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Description of Work This spring (2014) we will measure Asian carp eDNA over time at a Missouri River site downstream of multiple spawning areas before and during spawning. We will measure the amount of Asian carp eDNA in water samples. The amount of eDNA will be related to the numbers of eggs and larvae counted in matched samples (water samples taken at the same time and place). The time since the eDNA was released by the carp will be estimated and these results will be related to the average age of AC eggs and larvae in matched samples. We will also test for substances which interfere with the eDNA measurement techniques and can lead to false negatives. We will also be validating markers developed by USGS and...
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Description of Work In separate studies, bighead carp and silver carp were raised in waters of varying hardness. Survival, correct development, and hatching success were monitored. Additionally, a search of the Asian literature (including Chinese-language literature) on water hardness in areas where Asian carp are native was performed. Relevance & Impact If soft water limits Asian carp hatching success, then this would mean that large areas of the Great Lakes and east and west coast drainages would not be at risk of Asian carp establishment. Key Findings Both bighead carp and silver carp developed normally and the eggs hatched normally in all water hardnesses tested, including very soft water. The Yangtze River,...
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Description of Work Bighead, silver and grass carp larvae were raised in the laboratory. Larvae were observed during the hatching process. Recently hatched larvae were placed in 10 feet tall clear vertical containers where the carp were exposed to light for a similar amount of time during the day as they would experience in a river during the spawning period. Depth selection, swimming behavior, and swimming speed were observed in both day and night periods. Relevance & Impact Understanding the stage at which Asian carps begin swimming is critical to development of models that predict whether a river is adequate for reproduction by Asian carps. Knowledge of where and how Asian carp larvae arrive in nursery areas...
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Description of Work USGS employees worked with Chinese scientists to acquire and translate existing Chinese science on development. Then, bighead and silver carps were spawned and the eggs and larvae reared in the laboratory, with close control on temperature and very close observation of the different developmental stages. Multiple spawning events of each species were necessary to understand variability in developmental rate. Preserved voucher specimens and microscope photography were taken of all developmental stages. Relevance & Impact These data were first used to model the spawning locations of Asian carps in the Missouri River. They were later used in the development of the more advanced FluEgg model, which...
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Description of Work To achieve a better understanding of seasonal habitats and migratory behaviors of Asian carp, we will conduct studies using telemetry, sonar and conventional fish sampling to determine 1) if, when, and where Asian carp congregate, 2) habitat overlap between Asian carp and native fishes, especially native filter-feeding fishes and potential predators, and 3) the suitability of large rivers and tributaries for spawning by Asian carp. We will also assess feeding behaviors by sampling food particles from areas with telemetry-tagged fish, at random sites and in Asian carp stomachs. Food from these sources will be characterized with a particle analyzer, genetics and microscopy to determine preferences...
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Description of Work USGS researchers have determined the densities of the eggs as these develop, and how much time the bighead and silver carp require to begin swimming and migrating laterally from flowing water into nursery habitat. This information about egg transport requirements was used to create a Tributary Assessment Tool also referred to as the Fluvial Egg Drift Simulator (FluEgg) model. The development of this tool was a collaborative effort between USGS and the University of Illinois. The tool takes into account the hydraulics of a river (water velocity and dispersion rates) and the water temperature (affects egg and larvae development rates) in order to determine if a river is sufficiently long and the...