Disturbance Effects on the Harbour Porpoise Population in the North Sea (DEPONS)



Harbour porpoises are affected by a wide range of anthropogenic disturbances such as noise from wind farms and ships, and are often by-caught in commercial gillnet fisheries. These factors have a direct impact on the individual porpoises, but until recently their cumulative impact on a porpoise population had never been investigated. An in-depth understanding of the joint effect of the different kinds of disturbances on the population’s dynamics is necessary to address whether its long-term survival is jeopardised. Such understanding is integral to the protection of endangered species in Europe (EU 1992).



In a recent study Nabe-Nielsen et al. (2011, 2013, 2014) demonstrated how the population consequences of anthropogenic disturbances could be analysed using an agent-based simulation model, where the population size emerged from the individuals’ responses to environmental variations. This is the first study of the population-level effects of disturbances for the harbour porpoise. The model was based on knowledge of the fine-scale movement patterns of porpoises, their foraging for a dynamic food resource and life-history traits obtained from literature. The primary goal of the model was to simulate how post-construction noise emitted by wind turbines affected the dynamics of the population in the Inner Danish Waters (IDW). Although the porpoises were modelled to be deterred by the turbines, the wind farms had only minor effects on the population size.



The agent-based model developed by Nabe-Nielsen et al. (2011, 2014) can be used outside the IDW and for various types of anthropogenic disturbances. In order to parameterise the model for these scenarios, and to validate the results, it is necessary to procure various types of data. The DEPONS project is aimed at extending and re-parameterizing the model presented by Nabe-Nielsen et al. (2014) in order to simulate the effects of noise emitted from wind turbines in the North Sea during and after their construction.



Literature

EU (1992) Council Directive 92/43/EEC on the Conservation of natural habitats and of wild fauna and flora, http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:31992L0043:EN:HTML.



Nabe-Nielsen, J., Tougaard, J., Teilmann, J. & Sveegaard, S. (2011) Effects of wind farms on harbour porpoise behavior and population dynamics. Scien-tific Report from Danish Centre for Environment and Energy, pp. 48. Danish Centre for Environment and Energy, Aarhus University.



Nabe-Nielsen, J., Teilmann, J., & Tougaard, J. (2013). Effects of wind farms on porpoise population dynamics. In Danish Offshore Wind. Key Environmental Issues – a Follow-up (pp. 61–68). Copenhagen, Denmark: The Environmental Group: The Danish Energy Agency, The Danish Nature Agency, DONG Energy and Vattenfall.



Nabe-Nielsen, J., Sibly, R. M., Tougaard, J., Teilmann, J., & Sveegaard, S. (2014). Effects of noise and by-catch on a Danish harbour porpoise population. Ecological Modelling, 272, 242–251. doi:http://dx.doi.org/10.1016/j.ecolmodel.2013.09.025