Interactions between age-0 herring and juvenile Chinook and coho salmon
Herring in their first year of life (age-0) are critically important prey for Chinook and coho salmon in their first year at sea. Comparing recent and historical salmon diet information suggests that age-0 herring may be less available to juvenile salmon than they were during periods of higher salmon survival and abundance (prior to the 1990s). This reduced availability could be a consequence of lower age-0 herring abundance, later appearance of age-0 herring in the spring, increased herring size relative to juvenile salmon (making them too large to eat), or some combination of these three factors operating at different regional scales in the Strait of Georgia.
The focus of the first activity will be on factors controlling the availability of age-0 herring to salmon. A key question will be to understand whether loss of spatial and temporal diversity in spawning is impacting the availability of juvenile herring to juvenile salmon.
Part of this activity will be a desktop exercise, revisiting historical data from DFO’s herring spawn and juvenile herring surveys to determine whether the presence of local spawns may influence when, at what abundance, and at what size, juvenile herring become available to juvenile salmon. The other part will be a field sampling program in collaboration with Strait of Georgia First Nations to investigate the availability of juvenile herring to juvenile salmon in periods and regions not covered by existing sampling programs.
