Fish are stocked for a variety of reasons. Most stocking is statutory for operators that have altered the environment or subjected it to pollution. Such stocking seeks to compensate for lost natural fish catches.
Fish are also stocked by the owners of water areas and fishing associations in order to provide anglers with better opportunities to fish for coveted fish species. Attempts are made to restore endangered fish species and populations by stocking fish representative of the original population in waterways where they currently occur or previously occurred and by supporting their weakened natural reproduction.
As fish populations recover, fewer fish are being stocked
The number of stocked fishes have been reduced in recent years. This is due to the recovery of natural reproduction capability among fish populations, advances in stocking methods and the increasing transfer of the fishing water management focus to habitat restoration and fishing management. Stocking is increasingly switching to areas where it supports the natural reproductive cycle of fish, thereby reducing the need for stocking in the long run.
Luke supports stocking, producing eggs for this purpose
Luke holds and retains broodfish stocks for many fish species and stocks, many of which are endangered in the natural environment; these stocks are used to produce parent material – fertilised eggs – for use by private juvenile producing farms. This is a regulatory task which Luke has been designated to carry out as part of maintaining a genetic pool of fish species.
Fry bred in Luke’s own farms are stocked in Lake Inari, for which Luke fulfils the obligatory compensation measures on behalf of the state of Finland. A certain number of juveniles are also reared for research needs in support of stocking and for the restoration of endangered fish populations.
In addition to its own fish farming operations, Luke manages the contract rearing of valuable fish, where juveniles required for the recovery of endangered fish species and populations are procured from private fish farms on a large scale.
Luke investigates means of improving the outcome of stocking
Luke monitors the results of stocking, investigating means of enhancing the outcome of stocking. A key research innovation in recent years lies in the introduction of a method known as enriched rearing which, in a number of ways, helps stocked juveniles to survive in wild waters.
Luke’s fish tagging services maintain a database on tagging operations and returned fish tags, generating data that can be used to assess the success rate of stocking and the migratory patterns of fish.
Data on stocking and returned tags is used by the ministry, fishery administration, fishery regions and researchers when planning fishing water management measures and assessing the success rate of operations. Fish farming enterprises and a range of parties responsible for fishery obligations use the results to assess their operations and operational development.
Photo at the top of the page: Eetu Ahanen / Luke