The PIKE database are assembled by Göran Englund and co-workers at the Department of Ecology and Environmental Science at Umeå University. It contains information on presence of fish species, as well as introductions of new species, extinctions and rotenone treatments. Most data has been collected by governmental agencies and individuals who have shared their knowledge and data sets. The information derives from field surveys, interviews and inquires. A few hundred lakes have been surveyed within the project to obtain complementary data. Most of the occurrence data have been collected in the period 1890-2012. PIKE also includes information on water chemistry, lake depth, lake area,and much more. Most of the lakes are found in Sweden, but Norway and Finland are also represented.