Spring 2007

Abstract: Archaeological fish bone records from the Columbia River system provide a ~13,000 year history of fishes in the basin. Salmon represent over 2/3 of the specimens, the rest being sturgeon and various fresh water fish. A variation in salmon to non-salmon bone ratios suggests ways fishes adjusted to post-glacial stream conditions and changing climates. The earliest salmon records are from the Snake River (~13,000 to 11,000 year old) while earliest remains on the upper Columbia River date ~4,000 year later. These ages suggest the Snake River system provided spawning habitat much earlier than the Upper Columbia, which is expected, since the Snake River was ice-free throughout the Pleistocene and the Upper Columbia was blocked by continental ice until ~15,000 years ago, and then would have carried a significant silt load as continental ice melted and streams re-worked fine glacial sediments. Huge numbers of salmon remains from 8 to 9 thousand year old deposits indicate salmon populations were well established in some parts of the river system by then. Salmon abundance declined sharply ~7,500-4000 years ago, reflecting deteriorated stream conditions (higher temperatures, increased silt loads, lower stream flows). Increased salmon abundance after 4,000 years ago likely reflect improved conditions in the fresh water system that led to increased survival of developing young.

Comparisons of archaeological bone records and 19th century historic accounts, highlight the profound changes to our regions fish fauna that have occurred in just 200 years. By establishing the more ancient history of native fishes through history and archaeology, the case can be made that these impressive creatures deserve a place here long into the future.