Metsähallitus uses methods such as exploratory fishing and exploratory crayfishing to determine the state of the fishing waters it controls. The most essential methods of exploratory fishing are net fishing and electrofishing. Sometimes lure fishing tackle is also used for these purposes. The state of crayfish stocks, especially European crayfish (Astacus astacus) stocks, is surveyed with exploratory fishing conducted using crayfish traps. In 2013, wide-ranging exploratory crayfishing was conducted in Southern and Eastern Finland to chart the European crayfish stocks in these regions.
The purpose of exploratory fishing is to discover how widely a species has spread, what the relationships between different species are, what the current state of fish stocks is and how they are developing. These days important information on the state of fish species and fish stocks is also received in the form of catch feedback, which fishers can submit via the free Tuikki.fi fishing log.