Marine mammals play an important role in marine ecosystems being at the top of the food chain but just as similarly to other long-lived organisms, the populations are often vulnerable. In order to protect marine mammals, it is important to gain knowledge about their biology and how they are influenced by natural and human changes in the environment. Food availability and suitable breeding areas are among the most important factors that can affect population development in marine mammals. The presence of environmental contaminants is another important factor, as environmental toxins accumulate in the food chain and affect the animals' ability to fight infections and have viable offspring. These factors are therefore key areas of research in the section.
In Danish waters, our focus is on porpoise, harbour seal, grey seal and white-nosed dolphin. The species are all listed in the Habitats Directive as species we have a special obligation to protect and monitor (read background information on porpoise, harbour seal, grey seal - links are in Danish only). To prevent population, it is important to understand the environmental conditions required to ensure adequate breeding success and survival. Some of the factors we pay special attention to are the different types of human interference from boats, seismic surveys, and on the part of porpoises, by-catch in fishing gear. In order to assess whether the species are protected sufficiently, we carry out regular assessments of their distribution and the size of each population. The knowledge the section staff provides is vital to ensure sustainable management of the different populations.
Human pollution is also of great importance to the health and survival of marine mammals. In the Arctic regions, the observed concentrations of mercury, PCBs, organic fluorine and bromine are often so high in e.g. polar bears, seals and killer whales that there is a reason to fear that it may affect animal survival (read about our polar bear projects here). To better understand how the toxic substances are transported and accumulated in the Arctic, we have studied a number of other species including trout, reindeer and glaucous gulls. A better understanding of toxic substance transport through the food chain increases our knowledge on the presence of environmental toxins in different animals caught species of hunted animals. This ensures that the local population of sealers gets better advice on to which extent marine mammals and fish should be included in the diet.