Factors linking Pacific herring (Clupea pallasi) productivity and the spring plankton bloom in the Strait of Georgia, British Columbia, Canada

•We compared young of year herring abundance end of September to spring bloom timing.•Survival was enhanced when timing of herring spawning matched plankton bloom.•We compared mean weight young of year herring to spring plankton bloom timing.•Weight of herring not related to abundance at end of first summer.•Herring weight inversely related to recruit abundance after migration from Georgia Strait.

The Pacific herring (Clupea pallasi) resource has supported one of the most important commercial fisheries on Canada's west coast for more than a century. Like many pelagic species, herring productivity has fluctuated throughout this period, especially for the largest population, which spawns in the Strait of Georgia. To provide long term sustainability and cogent management advice it is critical to understand the factors determining herring productivity. Since productivity can be influenced by survival of early life history stages, especially for pelagic species such as herring, we assessed the contribution of bottom-up forcing factors on young of the year (YOY) herring abundance and growth. Herring spawning is closely linked to the annual plankton production cycle and the match (or mismatch) between egg deposition and the initiation of the spring plankton bloom has a substantial impact on survival and production of YOY herring. Enhanced long-term monitoring of the production cycle could provide a better understanding and ultimately a prediction of Pacific herring production within the Strait of Georgia.