The size of the Dutch otter population continues to grow, 16 years after the fish-eating mammals were reintroduced, according to website Nature Today.
Genetic analysis shows there are now some 360 otters in Dutch lakes and waterways, compared with 275 a year ago and 200 in 2017.
Wageningen’s environmental research department Alterra has been monitoring the otter population since 2002 when the first group of 31 otters was introduced back into the wild.
Otters are now established in Overijssel, Friesland, Drenthe, Groningen, Flevoland, Gelderland and Zuid-Holland and some Dutch otters have been found in Germany and Belgium.
Nevertheless, a large number of otters are still killed by cars and nearly 100 dead animals were found on the roads last winter. Fish traps also prove another health hazard to otters, Nature Today said.