What do we investigate in Utrecht and how?

What did the porpoise die from?

It is not possible to determine the cause of death of a stranded porpoise on the beach. Therefore the Stranding Network’s volunteers bring the carcasses to the necropsy room at the Department of Pathobiology in Utrecht where Lonneke IJsseldijk and her colleagues receive them.

Data collection
Basic data including weight, length, age and sex are recorded from all stranded porpoises. In addition, the carcasses are photographed and the outside of the animal is thoroughly inspected. This is particularly important for recognising the signs of certain causes of death. For example, by-catch can only be confirmed if there are clear imprints of fishing nets on the skin of the porpoise.

Examination of all tissues
Then it is time to examine the inside: Lonneke and her colleagues examine all of the porpoise’s tissues. In this way they can see if the animal was healthy up until the point that it died. If this is the case then the death is likely to have occurred suddenly, for example, a grey seal may have attacked it, which is a common cause of death in porpoises in the Netherlands.

During the necropsy I check to see if an animal is emaciated. If an animal has been ill for a while then it may not have managed to catch enough fish.

Under the microscope
Small pieces of every organ are collected and prepared in the tissue-processing lab for examination under the microscope. The tissues are stained in such a way that the pathologist can spot any abnormalities. In this way we can look closely at a piece of lung.

Tissue for the tissue bank
In addition to collecting material for our own investigations we also collect samples for the tissue bank. Researchers from other universities, both within the Netherlands and abroad, can use this tissue database.

Determining the cause of death
By combining our findings from the examination of tissues in the necropsy room and under the microscope we can determine the cause of death. By doing this we are increasing our knowledge about the lives of these intriguing animals and our shared ecosystem.