from the National Fish Habitat Partnership's 2015 Through a Fish's Eye Report
Summary
This report updates and revises the 2010 “ Status of Fish Habitats in the United States” that summarized initial results of a comprehensive national assessment of aquatic habitats at an unprecedented scale and level of detail. This 2015 report provides even greater detail and improves our knowledge of the condition of fish habitat in the United States. The 2010 inland streams assessment characterized fish habitat condition using stream fish data from more than 26,000 stream reaches, while the 2015 assessment was based on fish data from more than 39,000 stream reaches nationally. To increase accuracy, the 2015 inland stream assessment incorporated 12 additional human disturbance variables into the fish analysis when compared to the [...]
Summary
This report updates and revises the 2010 “ Status of Fish Habitats in the United States” that summarized initial results of a comprehensive national assessment of aquatic habitats at an unprecedented scale and level of detail. This 2015 report provides even greater detail and improves our knowledge of the condition of fish habitat in the United States. The 2010 inland streams assessment characterized fish habitat condition using stream fish data from more than 26,000 stream reaches, while the 2015 assessment was based on fish data from more than 39,000 stream reaches nationally. To increase accuracy, the 2015 inland stream assessment incorporated 12 additional human disturbance variables into the fish analysis when compared to the 2010 assessment. Associations between all human disturbance variables summarized in both catchments as well as stream buffers were tested against stream fish metrics to develop assessment scores. Additional variables incorporated into the 2015 assessment and their summary within catchments and buffers allowed for more explicit characterization of the diverse set of disturbances to stream fish habitats occurring across the Nation than what occurred in 2010, and this was made possible due in part to advances in available GIS layers. With incorporation of these additional disturbances, managers and decision makers can use assessment results to more explicitly identify limits to stream fish habitats. Even with the additional disturbances incorporated into 2015 assessment, results may overestimate fish habitat condition, as localized and regionally-specific disturbances are still not available in some cases.
The estuarine assessment evaluated a total of 220 estuaries, with sufficient data available to produce risk scores for 196 estuaries in both the 2010 and 2015 assessments. Five additional human disturbance variables were used to improve accuracy of the 2015 estuarine assessment relative to 2010.
This assessment should be viewed as one complementary tool of many to be used when examining fish habitat condition. Additional fish habitat information from Fish Habitat Partnerships along with other regional and local assessment information should be used to paint a complete fish habitat picture for a particular location or watershed.
This report divides the 50 states into 14 sub-regions based on geographic borders and ecoregions. Time and resources did not permit a quantitative assessment of lakes, reservoirs, the Great Lakes, and marine areas, nor updates to the previous assessment of estuaries in Southeast Alaska. Future reports may include habitats not addressed in this report as well as those in U.S. territories as time and resources become available.
Assessment results are characterized as “risk of current habitat degradation,” and this should be interpreted as reflecting the relative degree of threats to aquatic habitats in a particular region (very high, very low, or in between). The assessments use “risk” of habitat degradation instead of known habitat degradation because habitat condition has not been objectively or consistently measured for a majority of aquatic habitats or the processes that influence them in the United States. As a result, the inland assessments for this report focus on identifying factors that have been found to have significant associations with desirable measures of stream fish communities, rather than using direct measurements of habitat condition. For example in the national streams assessment, if numbers of stream fishes sensitive to disturbances decreased with an increase in road density in watersheds drained by streams where those fish were found, the assessment would reflect that all streams in the region having a high density of roads in their watersheds may be at risk of being degraded. Roads can lead to increased sedimentation and pollution in streams, and while such data are not currently available throughout the United States, the sensitivity of fishes to roads suggests that sedimentation, connectivity, and pollution may in fact be problems for streams draining watersheds with many road crossings. The national estuarine assessment focuses on variables representing anthropogenic activities that are known to affect estuary habitats, while the regional estuary assessment incorporates available information on fish presence and distribution to directly measure the influence of these anthropogenic stressors.
Although a large amount of information went into the assessments, some human disturbance factors are missing due to the lack of nationally consistent data. Because all information cannot be accounted for, risk scores represent conservative estimates; areas mapped as having a low risk of current habitat degradation due to the factors available for this report may be under the influence of factors not included in the assessment, and thus actually may be at a higher risk of current habitat degradation than depicted on the maps. For example, consistent nationally-available data is not available for water flow patterns or grazing density, and scores in some areas of the western United States are likely overestimates of actual conditions. Similarly, if a problematic area, such as an estuary with a large dairy farm in its watershed, has been mitigated by development of retention ponds to capture waste runoff, this assessment would still rate the aquatic resource as at high risk because we do not have data that characterizes locations and types of mitigation efforts nationally. For the reasons explained above, readers should interpret the maps carefully. The maps should not be understood as depicting absolute habitat condition. They instead serve as a guide to the relative magnitude and geographic distribution of many important factors that contribute to aquatic habitat degradation. Future reports, planned for 5-year intervals, will continue to improve the description of aquatic habitat condition, as data sources become more consistent and comprehensive.
The assessment methodologies are summarized below. More detailed information about how the assessments were developed can be found here. Interested readers can find peer-reviewed articles of assessment methods and results in the “ Supportive Literature” section.
The U.S Geological Survey (USGS) is partnering with the National Fish Habitat Partnership (NFHP) to produce the 2015 report entitled, "Through a Fish's Eye: The Status of Fish Habitats in the United States 2015". The information contained within this item is a product of NFHP. The Bureau is neither responsible nor liable for the accuracy or the use of the scientific content within this item. This content is considered preliminary pending subsequent review and approval.
