Reconstruction of Atlantic herring (Clupea harengus) recruitment in the North Sea for the past 455 years based on the δ¹³C from annual shell increments of the ocean quahog (Arctica islandica)

Abstract

Understanding the recruitment variability of the Atlantic herring North Sea stock remains a key objective of stock assessment and management. Although many efforts have been undertaken linking climatic and stock dynamic factors to herring recruitment, no major attempt has been made to estimate recruitment levels before the 20th century. Here, we present a novel annually resolved, absolutely dated herring recruitment reconstruction, derived from stable carbon isotope geochemistry (δ13C), from ocean quahog shells from the Fladen Ground (northern North Sea). Our age model is based on a growth increment chronology obtained from fourteen shells. Ten of these were micromilled at annual resolution for δ13C analysis. Our results indicate that the anthropogenically driven relative depletion of 13C, the oceanic Suess effect (oSE), became evident in the northern North Sea in the 1850s. We calculated a regression line between the oSE‐detrended δ13C results (δ13CṠ) and diatom abundance in the North Sea, the regression being mediated by the effect of phytoplankton on the δ13C of the ambient dissolved inorganic carbon. We used this regression to build an equation mediated by a nutritional link to reconstruct herring recruitment using δ13CṠ. The reconstruction suggests that there were five extended episodes of low‐recruitment levels before the 20th century. These results are supported by measured recruitment estimates and historical fish catch and export documentation. This work demonstrates that molluscan sclerochronological records can contribute to the investigation of ecological baselines and ecosystem functioning impacted by anthropogenic activity with implications for conservation and stock management.

Oceanic cooling recorded in shells spanning the Medieval Climate Anomaly in the subtropical eastern North Atlantic Ocean

“…They also reported that, across the same 100 years, the d 13 C values of Atlantic sclerosponges dropped by a similar magnitudedapproximately 0.75‰dat a rate of À0.0074 ± 0.0065‰ yr À1 (Swart et al, 2010). Estrella-Martínez et al (2019b) found that in the North Atlantic basin the rate of change for the oceanic Suess effect was variable through time, but observed a net ~1.5‰ reduction of d 13 C shell values in the bivalve Arctica islandica between 1850 and 2000 AD. The oceanic Suess effect is also more pronounced in subtropical latitudes due to the increased ventilation of the surface waters within the subtropical gyres (Eide et al, 2017;Swart et al, 2010).…”

Differences in metabolic rate between two Atlantic cod (Gadus morhua) populations estimated with carbon isotopic composition in otoliths

“…Neglecting this effect may seriously hamper the interpretation of the changes in δ 13 C oto and lead to an overestimation of the metabolic rates in the most recent periods [ 74 ]. Because the decrease in the seawater δ 13 C has a nonlinear form, with a stronger decreasing trend over the last two decades, more precise methods for the correction for the Suess effect than linear approximation should be applied [ 75 ].…”

Shifting Baselines to Thresholds: Reframing Exploitation in the Marine Environment

“…Stable isotope analysis often relies on proxies for data collection. For example, using an innovative approach based on extracting isotopes from ocean quahog, Estrella-Martínez et al (2019) were able to reconstruct recruitment estimates for the North Sea herring population. Using a marine historical ecology approach, they then cross-checked these estimates with historical resources regarding fishing pressure and catch-per-unit-effort over time.…”