Comparison of the iPCoD and DEPONS models for modelling population consequences of noise on harbour porpoises

Der findes to forskellige modelleringsværktøjer til vurdering af, hvordan støj fra konstruktion af havvindmøller kan påvirke marsvin: iPCoD (Interim Po- pulation Consequences of Disturbance) og DEPONS (Disturbance Effects of Noise on the Harbour Porpoise Population in the North Sea) modellerne. Selv om begge modeller simulerer marsvinenes populationsdynamik på baggrund af fødselsrater og de enkelte individers overlevelse bliver deres overlevelse beregnet forskelligt i de to modeller. iPCoD benytter de gennem- snitlige overlevelses-rater for dyr i Nordsøen. I DEPONS-modellen bliver de enkelte individers overlevelse bestemt af, hvor gode de er til hele tiden at finde føde. I denne rapport sammenligner vi strukturen af de to modeller og beskriver hvilke data, der skal til for at parametrisere dem, samt hvilke typer output de kan generere. Derefter beskriver vi de vigtigste forskelle mellem de to modeller og diskuterer hvordan outputtet fra de to modeller kan sam- menlignes. Two different frameworks have been developed to assess the potential effects of noise associated with offshore renewable energy developments on harbour porpoise populations: The Interim Population Consequences of Disturbance (iPCoD) and Disturbance Effects of Noise on the Harbour Porpoise Population in the North Sea (DEPONS). Although both models simulate population dynamics based on the birth and survival rates of individual animals, they model survival in a different way. iPCoD uses average survival rates derived from data from North Sea animals. In the DEPONS model, survival emerges from the individuals’ ability to continuously find food. In this report we compare the structure of the two models, and describe the data they require and the kinds of output they provide. We then identify key differences between the approaches and discuss how their outputs can be compared.