bluuebunny/crossref_metadata_2025_split huggingface dataset:
Age-Dependent Susceptibility of Chinook Salmon to Myxobolus cerebralis and Effects of Sustained Parasite Challenges
Authors: Sollid Sarah A. , Lorz Harriet V. , Stevens Donald G. , Bartholomew Jerri L. 
Published: June 2004

Abstract
Laboratory challenges with triactinomyxons of Myxobolus cerebralis demonstrate that Chinook salmon Oncorhynchus tshawytscha have a lower susceptibility to infection and the development of whirling disease than rainbow trout O. mykiss. In age-dependent challenges, triplicate groups of each species were exposed at 1, 3, 5, 7, and 9 weeks posthatch to 1,000 triactinomyxons per fish and juvenile Chinook salmon were exposed to a high dose of 10,000 triactinomyxons per fish. Assessment of infection at 5 months postchallenge showed that Chinook salmon acquire resistance to clinical disease after 3 weeks posthatch, as compared with 7 weeks posthatch for rainbow trout. Furthermore, all measures of infection severity, including myxospore burden and lesion score, were lower in Chinook salmon. To model natural exposure and evaluate the ability of the fish to retain resistance following repeated challenge, replicate groups of Chinook salmon and rainbow trout were exposed daily to low parasite doses (5–200 triactinomyxons per fish) for 4 weeks. A low prevalence of infection and no clinical disease signs were recorded in the sustained exposure. These challenges indicate an overall lower susceptibility to M. cerebralis for Chinook salmon.
Ulcerative Mycosis Caused by Aphanomyces invadans in Channel Catfish, Black Bullhead, and Bluegill from Southeastern Louisiana
Authors: Hawke John P. , Grooters Amy M. , Camus Alvin C. 
Published: June 2004

Abstract
Eight cases of chronic ulcerative mycosis affecting populations of channel catfish Ictalurus punctatus, black bullhead Ameiurus melas, and bluegill Lepomis macrochirus cultured in recreational fishing ponds were submitted to the Louisiana Aquatic Diagnostic Laboratory between April 2000 and January 2002. Diseased clinical specimens presented with multiple foci of skin ulceration, typically overlying more extensive areas of granulomatous myositis that extended to the vertebral column in advanced cases. Lesions were predominated by fields of plump macrophages and multinucleated giant cells surrounding nonseptate, thick-walled hyphae with nonparallel cell walls suggestive of an oomycete. Because deep ulcerative mycoses in other fish species in the western Atlantic (USA), Australia, and Southeast Asia have been attributed to Aphanomyces spp., diagnostic methods were employed to isolate and identify this oomycete along with other potential pathogens. The organism was isolated from sites deep in the musculature with modified peptone−yeast−glucose medium containing 200 μg/mL streptomycin and 100 μg/mL ampicillin. Morphological features were consistent with A. invadans; the internal transcriber spacer (ITS) and 5.8S subunit regions of the rRNA gene were amplified, sequenced, and found to be identical with the ITS1 sequences from five isolates of A. invadans deposited in the GenBank database, indicating complete homology. Koch's postulates were fulfilled in juvenile (40–50-g) channel catfish. This report of ulcerative mycosis caused by A. invadans represents new host records for channel catfish and black bullheads from freshwater ponds in southeastern Louisiana.
Electroshocking-Induced Injuries in Newly Transformed Juvenile Fish
Authors: Henry Theodore B. , Grizzle John M. 
Published: June 2004

Abstract
Electroshocking-induced injuries in fish have not been described histologically, and little is known about such injuries in fish that have recently completed the transformation from larva to juvenile. We electroshocked newly transformed juvenile channel catfish Ictalurus punctatus, rainbow trout Oncorhynchus mykiss, striped bass Morone saxatilis, largemouth bass Micropterus salmoides, bluegill Lepomis macrochirus, and Nile tilapia Tilapia nilotica (also known as Oreochromis niloticus). Fish were exposed for 5 s (bluegills only) or 20 s to homogeneous electric fields of 30-Hz to 120-Hz pulsed DC. Only 2.8% of the survivors (N = 800) and 0.7% of the fish that died immediately after electroshocking (N = 600) had gross injuries. Hemorrhage in the posterior trunk or anterior tail was the most common gross lesion, occurring in 17 fish. Nine of these fish were examined histologically, and 8 had an injured vertebra, sometimes associated with a notochord hernia, at the location of hemorrhage. In largemouth bass, bluegills, and channel catfish that survived electroshocking without gross injuries, a vertebral lesion occurred in 17% (N = 12) of the bluegills exposed for 5 s (8 V/cm) and in 40% (N = 15) of the channel catfish (4 V/cm). No vertebral injuries occurred in 16 bluegills exposed for 20 s (4 V/cm) or in 22 largemouth bass (2 V/cm). Necrotic skeletal muscle was the most common histological lesion, occurring in 60% of the channel catfish, 64% of the bluegills, and 18% of the largemouth bass that survived electroshocking without gross injuries. Necrotic muscle was also found in one control largemouth bass (8%) and one control bluegill (20%). The types and frequencies of lesions were similar in fish that survived and in those that died after electroshocking.
Estimating the Relative Contribution of Spring‐ and Summer‐Spawned Cohorts to the Atlantic Coast Bluefish Stock
Authors: Conover David O. , Gilmore Todd , Munch Stephan B. 
Published: June 2004

AbstractThe timing of recruitment for age‐0 bluefishPomatomus saltatrixalong the southern and mid Atlantic coast of the USA is bimodal, consisting of spring‐spawned and summer‐spawned cohorts. We present evidence from surveys of age‐0 fish that the recent precipitous decline in the Atlantic bluefish stock over the past decade has been associated with a switch in the relative production of the two cohorts from predominance by spring‐spawned fish throughout the 1970s and 1980s to predominance by summer‐spawned fish in most years from 1992 to 2002. Given this evidence of a shifting recruitment pattern, we reexamined the contribution of the two cohorts to the adult portion of the population and compared our results with similar earlier assessments. Cohort origin of adults was identified based on back‐calculated length at age 1. In four year‐classes in which age‐0, summer‐spawned bluefish predominated, there was little evidence of summer‐spawned fish among harvested adults from the same year‐classes captured one or more years later. Most adults examined in this study (N= 976) displayed lengths at age 1 greater than 20 cm, as predicted for spring‐spawned bluefish. This contrasts with year‐classes of bluefish from the late 1950s, when back‐calculated size at age 1 was clearly bimodal, consisting of both spring‐spawned and summer‐spawned cohorts. Low numbers of summer‐spawned bluefish in our samples did not appear to be an artifact of inaccuracies in aging or back‐calculation. The recent decline in the abundance of Atlantic coast bluefish appears to result from poor age‐0 recruitment of the spring‐spawned cohort and failure of the summer‐spawned cohort to contribute substantially to the adult population.
Competitive Interactions between Age‐0 Bighead Carp and Paddlefish
Authors: Schrank Sally J. , Guy Christopher S. , Fairchild James F. 
Published: June 2004

AbstractThe effects of bighead carp Hypophthalmichthys nobilis on native planktivores in the USA is unknown. The objectives of this study were to experimentally test for competitive interactions between age‐0 bighead carp and age‐0 paddlefish Polyodon spathula. Differences among water chemistry variables, invertebrate densities, and relative growth of fish were assessed in mesocosms. Water chemistry variables were similar among treatments throughout the experiment and only exhibited a temporal effect. Zooplankton density declined in mesocosms after fish were introduced. In general, zooplankton densities did not differ among treatments but did differ from the control. The relative growth of paddlefish was negative in the paddlefish and paddlefish–bighead carp treatments. The relative growth of bighead carp was negative in the bighead carp treatment but positive in the paddlefish–bighead carp treatment. Age‐0 paddlefish exhibited the greatest decrease in relative growth in mesocosms with bighead carp. Bighead carp exhibited the greatest increase in relative growth in mesocosms with paddlefish. These data suggest that bighead carp have the potential to negatively affect the growth of paddlefish when food resources are limited.
Diel Feeding Patterns of Red Snapper on Artificial Reefs in the North‐Central Gulf of Mexico
Authors: Ouzts Allyson Clair , Szedlmayer Stephen T. 
Published: June 2004

AbstractDiets of red snapper Lutjanus campechanus were compared among four diel feeding periods (dawn, day, dusk, and night) and among three standard length size‐classes: small (200–299 mm), medium (300–399 mm), and large (400–499 mm). Fish were collected from August through October 2000 in the north‐central Gulf of Mexico. A total of 432 stomachs were examined, of which 164 (37%) contained prey. Size‐class influenced diets; diets of small red snapper were dominated by fish, those of medium red snapper by fish and tunicates, and those of large red snapper by crabs and fish. Red snapper fed on prey from several different habitats. Small red snapper fed mostly on reef and sand prey types; medium red snapper fed on similar portions of reef, sand, and mixed prey types; and large red snapper fed on mixed prey types. Adjusting for fish size, mean gut fullness was significantly lower for the dusk than for the day period. Fish were the most important prey for all periods. The second most important prey group changed with period: stomatopods for dawn, tunicates for day, and crabs for dusk and night periods. Prey habitat type also varied over periods. Sand prey type dominated dawn and dusk periods, whereas reef prey type dominated day and night periods. We used multidimensional scaling analysis to compare the relative influence of diel period to size‐class on red snapper diets. This analysis suggested that fish size‐class had a greater influence on red snapper diet than did period. However, with size effects removed, red snapper still showed significant diet shifts with periods.
Development of Ninety‐Seven Polymorphic Microsatellite Markers for Rainbow Trout
Authors: Rexroad C. E. , Palti Y. 
Published: June 2004

AbstractA high‐density microsatellite genetic map for rainbow trout Oncorhynchus mykiss is needed for the identification of quantitative trait loci affecting traits of economic interest to the aquaculture industry. These markers are also useful for evolutionary and population genetic studies. The candidate marker sequences that are identifed must be characterized with respect to their uniqueness, polymorphism, heterozygosity, ploidy, and usefulness as comparative mapping markers within the family Salmonidae. Ninety‐seven microsatellite markers were developed and characterized in this study. Twenty‐eight of these markers have been identified as duplicated in the rainbow trout genome based on the observation of more than one allele in at least one homozygous individual from clonal (doubled haploid) lines and more than two alleles in diploid fish. All of the 69 single‐copy markers were polymorphic in the rainbow trout sampled, with an average heterozygosity of 58%.
Decline of the Razorback Sucker in Lake Mohave, Colorado River, Arizona and Nevada
Authors: Marsh Paul C. , Pacey Carol A. , Kesner Brian R. 
Published: June 2004

AbstractThe razorback sucker Xyrauchen texanus is an endangered fish endemic to the Colorado River basin in the western United States. Once widely distributed and common throughout the basin, the species has been eliminated from most of its former range by establishment of nonnative fishes and water development, and remaining numbers have dwindled precipitously from historical levels. Although Lake Mohave, Arizona and Nevada, supports the largest and genetically most diverse remaining population, razorback sucker abundance in the lake plummeted from historical numbers in the hundreds of thousands to only 44,000 in 1991 and fewer than 3,000 in 2001. This population is limited primarily to large, old adults because predation on their larvae by nonnative fishes has precluded measurable recruitment for nearly half a century. At the current rate of decline, extirpation is anticipated within this decade because, at this time, there is no practicable method to remove the continuing threat of nonnative predators to razorback sucker larvae. As such, the persistence of razorback suckers in Lake Mohave depends on a repatriation program begun in 1991, which uses wild‐produced larvae that are reared in captivity and returned to the lake at a size that is less susceptible to predation.
Behavioral Thermoregulation of Brook and Rainbow Trout: Comparison of Summer Habitat Use in an Adirondack River, New York
Authors: Baird Owen E. , Krueger Charles C. 
Published: June 2004

AbstractThe body temperatures of 15 hatchery‐origin and two wild brook trout Salvelinus fontinalis and 11 hatchery‐origin rainbow trout Oncorhynchus mykiss were monitored with internally implanted, temperature‐sensitive radio transmitters from June through September 1997 in a fifth‐order Adirondack river (New York). The fish were released into a 12‐km reach that during summer had maximum temperatures near those that are lethal for salmonids. Body temperatures were compared between species and with river temperatures. In 1997, the maximum river temperature was 26.4°C, and the highest average daily temperature was 25.0°C. The brook trout were usually cooler than the main river flow because they used two of five tributary confluences or groundwater discharge areas in two pools within the main river. The temperatures of the brook trout from June through September were an average of 2.3°C cooler than the main flow of the river and differed significantly (P = 0.002) from those of the rainbow trout, which were 1.5°C cooler than the river. When the river temperatures were 20°C or higher, the mean temperatures of the brook trout were 4.0°C cooler than the river and differed significantly (P = 0.002) from those of the rainbow trout, which were 2.3°C cooler than the river. Brook trout, and to a lesser extent rainbow trout, used localized coolwater areas to lower their body temperatures below that of the main river. Groundwater discharge areas within pools and some tributary confluences were critical habitats for behavioral thermoregulation because they provided refuge areas from warm river water during the summer.
Patterns of Diet and Growth in Co‐occurring Populations of Largemouth Bass and Smallmouth Bass
Authors: Olson Mark H. , Young Brian P. 
Published: June 2004

AbstractLargemouth bass Micropterus salmoides and smallmouth bass M. dolomieu both undergo ontogenetic diet shifts from insects and zooplankton (as juveniles) to fish and crayfish (as adults). This diet similarity leads to the expectation that the growth rates of co‐occurring largemouth bass and smallmouth bass should covary positively. However, the relative abundance of the two species varies widely among lakes, suggesting that there are important ecological differences and making it difficult to predict how the individual growth rates of the two species will covary among systems. We quantified the diets and growth rates of largemouth bass and smallmouth bass in a set of lakes in New York State that varied in the relative abundance of the two species. Despite changing diets as a function of size, largemouth bass and smallmouth bass consumed similar prey across the size range. As expected based on diets, the growth rates of the two species were also positively correlated among lakes for most size‐classes. However, the growth rates of small, invertebrate‐feeding fish were negatively correlated with those of larger fish that fed on fish and crayfish. These results suggest that largemouth bass and smallmouth bass growth rates respond similarly across environmental gradients but that both species are composed of ecologically distinct stages.
Temperature during Incubation as One Factor Affecting the Distribution of Snake River Fall Chinook Salmon Spawning Areas
Authors: Connor William P. , Piston Charles E. , Garcia Aaron P. 
Published: June 2004

AbstractSpawning areas of ocean‐type fall Chinook salmon Oncorhynchus tshawytscha in the Pacific Northwest are largely restricted to relatively warm coastal rivers. Fall Chinook salmon spawners in the Snake River basin clearly favor the main‐stem Snake River and the relatively warm lower reaches of its tributaries. In this note, we describe how mean temperature during incubation affects fry emergence date and influences the distribution of fall Chinook salmon spawning areas in the Snake River basin. Using laboratory results and field data, we estimated fry emergence dates for three brood years of fish in seven areas that are consistently used by spawners and in five areas that are rarely used by spawners. Mean incubation temperature was significantly (P < 0.0001) higher in consistently used areas (5.6 ± 0.1°C) than in rarely used areas (4.5 ± 0.1°C). The mean estimated emergence date for the consistently used areas was 12 May (± 20 d), compared with 26 June (± 20 d) for rarely used areas. A logistic discriminant rule fitted from the mean incubation temperatures of the 12 areas discriminated between consistently and rarely used areas with 97% accuracy. We conclude that temperature is one factor that influences the distribution of fall Chinook salmon spawning areas in the Snake River basin.
Relations between Physical Habitat and American Eel Abundance in Five River Basins in Maryland
Authors: Wiley Derek J. , Morgan Raymond P. , Hilderbrand Robert H. , Raesly Richard L. , Shumway Durland L. 
Published: June 2004

AbstractAlthough the American eel Anguilla rostrata occurs in a variety of habitats over large geographic areas, little is known regarding the specific habitat relations that regulate eel distribution and abundance in freshwater streams. We evaluated the importance of 17 physical habitat, chemical, and biological variables in predicting eel density in five major river basins in Maryland. Because artificial structures impede eel migration in all five basins, only sites determined to be on unblocked streams or downstream of structures that significantly restrict eel passage were used in the analysis. Stepwise regression identified a model consisting of four variables—velocity–depth diversity, the log‐transformed distance (km) to the Chesapeake Bay, the log‐transformed density of noneel fishes, and the distance to a semipassable or impassable structure—as the best predictor of eel densities. When applied to a random subset of data not used for model development, the model correctly predicted 44.4% of eel densities and had a high mean prediction error (1.86 eels/75 m2) compared with the mean eel density for all sites included in model development (3.33 eels/75 m2). However, the Pearson correlation coefficient between the observed and predicted eel densities (r = 0.64; P < 0.05) indicated that the model was generally successful in predicting trends in observed densities. The study results are consistent with previous research suggesting the lack of significant eel–stream habitat associations, although the presence of a variety of velocity–depth regimes may support higher eel densities. Higher eel densities near artificial structures known to affect upstream movement suggest that eels are accumulating downstream of these structures because of impeded migration.
Genetic Variation and Relatedness of Juvenile Red Snapper Sampled from Shrimp Trawls in the Northern Gulf of Mexico
Authors: Saillant Eric , Mousseau Timothy A. , Gold John R. 
Published: June 2004

AbstractWe studied genetic variation and genetic relatedness among young‐of‐the‐year (age‐0) Gulf of Mexico red snapper Lutjanus campechanus sampled as bycatch in two separate shrimp trawl tows offshore of Galveston, Texas, and in a reference (control) group composed of multiple samples from within the same geographic area. Allelic and haplotypic variation was assayed at 11 microsatellite loci and mitochondrial DNA, respectively. Samples taken as bycatch from shrimp trawls did not differ from the reference group in allele richness, gene diversity, or allele frequency, indicating that most of the genetic variability within the cohort studied was attributable to fish sampled during single, localized tows of the shrimp trawler. Estimates of the variance of pairwise relatedness in the reference sample and in one of the bycatch samples were zero, whereas in the other bycatch sample the variance estimate was 0.001 (P = 0.1). A positive variance suggests that this sample contained individuals that were more closely related genetically than would be expected by chance alone. Because the relatedness estimators are sensitive to sample size, the number of loci, and allele distributions, further studies employing larger sample sizes and additional loci are warranted.
Combining Telemetry and Fisheries Tagging Models to Estimate Fishing and Natural Mortality Rates
Authors: Pollock Kenneth H. , Jiang Honghua , Hightower Joseph E. 
Published: June 2004

AbstractThe traditional multiple‐year tag return method is a fundamental approach to estimating fishing and natural mortality rates in fisheries. It can provide reliable and precise estimation of the parameters when the tag reporting rate, λ, is known. However, it is often difficult to estimate λ accurately. An additional disadvantage is that this method has to estimate natural mortality indirectly because natural deaths are not observable. Recently, fisheries biologists have begun to implement telemetry methods to estimate fishing and natural mortality. The advantage of a telemetry method is that it contains direct information about natural mortality and survival. A shortcoming is that there is no direct information on fishing deaths. In this paper, we combine the two methods, using direct information about both fishing and natural mortality to obtain more precise and effectively unbiased parameter estimates, including reporting rate estimates for the regular tags. Using simulation when the telemetry tag relocation probability equals 1, we found that the relative standard error (RSE) of natural mortality estimates in the combination method is much improved relative to those of the tag return and telemetry methods. Annual fishing mortality estimates can also be estimated precisely. As expected, as the relocation probability of telemetry tags decreases the RSE of natural mortality and the other parameter estimates increases, but only slightly. Studies clearly should have relocation probabilities that are as high as possible. The tag reporting rate estimates are typically precisely estimated in the combined model. This is very important, as the tag reporting rate is not easy to estimate with other methods.