in deeper waters of the low‐DOC lake. Scuba surveys revealed that spawning in the low‐DOC lake occurred at greater depths than previously recognized. Ninety‐two percent of the eggs spawned in the low‐DOC lake were located at depths greater than 3 m, while 76% of eggs in the higher‐DOC lake were spawned in water less than 1 m deep. Temperature and UVR are both important in determining among‐lake differences in spawning depths of yellow perch. Yellow perch are able to spawn at shallow depths in higher‐DOC lakes, where warmer temperatures accelerate developmental rates and DOC blocks potentially damaging UVR. In low‐DOC lakes, yellow perch must spawn at greater depths to avoid UVR damage. Spawning at greater depths may be costly due to the substantially slower developmental rates at lower temperatures. Our data suggest that the conflicting selective pressures of UVR and temperature create an optimal spawning‐depth range for yellow perch that differs among lakes as a function of DOC concentration.
Susceptibility of Ten Fish Species to Electroshock‐Induced Mortality
Authors: Henry Theodore B. , Grizzle John M. , Johnston Carol E. , Osborne Jason A. 
Published: June 2004

AbstractTen species of fish were exposed to homogeneous electric fields of 60‐Hz pulsed DC in water having an ambient conductivity of 100 μS/cm. A range of voltage gradients was used for the electroshock, and the percentage of fish dead after 1 h was determined. A logistic model was used to compare species, and the voltage gradient that was lethal within 1 h to 50% of the fish (LV50) was computed. Except for blackbanded darters Percina nigrofasciata (juveniles and adults) and western mosquitofish Gambusia affinis (adults), all fish were newly transformed juveniles, which for some species are more sensitive to the lethal effects of electroshock than are younger or older fish. The most susceptible species was the blackbanded darter (LV50 = 1.7 V/ cm), followed by largemouth bass Micropterus salmoides (LV50 = 3.0 V/cm), striped bass Morone saxatilis (LV50 = 4.0 V/cm), and channel catfish Ictalurus punctatus (LV50 = 4.1 V/cm). Species of intermediate susceptibility were the rainbow trout Oncorhynchus mykiss (LV50 = 5.7 V/cm), bluegill Lepomis macrochirus (LV50 = 5.7 V/cm), and black crappie Pomoxis nigromaculatus (LV50 = 6.3 V/cm). Nile tilapias Oreochromis niloticus died only at the highest voltage gradient (27% mortality at 16 V/cm); paddlefish Polyodon spathula and western mosquitofish did not die after exposure to 16 V/cm. The wide variation in susceptibility to electroshock‐induced mortality among species indicates that caution should be used in habitats where sensitive species are present.
Habitat Fingerprints for Lake Superior Coastal Wetlands Derived from Elemental Analysis of Yellow Perch Otoliths
Authors: Brazner John C. , Campana Steven E. , Tanner Danny K. 
Published: June 2004

AbstractAssessing the ecological importance of coastal habitats to Great Lakes ecosystems requires an understanding of the ecological linkages between coastal and offshore waters. Elemental analysis of fish otoliths has emerged as a powerful technique that can provide a natural tag for determining nursery area affiliation, population structure, and movement of individual fish. Since the elemental composition of fish otoliths reflects some of the environmental conditions under which a fish was reared, otolith chemistry can record differences in ambient water conditions specific to habitats used during a fish's life history. Although few studies have been conducted in freshwaters, trace element analysis of marine fish otoliths has proven useful in identifying the chemical signatures unique to particular spawning and nursery habitats. To examine the utility of this method in freshwater, sagittae were removed from 275 young‐of‐the‐year yellow perch Perca flavescens captured from eight wetlands in western Lake Superior during August 2001. They were analyzed for Ca and 13 minor and trace elements using inductively coupled plasma mass spectrometry (ICPMS) and inductively coupled atomic emission mass spectrometry (ICPAES). Otolith concentrations of Ba, K, Mg, Mn, Na, and Sr differed significantly among wetlands (ANOVA, P < 0.001). Interwetland differences were also pronounced when analyzed as a multivariate fingerprint (MANOVA, P < 0.001). Discriminant function analysis revealed relatively distinct chemical fingerprints associated with each wetland. Wetland classification accuracy based on a five‐element model (Sr, Mn, K, Ba, and Mg) ranged from 62% to 100% and averaged 76%. Differences in fingerprints between wetland types (river‐influenced versus lagoon) were also distinct (MANOVA, P < 0.001). Classification accuracy for wetland type was 81% based on a five‐element model that included Ba, Mg, Mn, Na, and Sr. Our results suggest that otolith elemental fingerprints may be useful for quantifying the relative contributions of different wetland nursery areas to recruitment in adjacent lake populations.
Diet and Daily Ration of Bay Anchovy in the Hudson River, New York
Authors: Hartman K. J. , Howell J. , Sweka J. A. 
Published: June 2004

AbstractAlong the U.S. Atlantic coast, bay anchovy Anchoa mitchilli form an important component of estuarine and coastal food webs. The combination of its trophic position and abundance makes the diet and ration of this fish important in the study of estuarine systems. Diet and ration have been studied in this species in the middle and southern parts of its range, but information is lacking for the northern parts. Therefore, this study sought to quantify the diets and daily ration of bay anchovy on a seasonal basis within the Hudson River, New York, estuary. Diets of bay anchovy in the Hudson River were similar to those reported in other parts of their range. Bay anchovy ate mostly copepods, barnacle Balanas spp. nauplii, and mysid shrimp Neomysis americana. Mysids were seasonally important, contributing up to 81% (by weight) for adult fish in August. No differences were detected in diet composition or prey length between age‐0 and adult bay anchovy within months, but age‐0 fish did have an estimated ration up to 2.7 times as high as that of adults. The adult ration ranged from 0.061 g per gram of body weight per day in May to 0.252 g g−1 d−1 in August. The ration of age‐0 fish ranged from 0.449 to 0.684 g g−1 d−1 in August and September. The daily ration of bay anchovy was higher than reported for the mid‐Chesapeake Bay. This was surprising, as the Hudson River fish are older and larger than those studied in the Chesapeake Bay and physiological allometry indicates that larger individuals should have lower specific rates than smaller ones. This counterintuitive finding suggests that food availability was higher in the Hudson River than in the Chesapeake Bay studies.
Estimating Indices of Abundance and Escapement of Pacific Salmon for Data‐Limited Situations
Authors: Shotwell S. Kalei , Adkison Milo D. 
Published: June 2004

AbstractWe demonstrate the process of synchronously combining multiple sources of available fishery information to estimate total abundance in data‐limited situations. The application is specific to semelparous populations, such as Pacific salmon, where only data for spawners and recruits are necessary to describe the dynamics of these populations. We apply this technique to summer chum salmonOncorhynchus ketaof the Kuskokwim and Yukon rivers of Alaska. Since 1997, low numbers of returning chum salmon to these rivers have resulted in low harvests, with significant negative economic and social impacts to rural residents of the region. The existing programs for assessing salmon stock in these river basins are inadequate for conventional estimates of total run abundance and the modeling of stock dynamics necessary to derive a quantitative assessment of the returns. Our approach was to utilize the pattern extraction qualities of principal components analysis (PCA) to estimate the underlying trend in escapement. We then combined this index with other available fishery data in a maximum likelihood statistical framework, weighting the data sets according to their quality. Using this methodology, we derived indices of chum salmon abundance and escapement for the Kuskokwim and Yukon rivers. Data sources included commercial catch and effort, escapement surveys, test fishery catch rates, and whole‐river sonar counts. Error estimates of the time series of abundance and escapement as well as of the model parameters were generated by bootstrap methods. We found that several parameters of the model were confounded without some independent measure of total abundance or escapement. We also determined that the escapement trend estimated by PCA was consistent over a large geographic area, suggesting that survival was predominantly influenced by conditions where the fish share a common environment. We suggest that our methodology may be appropriate to other regions and different semelparous species.
What's on the Menu? Evaluating a Food Availability Model with Young‐of‐the‐Year Chinook Salmon in the Feather River, California
Authors: Esteban Elaine M. , Marchetti Michael P. 
Published: June 2004

AbstractWe adapted a salmonid food availability model by Rader to the Feather River in California and evaluated the ability of the model and two alternative measures of invertebrate abundance to predict the diet of young‐of‐the‐year salmonids. We compared the stomach contents of 240 Chinook salmonOncorhynchus tshawytschawith the model rankings and the taxonomic abundances in the benthos and drift. Rader's model did not adapt well to the Feather River. The model was correlated with the stomach contents of Chinook salmon but not with invertebrate drift, as theorized by the model's conceptual framework. Invertebrate abundance alone was a better indicator of salmonid feeding, and salmonid diet was correlated with both benthic and drift abundances. We urge caution in applying the model to novel regions and taxa without first examining the correlations between the drift and benthos. Observational studies of salmon foraging behavior, coupled with stomach content and invertebrate collections, may provide more information about food availability in little‐studied systems.
Epidemiology, Resistance, and Outcomes of Acinetobacter baumannii Bacteremia Treated with Imipenem‐Cilastatin or Ampicillin‐Sulbactam
Authors: Jellison Tara K. , McKinnon Peggy S. , Rybak Michael J. 
Published: June 2004

Study Objective. To evaluate epidemiology, resistance, and treatment outcomes of Acinetobacter baumannii bacteremia treated with imipenemcilastatin or ampicillin‐sulbactam for 72 hours or longer.Design. Retrospective analysis.Setting. University teaching hospital.Patients. Forty‐eight patients with A. baumannii bacteremia.Intervention. Evaluation of susceptibility and clinical data from 48 patients treated with either ampicillin‐sulbactam or imipenem‐cilastatin from 1987–1999.Measurements and Main Results. Comparing ampicillin‐sulbactam and imipenem‐cilastatin, there were no differences between days of bacteremia (4 vs 2 days, p=0.05), days to resolution of temperature or white blood cell count, success or failure during or at end of treatment, or intensive care unit total or antibiotic‐related length of stay (13 vs 10 days, p=0.05). Patients treated with ampicillin‐sulbactam had significantly decreased antibiotic treatment costs ($1500 vs $500, p=0.004).Conclusion. Ampicillin‐sulbactam is at least as effective as imipenemcilastatin based on clinical response at days 2, 7, and end of treatment and is a cost‐effective alternative for treatment of A. baumannii infections.