Dam passage, thermal experience, and spawning success: how are Gates Creek sockeye salmon impacted b
Salmon Conservation & Ecology lab at the University of British Columbia in January 2014. Her research focuses on the migration behaviour and thermal experience of adult sockeye salmon (Oncorhynchus nerka) during freshwater spawning migrations in the Fraser River watershed.
Sockeye salmon are a particularly ecologically, culturally, and commercially important species of Pacific salmon to British Columbia. The fish bring nutrients from marine to terrestrial environments, and provide sustenance for First Nations, recreational, and commercial fishers. Like other Pacific salmon species, sockeye are semelparous, meaning they have just one opportunity to reproduce, followed by death. Anything that interferes with or prolongs the freshwater migration to spawning grounds, from high flows during freshet to high river temperatures, jeopardizes their lifetime fitness.
Vanessa is one of several graduate students from the Hinch lab whose research is part of a five-year monitoring contract with BC Hydro. The group includes Matthew Casselman (Project Biologist), Nich Burnett (Research Biologist and former MSc student), Nolan Bett (PhD candidate), Collin Middleton (MSc student), and Doug Braun (Postdoctoral Fellow). Collaborators and funders for the project include St’át’imc Eco-Resources, InStream Fisheries Research, Fisheries and Oceans (DFO) Environmental Watch, Fisheries and Oceans Stock Assessment, and the N’Quatqua First Nation. Their work has used acoustic and radio telemetry, in conjunction with behavioural experiments, to study the movements and olfaction of adult salmon within the Seton-Anderson hydropower system and fish passage at the Seton Dam. Completed in 1956, the Seton Dam controls the flow of water from Seton
Lake into Seton River, a tributary that enters the Fraser River near Lillooet, approximately 300 kilometres upstream of Vancouver.
The dam is just one component of the hydroelectric development in the Seton-Anderson-Bridge River system, which poses multiple navigation challenges for salmon. Ultimately, the monitoring project will assess how hydropower operational procedures affect the ability of fish to locate and ascend the fishway at Seton Dam and reach their spawning grounds. Two stocks of sockeye salmon spawn upstream of the Seton Dam: the Gates Creek and Portage Creek populations.
Vanessa and the other members of the group lived in Lillooet for three months during the summer of 2014, the third year of fieldwork associated with the monitoring project. The landscape is arid, and it is often the hottest place in Canada (over 40°C when the UBC group moved to Lillooet in July). In the 1860s, the town was Mile 0 for the Fraser Canyon gold rush, and the names of towns in the Cariboo district reflect their distance from the bend in Main Street in Lillooet. Just upstream of town, the Bridge River Rapids are one of the most important traditional First Nations fishing sites on the Fraser River.
For her MSc research, Vanessa is integrating telemetry detections and thermal profiles from Gates Creek sockeye migrants in Seton and Anderson lakes to determine if fish use particular water temperatures to recover from the physiological stress of dam passage. She uses
iButton temperature loggers, which are waterproofed and attached to the end of radio transmitters that are placed in the gastric cavity of each fish. The loggers record a
temperature measurement every 15 minutes and can be used to reconstruct the in-lake thermal experience of individuals when they are recovered on spawning grounds. A single thermal profile can consist of over 2,000 temperature measurements, so Vanessa has been working to summarize and compare the thermal experiences of tagged fish, based on predictors like physiology and environmental conditions.
After multiple years of telemetry research at Seton Dam, the Pacific Salmon Conservation & Ecology lab is identifying trends in dam passage and migration success for Gates Creek sockeye in the Seton-Anderson system. However, in 2013 and 2014, the group began working with DFO Stock Assessment and N’Quatqua First Nation technicians to assess the spawning success of tagged females. Vanessa will use this information to determine how dam operations and in-lake temperature experience affect the ability of female sockeye salmon to spawn, once they successfully reach Gates Creek. This work will provide insight into the effects of hydropower development on both the abundance of adults on spawning grounds and also their ability to contribute to the next generation of sockeye salmon.
The monitoring project will include at least one additional year of fieldwork in the Seton-Anderson system. It has been an incredible opportunity for graduate students, First Nations technicians, environmental consultants, biologists, and BC Hydro to work together to assess the impact of hydropower development on adult salmonids.