Burman River hydrology method validation project: indexing WCVI Chinook spawning area residence time beyond the Burman River

The goal of this study is to validate if the Discounted Survey Life (DSL) /Hydrology method of indexing residence time related to flow timing developed at Burman River can be used more extensively.  More specifically we hope to estimate escapement of the adjacent and neighboring Pacific Salmon Treaty (PST) wild population indicators in the Nootka-Kyuquot Conservation Unit (CU) and the Southwest Vancouver Island CU, (Kaouk, Tahsish, and Artlish, Megin, Mooyeha, Bedwell). Modern mark-recapture (MR) methods  will be employed at Conuma River and Tranquil Creek, to precisely estimate spawning escapement of Chinook salmon as per the methods applied at Burman River 2009-2018. Periodic snorkel surveys will allow estimation of the annual observed fish-day integral (AUC). Dividing the snorkel fish-day integral by the MR estimate provides the DSL parameter which is largely explained by flow related migration timing. The later the freshet arrives in the fall, the less stored fat reserves remain in the salmon and residence time is reduced. Some timing differences are expected due to orographic differences in storm arrival timing although large frontal systems typically strike across the entire region. Although these two streams are not current Pacific Salmon Commission indicators of natural Chinook salmon escapement we believe they contain sufficient fish from hatchery production or supplementation to successfully conduct MR studies, estimate the DSL parameter, and validate if the new method can be applied more broadly to WCVI Chinook in general and specifically to the wild PST escapement indicator populations established in the new Agreement.

S19-I30 Tranquil Creek escapement and origin of adult Chinook salmon (Onchorhynchus tshawytscha) in 2019 Report