There is however controversy whether whitefish surviving in the southeasternNorth Seasector of Denmark and considered there as houting represent the same species as the houting that was extirpated from the more southwestern parts of the North Sea. Like the more southwestern population, the Danish North Sea population has a long, pointed snout and an inferior mouth, and it is anadromous, spending most of its adult life in coastal waters, but migrating into rivers to breed. The Danish houting is genetically part of the widespread Coregonus lavaretuscomplex, while its genetic relationship to the extinct population cannot be confirmed due to a lack of sufficient samples of the latter. Nevertheless, there are some minor differences in the genetics of the Danish houting compared to other living members in the C. lavaretus complex, as well as the differences in morphology and ecology, making it an evolutionarily significant unit. Hybridization and introgression between North Sea houting and its relatives is well-documented, and likely the result of translocations of Coregonus between different regions by humans. Some researchers argue that the morphological differences between different houting populations are not exceptional within the broader variation of the European whitefish, and probably no species-level extinction has taken place. The primary reason for treating the Danish houting and the extinct houting as separate are differences in the number of gill rakers, but this number can vary extensively in Coregonus, even within a single population and species, and genetic studies of Coregonus have shown that gill rakers are of limited use in predicting relationship among populations. Some think that the morphological differences in number of gill rakers are sufficient for treating them as separate, and that the last true houting was caught in the lower Rhine in 1940. Studies in the early 2000s indicated that there was no overlap in the possible number of gill rakers of the two, but later reviews have shown that there is an overlap. A €13 million restoration project of the Danish houting, partly funded by the European Union's LIFE programme and the Danish Natural Agency, was undertaken in 2005–2013, and there is ongoing monitoring of the species and regulation of the fish-eating great cormorant from important locations. As of 2019, a total of more than €20 million has been used on its conservation, with almost two-thirds funded by Denmark and the remaining by the European Union. However, the only remaining fully natural and significant population of Danish houting is in the Vidå River, estimated in 2014 to consist of about 3,500 adults. Little is known about its exact spawning and juvenile requirements, and despite the earlier project it was still declining, leading to fears that it could become fully extinct unless more is done to preserve it. After years with a downward trend in its numbers, an increase to about 4,000 adult Danish houtings was registered in 2018–19, with most individuals in the Vidå and fewer in . Individuals from the Danish population have been used as a basis for re-establishing houting in the Eider, Elbe and Rhine.
