Temporal trends in pelagic communities and forage fish removals: Connections between zooplankton, Atlantic herring (Clupea harengus), and herring consumption across the northeast U.S. continental shelf

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Forage fishes are critical components of continental shelf foodwebs. Atlantic herring (Clupea harengus) is one northwest Atlantic forage species that is both commercially targeted and links lower and upper trophic levels, including fish predators of commercial value. Here we examined temporal trends in zooplankton, herring abundance, and herring removals through consumption by fishes and commercial landings for the northeast U.S. continental shelf from 1977-2011. Zooplankton abundance on the shelf cycles over time with 10-year periods, increasing in the 1980s, and more notably, increasing in the late 1990s to early 2000s. Copepods, euphausiids, gammarids, and other small zooplankton dominate the diet of herring. Interestingly, the cross-correlations between zooplankton, herring abundance, consumption, and landings were significant near time lag zero, implying tight coupling and concurrent surges among these pelagic communities. With multivariate autoregressive state-space models, common trends within the herring consumption time series were identified and model fit improved when related to trends in zooplankton abundance. Managing fisheries resources, particularly forage fishes, remains an intriguing challenge given their pivotal roles as major prey for commercial fishes and fisheries; thus, continuing to incorporate oceanographic and foodweb processes into fish stock assessments is essential given their potential disruption due to global change.