Fishing Amplifies Collapse of Forage Fish: Management Thresholds for Ecosystem-Based Management

Forage fish support the largest fisheries in the world yet also play key roles in marine food webs as prey for large fish, seabirds, and marine mammals.  Fishing can thereby have far reaching consequences on marine food webs unless safeguards are in place to avoid depleting forage fish to low levels. Disentangling the contributions of fishing versus natural processes on population dynamics has been difficult because of the sensitivity of these stocks to environmental conditions. Here we overcome this difficulty by collating population abundance time series for forage stocks that account for nearly two-thirds of global catch of forage fish and use this information to identify the fingerprint of fisheries on their population dynamics. Stock collapses have been occurring regularly, and are increasing in frequency, implying that modern science-based management has not been able to adaptively respond to rapid changes in stock productivity. Forage fish stock collapses are preceded by high fishing rates and sharp drops in stock productivity. Consequently, collapses have been more frequent and more severe than they would be in the absence of fishing. A precautionary fisheries management scheme that limits fishing when populations become scarce would benefit both fisheries and ecosystems.