Towards an early weaning in Senegalese sole: A historical review

Senegalese sole (Solea senegalensis) is a highly valuable flatfish species targeted for aquaculture diversification in Southern-European countries. Although its adaptation to captivity was foreseen in the 1970 ' s, its commercial production at a relevant industrial scale is extremely recent. One of the factors causing this delay in commercialisation was a severe bottleneck occurring during weaning, where incipient larval growth performances and survivals were impairing farming during the first decades of farming. However, a significant evolution has recently occurred for Senegalese sole weaning, with larval growth rates, survivals and quality drastically increasing, and good results becoming more reproducible. These progresses were only possible following significant R&D efforts leading to increased knowledge on larval nutritional physiology, weaning strategies, feeding practices and microdiet formulation and production. To this end, this work reviews the advancements that contributed for the evolution occurring in Senegalese sole weaning during the last decades. This overview shows that, for instance, while in the year 2000 larval weaning would only be achieved at around 60 days after hatching (DAH), with fish achieving 1 g (wet weight basis) at around 120 DAH, nowadays it is possible to perform an early weaning starting immediately after settling (15 DAH) and achieving 1 g at 65 DAH. Future perspectives on Senegalese sole weaning should target an optimisation of microdiet nutritional and physical properties to a further adequacy for the pelagic larvae, where the predatory capacity is reduced and lower particle sizes lead to fast and high nutrient leaching. Nevertheless, this work shows that early life-feed replacement is a reality for Senegalese sole, although it remains uncertain if it will ever occur at the onset of exogenous feeding.