Zoeken naar een historische referentie voor otters [Lutra lutra) in Nederland

摘要

Searching for a historical reference of otters (Lutra lutra) in the Netherlands.Mid 20th century a reconstruction was made of the distribution of otters (Lutra lutra) in the Netherlands around 1900. According to this reconstruction, otters were present in almost all waters of the Netherlands. This reconstruction became an important historical reference, especially after the extinction of otters in 1988 and the planning of reintroducing the species shortly afterwards. Modern historical research makesit possible to find much more information on the historic presence of otters. With this information a better underpinned historical reference could be made. Archeo-zoological data reveal that otters have been present in the Netherlands for thousands of year. Already in those days, otters were hunted by man. The first written accounts from the 16th and 17th century show that otters were present in different parts of the Netherlands. In the 18th century a lot of regional administrations enforced persecution of otters with premium systems. Payment data of premiums suggest they weren’t abundant. In 1814, after the French period, regional premium systems were replaced by national regulations. For the years 1825-1826 and 1849-1851 the administration looks complete. In the 25 years between these periods the population fell down from an estimated maximum of 1000 otters to 300 otters. Especially the population in Holland, i.e. the western part of the Netherlands, was reduced. In the southern part, otters werescarce. In 1852 the premium system stopped. Because of the valuable fur, hunting otters stayed intense. Only after 1942 this human pressure on otters was reduced. The historic data on otters show that numbers were surprisingly small for the watery Dutchlandscape, especially since about 1840. In most areas otters were recorded in the period 1800-1950, but only in a few wetlands their presence may have been permanent. In the south of the Netherlands, otters seemed to be absent in large areas. So, this new historic reference shows the former status of otters in the Netherlands was very dynamic in both numbers and distribution. In 2002 otters were reintroduced and have spread since. They are distributed now over half of the Netherlands and have a population size of circa 270 otters. Hunting and persecution have always been dominant factors for the population size. For species like cormorant (Pha-lacrocorax carbo) and fox (Vulpes vulpes) the response to absence of these factors has become already clear.Population size of these species has transcended any historic reference. The near future will learn how otters respond.