The Gulf of Maine has historically supported some of the most productive lobster fishing grounds on earth. Over the past decade, however, a surprising disconnect has emerged between the burgeoning numbers of breeding lobster and declines in their young offspring recruiting to coastal nurseries. A recent correlative analysis suggests these declines in young lobsters may be linked to shrinking production of zooplankton, and in particular the energy-rich copepod <em>Calanus finmarchicus</em>, a foundational member of the Gulf’s zooplankton assemblage. Here we first provide a more comprehensive analysis of that correlation by drawing upon NOAA’s three-decade EcoMon zooplankton data time series to evaluate the spatial extent of trophic and other oceanographic correlates over the full area of the Gulf of Maine. Our findings suggest that the weakening influence of cold, nutrient rich, Labrador Slope Water and strengthening effects of warm, nutrient poor, Gulf Stream waters have precipitated an ecosystem-wide regime shift in the Gulf over the past decade that may have greater implications for lobster recruitment than previously suspected. This correlative analysis sets the stage for subsequent presentations in this session that provide a more mechanistic test of the hypothesis that larval lobster survival is limited by their planktonic food supply.  

Primary Presenter: Richard Wahle, University of Maine (richard.wahle@maine.edu)

Authors:

Burton Shank, National Marine Fisheries Service - Northeast Fisheries Science Center  (burton.shank@noaa.gov)

David Fields, Bigelow Laboratory for Ocean Sciences  (dfields@bigelow.org)

Rachel Lasley-Rasher, University of Southern Maine  (rachel.lasleyrasher@maine.edu)

Joshua Carloni, New Hampshire Fish & Game Department  (Joshua.Carloni@wildlife.nh.gov)

Peter Countway, Bigelow Laboratory for Ocean Sciences  (pcountway@bigelow.org)

Alex Ascher, University of Maine  (alexander.ascher@maine.edu)

Evie Layland, University of Maine  (evelyn.layland@maine.edu)

Maura Niemisto, Bigelow Laboratory for Ocean Sciences  (mniemisto@bigelow.org)

Paul Geoghegan, Normandeau Associates, Inc.  (pgeoghegan@normandeau.com)