Forecasting ocean front movements for fisheries management
Adrienne Silver, a former WHOI postdoc working with Glen Gawarkiewicz and me, recently published her first postdoc paper in ICES Journal of Marine Science, which describes an index to forecast the movements the foot of the New England shelfbreak front. Congratulations Adrienne!
Why the front matters: The shelfbreak front in the Northern Middle Atlantic Bight marks the boundary between cold shelf water and warmer slope water, affecting commercial fishing grounds worth billions annually. Its movements can cause rapid temperature bottom temperature shifts of 4-6°C, severely impacting marine species, including scallops (optimal temperature 10-15°C, with high mortality above 21°C), black sea bass (which overwinter in the warmer waters near the front), and golden tilefish.
The problem: While the location of the surface expression of the front can be detected by satellites, the surface expression of the front often deviates from the location of the foot. These changing dynamics make the foot of the front particularly difficult to quantify without in situ measurements at depth.
Method: Adrienne has developed two complementary indices (one using 30+ years of direct ocean measurements, the other using global ocean model reanalysis, which both showed significant correlation with upstream water flow velocities) tracking the position of the foot of the front.
Results: These indices explain 40-50% of the variability in the location of the foot of the front, and can predict movements of the foot of the front up to three seasons in advance using readily available satellite data. The indices also explained significant variability in golden tilefish recruitment patterns, which had a 40-43% correlation with the front position. The paper also shows that the front has moved approximately 14-35km inland over 30+ years.
Golden tilefish recruitment estimate from an Age Structured Assessment Program model (Legault and Restrepo 1998) is shown in the solid black line compared to the fall values from the observational front index (FFI) and the GLORYS front index (FFIG) in blue dotted and red dashed lines, respectively.
Takeaway: This work provides a methodology for including variability of the foot of the Northern Middle Atlantic Bight shelfbreak front into ecosystem and stock assessment models using readily available near-real-time satellite altimetry data.
Citation: Silver, A., Oliver, H., Gawarkiewicz, G., Fratantoni, P., & Salois, S. L. (2025). Forecasting and seasonal variability of the foot of the Shelfbreak Front in the Northern Middle Atlantic Bight. ICES Journal of Marine Science, 82(2), fsae156. https://doi.org/10.1093/icesjms/fsae156