@Mr Gharial
Yes, I guess that's one of the motives Itatiba zoo has so much success breeding this species. There are fortunately plans to spread this considerably big population of mergansers they have to other zoos in the country.
Indeed Parque das Aves is I think the front-runner in this project. I heard that even European institutions were interested in participating in the project but I think ICMBio do not want export of endangered native species.
@Therabu
Yes, Belo Horizonte zoo has projects of bringing them too. Afaik, the only issues now is the building of exhibits for them in the backstage. Probably the same with Parque das aves...