bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular and Phenotypic Characterization of Strains of Photobacterium damselae subsp. piscicida Isolated from Hybrid Striped Bass Cultured in Louisiana, USA
Authors: Hawke John P. , Thune Ronald L. , Cooper Richard K. , Judice Erika , Kelly-Smith Maria 
Published: June 2004

Abstract
Photobacteriosis, which is caused by the bacterium Photobacterium damselae subsp. piscicida (formerly Pasteurella piscicida) was found to be a primary cause of mortality in hybrid striped bass (striped bass Morone saxatilis × white bass M. chrysops) cultured in brackish water in southern Louisiana. The disease was diagnosed on 50 occasions from 1990 through 2000 by the Louisiana Aquatic Diagnostic Laboratory, and mortality ranged from 5% to 90% in individual culture units. Strains of the bacterium from the Louisiana coast of the Gulf of Mexico were identified by means of biochemical tests, guanine–cytosine ratio, and Aquarapid Pp kit. Strains were characterized according to their biochemical phenotype, enzyme activities, plasmid profile, genotypic profile as determined by randomly amplified polymorphic DNA (RAPD) analysis, and antimicrobial susceptibility. When compared with representative isolates from the Chesapeake Bay, Greece, Japan, and Israel, Louisiana Gulf Coast isolates of P. damselae subsp. piscicida were found to be almost identical in biochemical phenotype and enzyme activity. The isolates differed in their plasmid profiles and antimicrobic susceptibilities. Louisiana isolates were found to possess a unique plasmid banding profile relative to strains from other geographic locations. The Louisiana isolates typically produced two large plasmid bands greater than 30 kilo–base pairs (kb) and two smaller bands 8.0 kb and 5.0 kb in size. Isolates from Israel and Greece exhibited similar banding patterns but were different from Louisiana and Japanese isolates. Resistance to Romet and Terramycin by some Louisiana strains was the result of acquisition of an R plasmid. When analyzed by RAPD, the Louisiana Gulf Coast strains were found to belong to clonal lineage group 2, which displays a fingerprint similar to that of the Japanese strains.
Distribution of Myxobolus cerebralis within a Free-Flowing River System during the Migration Period for Juvenile Anadromous Salmonids in Idaho
Authors: Cavender Wade P. , Johnson Keith A. , Cain Kenneth D. 
Published: June 2004

Abstract
To gain a better understanding of the pathogen-associated risk to resident and anadromous salmonid populations, the distribution, prevalence, and intensity of Myxobolus cerebralis infections were assessed during the smolt migration period in the Salmon, Snake, and Clearwater rivers of Idaho. Sentinel exposures of rainbow trout Oncorhynchus mykiss fry (0.6 g) occurred at 10 locations beginning at the headwaters of the Salmon River and extending downstream to the Snake and Clearwater rivers from April 18–28 and May 15–25, 2001. Following exposure, fish were examined for the prevalence and severity of infection by means of histological, pepsin−trypsin digest, and nested polymerase chain reaction analyses. Infections did not occur in the portions of the Snake or Clearwater rivers included in this study but were found in the Salmon River at five locations during April and seven locations during May. The results during April demonstrated moderate to high prevalence of infection (65% and 75% at 900 and 1,800 Celsius temperature units (CTUs), respectively) at the most upstream headwater site (river kilometer (rkm) 619, measuring from the mouth of the Salmon River), but intensity decreased 28 km downstream (rkm 591) to 10% and 0% at 900 and 1,800 CTUs, respectively. Fish exposed at two sites further downstream (rkm 454 and 416) showed 100% prevalence in both April and May. The most downriver sites at which infections were detected in April and May were sites 5 (rkm 308) and 7 (rkm 86). Significant correlations were not found between M. cerebralis infection and the environmental conditions examined in this study. However, the findings from this study show a temporal (April−May) increase in distribution and prevalence and a trend toward decreasing prevalence downstream of rkm 416. Therefore, resident and anadromous salmonids emerging or migrating through the Salmon River during April and May are probably exposed to the infectious stage of M. cerebralis.
Effects of Sublethal Dissolved Oxygen Stress on Blood Glucose and Susceptibility to Streptococcus agalactiae in Nile Tilapia Oreochromis niloticus
Authors: Evans Joyce J. , Shoemaker Craig A. , Klesius Phillip H. 
Published: June 2004

Abstract
The stress effects of sublethal dissolved oxygen (DO) exposures on blood glucose levels and susceptibility to Streptococcus agalactiae infection in Nile tilapia Oreochromis niloticus were determined with the One Touch Ultra blood glucose monitoring system. Fish were monitored for temporal changes in blood glucose concentration before, during, and after exposure to up to 1 mg DO per liter for 24 h. Blood glucose was found to increase significantly (P &lt; 0.001) in response to sublethal DO exposure. In additional experiments, fish were exposed to acceptable or sublethal DO. After exposure, fish were administered 9.5 × 101 or 7.5 × 102 colony-forming units (CFU) of S. agalactiae (infected) or tryptic soy broth (uninfected) by intraperitoneal injection. Significantly higher mean blood glucose levels were found in both infected and uninfected fish following sublethal DO exposure. None of the fish exposed to acceptable DO died due to streptococcal infection after challenge with either dose. Fish exposed to sublethal DO had significantly higher mortality rates (27% and 80%) after infection with S. agalactiae at 9.5 × 101 or 7.5 × 102 CFU than fish exposed to acceptable DO (0%). Increases in the susceptibility of Nile tilapia to S. agalactiae may be the result of the stress response to the sublethal DO exposure.
Shortnose Sturgeon in the Santee–Cooper Reservoir System, South Carolina
Authors: Collins Mark R. , Cooke Doug , Post Bill , Crane John , Bulak James , Smith Theodore J. I. , Greig Thomas W. , Quattro Joseph M. 
Published: June 2004

AbstractThe Santee–Cooper system in South Carolina, USA, is a complex of reservoirs, rivers, and canals. The endangered shortnose sturgeon Acipenser brevirostrum inhabits the rivers below the reservoirs and has also occasionally been reported anecdotally in the reservoirs themselves. During 1998–1999, we conducted a study to determine whether shortnose sturgeon were reproducing in the reservoirs, and if so, to evaluate habitat use and degree of separation from the riverine groups. Fourteen shortnose sturgeon were captured from the reservoirs, and all (even gravid females) appeared qualitatively less robust than riverine fish previously captured below one of the dams. Ten of the fish were implanted with transmitters and tracked at least once per week. Fish tracked in the upper reservoir, Lake Marion, stayed in the upper portion of that lake or in tributary streams flowing into it. We documented seasonal movements among four primary areas of upper Lake Marion and its tributaries. A spawning site on one of the tributaries, the Congaree River, was verified by collection of viable eggs. Genetic analysis demonstrated significant differences between samples from the Santee–Cooper reservoirs and three nearby coastal rivers. Cooper River samples, however, were not significantly different from reservoir samples, although appreciable differences in haplotype frequencies were observed. The need for a larger sample size was apparent. Although telemetry, spawning, genetic, and observational evidence suggests that the shortnose sturgeon in the reservoirs form a separate population segment, the results are not conclusive because possible downstream movement, especially of juveniles, through the dams has not been investigated.
Cardiovascular Responses of Largemouth Bass to Exhaustive Exercise and Brief Air Exposure over a Range of Water Temperatures
Authors: Cooke Steven J. , Ostrand Kenneth G. , Bunt Christopher M. , Schreer Jason F. , Wahl David H. , Philipp David P. 
Published: June 2004

AbstractIn this study we examined the effects of exhaustive exercise and brief air exposure on the cardiovascular function of largemouth bass Micropterus salmoides at four water temperatures (13, 17, 21, and 25°C). We used Doppler flow probes to monitor cardiac output and its components (i.e., stroke volume and heart rate) while we manually chased fish to exhaustion to simulate angling, exposed them to air for 30 s, and then recorded patterns of recovery. Resting cardiac variables generally increased with increasing water temperature except for stroke volume, which was temperature independent. Fish heart rate became erratic during exercise, and during air exposure fish exhibited severe bradycardia before becoming tachycardic when returned to the water. Maximal change occurred most rapidly for cardiac output (about 5 min). Several minutes later, changes in heart rate (increase) and stroke volume (decrease) simultaneously reached maximal deviations from resting values. Cardiac output and heart rate increased 150–200% relative to resting values despite 50% reductions in stroke volume, suggesting that largemouth bass are primarily frequency modulators. Maximal changes generally increased with water temperature for cardiac output and heart rate but not for stroke volume, resulting in heightened scope for cardiac output and heart rate with increasing water temperature. Recovery patterns were not influenced by water temperature. Cardiac output and heart rate generally returned to predisturbance levels in approximately 135 min, whereas stroke volume recovered more rapidly (about 110 min). Based on these findings, we suggest that largemouth bass exposed to exhaustive exercise and brief air exposure are capable of recovering from handling disturbances in several hours across the range of water temperatures that we examined (13–25°C).
Do Endangered Razorback Suckers Have Poor Larval Escape Performance Relative to Introduced Rainbow Trout?
Authors: Wesp Heather M. , Gibb Alice C. 
Published: June 2004

AbstractPoor recruitment has generated the hypothesis that the endangered razorback sucker Xyrauchen texanus is particularly vulnerable to predation early in its life history. We compared the escape responses of razorback suckers, which are adapted to the historically warm waters of the Colorado River, with those of rainbow trout Oncorhynchus mykiss, an introduced coldwater species, throughout early development at water temperatures of 12°C and 18°C. We quantified escape performance using maximum velocity, acceleration, and time to maximum velocity and acceleration. Both species showed complete temperature compensation for escape performance; individuals reared at 12°C performed as well as those reared at 18°C. Performance was also similar between species, although two variables exhibited a species × size interaction. Small razorback suckers were faster (greater maximum velocity and acceleration) than small rainbow trout, while large larvae performed similarly. We also determined that razorback sucker larval escape performance falls within the range reported for other fishes. Therefore, we conclude that razorback suckers do not have “poor” escape performance and that temperature does not directly cause decreased performance. However, a cold temperature reduces growth rates and delays razorback suckers' attainment of a “predator‐proof” size. Small larvae are also more likely to perform uncoordinated, ineffective escape responses. Hence, razorback sucker performance is indirectly diminished by temperature.
Acute Sensitivity of Juvenile Shortnose Sturgeon to Low Dissolved Oxygen Concentrations
Authors: Campbell Jed G. , Goodman Larry R. 
Published: June 2004

AbstractThere is considerable concern that factors such as eutrophication, industrial pollution, and dredging are adversely affecting the habitats of the endangered shortnose sturgeon Acipenser brevirostrum. Specific knowledge of the environmental requirements of this species is required if environmental managers are to adequately protect it. We conducted experiments to obtain information on the acute sensitivity of young‐of‐year shortnose sturgeon to a low dissolved oxygen (DO) concentration. Flow‐through tests were conducted with hatchery‐produced fish exposed to the ranges of DO, salinity, and temperature expected in the southeastern United States coastal river–estuary interfaces during spring and summer. The estimated concentration lethal to 50% of the test organisms (the LC50 value) after 24 h that we derived for approximately 77‐d‐old fish tested at 2‰ salinity and a nominal temperature of 25°C was 2.7 mg/L (32% saturation). An estimated LC50 of 2.2 mg/L (26% saturation) was obtained for approximately 104‐d‐old fish tested at 4‰ and 22°C. The 24‐h, 48‐h, and 72‐h LC50 values for approximately 134‐d‐old fish tested at 4.5‰ and 26°C were also 2.2 mg/L (28% saturation). However, the test with approximately 100‐d‐old fish at 2‰ and a nominal temperature of 30°C yielded a 24‐h LC50 of 3.1 mg/L (42% saturation). These data should be of value in derivating DO‐protective values for shortnose sturgeon inhabiting estuaries along the Atlantic coast.
Test of a Power Transfer Model for Standardized Electrofishing
Authors: Miranda L. E. , Dolan C. R. 
Published: June 2004

AbstractStandardization of electrofishing in waters with differing conductivities is critical when monitoring temporal and spatial differences in fish assemblages. We tested a model that can help improve the consistency of electrofishing by allowing control over the amount of power that is transferred to the fish. The primary objective was to verify, under controlled laboratory conditions, whether the model adequately described fish immobilization responses elicited with various electrical settings over a range of water conductivities. We found that the model accurately described empirical observations over conductivities ranging from 12 to 1,030 μS/cm for DC and various pulsed‐DC settings. Because the model requires knowledge of a fish's effective conductivity, an attribute that is likely to vary according to species, size, temperature, and other variables, a second objective was to gather available estimates of the effective conductivity of fish to examine the magnitude of variation and to assess whether in practical applications a standard effective conductivity value for fish may be assumed. We found that applying a standard fish effective conductivity of 115 μS/cm introduced relatively little error into the estimation of the peak power density required to immobilize fish with electrofishing. However, this standard was derived from few estimates of fish effective conductivity and a limited number of species; more estimates are needed to validate our working standard.
Use of Existing and Reconnected Backwater Habitats by Hatchery‐Reared Adult Razorback Suckers: A Predictive Model for the Imperial Division, Lower Colorado River
Authors: Gurtin Scott D. , Slaughter Joe E. , Sampson Schuyler J. , Bradford Richard H. 
Published: June 2004

AbstractInformation regarding the life history and biological requirements and preferences for the razorback sucker Xyrauchen texanus is limited. Current recovery efforts involve rearing fish to juvenile or adult stages in hatcheries before they are released into areas of critical habitat that increase their survival. Our objectives were to develop a model based on habitat use by hatchery‐reared razorback suckers in the lower Colorado River of Arizona and California for predicting preferred habitat and to determine whether fish would use reconnected off‐channel habitats. To this end, we monitored the use of existing and reconnected habitats by hatchery‐reared razorback suckers implanted with sonic transmitters. Off‐channel (backwater) habitats were preferred over main‐channel or side‐channel habitats. We constructed a model using logistic regression to predict which types of backwaters (based on morphology and water quality) were most suitable for use by razorback suckers. The model works well for predicting sites that are less suited for use and can be used to prioritize habitats for reconnection purposes because razorback suckers were found to utilize reconnected habitats.
Winter Ecology of Kokanee: Implications for Salmon Management
Authors: Steinhart Geoffrey B. , Wurtsbaugh Wayne A. 
Published: June 2004

AbstractWe sampled various limnological parameters and measured growth and diet of age‐0 kokanee Oncorhynchus nerka (lacustrine sockeye salmon) during two winters in a high‐mountain lake of the Sawtooth Valley, Idaho. Although winter has been recognized as an important period for many warmwater fishes and for stream‐dwelling salmonids, winter limitations have only recently been studied for coolwater and coldwater species. Ice and snow cover in winter limited light penetration. As a result, chlorophyll‐a and zooplankton density were lower in ice‐covered periods than during ice‐free periods. The weight of stomach contents was often below a maintenance ration, yet the incidence of empty stomachs was extremely low (1 of 63) and the weight of stomach contents increased as energy reserves declined, indicating that kokanee were actively foraging during winter. Kokanee length and weight remained constant during the winter of 1993–1994 but increased from November through May in 1994–1995. Condition factors, however, declined significantly over the winter in both years, and lipid content approached levels associated with mortality. Differences in growth patterns may have been caused by a combination of changes in zooplankton density and kokanee abundance and in kokanee behavior to defend energy reserves or avoid predation. Results demonstrated the ambiguity of some growth measurements and the importance of choosing the correct metric for measuring growth in fishes. Because juvenile kokanee and sockeye salmon are ecologically similar, management efforts to restore the endangered Snake River sockeye salmon to the Sawtooth Valley lakes should recognize that winter conditions might be a bottleneck for this species.
Respiratory and Circulatory Responses to Hypoxia in Largemouth Bass and Smallmouth Bass: Implications for “Live‐Release” Angling Tournaments
Authors: Furimsky Marosh , Cooke Steven J. , Suski Cory D. , Wang Yuxiang , Tufts Bruce L. 
Published: June 2004

AbstractArterial blood respiratory variables, ventilation rate, and cardiac output were examined in largemouth bass Micropterus salmoides and smallmouth bass M. dolomieu to compare their physiological responses to graded levels of hypoxia. Reduction in water Po2 (Pwo2) from 150 to 45 torr (1 torr ≈ 133.3 Pa) caused similar decreases in arterial Po2 (Pao2) in both species, although total blood O2 content was markedly higher in largemouth bass at the lower oxygen tensions. Curves for in vitro O2 dissociation in normoxic fish indicated that largemouth bass blood had a higher affinity for O2 than smallmouth bass blood. Severe hypoxia caused a significant increase in blood concentrations of catecholamines in smallmouth bass but not in largemouth bass. Increases in ventilation rate (54%) and decreases in cardiac output (27%) during hypoxia were also more pronounced in smallmouth bass than in largemouth bass. Arterial blood pH did not change during hypoxia exposure in largemouth bass but decreased significantly during severe hypoxia in smallmouth bass. The results of this study indicate that smallmouth bass are more sensitive to hypoxia than largemouth bass are. These results have important implications for situations in which these two bass species may be exposed to periods of hypoxia, such as during live‐release angling events.
Atlantic Sturgeon Marine Distribution and Habitat Use along the Northeastern Coast of the United States
Authors: Stein Andrew B. , Friedland Kevin D. , Sutherland Michael 
Published: June 2004

AbstractThough the distribution of Atlantic sturgeon Acipenser oxyrinchus is relatively well known in freshwater and estuarine habitats in the northern portion of their range, their distribution in marine habitats is poorly understood. Sturgeon migrate into marine waters to forage between spawning events and probably maintain gene flow between river populations by entering nonnatal river systems to spawn. While at sea, they are captured in commercial fishing gears. We investigated data collected by onboard fishery observers to determine the occurrence and habitat preference of Atlantic sturgeon off the northeastern coast of the United States. Sturgeon distributions were based on monitored fishing trips over the period 1989–2000 and referenced to local bathymetry and sediment data. The results show that peak sturgeon captures along the coast were approximately bracketed by isobaths ranging from 10 to 50 m. Sturgeon were present more frequently on gravel and sand sediment types and were associated with specific coastal features. The factors that may concentrate Atlantic sturgeon in particular coastal areas are discussed.
Evaluation of Nonlethal Methods for the Analysis of Mercury in Fish Tissue
Authors: Baker R. F. , Blanchfield P. J. , Paterson M. J. , Flett R. J. , Wesson L. 
Published: June 2004

AbstractThousands of fish are sacrificed each year to determine potential human exposure to mercury (Hg) from fish consumption. In this paper, we use lake whitefish Coregonus clupeaformis and northern pike Esox lucius to demonstrate that accurate and reliable measures of fish muscle Hg concentrations can be determined from small samples (<100 mg) harvested with biopsy tools. Reliability of results primarily depends upon analytical methodology and tissue sample weight. Mercury concentrations estimated by use of cold‐vapor atomic absorption spectrophotometry (CVAAS) on small composite tissue samples harvested with a Tru‐Cut (TC) biopsy needle (mean sample wet weight = 47 mg) were less precise than estimates from tissue samples harvested with a dermal punch (DP; mean sample wet weight = 126 mg). Precision differences presumably occurred because TC samples weighed less than the prescribed minimum weight (>100 mg) for CVAAS. There was no difference in precision of Hg concentrations among tissue extraction methods when biopsy samples were analyzed via cold‐vapor atomic fluorescence spectrophotometry (CVAFS). Mean tissue Hg concentrations obtained with the biopsy techniques and CVAAS or CVAFS were similar to benchmark concentrations in fillet samples (within 6%), even for TC– CVAAS. A field study of the effects of the DP biopsy method on survival of northern pike showed that tissue harvesting did not reduce survival. Our results clearly demonstrate that analysis of Hg content in muscle harvested with biopsy tools provides Hg measures comparable in accuracy to traditional, whole‐fish methods but without causing mortality.