Innovative production strategies for fish conservation and management

In response to the dramatic decline in wild stocks of many of the world´s fish species, many attempts have been made to bolster declining stocks by releasing hatchery-reared juveniles back into the wild. However, current intensive hatchery procedures result in behaviourally naive juveniles which display physiological adaptations towards hatchery rearing conditions. These production deficiencies results in reduced survival and reproduction in the wild, and adapted rearing practices are required to increase the overall fitness under natural conditions instead of a focus on performance in a near constant commercial rearing environment. New production protocols will be designed that will increase the cognitive ability and physiological capabilities of fish as compared to those raised under traditional intensive hatchery conditions. This calls for a paradigm shift in hatchery management, moving away from traditional husbandry practices to new hatchery procedures (optimal stocking density, adapted fertilization strategies, environmental enrichment, variable feeding, variable physical parameters such as flow rate, direction of flow, temperature) aimed at increasing the physiological fitness and cognitive ability of raised fish, which in turn leads to increased post-release survival (stock enhancement), as well as improved release strategies.