A productivity bottleneck in the Baltic herring (Clupea harengus membras): Early life-history processes and recruitment variability. (May 2022)

• Record Type: Journal Article
• Authors: Arula, T.; Simm, M.; Herkül, K.; Kotta, J.; Houde, E.D.
• Is Part Of: Marine environmental research. Volume 177(2022)
• Publication Date: 2022-05
• Subjects: Baltic herring -- Gulf of Riga -- Growth rate -- Postflexion herring larvae -- Recruitment -- Boosted regression tree model -- Climate effect; Marine pollution -- Environmental aspects -- Periodicals; Marine ecology -- Periodicals; Mer -- Pollution -- Aspect de l'environnement -- Périodiques; Écologie marine -- Périodiques; Electronic journals; 577.705
• DOI: 10.1016/j.marenvres.2022.105638
• Languages: English
• ISSNs: 0141-1136

Abstract

Abstract: Exogenous anomalies induced by contemporary climate change may severely impact dynamics of early life stages of fish. Here, we modelled how growth rate and abundance of postflexion larvae, and recruitment of Baltic spring-spawning herring ( Clupea harengus membra s) in the Pärnu Bay, Gulf of Riga (GoR) may respond to shifting climate variables. Higher larval growth rates were aligned with later seasonal emergence of yolk-sac larvae, while lower abundance of postflexion larvae occurred in years of earlier seasonal seawater warming. Cooler temperatures (<16 °C) in spring expanded the optimal thermal window for first-feeding herring larvae, attributable to the absence of early seasonal water temperature warming. Higher recruitment levels emerged in years of seasonally delayed warming and were associated with higher abundance of postflexion larvae. In recent decades, the trend towards earlier warming of the Baltic Sea in spring threatens to create a bottleneck to successful recruitment of herring. The existing paradigm that abundant Baltic herring year-classes occur only in the years following mild winters no longer stands as environmental conditions undergo rapid change. The relative contribution of Pärnu Bay larval nursery areas to recruitment has diminished as the suitable thermal window has been dramatically reduced in recent decades. Evolving thermal dynamics in the GoR have developed relatively recently and in future present a bottleneck for herring production. Highlights: Lower growth rates, postflexion larvae abundance and recruitment occur along earlier warming of spring water temperature. Lethal water temperatures for herring larvae has shifted earlier in season with a pace of five days per decade. Water temperatures >16 °C occurred in DoY 170-180s in 1960s and '70s, while in recent decades it is in DoY 130-150s. Evolving thermal dynamics have developed relatively recently and in future present a bottleneck for herring production.