The abundance and recruitment of the European anchovy (Engraulis encrasicolus) recently has increased significantly off Western Iberia, leading to a 5-fold increase in anchovy catches in this region since 2016. However, the drivers of this increase are still poorly understood. To that aim, PRIMUS members Afonso Ferreira, Vanda Brotas and Ana C. Brito from MARE-FC.ID, Susana Garrido (MARE/IPMA) and Ana Teles-Machado (IDL/IPMA), have published a study based on a satellite data spanning 1999–2021 to investigate the biological and physical factors driving the persistent increased anchovy productivity. The paper has just been published in Marine Ecology Progress Series, and represents the third publication output from PRIMUS.
European anchovies are a species of small forage fish living off the coasts of Europe and Africa that often migrate northwards during summer and southwards during winter. They feed on plankton, foremost copepods and the eggs and larvae of fish. Similar to sardines, anchovies provide an important source of food to larger forms of marine life as well as to humans. Image credits here.
In this study, Afonso Ferreira and colleagues reveal that the highest anchovy recruitment appears to coincide with the annual spawning peak occurring from April through June, a period characterized by weak downwelling events and marked by lower salinities (<35) and temperatures of 15–17°C, often linked to the positive phase of the Winter North Atlantic Oscillation (NAOW). Results suggest that local surface ocean circulation linked to the Iberian Poleward Current and the Western Iberia Buoyant Plume promotes a higher onshore retention of anchovy larvae, ensuring their life cycle closure and, this, higher chances of survival.
Interestingly, the study also reports that relatively strong anchovy recruitment years roughly coincide with periods of low abundance of European sardine (Sardina pilchardus), suggesting that intra-guild processes (such as foraging competition and egg predation) may also play a role in establishing potential of anchovy recruitment off Western Iberia.
Location of the studied region off NW Iberia (left) and yearly estimates of European anchovy recruit abundance and spawning stock abundance (SSA, Mil.: million), and total European anchovy landings in western Portugal during the period 1999–2021 (PC: Portugal Current; IPC: Iberian Poleward Current; WIBP: Western Iberia Buoyant Plume).
New understanding of the environmental drivers of anchovy recruitment increase gained from this PRIMUS output will contribute to improve projections of the potential impacts of climate change, crucial to provide robust, science-based recommendations to managers and policymakers. if you want to know more about this novel study, click here.