Why do we investigate strandings?
To determine the cause of death
The main purpose of the investigations commissioned by the Ministry of Agriculture Nature and Food is to determine the cause of death of the porpoises that get washed ashore and more specifically to identify cases in which humans activities are likely to have been involved. There are often many factors that contribute to the death of an animal and in some cases the cause of death remains unclear.
The consequences of hearing damage
Cetaceans depend on their hearing for hunting prey, communication, the detection of predators and for navigation. Disturbances or hearing damage can have serious consequences for individuals and ultimately the whole population.
The human threat
Cetaceans can be exposed to many human threats as their territories often overlap with our marine-based industrial and leisure activities. In recent decades there has been an enormous increase in our presence in the marine environment through increased shipping, the construction of off-shore wind farms and additionally through rising sea temperatures. Sadly, when shipping routes traverse cetacean territories it is almost inevitable that collisions will occur.
Collisions and sound pollution
In the Netherlands in 2011, 2012, 2013 and 2015, four whales (3 rorquals and a common minke whale) were found on the bow of container ships entering Rotterdam harbour. The construction of off-shore wind farms and seismic research are both sources of underwater noise pollution and can cause hearing damage in cetaceans. Changes in sea temperature can affect currents which have an impact on the migration routes of cetaceans and their food sources. The impact of such human activities depends on their extent and varies between species, reflecting differences in territories and migration patterns.
There is public and political support for research into marine mammal strandings both in the Netherlands and abroad. This has been evidenced by the large amount of interest shown by public and the media during recent stranding events. Additionally, the position of cetaceans at the top of the food chain means that they can be used by scientists as indicator species for the ecosystem in which they live; changes can be reflected in altered ecology, geographical range and health status of these species.