Data described herein was collected by USGS personnel and the project funded by USGS. Northern snakehead specimens were collected from the Potomac River and its tributaries by regional natural resource management agencies in the course of their field investigations working with this priority invasive aquatic species. Specimens were provided to USGS for the purpose of conducting health related assessments of northern snakehead in the region, with approximately 90 specimens evaluated grossly and histologically for the presence of lesions and abnormalities. Data presented here was collected seasonally (spring through fall) in 2006 and from 2015 to 2017. Data for each specimen includes date and location of collection, morphometrics, gender (if known), and gross abnormalities, and histological lesions observed. This body of data is stored in spreadsheet format.

This dataset contains information on all snakehead fishes found in the United States. It is a subset of a larger database, the Nonindigenous Aquatic Species Database (NAS). This information resource is an established central repository for spatially referenced biogeographic accounts of introduced aquatic species. The NAS website provides scientific reports, online/real-time queries, spatial data sets, distribution maps, fact sheets, and general information.

This dataset includes field hydrologic measurements and laboratory analyses of surface and pore waters, sediments, benthic plants/biofilms, and biota along the Middle Snake River upgradient of the Hells Canyon Complex. The study region for this work focuses on a section of the Snake River heavily utilized for agriculture, with complex systems of irrigation diversion and return drainage, spanning 164 km above the Hells Canyon Complex (Idaho, Oregon). The goal of this study was to identify potential loading sources of methylmercury from the upgradient Snake River into the reservoir complex, with a focus on the tributaries, irrigation return drains, and riparian zones adjacent to agricultural lands along the river. To this end, 16 locations along the Snake River between River Miles 448 and 346 were sampled over a four-day period, July 11 – 14, 2022. At each sampling site, pore water and sediment cores were collected in the shallow riparian zones along the edge of the river, surface waters were collected from cross-sections of the river, river flow and velocity were measured, submerged macrophytes and associated biofilm was collected, and biota (snails, amphipods, clams, periphyton, dragonfly larvae) were sampled from shallow riparian margins using a boat-mounted benthic suction dredge. Concurrently, water samples were collected from the six major tributaries that enter the Snake River in the study reach (Succor Creek, Owyhee River, Boise River, Malheur River, Payette River, Weiser River) and from six irrigation return drains that were actively discharging to the Snake River. Data from additional irrigation return drains to the study reach, sampled in June 2021 and May 2022, are also included. All water samples (surface and pore water) were processed and analyzed for filter-passing total mercury and methylmercury, dissolved organic carbon (DOC), dissolved organic matter (DOM) composition (UV-vis absorption and fluorescence), inorganic anions (chloride, nitrate, sulfate), and filter acidified metals (iron, manganese). In addition, the surface waters were analyzed for total suspended solids (TSS), particulate total and methylmercury, particulate organic carbon (POC) and stable isotopic composition, particulate nitrogen (PN) content and stable isotopic composition, and particulate metals (iron, manganese); and the pore waters were analyzed for inorganic sulfide (S(-II)). Sediment, submerged macrophytes and biofilms, and biota samples were dried, ground, and analyzed for total and methylmercury. Loss on ignition was also measured on the sediment samples. This data release includes eight metadata and data tables in machine readable format (*.csv). All data columns in tables 3-8 are defined in Table 2. Reference Table 2 for associated units, abbreviation definitions, laboratory information, and method citations. Table_1_Site_Descriptions.csv - site descriptions Table_2_Analysis_Descriptions.csv - data dictionary defining column headings in Tables 3-8 Table_3_Water_SW.csv - surface water chemistry data Table_4_Water_PW.csv - pore water chemistry data Table_5_Sediment.csv - sediment chemistry data Table_6_Macrophytes_and_Biofilms.csv - submerged macrophyte and biofilm data Table_7_Hydrology.csv - hydrologic data Table_8_Biota.csv - biota data

This dataset includes field hydrologic measurements and laboratory analyses of surface and pore waters, sediments, benthic plants/biofilms, and biota along the Middle Snake River upgradient of the Hells Canyon Complex. The study region for this work focuses on a section of the Snake River heavily utilized for agriculture, with complex systems of irrigation diversion and return drainage, spanning 164 km above the Hells Canyon Complex (Idaho, Oregon). The goal of this study was to identify potential loading sources of methylmercury from the upgradient Snake River into the reservoir complex, with a focus on the tributaries, irrigation return drains, and riparian zones adjacent to agricultural lands along the river. To this end, 16 locations along the Snake River between River Miles 448 and 346 were sampled over a four-day period, July 11 – 14, 2022. At each sampling site, pore water and sediment cores were collected in the shallow riparian zones along the edge of the river, surface waters were collected from cross-sections of the river, river flow and velocity were measured, submerged macrophytes and associated biofilm was collected, and biota (snails, amphipods, clams, periphyton, dragonfly larvae) were sampled from shallow riparian margins using a boat-mounted benthic suction dredge. Concurrently, water samples were collected from the six major tributaries that enter the Snake River in the study reach (Succor Creek, Owyhee River, Boise River, Malheur River, Payette River, Weiser River) and from six irrigation return drains that were actively discharging to the Snake River. Data from additional irrigation return drains to the study reach, sampled in June 2021 and May 2022, are also included. All water samples (surface and pore water) were processed and analyzed for filter-passing total mercury and methylmercury, dissolved organic carbon (DOC), dissolved organic matter (DOM) composition (UV-vis absorption and fluorescence), inorganic anions (chloride, nitrate, sulfate), and filter acidified metals (iron, manganese). In addition, the surface waters were analyzed for total suspended solids (TSS), particulate total and methylmercury, particulate organic carbon (POC) and stable isotopic composition, particulate nitrogen (PN) content and stable isotopic composition, and particulate metals (iron, manganese); and the pore waters were analyzed for inorganic sulfide (S(-II)). Sediment, submerged macrophytes and biofilms, and biota samples were dried, ground, and analyzed for total and methylmercury. Loss on ignition was also measured on the sediment samples. This data release includes eight metadata and data tables in machine readable format (*.csv). All data columns in tables 3-8 are defined in Table 2. Reference Table 2 for associated units, abbreviation definitions, laboratory information, and method citations. Table_1_Site_Descriptions.csv - site descriptions Table_2_Analysis_Descriptions.csv - data dictionary defining column headings in Tables 3-8 Table_3_Water_SW.csv - surface water chemistry data Table_4_Water_PW.csv - pore water chemistry data Table_5_Sediment.csv - sediment chemistry data Table_6_Macrophytes_and_Biofilms.csv - submerged macrophyte and biofilm data Table_7_Hydrology.csv - hydrologic data Table_8_Biota.csv - biota data

Environmental DNA detection results from samples collected using autonomous water sampling robots and manual approaches. Samples were collected in the Upper Yellowstone River (Montana) and Upper Snake River (Idaho/Wyoming) in 2018 and 2019. Samples were tested for the DNA of the following species: the waterborne protozoa Naegleria spp., the fish pathogen Tetracapsuloides bryosalmonae, Scomber japonicas (mackerel fish), kokanee salmon (Oncorhynchus nerka) and dreissenid mussel (Dreissena spp.).

Environmental DNA detection results from samples collected using autonomous water sampling robots and manual approaches. Samples were collected in the Upper Yellowstone River (Montana) and Upper Snake River (Idaho/Wyoming) in 2018 and 2019. Samples were tested for the DNA of the following species: the waterborne protozoa Naegleria spp., the fish pathogen Tetracapsuloides bryosalmonae, Scomber japonicas (mackerel fish), kokanee salmon (Oncorhynchus nerka) and dreissenid mussel (Dreissena spp.).

This dataset contains information on the Bullseye Snakehead fish found only in southeastern Florida. It is a subset of a larger database, the Nonindigenous Aquatic Species Database (NAS). This information resource is an established central repository for spatially referenced biogeographic accounts of introduced aquatic species. The NAS website provides scientific reports, online/real-time queries, spatial data sets, distribution maps, fact sheets, and general information.

Critical habitat includes the stream channels within the designated stream reaches, and includes a lateral extent as defined by the ordinary high-water line (33 CFR 319.11). In areas where ordinary high-water line has not been defined, the lateral extent is defined by the bankfull elevation. Bankfull elevation is the level at which water begins to leave the channel and move into the floodplain and is reached at a discharge which generally has a recurrence interval of 1 to 2 years on the annual flood series. Critical habitat in lake areas is defined by the perimeter of the water body as displayed on standard 1:24,000 scale topographic maps or the elevation of ordinary high water, whichever is greater.See the final rule (70 FR 52630) for descriptions of areas excluded from this critical habitat designation. Excluded Indian lands were not clipped out of the data.

Critical habitat includes the water, waterway bottom, and adjacent riparian zone of specified lakes and river reaches. Adjacent riparian zones are defined as those areas within a horizontal distance of 300 feet (91.4 m) from the normal line of high water of a stream channel (600 feet or 182.8 m, when both sides of the stream channel are included) or from the shoreline of a standing body of water.Critical habitat includes the Columbia River from a straight line connecting the west end of the Clatsop jetty (south jetty, Oregon side) and the west end of the Peacock jetty (north jetty, Washington side) and including all Columbia River estuarine areas and river reaches proceeding upstream to the confluence of the Columbia and Snake Rivers; all Snake River reaches from the confluence of the Columbia River upstream to Hells Canyon Dam. Critical habitat also includes river reaches presently or historically accessible (except reaches above impassable natural falls (including Napias Creek Falls) and Dworshak and Hells Canyon Dams) to Snake River spring/summer-run Chinook salmon in the following hydrologic units: Hells Canyon, Imnaha, Lemhi, Little Salmon, Lower Grande Ronde, Lower Middle Fork Salmon, Lower Salmon, Lower Snake-Asotin, Lower Snake-Tucannon, Middle Salmon-Chamberlain, Middle Salmon-Panther, Pahsimeroi, South Fork Salmon, Upper Middle Fork Salmon, Upper Grande Ronde, Upper Salmon, Wallowa.

The goals of this study are to develop methods to reduce wandering and straying of steelhead (Oncorhynchus mykiss) that are collected and barged from the Snake River to below Bonneville Dam. Salmon and steelhead that stray and spawn in non-natal streams are a significant conservation concern, because they may confound accurate assessment of the VSP parameters of recovering native populations and decrease the productivity of these populations through genetic introgression or ecological competition. These issues are a particular concern for listed mid-Columbia River stocks because salmon that are collected and barged downstream as juveniles have shown higher stray rates into these watersheds as returning adults relative to in-river migrants. However, while barging may contribute to elevated stray rates, there are substantial benefits from barging because transported Snake River steelhead consistently have higher smolt-to-adult returns than steelhead left to migrate in-river. Therefore, it is important to identify and develop strategies for reducing the stray rates of transported steelhead while maintaining the survival benefits consistently observed for barged steelhead. The specific aims of this proposal are as follows: 1) Conduct an analysis of existing coded wire (CWT) and PIT tag data to identify causative factors associated with straying by Columbia River salmonids, particularly as it relates to natural rates of straying and straying associated with transport. 2) Assess imprinting of barged and in-river migrants by monitoring imprinting associated changes in physiological function and gene expression as indicators of imprinting success. 3) Identify key environmental parameters (e.g. orienting current, water exchange rate, novel tributary water) that are important for imprinting barged fish and develop barging protocols to optimize imprinting success and thereby minimize straying using a controlled laboratory study. 4) Initiate tests of a modified barge protocol designed to maintain survival benefits while reducing wandering, delay, and straying behavior of returning adults. The work is being conducted by NWFSC scientists in collaboration with the University of Washington. Products for this project will include annual reports, peer-reviewed publications, presentation of results at local and national meetings, and consultation with the FCRPS managers. Physiological data on hatchery-reared steelhead.