Evaluation of Fall Chinook and Chum Salmon Spawning below Bonneville, The Dalles, John Day, and McNary Dams; 2001-2002 Annual Report.

摘要

In 2001 a total of 309 adult fall chinook and 264 chum were sampled in the Ives and Pierce islands area below Bonneville Dam. The peak redd count for fall chinook was 48. The peak redd count for chum was 181. Peak spawning time for fall chinook was set at approximately 16 November. Peak spawning time for chum occurred approximately 26 November. There were estimated to be a total of 721 fall chinook spawning below Bonneville Dam in 2001. The 2001 chum population below Bonneville Dam was estimated to be 532 spawning fish. Temperature unit data suggests that below Bonneville Dam 2001 brood chinook emergence began on 11 March 2002 and ended 18 May 2002, with peak emergence occurring 26 April. 2001 brood juvenile chum emergence below Bonneville Dam began 29 January and continued through 31 March 2002. Peak chum emergence took place 25 February. A total of 5,487 juvenile chinook and 678 juvenile chum were sampled between the dates of 22 January and 30 July 2002 below Bonneville Dam. Juvenile chum migrated from the study area in the 40-55 mm fork length range. Migration of chum occurred during the months of March, April and May. Sampling results suggest fall chinook migration from rearing areas took place from mid June through early July 2002 when juvenile fall chinook were in the 65 to 80 mm fork length size range. Adult and juvenile sampling below Bonneville Dam provided information to assist in determining the stock of fall chinook and chum spawning and rearing below Bonneville Dam. Based on observed spawning times, adult age and sex composition, GSI analysis, juvenile emergence timing, juvenile migration timing and juvenile size at the time of migration, it appears that in 2001 and 2002 the majority of fall chinook using the area below Bonneville Dam were of a late-spawning bright stock of fall chinook. Observed spawning times, adult age and sex composition, GSI analysis, juvenile emergence timing, juvenile migration timing and juvenile size at the time of migration suggests chum spawning and rearing below Bonneville dam are similar to stocks of chum found in Hamilton and Hardy creek and are part of the Lower Columbia River Chum ESU.