Eggs from the female fish are hatched in captivity before being released back into the lake
The future of a protected fish species is being safeguarded with an egg collection scheme.
Arctic char living in Llyn Padarn in Llanberis, Gwynedd, are being caught as they move into the river to spawn.
The eggs will then be stripped from the fish, fertilised and taken to the Environment Agency's hatchery at Dolgellau.
Llyn Padarn was closed to users for long periods over the summer because of a problem with algae.
A similar process has already been used for other types of fish, but this is the first time it has been used for the Arctic char [torgoch in Welsh].
The Arctic char are caught in nets in Llyn Padarn
Environment Agency Wales officer Iwan Williams said the decision to carry out the work was taken after research showed there were fewer mature fish now in the lake.
"The plan is to catch a few of the hens before they get to the river to spawn," he said.
"The the eggs will be stripped, fertilised, and then they will be taken to our hatchery at Dolgellau.
"How well it goes depends on how many we catch, that'll be the challenge," he added.
After the fish hatch at Dolgellau they will be grown on and then the decision will be taken to either reintroduce them into Llyn Padarn, or another lake.
"There are concerns about the number of Arctic char in Padarn, it's an experiment and I hope it's successful to protect the char for the future," Mr Williams added.