Por Ana Machado (IPMA, Lisboa, Portugal).
Unlike other upwelling areas, where sardine and anchovy species dominate pelagic ecosystems, the Iberian West Coast ecosystem has been consistently dominated by European sardines, while anchovy had a residual presence, from the beginning of acoustic surveys in 1989 until 2014. Since 2016, anchovy abundance has increased markedly and continues to show an increasing trend. It is unclear whether this increase results from dispersal from nearby recruitment areas, higher survival rates of early life stages due to favorable environmental conditions, or both. This study used a set of numerical models to simulate the dispersal and survival of early life stages of anchovy in the Iberian region for the years preceding the increase in anchovy abundance in the area. A regional ocean model simulation (IB2v2, using the model CROCO) provided the current and temperature fields used to run the Lagrangian simulations (using the model Parcels), coupled with an individual-based model (IBM) of anchovy eggs and larvae. We simulated the years 2013, 2014 and 2015. The results of the study show that connectivity patterns have great variability over time, and that anomalous episodes of ocean circulation, when coinciding with a high presence of eggs, can lead to the colonization of new areas.
