Use of radio telemetry to study upriver migration of adult Klamath River Chinook salmon

Adult Klamath River fall chinook salmon (Oncorhynchus tshawytscha) were tagged from July to October 1980 with internal radio transmitters placed in the anterior digestive tract. Six salmon tagged in the estuary were lost immediately after release and not located again. Sixteen salmon tagged upriver of saltwater influence generally moved downstream after release. Five tagged salmon were located up-river of the tagging site. Delay from tagging to subsequent location upriver ranged from 0 to 14 days. Long term tracking was successful for three salmon. These three radio tagged salmon exhibited consistent upstream progress, no observable downstream movements, and only minor delays. Migration rates were 4.3, 6.3, and 6.7 km/day. Reliability of study results were assessed by comparison with marked control salmon. Downstream movements by salmon tagged with spaghetti tags but not with radio tags (control salmon) were indicated by tag returns in the estuary. Control salmon which ascended the mainstem Klamath River had significantly higher migration rates and shorter travel times than salmon which ascended the Trinity River, the largest tributary. Migration rates for two radio tagged salmon which ascended the mainstem Klamath River were within the range of 5.6 to 9.6 km/day determined from two groups of control salmon. The migration rate for the single radio tagged salmon which ascended the Trinity River was within the range of 3.2 to 6.5 km/day determined from control salmon.