If I may, to our knowledge it hasn't been invoked, but it's covered in subsection 29(1):
If the Minister is of the opinion that there is an imminent threat to the survival of a wildlife species, the Minister must, on an emergency basis, after consultation with every other competent minister, make a recommendation to the Governor in Council that the List be amended to list the species as an endangered species.
Presumably, groups such as ours might make the suggestion to the minister that this be done. I don't think it's been done in the past.