KMZs and other files showing the distribution of Bull Trout are available from the download system.
The bull trout is a highly migratory char native to the Northwest US, with an extensive range across Washington, Idaho, western Montana, Oregon, and sneaking into one basin in northern Nevada. The Bull trout is similar in appearance to a Dolly Varden (into the early 20th century they were thought the same species), and close cousins to both Brook Trout and Lake Trout. Bull Trout will often hybridize with Brook Trout which now live as “exotics” in many NW headwaters streams (descended from fished stocked from the 19th century on). The hybrids are usually sterile. Anglers are often encourage to take Brook Trout, but generally must release all Bull Trout caught.
Photo: Google Earth image showing data distributed by StreamNet.org, compiled from multiple sources.
The KMZ we’ve created is based on a dataset published by StreamNet.org, which integrates data from multiple sources. It is color coded for the “use id” in the dataset. As described in the Bull Trout Status Report (also available in the download system):
Bull trout have narrower habitat requirements than most other salmonids and exhibit a number of life history strategies. Most bull trout are highly migratory, spawning in tributary streams where juvenile fish usually rear from 1 to 4 years before migrating to either a larger river (fluvial), lake (adfluvial), or ocean (anadromous) where they spend their adult life, typically returning to the natal tributary stream to spawn. Resident trout may complete their entire life cycle in the tributary streams where they spawn and rear. Resident and migratory forms of bull trout may be found together, and it is generally believed the life history form of individuals is more a product of the environment than of any specific genetic combination.
The original StreamNet.org shapefile, which we’ve converted to a KMZ, provided information about Bull Trout usage of the different stream segments. These include streams which are migration only (coded blue) and different patterns of use including spawning, rearing, and year round residence, which are coded in other colors. Coding is slightly inconsistent from state to state, but if you study the terminology in the quoted paragraph and study the db table by clicking on each stream, it should make sense.