Milt bank

Besides of living gene banks and stocking programs, maintaining cryopreserved milt bank for endangered fish species is the third function of FGFRI to maintain native stocks and implement international biodiversity contracts.

The systematic freezing of milt serves the following purposes:

• preserving genetic diversity for possible use in the future, e.g. salmon in the River Teno
• expanding genetic diversity when establishing broodstock, e.g. landlocked salmon in the Vuoksi water system
• increasing opportunities to use the genes of bred stocks, e.g. the selective breeding of rainbow trout for food production

Method

Canning the milt of Arctic charr

Milt freezing is a method for preserving the genetic material of fish in a usable form for a long time. A portion of frozen milt comprising billions of spermatozoa is preserved in a tank of liquid nitrogen at temperature of -196 °C degrees. In this way the milt can be preserved for unlimited time periods.

History

Milt being transferred from a box into a tube

Freezing of milt already began at the FGFRI in early 1980's because the landlocked salmon (Salmo salar m. sebago) stock in the Vuoksi water system was endangered. More systematic collection of milt started in 1993 because of threat posed by salmon parasite in the River Teno. In 1999-2002 genetic material from the broodstocks of the FGFRI's Aquaculture Unit were collected and frozen.

Current situation

Milt straws in lquid nitrogen

Milt from 42 stocks representing 12 fish species or stocks have been stored in the milt bank. Milt from over 3,200 fish has been collected. Cryopreserved species and stocks:

• Atlantic salmon (Salmo salar), 8 stocks
• Landlocked salmon (Salmo salar m. sebago), 1 stock
• Sea trout (Salmo trutta) 5 stocks, migratory brown trout (Salmo trutta m. lacustris) 10 stocks, and non-migratory brown trout (Salmo trutta m. fario) 4 stocks
• Arctic charr (Salvelinus alpinus), 2 stocks
• Whitefish (Coregonus lavaretus), 7 stocks
• Asp (Aspius aspius), 1stock
• Imported species: lake trout (Salvelinus namaycush) 2 stocks, brook trout (Salvelinus fontinalis) 1 stock, peled whitefish (Coregonus peled) 1 stock

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