DATA AVAILABILITY : Data and scripts are available in Zenodo https://zenodo.org/doi/10.5281/zenodo.10948827Highly polymorphic single tandem repeat loci (STR, also known as microsatellite loci) remain a familiar, cost efficient class of genetic markers in genetic studies in ecology, behavior and conservation. Here we characterize a new, universal set of ten STR loci in seven species of baleen whales, optimized for PCR amplification in two multiplex reactions along with a Y chromosome marker for sex determination. The optimized, universal set of STR loci provides a convenient starting point for new genetic studies in baleen whales aimed at identifying individuals and populations. Data from the new STR loci were combined with genotypes from previously published STR loci to assess the power to assign parentage using paternity exclusion in four species: fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), blue whale (B. musculus) and bowhead whale (Balaena mysticetus). Our results suggest that parentage studies should always be accompanied by a power analysis in order to ascertain that each individual specific study is based upon data with sufficient power to assign parentage with statistical rigor.The University of Groningen, University of Copenhagen, University of California Berkeley, Stockholm University, Aage V. Jensen Foundation), US National Marine Fisheries Service, the International Whaling Commission Scientific Committee, WWF-DK, the Commission for Scientific Research in Greenland, the Greenland Home Rule and by AZORES 2020, through the EU Fund.https://www.elsevier.com/locate/geccohj2024Mammal Research InstituteSDG-14:Life below wate
