The Mystery Behind the Drop in Atlantic Herring Numbers

Atlantic herring, once the most landed sea species in Canada, has seen a significant decline in the Scotian Shelf-Bay of Fundy area (NAFO Division 4VWX). This region used to contribute up to 75% of Canada's total herring catch. Despite efforts to boost the stock's health since 2003, the population has continued to decrease, puzzling researchers.To solve this mystery, scientists examined 52 time-series describing the 4VWX herring population and factors affecting it. They found that overfishing, temperature changes, and predation on herring eggs were key factors. Overfishing directly reduced adult herring numbers. Warmer waters and changes in temperature timelines affected the survival of baby herring. Surprisingly, increased egg predation also indirectly boosted adult biomass by thinning out weaker individuals. Understanding these factors is crucial for effective management. Currently, the management strategy doesn't consider early life stage dynamics or climate change's impact on herring. This leaves crucial aspects of herring survival unaddressed.