Coquille Subbasin Working Atlas - p9
Fish Distribution and Habitat
Page 6: Vegetation and Land Cover
Page 8: Water Use and Availability
Page 9: Fish Distribution & Habitat
Fish distribution
Spawning and rearing sites for Coho, Winter Steelhead, Fall Chinook, and Spring Chinook are show in the Fish Distribution by Species display. This display is based on fish distribution data collected by biologists from the Oregon Department Fish and Wildlife (ODFW), the US Forest Service (USFS) and the Bureau of Land Management (BLM). The distributions shown on the maps are general estimates based on surveys and professional knowledge. Sample surveys are made every year to update this information base and to add additional streams. While the date of source data may vary from area to area, most data has been collected within the last five years. The maps shown in the Fish Distribution by Species display are a snapshot of a very dynamic database. Future estimates of fish distributions may fluctuate due to variations in water years or other external factors.
Based on this data, Spring Chinook distributions appear to be the most limited of the four species. Rearing of Spring Chinook occurs in the main branch of the Coquille River and upstream into the South Fork of the Coquille. Spawning occurs only in the South Fork of the Coquille upstream of the South Fork Catching Creek. Spawning and rearing of Fall Chinook have similar distributions to Spring Chinook, except that they have much more extensive spawning sites, which include sites in the North, Middle and East Forks of the river. Winter Steelhead and Coho have the same spawning and rearing distributions. Rearing occurs in the main branch of the Coquille as well as throughout many of the tributaries in the South, Middle, East and North Forks of the Coquille. Spawning occurs upstream of Dement Creek in the South Fork and upstream of Middle Creek in the North Fork, as well as in the East and Middle Forks.
[click on map for larger version]
Fish habitat
The quality of in-stream and riparian fish habitat are assessed based on several parameters including large woody material, pool frequency, width and depth, embeddedness or fines, stream shading, and bank stability. Large woody material and pool frequency are indicators of habitat complexity; width and depth, stream shading and bank stability are indicators of riparian condition; and embeddedness or fines are indicators of water column and substrate conditions. Several agencies and groups have developed target objectives for the above parameters, which are generally based on habitat requirements of salmonids and stream or riparian values considered essential to productive aquatic systems. Information on stream habitat conditions is captured in in-stream surveys conducted by agencies such as the USFS, BLM and ODFW. Some of the stream surveys for the Coquille subbasin have been attached to GIS coverages using an Arc/Info procedure called "dynamic segmentation." Dynamic segmentation attaches attribute information to linear systems using routes that specify the distance of attributes from a known beginning point. The measures used to create the routes for the stream habitat databases were based on the survey data. These measures were not calibrated so positional accuracy is considered poor. Nonetheless, these databases provide a wealth of information on conditions of several major streams within the Coquille system. The Stream Habitat Conditions for Big Creek display illustrates some of the attributes available in these databases for a small segment of Big Creek in the North Fork of the Coquille subdivision.
