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Key elements of the 2015 national assessment of stream fish habitats follow the 2010 assessment, including: 1) the idea that distributions and numbers fishes reflect the quality of habitat in which they live; and 2) human landscape factors pose a risk to the condition of stream habitat, and indirectly, to fishes. The 2015 inland stream assessments for the contiguous United States, Alaska, and Hawaii all followed five broad steps (Figure 1) that are described in detail below for the inland stream assessment for Alaska. Note that analytical details for the Alaska assessment differed in southeast Alaska as compared to the remainder of the state (referred to as greater Alaska) due to differences in the resolution of...
Accounting for natural variation With the exception of differences in spatial units, assessments for greater Alaska and southeast Alaska were conducted similarly across regions. Because stream fish assemblage data were not available for the state, no steps were taken to account for natural variation in stream habitats for either southeast or greater Alaska. This represents an important need for future work.
The habitats of the Southeast Atlantic states range from the mountains and uplands in the Blue Ridge and Piedmont areas in the western portion of this region to the Southeastern and Coastal Plains. Fish habitats in the higher elevation regions are typically fast-moving, clear, coldwater streams originating from seeps and springs, while warmwater rivers of the plains carry more organic material and sediment. This diversity of habitats along a very long period of stable geologic activity produces one of the most diverse assemblages of aquatic species in the nation. The Altamaha, Chattahoochee, Flint, Savannah, Catawba, Pee Dee, Broad, and Neuse are major rivers of the region. There are a large number of dams on waterways...
State-wide data on fish populations were limited in Alaska for use in this assessment, as was a detailed spatial (mapping) framework that fully characterizes watersheds throughout the state at the time this assessment was conducted. Because of these factors, we modified our assessment methods to account for these limitations. Twenty-one landscape disturbance variables were assembled from medium-sized watersheds throughout the state (i.e., 12-digit hydrologic unit code watersheds). Variables were then assigned to one of six categories based on their disturbances to stream habitats. Categories include: urban land use, agricultural land use, point source pollution and water quality, barriers to fish movement, human...
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2015,
HowToReadUnderstand,
MethodSummary,
Methods
In the mostly arid Southwestern United States, water availability (hydrology – a key fish habitat process), wildfires, and grazing intensity are important disturbances that are known to have major, negative effects on fish habitats. While this assessment indicated that many of the streams in this region are in good condition, a number of key habitat variables (i.e. water availability, wildlife frequency and intensity, and grazing intensity) could not be directly included in this assessment because national datasets of these disturbances and their measured variable are unavailable. Their absence from this assessment, along with absences of other disturbances, has likely produced an overestimation of habitat condition...
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2015,
RegionalSummary,
SouthwesternRegion,
SouthwesternStates
Table showing human and natural landscape factors used for the 2015 national assessment of stream fish habitat.
A. Pervasive disturbances: The most common disturbances based on total stream length in a given region. Top five overall most pervasive disturbances to all stream reaches, regardless of stream size and across all spatial scales (ranked highest first): Total excessive (anthropogenic or man caused) sediment yield Impervious surface cover Road crossing density Population density Pasture and hay land use Top three most pervasive disturbances to creeks (<100 km 2 watersheds) across all spatial scales : Total excessive sediment yield Impervious (hard) surface cover Road crossing density Top three most pervasive disturbances to rivers (>100 km 2 watersheds) across all spatial scales: Upstream dam density...
Relative condition of fish habitat in streams of the Eastern Gulf of Mexico States. Histogram shows percentage of total stream length in each condition class.
Integrating data into a spatial framework After acquiring data, variables were attributed to a national stream coverage for use in assessment following Wang et al. (2011). The National Hydrography Dataset Version 1 (NHDV1) is a 1:100,000 scale representation of streams from throughout the conterminous United States. The NHDV1 identifies stream reaches as sections of streams occurring between confluences (Figure 2). We attributed all data to stream reaches (i.e., fish data, fragmentation metrics by dams) or to local catchments and 90m buffers draining to stream reaches (i.e., human land uses, mining activities, impervious surfaces, etc.). Local catchments (watersheds) and buffers are the land areas draining directly...
Spatial scales to which data were attributed for Hawaii inland stream assessment. Units include local catchments (A), network catchments (B), and downstream main channel catchments (C).
Map of the risk of current fish habitat degradation of inland streams of the Mid-Atlantic States region.
Identifying disturbances to fish habitat The approach for identifying disturbances to fish habitat was based on the assumption that greater intensities and types of human landscape disturbances would most likely lead to more disturbed stream fish habitat (e.g., Danz et al. 2007, Esselman et al. 2011). Twenty-two human landscape variables were identified for the Alaska assessment, with 21 variables used in the southeast and 19 in greater Alaska. We grouped variables into six sub-indices representing specific types of disturbances including: urban land use, agricultural land use, stream fragmentation, point source pollution, infrastructure, and active mines. Each sub-index of disturbance was represented by 2 to...
Integrating data into a spatial framework Greater Alaska For most of Alaska excluding the southeast portion of the state, watershed boundaries for individual stream reaches were unavailable, and the highest resolution spatial units available for assessment were 12-digit USGS hydrological units (HUC-12s). Greater Alaska includes 12,824 HUC-12s that partially follow watershed boundaries; however, boundaries are also intended to capture roughly similarly-sized regions vs. entire upstream landscape areas draining to streams (Figure 11). After acquiring data, variables were attributed to HUC-12s for the greater Alaska assessment. Southeast Alaska For the southeast portion of Alaska, watersheds were delineated from...
A. Pervasive disturbances: The most common disturbances based on total stream length in a given region. Top five overall most pervasive disturbances to all stream reaches, regardless of stream size and across all spatial scales (ranked highest first): Crop land use Low intensity urban land use Impervious surface cover Road crossing density Agricultural water withdrawal Top five most pervasive disturbances to , specific to spatial scale: Crop land use in network catchments Crop land use in network buffers Low intensity urban land use in network catchments Crop land use in local buffers Impervious surface cover in network catchments In the Northern Plains state group, 36.6% of streams are classified as low...
Map of the risk of current fish habitat degradation of inland streams of the Central Midwest States.
Thank you to all of the agencies, organizations and individuals that helped make this report happen. We would like to give a special thank you to the following groups and individuals. Web Report Development and Design Jacob Juszak and Don Brown – U.S. Geological Survey Fort Collins Science Center Steven Aulenbach and Sky Bristol - U.S. Geological Survey Core Science Analytics, Synthesis, and Libraries Assessment Contributors Alison Collins - Ocean Associates, Inc. in support of NOAA Fisheries (currently with the Metropolitan Water District of Southern California) Arthur Cooper – Michigan State University Correigh Greene - NOAA Fisheries Northwest Fisheries Science Center Daniel R. Obenour – North Carolina State...
Michigan, Wisconsin, and Minnesota border four of the five Great Lakes (lakes Michigan, Superior, Huron, and Erie) and have over 150,000 miles of rivers and streams and 50,000 inland lakes within their boundaries. The upper Mississippi River flows through the Upper Midwest states, from its headwaters in Minnesota along the boundary between Minnesota and Wisconsin. Much of the region has deep glacial deposits which has a tremendous influence over the habitat types and water flow (hydrology), providing for some of the most stable river flows in the United States. An exception to the glaciated region is a unique region of deeply carved unglaciated river valleys known as “The Driftless Area” which located in southwestern...
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2015,
RegionalSummary,
UpperMidwestRegion,
UpperMidwestStates
Map of the risk of current fish habitat degradation of inland streams of the Central Mississippi River States.
A. Pervasive disturbances: The most common disturbances based on total stream length in a given region. Top five overall most pervasive disturbances to all stream reaches, regardless of stream size and across all spatial scales (ranked highest first): Crop land use Low intensity urban land use Pasture and hay land use Impervious surface cover Population density Top three most pervasive disturbances to creeks (watersheds <100 km 2 in area) across all spatial scales: Crop land use Low intensity urban land use Pasture and hay land use Top three most pervasive disturbances to rivers (watersheds >100 km 2 in area) across all spatial scales : Crop land use Impervious surface cover Pasture and hay land use Top...
Map of current habitat degradation of Hawaii
Types: Map Service,
OGC WFS Layer,
OGC WMS Layer,
OGC WMS Service;
Tags: 2015,
HabitatDegradationMap,
Hawaii,
HawaiiRegion
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