Protection-induced selection and evolution of behavior within marine reserves and the impact on fisheries sustainability

Informations projet

BEMAR

N° de convention de subvention: 793627

DOI

10.3030/793627

Projet clôturé

Date de signature de la CE 28 Mars 2018

Date de début 1 Septembre 2018

Date de fin 7 Decembre 2020

Financé au titre de

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Coût total

€ 170 121,60

Contribution de l’UE

€ 170 121,60

Coordonné par

AGENCIA ESTATAL CONSEJO SUPERIOR DE INVESTIGACIONES CIENTIFICAS
Spain

Periodic Reporting for period 1 - BEMAR (Protection-induced selection and evolution of behavior within marine reserves and the impact on fisheries sustainability)

Période du rapport: 2018-09-01 au 2020-08-31

Résumé du contexte et des objectifs généraux du projet

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.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

The work performed so far has revealed important insights into the individual-level mechanisms of protection. BEMAR has successfully shown so far what are the important behavioural traits that determine protections within a fish community in Tveedstrand fjord. In particular, we have shown that the location, shape and size of the home range (i.e. how individuals use the available space) greatly determines the protection granted by a marine reserve. The project has also shown that the more time the individuals spend at risk, the higher the chances to be fished outside the reserve.
To conduct these analyses, we first developed a method to detect individual survival in nature using acoustic telemetry data. The method is able to determine fate of the individuals based on the pattern of detections and movements, the properties of the study areas, and the characteristics of the telemetry equipment. It is thus independent of reports from fishers which greatly expands the potential of telemetry data for studies on selection and evolution of coastal fish species.
In terms of selection gradients, we have shown for the first time how selection on body size changes after marine reserve implementation. We have done it using a series of replicated control-reserve pairs in the southern Norwegian coast using lobster as a model species. We have shown how selection on body size is reduced right after marine reserve implementation and how the demography of the population is restored. Given that body size and behaviour are correlated in many species, our findings suggest that protection may also change the selection gradients acting on behavioural traits in the protected populations.
In spite of the above results, we have not detected clear patterns of behavioural changes in the long term after protection. In spite of detecting an increase in survival right after protection, selection gradients acting on behavioural traits of cod didn't change after protection.
Results of BEMAR have been disseminated to the scientific community in 3 scientific papers so far (plus two under revision) and through the attendance of two international conferences: the 4th international conference on fish telemetry held in Norway in 2019 (three presentations), and the Wildlife Research and Conservation Conference in Germany in 2019 (one presentation). BEMAR results have been also communicated at Science Festivals such as the Ponteciencia 2019, and through meetings with local stakeholders. I have also disseminated my results through blog post such as the methodsblog.com (the blog of the journal Methods in Ecology and Evolution)

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

Before BEMAR project, we knew that the behaviour of the populations was important for marine reserve design. However, available evidence came for studies that considered mean behaviour of the populations, ignoring the among-individual variation in behaviour within populations. BEMAR results have gone beyond the state of the art to show that individual-level behaviour is indeed key to understand how individuals perform and what we should expect in terms of populations responses within a marine reserve context. We have also pushed the state of the art on marine reserve science by showing that changes after protection are not limited to demographic changes, but also can involve changes in selection gradients in key traits, opeining the door to potential evolutionary changes. We didn´t detect long-term changes in behaviour after protection which is a result in itself and which clearly shows the complexity associated with protection and the need for further research in this area.

Atlantic cod navigating in a Norwegian fjord