Potential population-level impacts of future oil spills on Pacific herring stocks in Puget Sound Human and Ecological Risk Assessment: An International Journal

Oil spills threaten the productivity of marine forage fish that spawn in shallow shoreline habitats. In western North America, this includes Pacific herring (Clupea pallasii), a keystone species for marine food webs. Crude oil-derived polycyclic aromatic hydrocarbons (PAHs) are highly toxic to herring embryos and larvae. Despite our understanding of individual-based toxicity, the impacts of oil spills at the population-scale remain uncertain. We modeled the response of Puget Sound herring stocks to simulated oil spills and found that declining stocks are less likely to withstand the short-term impacts of a small, localized spill. Moreover, conventional stock assessment methods may only detect large population declines in response to high rates of mortality in a single year, or sustained losses across multiple year classes. We discuss the importance of herring life history and environmental variation on the predictive usefulness of conventional population modeling as a basis for estimating injury to highly variable marine forage fish resources.