Developing Indices of Climate and Trophic Linkages of Euphausiids and Atlantic Herring in the Gulf of Maine Ecosystem

Gareth Lawson, Associate Scientist, Woods Hole Oceanographic

Institution

ABSTRACT

Atlantic herring (Clupea harengus) is a key prey species at the nexus of ecosystem function in the Northeast U.S. Shelf Large Marine Ecosystem (NES-LME) and also supports a large commercial fishery. There is a growing body of evidence suggesting that euphausiids are also a critical component of the NES-LME ecosystem and provide an important forage base for numerous commercially important fishes, including Atlantic herring. Surprisingly little information is available, however, on the spatial and temporal patterns of euphausiid distribution, biomass, and trophic role in the GOM/GB region. Both Atlantic herring and euphausiids are strongly influenced by the environment, exhibiting strong inter-annual variability in abundance that likely relates to climate-related and oceanographic variability.

We propose to examine climate- and environment-related drivers of euphausiid distribution and abundance, as well as their trophic importance to Atlantic herring, using a combination of existing data collected by the Northeast Fisheries Science Center (NEFSC). These include multi- frequency acoustic data from dedicated surveys, long-term bottom trawl and food habits data, and associated oceanographic data from surveys covering the entire pre-spawning concentration of Atlantic herring in the GOM/GB region. The resulting insight into euphausiid abundance and trophic interactions will furthermore be used to improve parameterization of regional mass- balance ecosystem models.

Successful completion of the project will provide the basis for integrated scientific advice to managers by addressing a persistent gap in our understanding of the influence of climate, habitat factors, and species interactions on Atlantic herring bioenergetics and population dynamics. The work thus addresses the CINAR themes of Ecosystem Monitoring and Ecosystem Management, is directly aligned with the NEFSC Strategic Science Plan’s theme of Science in Support of Ecosystem-Based Fisheries Management, and more generally is consistent with NOAA’s Healthy Oceans goal of achieving marine fisheries, habitats, and biodiversity sustained within healthy and productive ecosystems.