Kokanee salmon  The kokanee salmon ("Oncorhynchus nerka"), also known as the kokanee trout, little redfish, silver trout, kikanning, Kennerly's salmon, Kennerly's trout, or Walla, is the non-anadromous form of the sockeye salmon (meaning that they do not migrate to the sea, instead living out their entire lives in freshwater). There is some debate as to whether the kokanee and its sea-going relative are separate species; geographic isolation, failure to interbreed, and genetic distinction point toward a recent divergence in the history of the two groups. The divergence most likely occurred around 15,000 years ago when a large ice melt created a series of freshwater lakes and rivers across the northern part of North America. While some members of the salmon family (salmonids) went out to sea (anadromous), others stayed behind in fresh water (non-anadromous). The separation of the sockeye and the kokanee created a unique example of sympatric speciation that is relatively new in evolutionary terms. While they occupy the same areas and habitats during the breeding season, when ocean-going sockeye salmon return to freshwater to spawn, the two populations do not mate with each other in some regions, suggesting speciation. The kokanee species can be found in the northern United States of Alaska, Washington, Idaho, California, and Oregon. It can also be found up through British Columbia and the Yukon in Canada. Subdivisions of the kokanee are found in Japan and Russia. The kokanee was introduced to several other states, including New England, New York, Montana, North Dakota, California, Wyoming, Utah, Colorado,  New Mexico and Nevada. It was also introduced to parts of Canada. There is debate as to whether the kokanee has enough genetic distinction to be classified as a subspecies or a separate species from the sockeye salmon. Genetic evidence suggests that the evolution of landlocked sockeye has occurred more than once with different kokanee populations, showing genetic differences between populations. Most evidence points to events that land-locked the lake-type sockeye (which spawns in streams and lakes, rather than tributaries like the sea-type sockeye, but is still anadromous and spends most of its adult life out at sea), which evolved into the non-anadromous form.