The Hydrodynamic-Related Dispersal of Early-Life Stages Shapes the Vulnerability to Fisheries-Induced Evolution in a Highly-Sedentary Marine Coastal Species

Recent development in genetics and hydrodynamic modelling dispersal of fish early-life stages shows that many marine fish populations are not as open as expected. When such dispersal is low and the gene flow is therefore limited, intensive fishing may alter life-histories. Here, we provide empirical evidence of downsizing of adults in small-bodied coastal, Serranus scriba according to this claim. First, we modelled the production of eggs in real populations subjected to a different degree of exploitation. Second, we assessed the dispersal of such early-life stages production using a high-resolution hydrodynamic model simulation based on the historical records of flow fields. By means of the Lagrangian trajectories of the early-life stages, we show how local hydrodynamics generate patterns of limited connectivity and enhanced self-recruitment. We found that the life-histories observed in isolated populations of S. scriba subjected to a differential exploitation pressures matched expectations of fishing-induced downsizing of adult body size and the results of the hydrodynamic dispersal of their reproductive output. We propose that the dispersal of the early life-history stages can play a major role in the evolutionary trajectory of harvested marine populations even for small-bodied, geographically restricted fish species that are mainly harvested by recreational anglers.