Can changes in Silver Hake be related to and forecast by changes in the Gulf Stream path?

Terry Joyce, Physical Oceanography
Young-Oh Kwon, Physical Oceanography
Xujing Jia Davis, Physical Oceanography


OCCI Funded Project: 2010


Changes in the Atlantic Meridional Overturning Circulation (AMOC) can have effects that downscale to regional significance.  A component of the AMOC is the Deep Western Boundary Current (DWBC) System which can be found off our continental slope south of New England.  This flow has components that can be seen from the ocean bottom reaching to the ocean surface, and is associated with the general circulation of the Slope Water.  The changes in the AMOC also are associated with changes in the temperature and salinity of the waters of the DWBC and Slope Water.  We have observed that when the GS is southerly, the DWBC flow is larger and the Slope Water is colder (and fresher), and vice versa for a northerly GS path.  We are now also seeing indications that decadal variations in some commercial fish stocks, monitored for years by the National Marine Fisheries Service (NMFS), are responding to these environmental changes.  Working with a colleague at NMFS in Woods Hole, we are finding that both types of Silver Hake (northern and southern) show significant changes that are correlated with the GS path, and that path changes may precede changes in Hake distribution and biomass.  The co-variability itself is of interest as it explains more than 50% of the interannual variability of distribution changes in southern Hake, for example.  But of perhaps equal interest is that GS path changes appear to lead changes in Hake distribution by about a year, giving some predictive capability using GS path for future Hake changes.  In this proposal we seek some limited support to gather additional data, perform more analyses, and work collaboratively with scientists at NMFS to submit and publish our joint results.  We also envision extending this analysis to other commercially important fish found in New England Waters.