Nyhed
The white-nosed dolphin breeds in inner danish waters
Lagt online: 09.04.2024
![Hanne Lyngholm Larsen, Natacha Mia Kristensen, and Aage Kristian Olsen Alstrup take samples from the white-nosed dolphin. Photo: Aalborg University](https://prod-aaudxp-cms-001-app.azurewebsites.net/media/hy3hrmuw/hvidnæsen01.jpg?width=2)
Nyhed
The white-nosed dolphin breeds in inner danish waters
Lagt online: 09.04.2024
![Hanne Lyngholm Larsen, Natacha Mia Kristensen, and Aage Kristian Olsen Alstrup take samples from the white-nosed dolphin. Photo: Aalborg University](https://prod-aaudxp-cms-001-app.azurewebsites.net/media/hy3hrmuw/hvidnæsen01.jpg?width=2)
The white-nosed dolphin breeds in inner danish waters
Nyhed
Lagt online: 09.04.2024
Nyhed
Lagt online: 09.04.2024
By Jeannette Bylov, AAU Communication og Public Affairs
Climate change means that species disappear from the land, air, and sea, so it is not every day that researchers can document a new breeding whale species in Denmark – especially not a large one weighing up to 350 kg.
It involves the white-nosed dolphin, which can now safely be said to breed in inner Danish waters. White-nosed dolphins are not uncommon in Danish waters, but it has been assumed until now that the porpoise is the only whale species that breeds in inner Danish waters. It is known that the white-nosed dolphin breeds in the North Sea. Every year, there are reports of sightings of white-nosed dolphins.
"The white-nosed dolphin is the most frequently stranded whale species after the porpoise, but we have not previously been able to document that they actually breed in inner Danish waters. The white-nosed dolphin is protected under the Habitat Directive, and it would be a good idea to begin monitoring populations of white-nosed dolphins in Danish waters, just as we do with porpoises," says Sussie Pagh, a biologist and senior researcher at the Department of Chemistry and Bioscience at Aalborg University.
There is a lot of work involved in reviewing old autopsy reports and records to discover that the white-nosed dolphin breeds in inner Danish waters. In the summer of 2023, a white-nosed dolphin was collected by the Danish Nature Agency Central Zealand in Nekselø Bay, north of Havnsø. The dolphin was brought for autopsy at Aalborg University, which at the time was responsible for marine mammal autopsies for the Environmental Protection Agency as part of the 'Preparedness for stranded marine mammals in Denmark.' When the white-nosed dolphin was opened, an almost full-term fetus weighing 15 kg appeared.
A lone swallow makes no summer. Therefore, it took more documentation than a single full-term fetus for the researchers to conclude that white-beaked dolphins breed in inland Danish waters.
"We started reviewing autopsy reports and reported observations from several years back in time. The many findings confirmed our theory that the white-nosed dolphin breeds in several places in inner Danish waters," explains Charlotte Bie Tøstesen, natural history manager at the Fisheries and Maritime Museum.
The research group could specifically ascertain that there were eight instances where white-nosed dolphins were found either with a fetus or were lactating. In one instance, a newborn calf with milk in its stomach washed ashore near Strandby near Frederikshavn in 2017, in addition to a live white-nosed dolphin with a calf spotted at Sletterhage lighthouse in 2011.
"The many findings over time of white-nosed dolphin fetuses, lactating white-nosed dolphins, and a single mother with a live calf mean that we can now conclude that the white-nosed dolphin not only breeds in the North Sea near Denmark but also in the inner Danish waters," says Sussie Pagh, a biologist and senior researcher from AAU.
Behind the discovery is a team of whale researchers from various institutions in Denmark, including researchers at Aalborg University, Aarhus University and the Fisheries and Maritime Museum in Esbjerg, who set out to review the archives to investigate how many breeding white-nosed dolphins have been documented in inner Danish waters over the past 20 years.
Facts about the white-nosed dolphin
The white-nosed dolphin is known as Lagenorhynchus albirostris in Latin.
The white-nosed dolphin is acrobatic and socially inclined, often riding the bow waves of ships on fast boats and leaping free from the water's surface. The white-nosed dolphin breeds in the North Sea.
The white-nosed dolphin occurs in the temperate and subarctic parts of the North Sea and is especially common in the northern part of the North Sea, off the coasts of Norway and Iceland. It is also found near Greenland and Labrador.
The "Danish" white-nosed dolphins belong to the Northeast Atlantic stocks, and photo-identification suggests that the animals in the Danish part of the North Sea and off Scotland belong to the same breeding stock. Both females and males reach sexual maturity when they are between 9 and 14 years old. At sexual maturity, the females are about 245 cm long, and the males are about 10 cm longer. The typical group size in the Danish part of the North Sea is 4-6 animals, while groups of up to 1,000 animals have been reported in the distribution area.
Facts: Observations of white-nosed dolphin strandings in denmark
Little is known about the biology of the white-nosed dolphin, and they are often confused with porpoises and other smaller toothed whales. Each year, observations of both live and stranded white-nosed dolphins are reported to Naturbasen.dk.
In the past 15 years, 48 stranded white-nosed dolphins have been reported to the "Preparedness for Stranded Marine Mammals," which is managed in close collaboration by the Environmental Protection Agency, the Danish Nature Agency, the Fisheries and Maritime Museum in Esbjerg, the Natural History Museum of Denmark in Copenhagen, the Department of Ecoscience at Aarhus University in Roskilde, the Department of Chemistry and Bioscience at Aalborg University in Aalborg, and the Department of Veterinary and Animal Sciences at the University of Copenhagen.
Contact
Aage Kristian Olsen Alstrup, marine mammal veterinarian, dr.med.vet
Phone: 2289 9285
Sussie Pagh, biologist and senior researcher at the Department of Chemistry and Bioscience, Aalborg University
Phone: 51292292
Charlotte Bie Tøstesen, natural history manager at the Fisheries and Maritime Museum
Phone: 2964 1388
Carl Christian Kinze, whale expert:
Phone: 2168 2831
Journalist Jeannette Bylov
AAU Communikation and Public Affairs
Phone: 2423 0566
Email: jmb@adm.aau.dk
Sources: