New marine top predators in Denmark – indicators of climate change?

In recent years, several species of toothed whales have begun to colonize Danish waters. Despite some attention from the public and citizen science projects, neither of these species has been the subject of systematic scientific research in Denmark. The reason for their increased presence in Danish waters is unknown, and the potential consequences of further colonization by these and other top predators have not been studied.

Information about the presence of invasive top marine predators in the Danish waters will allow to test whether their increased occurrence is related to climate change, possibly revealing unknown effects of climate change on Danish marine ecosystems.

The long-term underwater acoustic recorders will be used in areas where vocalizing invasive top predators (delphinids) are suspected to be present in Danish waters. The recorders can record underwater sounds up to 1 year. This makes it possible to record highly vocal species (such as killer whales, pilot whales, bottlenose dolphins, white-beaked dolphins) that are difficult to detect by visual surveys because they are infrequent visitors in Danish waters.