The Cowichan River population of fall Chinook salmon is used as an indicator of the status of Lower Strait of Georgia Chinook salmon stocks and has been identified as “an important stock in need of rebuilding” by the Pacific Salmon Treaty Chinook Technical Committee. To investigate residency and survival, we captured and acoustic-tagged 80 age-0, wild and hatchery Chinook salmon in Maple Bay and Sansum Narrows (north of Cowichan Bay) in late summer and tracked their movements and fate until the transmitter batteries died in late February. Fish were also tagged with a PIT tag so that we could estimate adult survival back to the Cowichan River. Genetic stock identification (GSI) was used to determine stock, and molecular techniques were used to investigate if select infectious agents were present in tagged fish. A receiver array was deployed between Vancouver Island and Saltspring Island to estimate survival and residency in the Cowichan Bay area. Receivers were also deployed to monitor two seal haul-out islets in or adjacent to the study area to estimate a lower limit of seal predation, and mobile acoustic tracking was used to investigate fine-scale habitat occupancy and to help quantify time and location of death for individual tagged fish. The existing Pacific Ocean Shelf Tracking receiver array at JDF and NSOG, and several individual receivers maintained by Ocean Networks Canada were used to estimate residency in the Salish Sea. Finally, we supplemented the fixed receiver arrays with mobile-tracking within the Cowichan Bay area.

To visualize these data, we provide two animations: the first shows the detections from the passive array for the full interval between fish release and array recovery; the second shows the detections from the mobile and passive array combined with the default view set to show a day when mobile tracking occurred, and with the animation slowed to better display boat movement and detections. The default settings can be changed using the Timing menu.

Dynamic Animator for Cowichan Chinook 2017—all passive data. Access the animation here.

Dynamic Animator for Cowichan Chinook 2017—one day of passive and mobile data combined. Access the animation here.