Drivers of Spatial and Temporal Variability in the Distribution and Abundance of Krill in the Northeast U.S. Shelf Large Marine Ecosystem

Krill (order Euphausiacea) are abundant in all the world’s oceans and support valuable fisheries. Though there are currently no directed fisheries for krill in the Northeast U.S. Shelf Large Marine Ecosystem (NES-LME), they are routinely monitored in systematic ecosystem surveys because they are important forage for numerous commercially valuable fishes (e.g., Atlantic Herring, Silver Hake, and Pollock).  Despite their apparent importance, the underlying mechanisms controlling annual, seasonal, and spatial patterns of krill abundance remain poorly resolved.  There is also an inter-annual periodicity in the consumption of krill for certain fish predators, which likely relates to the interplay of krill population dynamics, the availability of other zooplankton, and the complex oceanography of the NES-LME.  In this study, we use long-term (1977-2010) zooplankton and oceanographic data collected by the NOAA's Northeast Fisheries Science Center in a generalized additive modeling framework to identify the environmental, biological, oceanographic, bathymetric, and climatic drivers of inter-annual, seasonal, and spatial abundance patterns of krill in the NES-LME.  Though we examine numerous potential correlates, initial modeling efforts suggest a complex linkage between inter-annual variability in krill abundance and the winter North Atlantic Oscillation Index and strong spatial associations with abrupt topographic features (i.e., canyons and continental shelf break).