At the facility I am working at we are primarily working with Hapuka and Kingfish; mainly with the puka at the moment, trying to improve the quality and consistency of eggs to produce family lines that would be ideal for starting a commercial project. The big broodstock Hapuka are about 34kg and the largest kingies are 42kg/1.5m, quite cool feeding them haha. There is also a growth study of NZ king salmon currently going on, and a long-term project investigating paddle crab pheromones.
Yeah, pretty much need a Masters degree to get anywhere tbh, although you can get experience at the BOP polytechnic I think.
Not really any work being done where I am at with whitebait/natives so I don't pretend to know that much about them, still going to need an extensive facility, and I don't think there is a large market for them internationally. If you're interested in farming natives you could look at the Mahurangi institute which does more of that sort of thing, they also do kinda 'skills'/'certificate' courses for preliminary techniques.