Prediction of silver hake distribution on the Northeast U.S. shelf based on the Gulf Stream path index

Abstract

Over the past ~40 years, the distribution of silver hake on the Northeast U.S. shelf is found to be significantly correlated with changes in the latitude of Gulf Stream path. The correlation coefficient between the fall Gulf Stream position and the center of biomass of spring silver hake reaches 0.75 when the Gulf Stream leads the silver hake for 6 months. Based on this lead-lag relationship and low-frequency variability of Gulf Stream position with a dominant periodicity of ~9-10 years, the Gulf Stream position is used as a predictor for the center of biomass of silver hake in linear autoregressive (AR) models. The goal of this study is then to optimize the AR model for the prediction of silver hake based on the observed changes in Gulf Stream position. Fall Gulf Stream position is first predicted out to 5 years using a 5 th order AR model and the observed Gulf Stream position in preceding years. An optimization process is proposed to choose best AR coefficients based on a newly proposed combined skill parameter. Furthermore, the robustness of our Gulf Stream prediction is verified by comparing the observed Gulf Stream path index data from 2009 to 2012, which are not used for optimizing the AR model, and the predicted Gulf Stream path values for the same time period. We then use this predicted Gulf Stream position to further predict the center of biomass of silver hake in the subsequent spring. Three different methods are used and compared for the silver hake prediction. The predicted silver hake time series can explain as much as 69% of the variance of the observation for the 1 st year prediction and 41 % for the 5 th year prediction. Our results indicate that including Gulf Stream as a predictor produces better prediction skills of silver hake center of biomass than the AR model prediction solely based on the observed silver hake time series.

Long‐Term SST Variability on the Northwest Atlantic Continental Shelf and Slope

“…Based on the high‐resolution NOAA OISST data set (1982‐2018), the two regions with prominent warming trends observed over the slope are likely related to Gulf Stream variability. The Gulf Stream has been reported to have a slight northward shift during recent years (Joyce et al, ), which is correlated with changes in fish distribution over the shelf (Davis et al, ; Nye et al, ) and associated with warmer ocean temperature in the NWA Ocean (Frankignoul et al, ; Peña‐Molino & Joyce, ; Zhang & Vallis, ). It is plausible that the enhanced warming trend concentrated along the Gulf Stream path is caused by a northward shift in the position of the Gulf Stream.…”

Moored observations of the Deep Western Boundary Current in the NWAtlantic: 2004–2014

“…(A southward shift of the Gulf Stream results in a wider DWBC and more transport if the layer‐averaged velocity is constant.) However, we note that regional meridional shifts in the Gulf Stream have been reported [e.g., Joyce et al ., ; Pérez‐Hernández and Joyce , ; Davis et al ., ] that are not always identifiable locally. In particular, these latter papers document a regional northward shift in the Gulf Stream path during the Line W field program.…”

Seasonal Prediction of Bottom Temperature on the Northeast U.S. Continental Shelf

“…Distribution, recruitment, and biomass of some commercially important fish stock are closely related to changes in bottom temperature on the shelf and changes in the latitude of the GS (Nye et al, 2011;. In addition, changes in GS position lead variations in silver hake distribution by ∼6 months, which implies predictability at seasonal-to-interannual time scales (Davis et al, 2017). In situ measurements also suggest a direct link between the GS position and the temperature and salinity near the shelfbreak south of New England on shorter time scales (G. G. Gawarkiewicz et al, 2012).…”