Since 1990, IDFG has conducted annual surveys to count the number of redds (nests salmon dig to deposit eggs) from Coeur d’Alene Lake Chinook Salmon. In early October after Chinook are done spawning, fisheries biologists walk and float 11 miles of the Coeur d’Alene River, 6 miles of the South Fork Coeur d’Alene River, and 14 miles of the St. Joe River looking for the defining characteristics of a salmon redd. Each female salmon uses her tail to excavate rocks (up to the size of a softball), creating a pit where her eggs are deposited and fertilized by the male. The female then covers her fertilized eggs with rocks for protection. This process occurs several times and results in a 6-10 foot circular area that forms a 1-2 foot deep pit immediately upstream of a large pile of rocks. It is this final rock structure that is counted by biologists to determine how many females successfully spawned. Eggs will incubate over the winter, hatch in the spring, and eventually the offspring produced will migrate downstream, creating the next generation of Chinook Salmon in Coeur d’Alene Lake.
In 2020, biologists counted 213 redds in the Coeur d’Alene River, 27 redds in the South Fork Coeur d’Alene River and 9 redds in the St Joe River for a total of 249 redds. This was the second highest count on record and the first time redds were observed in the St. Joe River since 2015 when 15 redds were found. Coincidentally, 2015 was the highest count on record with a total of 303 redds across all three rivers.
In addition to counting redds, biologists collected information on length, age, sex, and spawning success from a sample of the dead salmon on the spawning grounds. Do not be alarmed! After spawning, salmon complete their