The Swedish Crayfish Database contains information on the occurrence of European crayfish and Signal crayfish, data from test fishing and information on surface waters affected by crayfish plague.
Data on crayfish occurrences are collected by various methods with the help of county administrative boards, municipalities, non-profit organisations, private fishing water owners and fisheries management associations. For each occurrence there is information on species, methodology and density (number of crayfish caught). The earliest records in the database are from 1891.
Data from fish surveys, carried out by county administrative boards, municipalities, SLU Aqua and various private organisations, include information on the length, sex and possible damage of the crayfish, as well as the depth at which the test fishing was carried out.
Data on watercourses and lakes with crayfish plague is based on information received by the Swedish Agency for Marine and Water Management and SLU Aqua, as well as historical data. The database contains, among other things, information on bans decided by the county administrative boards for the plague-affected waters.
The National Crayfish Database also contains data from sampling of crayfish catches from commercial fishing carried out in the large lakes Vättern, Hjälmaren and Vänern. Among other things, growth, catch size, injuries, sex ratio, depth, bottom type, length, weight, sex, injuries and diseases are recorded.
The database is used in national evaluations, for example in the assessment of ecological status in Swedish watercourses and in the SLU Species Database's red list assessments. The data is also used in research projects and in the follow-up of fish conservation measures, such as liming, construction of fishways and biotope restoration.
The National Crayfish Database is part of the data stewardship for fish, a mission assigned to SLU by the Swedish Agency for Marine and Water Management. The assignment includes quality assurance of data and making it available.