Investigating the cause of death

Every year hundreds of dead porpoises are washed ashore on the Dutch coastline. The large porpoise populations in Dutch waters mean that the likelihood of carcasses being washed ashore is high, with in recent times up to 600 cases a year. As to what could be causing these deaths; that is what we are investigating at the Department of Pathology at the Faculty of Veterinary Medicine.

Human activities
This research programme was commissioned by the Ministry of Agriculture Nature and Food in 2008 to look into the cause of death in porpoises washed up on Dutch shores. Of particular interest to the Ministry are the cases in which human activities have caused or contributed to the death. This could be through collisions with shipping, by-catch (during commercial fishing operations porpoises and other non-target species can become caught in nets and suffocate), damage to hearing (caused by underwater construction projects such as windmill parks and seismic research), and pollution (PCBs and macro- and micro-plastics).

Expertise in animal species and animal disease
The Department of Pathology collects and presents data about the working of cells, tissues and organs in health and disease in a wide range of animal species. This means that we have much knowledge about disease processes in wildlife and other species of animal. This knowledge is used in our investigations of stranded animals. This vast knowledge of veterinary pathology, in combination with state-of-the-art facilities and a central location makes the Veterinary School’s Pathology Department the perfect base for the stranding project’s research activities. All necropsies carried out on porpoises found stranded in the Netherlands throughout the year are now performed in Utrecht which means that patterns in strandings and causes of death can be recognised, communicated, and promptly addressed.

Investigating marine mammal strandings 
In addition to the hundreds of porpoises washed up on the Dutch coast each year, whales and dolphins occasionally strand on these coastlines. Working closely with the National Stranding Network, the Ministry of Agriculture Nature and Food and several other partners, the Faculty of Veterinary Medicine plays a central role in the investigation of these events. In addition to cetaceans, seals are also examined to determine their cause of death.

Environmental data
By performing necropsies on stranded marine mammals we not only learn about the health of individual animals, but also that of the population and the environment in which they live, the North Sea and the Wadden Sea. Such findings will inform efforts to protect this ecosystem for future generations, and help protect these fascinating species.