A new scientific endeavour has taken to the sky using high-tech drones and satellite images to understand better the annual spring herring spawn vital to salmon and wildlife on the West Coast. Between February and March each year, frigid ocean waters transform to a milky tropical-looking turquoise green when male herring release milt to fertilize the countless eggs deposited by females on eelgrass, kelp and seaweed fringing coastal shores.
Unpredictable and dramatic, the small silver fishes’ spawning event is large and best monitored from great heights, said Loïc Dallaire, a researcher with the SPECTRAL Remote Sensing Laboratory at the University of Victoria. “It’s one of the very few animal formations that we can see from space, excluding human developments and towns,” Dallaire said.
Dallaire has been sprinting to areas on the east and west coasts of Vancouver Island to obtain drone footage and scientific samples at spawning events over the past couple of weeks. His work will help puzzle out how and why spawning distribution has changed and declined over time as part of a broader study on herring and their habitat being conducted by the Pacific Salmon Foundation (PSF) until 2026.
The research project in partnership with coastal First Nations First Nations communities, will tackle key knowledge gaps around herring ecology and the importance of their role in the Strait of Georgia, particularly for salmon, said Jess Qualley, project manager for the PSF study. Herring are a small forage fish with a huge role in the marine food web and are important not only for juvenile and adult salmon but a host of animals such as whales, sea lions, eagles and seabirds, Qualley said.
The PSF study will also examine how changes to herring spawning events might impact the availability of those baby fish as a food source for juvenile salmon, Qualley said. Another line of research involving Qualley’s scientific work is aimed at learning more about non-migratory or resident herring populations that live in the Georgia Strait year-round and their importance in the food web under stress from climate change and other pressures.
To fill in the gaps in knowledge about how herring spawns have changed over decades, Dallaire plans to analyze archives of coastal satellite images back to the 1980s along with historical data from Fisheries and Oceans Canada (DFO).
Aircraft surveys by DFO tend to focus on spawning events in core commercial fishing areas, Dallaire noted. However, satellite images can likely detect and track smaller or more transitory spawning events along B.C.’s lengthy coastline that could be overlooked but are important to First Nations eager to document herring activity in their territories. In addition to looking at herring’s role in salmon food webs, the PSF project will help tease out what causes variability in the distribution of spawning events, Qualley said.
