A two-year international investigation has started this week into dwindling common seal numbers in the Wadden Sea.

The research project, carried out by Dutch, German and Danish scientists, may uncover clues as to why common seal pups fail to reach maturity.

Common seals and grey seals make up the seal population in the Wadden Sea but while grey seals are doing well, common seal numbers have been declining. Just 7,211 common seals were counted in the Dutch part of the Wadden Sea in August last year, the lowest number since 2014.

“We see fewer pups, which is very worrying. About 15% disappear without a trace. We really have no idea what is happening,” head researcher David Goldsborough told Omrop Fryslân.

“We have formulated several possible causes, for instance a lack of food because fish are moving move further north to escape warmer temperatures, human intervention such as wind farms and changes to the Wadden Sea itself,” he said.

“If this trend continues we will end up with a very small population of common seals in the Wadden Sea and they may even become extinct there in time,” Goldsborough warned.

“We don’t want that to happen. It’s essential we get an insight into what may be happening because this is an iconic and important species,” he said.