In the OTTER SPOTTER app, evidence of the Eurasian otter can be reported across Europe, as a chance find or during an active search for traces. The Aktion Fischotterschutz e.V. has been running a database for almost 20 years in which evidence of otters from all over Europe has been collected. For this purpose, an extensive network of voluntary trackers was set up, who are regularly trained in seminars and thus make a significant contribution to the success of the data collection. In 2016 the sy