Monitoring the growth and survival of larval herring on B.C. central coast

Herring spawning on British Columbia’s central coast takes place in the early spring. Strength of a year class is largely dependent on successful recruitment from the larval stage to the adult population. The potential temporal and spatial overlap of herring larval distribution with spring bloom dynamics can be a major determining factor in the success of larvae in finding suitable prey, with delayed feeding potentially leading to mass mortality. Consequently the phenology and productivity of plankton blooms, as well as the interannual variability in spawning at active sites can be significant. Reporting on data since 2012, we observe that although spawn timing does vary from year to year, this variation is less than that associated with spring bloom timing. The prey conditions experienced by larvae are therefore expected to vary significantly from one year, and site, to the next. In fact, larval growth at 38% of sites sampled wa