Critical Habitat for Coho along the Central California Coast ESU

These data depict the habitat areas designated by the National Marine Fisheries Service (NMFS) as critical habitat under the U.S. Endangered Species Act (ESA) for Central California Coast coho salmon. The data were developed in 2019 as part of an effort to interpret and depict several salmonid critical habitat designations completed in the 1990s that relied on text-based descriptions but lacked GIS data. Habitat areas for Central California Coast coho were identified based on the following:

- The regulatory definition of ESA critical habitat for this species found at 50 CFR 226.210 (a) and the supporting final rule (64 FR 24061, May 5, 1999);

- U.S. Geological Survey (USGS) high resolution National Hydrography Dataset (NHD) - downloaded February 2018;

- Intrinsic Potential (IP) GIS data from a juvenile coho rearing model developed by the Southwest Fisheries Science Center (SWFSC);

- National Elevation Data and Digital Topographic Maps;

- California Fish Passage Assessment Database [ds69, published 2019-03-05] and Coho Distribution [ds326, published 2016-06-22] from the California Department of Fish and Wildlife (CDFW);

- The professional judgment of biologists from the NMFS California Coastal Office, Protected Resources Division, and SWFSC; and

- Maps and documentation found in the following references:

Spence, B.C., Harris, S.L., Jones, W.E., Goslin, M.N., Agrawal, A., and E. Mora. 2005. Historical occurrence of coho salmon in streams of the Central California Coast coho salmon Evolutionarily Significant Unit. Technical Memorandum NOAA-TM-NMFS-SWFSC-383. Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, U.S. Dept of Commerce.

Agrawal, A., Schick, R.S., Bjorkstedt, E.P., Szerlong, R.G., Goslin, M.N., Spence, B.C., Williams, T.H., and K.M. Burnett. 2005. Predicting the potential for historical coho, Chinook and steelhead habitat in Northern California. Technical Memorandum NOAA-TM-NMFS-SWFSC-379. Southwest Fisheries Science Center, National Marine Fisheries Service, NOAA, U.S. Dept of Commerce.

National Marine Fisheries Service. 2012. Final Recovery Plan for Central California Coast coho salmon Evolutionarily Significant Unit. National Marine Fisheries Service, Southwest Region, Santa Rosa, California.

The spatial analysis to produce these data involved the following general steps:

1) Clipped the NHD to the text description from the critical habitat designation

2) Partitioned the NHD into 100 m segments

3) Calculated the gradient of each 100 m segment using a 10 meter USGS digital elevation model (DEM)

4) Used the NHD's flow direction and a geometric network to analyze gradient, removed segments upstream of 7% gradients (reference: Agrawal et. al. 2005 - Figure 1 gradient suitability curve for coho)

5) Retained segments downstream of 7% gradients that were too small (<= 20 meters) to rely on the gradient value (i.e., 1 to 2 pixels in the DEM) or were artificial paths (NHD FCode 55800) to maintain network connectivity

6) Retained segments that overlapped with CDFW coho distribution data (field observations) and SWFSC intrinsic potential coho data (model) with the 21.5 deg C temperature mask applied (Agrawal et. al. 2005)

7) Removed segments upstream from total natural barriers, total anthropogenic barriers, and partial barriers that were specifically identified as blocking coho

8) Removed segments identified by NMFS biologists as not being accessible to or suitable habitat for coho

The following tribal lands were excluded from the Central California Coast coho critical habitat designation, but were not clipped out of the spatial data: Cloverdale Rancheria, Coyote Valley Rancheria, Dry Creek Rancheria, Guidiville Rancheria, Hopland Rancheria, Lytton Rancheria, Manchester/Point Arena Rancheria, Pinoleville Rancheria, and Stewarts Point Rancheria.

NOTE - These data are intended to assist in the construction of maps depicting areas designated as critical habitat for Central California Coast coho. Every attempt has been made to ensure the accuracy of this dataset, however these data DO NOT constitute a legal description of critical habitat. For legal descriptions of the areas designated as critical habitat please consult the final rule and regulations cited above.