Understanding the past to inform future conservation policy: Mapping traditional ecological knowledge of Pacific herring spawning areas through time

Pacific herring (Clupea pallasii) play a foundational role in human-ocean systems. While once abundant, herring have experienced declines and intermittent fisheries closures in British Columbia (BC) during the last century. I interviewed members of the Heiltsuk First Nation, and mapped their traditional ecological knowledge of the spatial distribution of observed herring spawns along the central coast of BC from the 1940s to the 2000s. The results show a marked contraction and aggregation in the distribution of spawns over time, with the total length of coastline with observed spawns declining at an average rate of 7.6% per decade. The concentration of spawns also shifted in space, with substantial declines on the exposed outer shores in the west of the region and the majority of recent spawns observed further inland to the east. In order to support resilient populations, fisheries management should account for such spatial characteristics and variation through time.