KMZs and other files showing the distribution of Coastal cutthroat are available from the download system.
Information about Coastal Cutts is hard to come by, paradoxically because they appear to be the least threatened of the cutt variants. While information about abundance is quite sketchy, we’ve found two fairly obscure datasets that at least paint a reasonably accurate picture of the coastal cutthroat’s range, which is considerable, encompassing most of the coastal drainages in Washington State, Oregon, and Northern California (where we haven’t developed any data).
Coastal Cutts have a complicated life cycle. Four different forms are documented: anadromous (sea run) – spawn in small streams and migrate to the ocean after 2 or 3 years; fluvial (river run) – grow in mainstem rivers much in the same way that anadromous grow in the sea; adfluvial (lake run) – migrate to lakes for growth; and resident – live full time in the streams where they spawn. Coastal cutts can spawn multiple times throughout their life, though spawning is dangerous – depending on the fishery, only 20%-40% of spawners are thought to survive.
The timing of river entry and spawning depends on the fishery. As a gross generalization, anadromous cutts enter fresh water in the late summer through early winter, and spawn early in the year. Resident and fluvial forms tend to spawn around the same time, though over a broader timeframe (some as late as August). The Washington State report (described below) provides timing information basin by basin.
As you can see in the image, the two datasets we’ve discovered and converted to KMZ form for you to download are very diffferent.
Washington State Cutthroat Survey
The coral-colored stream data in Washington State comes from a report published in 2000. The Washington Department of Fish and Wildlife performed a comprehensive survey of rivers which supported spawning runs of coastal cutthroat, including genetic analysis which identified 40 distinct genetic sub-populations.
The report published distribution maps for each sub-population. We’ve reproduced them here as overlays for use in Google Earth, though we’ve combined all subpopulations from a given basin onto one map per basin. Note that registration of these overlays is reasonably accurate, but not perfect. We suggest using these overlays in combination with the NHD layer, turning off the overlay once you zero in on a stream you’re interested in.
The report itself is on the download system. Besides providing some excellent background information on the life history of coastal cutts, it provides spawing timing for each basin, and abundance data for a few. If you’re planning on going out to seek coastal cutts, even in Oregon, it’s useful.
Oregon Fish Surveys
Tucked away in the “archive” section of the Oregon Department of Fish & Wildlife website is the dataset we used to create this KMZ. It summarizes survey samples taken state-wide between 1990 and 2002 for the “Aquatic Inventories Project” that showed the presence of at least 1 cutthroat trout. The surveys did not distinguish sub-species, but from location it’s pretty obvious which are Coastal Cutts (west), Lahontan (SE), and Westslope (NE).
The yellow icons in the image show the locations of the “successful” surveys. Roll over an icon and a number will appear. This is the number of cutthroat trout counted in the specific survey the icon represents. Click on the icon to bring up a balloon that provides the full data record which counts other fish species as well. Species counts are in the field XX_SP, where the XX is: CO: Coho Salmon; CH: Chinook Salmon; RB: Rainbow Trout; CT: Cutthroat; BUT: Bull Trout; BT: Brook Trout; BR: Brown Trout; KO: Kokanee Salmon; CS: Chum Salmon; US: unknown salmonid
Photo sources: Google earth image. Washington data: 2000 Washington State Salmonid Stock Inventory: Coastal Cutthroat Trout. Washington Department of Fish and Wildlife. Oregon data: Oregon Department of Fish & Wildlife. ODFW Aquatic Inventories Project Fish Distribution Coverage. KMZs by WildTroutStreams.com