Sonar Estimation of Salmon Passage in the Yukon River Near Pilot Station, 2016
The Pilot Station sonar project has provided daily passage estimates for Chinook (Oncorhynchus tshawytscha), chum (O. keta), and coho (O. kisutch) salmon for most years since 1986. Fish passage estimates for each species were generated in 2016 using a 2-component process: (1) estimation of total fish passage with 120 kHz split-beam sonar and an adaptive resolution imaging sonar (ARIS), and (2) apportionment to species by sampling using a suite of gillnets of various mesh sizes. An estimated 4,981,917 fish passed through the sonar sampling area between May 30 and August 31. Of those fish, 1,251,212 passed along the right bank and 3,730,705 passed along the left bank. Included, with 90% confidence intervals, were 135,013 plus or minus 16,607 large Chinook salmon (greater than 655 mm mideye tail fork), 41,885 plus or minus 8,075 small Chinook salmon (less than or equal to 655 mm mideye tail fork), 1,921,748 plus or minus 80,517 summer chum salmon, 994,760 plus or minus 64,434 fall chum salmon, 168,297 plus or minus 18,403 coho salmon, 1,364,849 plus or minus 87,145 pink salmon O. gorbuscha, 187,421 plus or minus 34,214 cisco Coregonus spp., 76,955 plus or minus 15,278 humpback whitefish C. pidschian, 10,674 plus or minus 3,641 broad whitefish C. nasus, 27,759 plus or minus 9,563 sheefish Stenodus leucichthys, and 52,556 plus or minus 11,041 other species.