This 1 January 2019 video says about itself:
World’s Rarest Duck Has Been Reintroduced Into Wild
Over the last seven years, around 100 Madagascar pochards were bred by British aviculturists on the island just off Mozambique. This month 21 of them have been successfully transferred to the wild to live on Lake Sofia in the north of the island. They had spent a week in the converted fish farm cages to protect them, get them accustomed to the environment and increase the chances of them returning when they can fly.
Staff from the Gloucestershire-based Wildfowl & Wetlands Trust and the Durrell Wildlife Conservation Trust say they have adapted well to the lake and the cages. They have been seen diving and flying, as well as mixing with other wild ducks, and have repeatedly returned to the aviaries where they are thought to feel safe.
With a wild population of now nearly 50, the duck may be even the rarest bird on the planet. The pochard was thought to have become extinct until it was rediscovered by American wildlife experts from The Peregrine Fund in 2006. Three years later teams from the UK organizations went over to Madagascar and helped rear some of the birds in captivity using a box and a Tupperware container as a ‘lake’.
For this reason, a plan was conceived to convert Scottish salmon-farming cages into the world’s first floating aviaries. After successful trials in 2017, the aviaries were shipped from the UK to Madagascar and assembled on Lake Sofia this summer. With much of the wetlands across northern Madagascar severely degraded due to human encroachment, conservationists have also been working to improve the condition of Lake Sofia. The state of the wetlands in Madagascar is so poor they would probably not survive if they left the lake. Consequently, the pioneering approach of using the cages helped ensure they settled on the lake and did not stray to less habitable environments.
The Madagascar pochard is a species endemic to the African island. While it was once common, widespread deforestation and water pollution caused by the arrival of humans on the island led to the decline in the species and the belief it had been entirely wiped out. The British organizations have about 80 pochards still in captivity, 21 have been released into the wild using the unique system of converted Scottish fish farm cages. A further 25 are believed to be living wild on the island.