Juvenile Pacific Herring (Clupea pallasi) and their interactions with ecosystem components in the Strait of Georgia, British Columbia

Pacific Herring (Clupea pallasi) are an important prey species for a variety of predators as well as important to First Nations communities and to the commercial fishing industry. The recruitment of Pacific Herring varies substantially on an annual basis and can represent a large proportion of the adult population biomass, adding uncertainty to population estimates. A leading indicator to forecast their recruitment prior to their harvest would be helpful to understand year class strength. British Columbia’s Strait of Georgia juvenile herring and nearshore pelagic ecosystem survey has collected data from ten core transects in September-October since 1992. This data may help improve the understanding of factors that influence herring recruitment and their availability to their predators, such as Chinook and Coho Salmon. An objective of this study was to update the survey time series of the relative biomass and abundance (and associated variance) of age-0 herring. Results indicate that age-0 herring abundance varies interannually with high abundances in recent, even years and there was an increasing trend in fish condition during 1997-2010. Preliminary results indicate age-0 herring biomass may be a leading indicator of recruitment to the adult herring spawning population and to Chinook Salmon survival. We also explore potential ecological and trophodynamic interactions between herring and ecosystem components, zooplankton abundance, and environmental variability. Investigating the dynamics of ecological linkages among pelagic species will improve our understanding of valuable species in BC’s marine ecosystems.