Marine reserves are a valuable tool for protecting against overharvesting and are expected to support fisheries beyond their boundaries through net export of pelagic eggs and larvae and spillover of juveniles and adults. Furthermore, marine reserves may guard against fisheries induced evolutionary changes in growth and maturation schedules and help to preserve natural genetic diversity. However, little attention has been paid to the potential for selection directly on behavioural traits posed by fisheries and to the role that marine reserves may play in buffering or strengthening those processes. In the context of marine spatial protection is therefore important to evaluate how behavioural traits determine protection granted by marine reserves, and in turn how marine reserves and protection, in general, may induce changes in behaviour in the protected populations. Understanding these processes is critical to expanding our understanding of marine reserve functioning and therefore better design and implement spatial protection measures.
BEMAR project aimed at understanding the interactions between individual fish behaviour and protection. On the one hand, this project investigated what are the key behavioural traits that determine protection at the individual level using a database of acoustic telemetry of >300 individuals of several species in a southern Norwegian fjord (Tvedestrand). On the other hand, it aimed at investigating changes in selection after protection using lobster and cod as case studies. Last, it aimed at detecting long-term changes in behaviour after protection using a 9yr dataset of cod in the Tvedestrand fjord. The objectives and results of this project are pioneering in that they provide, for the first time, information on the mechanisms that link fish individual behaviour and protection in marine systems.
Project conclusions: although the project objectives have not been accomplished in full due to the COVID situation, we have successfully demonstrated that individual fish behaviour is the main driver of fitness within a marine reserve. We have shown that survival and selection gradients acting on body size change after protection, but such changes were not detectable in behavioural traits. On the long-run, we haven´t detected changes in behaviour that can be associated to protection meaning that there must be other mechanisms such as density-dependent effects acting on long time scales that may have an impact on the behaviour of the protected populations.
