The number of otters has not grown significantly for the first time in years, researchers at the university of Wageningen report in Nature Today.

The otter population now stands at around 200, 15 up from last year. Wageningen’s environmental research department Alterra has been monitoring the otter population since 2002 when the first group of otters was introduced in nature reserve the Diepen-Weerribben in Overijssel.

With 80 animals, it is now home to the largest otter population in the country but otters are now established in Friesland, Drenthe, Groningen, Flevoland, Gelderland and Zuid-Holland as well.

Cause of the growth stagnation the high mortality rate among otters. A quarter of the population was killed by cars or drowned in fish traps. According to the researchers, more has to be done to make the sites where otters cross the road safer. They also say legislation is needed to adapt fish traps.

The good news is that the otter population is showing greater genetic variation, which will prevent inbreeding. The researchers also found that of the original population the oldest females are still alive.