Linking environmental variability and parental attributes to recruitment dynamics of the Southwest Nova Scotia/Bay of fundy Atlantic herring stock

Abstract High recruitment variability in marine small pelagic species, such as Atlantic herring (Clupea harengus), poses major challenges for stock assessment and resource management. A 48-year time series (1970–2017) of recruitment was analyzed using Generalized Additive Models (GAMs) and Empirical Dynamic Modeling (EDM) to evaluate the relative importance of environmental drivers and parental attributes in impacting recruitment of Southwest Nova Scotia/Bay of Fundy (SWNS/BoF) herring. Both modeling approaches identified ocean stratification, Spawning Stock Biomass (SSB), parental average length, and body condition as key predictors of recruitment. Stratification was identified to be the dominant driver, likely enhancing recruitment through larval retention in gyre and frontal systems and improved adult condition via prey concentration. In contrast, temperature, salinity, and haddock abundance had little detectable influence on recruitment. Despite some data limitations, our results provide both statistical and mechanistic evidence suggesting that environmental variability and parental attributes jointly influence herring recruitment across life stages, highlighting the importance of SSB, size structure, and parental condition. Incorporating these covariates into stock assessment frameworks could improve assessment accuracy, strengthen ecosystem-based management, and support recovery of the SWNS/BoF herring stock.