Furthermore, guiding principles were developed on the basis of historical documents, a fish ecological typing of the lakes was carried out and the evaluation method "Austrian Lake Fisch Index" (ALFI) was developed. In recent years, the Europe-wide intercalibration process was successfully completed and a methodology guideline was written.
According to the guideline, electrofishing, standardized multi-mesh nets and scientific echosounder technology are used in the investigations. The caught fish are determined to species level, subjected to a standard measurement program, sampled for age determination and the catch and measurement data are imported into the Fish Database Austria. The evaluations are carried out in the winter months and the reports including the fish ecological status assessment are usually completed in early summer.
By the end of 2016, 35 of Austria's 43 natural lakes (>50 ha) had been surveyed and assessed for fish ecology by the department. In "very good" fish ecological condition were 10 lakes and for another 16 lakes the "good" fish ecological condition could be determined. Seven lakes reached only a "moderate" and two lakes only an "unsatisfactory" fish ecological condition.