Some 153,000 baby eels will be flown to Finland from France on Wednesday to help boost the Nordic country's stock of the endangered fish, the Federation of Finnish Fisheries Association said.
The eels, due to land in Helsinki around noon (0900 GMT), will be released in waters around southern Finland to "support the Finnish and Baltic Sea eel stock", which has diminished drastically in recent years, the agency said in a statement.
"The aim is for 40 percent of the imported eels to be able to return to reproduce," Fisheries Association spokesman Tapio Gustafsson told AFP.
The "Anguilla anguilla" is a migratory fish that appears and lives most of its life in European waters, but swims thousands of kilometres (miles) across the Atlantic to mate in the Sargasso Sea.
The voyage, fuelled by stored body fat, can take up to three years. Once hatched, the larvae drift along currents for some 12 months, and by the time they arrive in Europe they are big enough to swim upstream along rivers.
"Due to the collapse in stocks, the eels no longer arrive on Finnish shores as they used to. The eels are also unable to rise to their feeding areas in lakes due to river dams," the Fisheries Association said.
The Finnish stock is now heavily dependent on eels imported for repopulation.
The European eel, which has been eaten to the edge of extinction, is subject to strict cross-border trade certification and quota requirements set in 2007 by CITES, the 171-nation Convention on International Trade in Endangered Species.
Finland, alongside other European Union (EU) countries, drafted its own national eel management plan in 2008, but Gustafsson said protection measures were yet to be fully implemented.
Explore further: Leave that iguana in the jungle, expert tells Costa Rica