I’ve had some questions about how “native” the delta smelt is too. The comments to the original article bring it up a couple of times & there are those who say it is native. However, I have also read that there have been at least 15 species introduced so that it is probably not “pure” delta smelt.
There were other comments about the overall health of the delta but previous discussions (I have been to 2 of their events) about the raw sewage being dumped from Sacramento & other cities in the area as there apparently is no sewage treatment plant. But their research does not take that into account.
There are also comments about the salmon. However, it appears that wild salmon are threatened in the UK, the NW Coast & in Norway & that has been attributed to nearby fish farms which harbor disease the wild salmon can’t survive.