#### Abstract

(…) Recently, van der Plas-Duivesteijn et al. (2015) presented a genetic assessment of harbour porpoises, Phocoena phocoena, along the Dutch coast, which concluded that all analysed Dutch harbour porpoises are part of the same interbreeding population while also concluding that Dutch harbour porpoises were inbred. These two main conclusions are contradictory as the same individuals cannot be both in- and outbred unless the population is very small, which is not supported by the data. Here we carefully review the analyses conducted by van der Plas-Duivesteijn et al. (2015) and revise the conclusions. (…)